Unit 5: Unit 5: Energy, Exercise and Energy, Exercise and CoordinationCoordinationRevision NotesRevision Notes

Topic 7Topic 7Run for Your LifeRun for Your Life

Muscles & MovementMuscles & MovementLigaments hold bones Ligaments hold bones together and restrict together and restrict their movements at their movements at joints. They’re made of joints. They’re made of elastic connective elastic connective tissuetissueTendons are non-elastic Tendons are non-elastic fibrous, cord-like tissue fibrous, cord-like tissue which attach muscle to which attach muscle to bonebone

Muscles & MovementMuscles & MovementKnee joint is a synovial joint:Knee joint is a synovial joint:

TendonTendon joins muscle to bone joins muscle to bone

MuscleMuscle

Ligament Ligament joins bone to bone, strong & flexiblejoins bone to bone, strong & flexible

Synovial Membrane Synovial Membrane secretes synovial fluid

secretes synovial fluid

Synovial Fluid

Synovial Fluid Acts as lu

bricant

Acts as lu

bricant

BoneBone

Cartilage Cartilage absorbs synovial fluid, acts as shock absorbs synovial fluid, acts as shock absorberabsorber

Cartilage Pad Cartilage Pad gives extra shock gives extra shock protectionprotection

Fibrous capsule Fibrous capsule encloses the encloses the jointjoint

Muscles & MovementMuscles & MovementSkeletal muscles are Skeletal muscles are usually in antagonist usually in antagonist pairs. These are pairs of pairs. These are pairs of muscles which pull in muscles which pull in opposite directionsopposite directionsFlexors contract to flex Flexors contract to flex or bend a joint (biceps)or bend a joint (biceps)Extensors contract to Extensors contract to extend or straighten a extend or straighten a joint (triceps)joint (triceps)

Muscles & MovementMuscles & MovementThe structure of skeletal The structure of skeletal muscles are shown right.muscles are shown right.

Myofibrils are made up of Myofibrils are made up of fibrous proteins: actin (thin fibrous proteins: actin (thin filaments) and myosin (thick filaments) and myosin (thick filaments)filaments)

Sarcolemma is the cell surface Sarcolemma is the cell surface membrane of a muscle cellmembrane of a muscle cell

Sarcoplasmic Reticulum is a Sarcoplasmic Reticulum is a specialised ER. It stores and specialised ER. It stores and releases Careleases Ca+ + ions.ions.

Sarcoplasm is cytoplasm Sarcoplasm is cytoplasm inside a muscle cell.inside a muscle cell.

Connective TissueConnective Tissue

Bundle of muscle Bundle of muscle fibresfibres

One muscle fibreOne muscle fibre

MyofibrilMyofibril

One Sarcomere

One SarcomereNeuromusculaNeuromuscula

r Junction r Junction is is the specialised the specialised

synapse synapse between between

neurones and neurones and muscle cells.muscle cells.

Muscles & MovementMuscles & MovementThe sliding filament theory of The sliding filament theory of music contraction is given music contraction is given most simply by a diagram (R)most simply by a diagram (R)

Myosin filaments have flexible Myosin filaments have flexible heads that can change heads that can change orientation, bind to actin and orientation, bind to actin and hydrolyse ATP using ATPasehydrolyse ATP using ATPase

Actin filaments are associated Actin filaments are associated with 2 other proteins: with 2 other proteins: Troponin & Tropomyosin which Troponin & Tropomyosin which control binding of myosin control binding of myosin heads to actin filaments.heads to actin filaments.

1 sarcomere1 sarcomere

MyosinMyosin ActinActin

Arrangement of filaments when relaxedArrangement of filaments when relaxed

Arrangement of filaments when contractedArrangement of filaments when contracted

Muscles & MovementMuscles & MovementWhen a nerve impulse arrives at a neuromuscular junction, Ca+ ions are released from When a nerve impulse arrives at a neuromuscular junction, Ca+ ions are released from sarcoplasmic reticulum. The process below then occurs:sarcoplasmic reticulum. The process below then occurs:

ActinActin

ActinActin TropomyosiTropomyosinn

Troponin

TroponinCaCa 2+2+ binding

binding sitesite

ADP + PADP + Pii

Myosin Myosin binding site binding site blocked by blocked by

tropomyosin. tropomyosin. Myosin head Myosin head cannot bind.cannot bind.

CaCa2+2+ attaches to troponin (on the actin) causing attaches to troponin (on the actin) causing it to move together with threads of it to move together with threads of

tropomyosintropomyosin

Myosin Myosin binding sitebinding site

ADP + PADP + Pii

CaCa22++

CaCa22++ CaCa22++

CaCa22++

CaCa22++ CaCa22++CaCa22++

CaCa22++ CaCa22++

CaCa22++

CaCa22++ CaCa22++

Myosin binding sites of actin are exposed so Myosin binding sites of actin are exposed so myosin form myosin form cross-bridges cross-bridges with actin filamentwith actin filament

ADP + PADP + Pii

ADP + PADP + Pi i ReleasedReleased

Myosin heads release ADP and Pi and change Myosin heads release ADP and Pi and change shape are a result. This is the POWER STROKE.shape are a result. This is the POWER STROKE.

ATP binds to myosin head causing ATP binds to myosin head causing it to detach from the actin.it to detach from the actin.

ATP BINDSATP BINDSATPATP

ATPase causes ATPase causes ATP hydrolysisATP hydrolysis

Myosin head returns to Myosin head returns to upright position.upright position.

ADP + PADP + Pii

Muscles & MovementMuscles & MovementThere are 2 types of muscle fibres - There are 2 types of muscle fibres - Fast Twitch and Slow Twitch Fast Twitch and Slow Twitch

Slow TwitchSlow Twitch Fast TwitchFast TwitchSpecialised for slower sustained Specialised for slower sustained contraction. Can cope with long contraction. Can cope with long

periods of exercise.periods of exercise.Specialised to produce rapid, Specialised to produce rapid,

intense contractions in short bursts.intense contractions in short bursts.

Many mitochondria - ATP comes Many mitochondria - ATP comes from aerobic respiration (in E.T.C.)from aerobic respiration (in E.T.C.)

Few mitochondria - ATP comes from Few mitochondria - ATP comes from anaerobic respiration (in glycolysis)anaerobic respiration (in glycolysis)

Lots of myoglobin (gives it a darker Lots of myoglobin (gives it a darker colour) to store Ocolour) to store O22 and lots of and lots of

capillaries to store Ocapillaries to store O22. . Little myoglobin and few capillaries. Little myoglobin and few capillaries.

The muscle has a light colour.The muscle has a light colour.

Fatigue resistant.Fatigue resistant. Fatigue quickly.Fatigue quickly.Low glycogen contentLow glycogen content High Glycogen contentHigh Glycogen content

low levels of creatine phosphatelow levels of creatine phosphate high levels of creatine phosphatehigh levels of creatine phosphate

Energy SystemsEnergy SystemsAerobic respiration:Aerobic respiration:glucose + oxygen → carbon dioxide + water + energyglucose + oxygen → carbon dioxide + water + energyCC66HH1212OO66 + 6O + 6O22 → 6CO → 6CO22 + 6H + 6H22O + O + ~~30ATP30ATPAnaerobic respiration:Anaerobic respiration:glucose → lactic acid + energyglucose → lactic acid + energyCC66HH1212OO66→ 3C→ 3C33HH66OO33 + 2ATP + 2ATPATP provides energy to cells. Energy is need to add a ATP provides energy to cells. Energy is need to add a third phosphate bond to ADP (which creates ATP). third phosphate bond to ADP (which creates ATP). When the bond is broken by hydrolysis, the energy When the bond is broken by hydrolysis, the energy released can be used in processes in the cell which released can be used in processes in the cell which need energy.need energy.

Energy Systems - Energy Systems - GlycolysisGlycolysis

Glucose (hexose)Glucose (hexose) (6C) (6C)

hexose phosphatehexose phosphate (6C) (6C)

hexose biphosphatehexose biphosphate (6C) (6C)

2x2x triose phosphate triose phosphate (3C)(3C)

intermediatesintermediates

2x2x pyruvate pyruvate (3C)(3C)

ATPATP

ATPATP

2ATP2ATP

2H2H

2ATP2ATP

2NAD2NAD

2 Reduced NAD2 Reduced NAD

Glycolysis=Glycolysis=Gluco (sugar) Gluco (sugar)

+ lysis + lysis (splitting)(splitting)

Energy Systems -Energy Systems -Anaerobic Anaerobic RespirationRespiration

Glucose Glucose

Pyruvate Pyruvate

2H 2H reduced NAD reduced NAD NAD NAD

2H 2H

Lactate Lactate

2ADP + 2ADP + 2Pi2Pi

2ATP2ATP

Lactate PathwayLactate PathwayGlycolysis doesn’t need Glycolysis doesn’t need molecular Omolecular O22. Instead, a . Instead, a constant NAD supply is constant NAD supply is required.required.

In anaerobic respiration, NAD is In anaerobic respiration, NAD is made by e.t.c. The reduced made by e.t.c. The reduced NAD must be oxidised to NAD.NAD must be oxidised to NAD.

During anaerobic respiration, During anaerobic respiration, this must come from this must come from elsewhere.elsewhere.In animals, pyruvate gets reduced into lactate, and NAD is formed.In animals, pyruvate gets reduced into lactate, and NAD is formed.

The anaerobic respiration allows animals to make a small amount of ATP. The process is The anaerobic respiration allows animals to make a small amount of ATP. The process is not very efficient, but it’s fast and delivers ATP to muscle cells when Onot very efficient, but it’s fast and delivers ATP to muscle cells when O22 isn’t delivered fast isn’t delivered fast enough.enough.

Lactate forms Lactic Acid in solution. This reduces the pH which can inhibit enzymes and Lactate forms Lactic Acid in solution. This reduces the pH which can inhibit enzymes and cause muscle cramp if allowed to build up.cause muscle cramp if allowed to build up.

Once aerobic respiration resumes most lactate is converted back into pyruvate. It is Once aerobic respiration resumes most lactate is converted back into pyruvate. It is oxidised via the Krebs cycle into COoxidised via the Krebs cycle into CO22 and H and H22O. Extra oxygen needed for this is the Oxygen O. Extra oxygen needed for this is the Oxygen debt, which must be paid back.debt, which must be paid back.

Investigating Rate of Investigating Rate of Respiration - Respiration - Core Core PracticalPractical

Rate of aerobic respiration can be Rate of aerobic respiration can be determined using a respirometer determined using a respirometer by measuring rate of oxygen by measuring rate of oxygen absorbed by small organisms.absorbed by small organisms.

Any COAny CO22 produced is absorbed by produced is absorbed by the soda lime, so that Oxygen the soda lime, so that Oxygen absorbed by the organisms results absorbed by the organisms results in the coloured liquid moving in the coloured liquid moving towards the organism in the tube.towards the organism in the tube.

There is problems with pressure There is problems with pressure changes in the apparatus, which changes in the apparatus, which can be solved by the syringe if can be solved by the syringe if necessary. necessary.

You need• Respirometer (see below)• 5 g of actively respiring organisms (eg Maggots)• Soda lime• Coloured liquid• Dropping pipette• Permanent marker pen• Solvent (to remove the marker)• Cotton wool

Aerobic RespirationAerobic RespirationAerobic respiration takes place in 2 stages:Aerobic respiration takes place in 2 stages:

First pyruvate is oxidised into Carbon Dioxide, and First pyruvate is oxidised into Carbon Dioxide, and Hydrogen (accepted by NAD and FAD). This takes Hydrogen (accepted by NAD and FAD). This takes place in the place in the matrix matrix of mitochondria and involved the of mitochondria and involved the Krebs cycle.Krebs cycle.In the 2nd stage, most of the ATP made in aerobic In the 2nd stage, most of the ATP made in aerobic respiration is synthesised by oxidative respiration is synthesised by oxidative phosphorylation associated in electron transport chain phosphorylation associated in electron transport chain (e.t.c.). This involves chemiosmosis and ATPase. It (e.t.c.). This involves chemiosmosis and ATPase. It takes place in the cristae of the mitochondria.takes place in the cristae of the mitochondria.

CytoplasmCytoplasm

The Link Reaction:The Link Reaction: Preparing for the Krebs cycle.Preparing for the Krebs cycle.

PyruvatePyruvate from glycolysis from glycolysis

2H2H

Acetyl Acetyl (2C) Co-enzyme A(2C) Co-enzyme A

COCO22

NAD or FADNAD or FAD

Reduced NAD or FADReduced NAD or FAD

To Krebs CycleTo Krebs Cycle

Each glucose Each glucose provides 2 provides 2

Pyruvate from Pyruvate from Glycolysis. This Glycolysis. This means the link means the link

reaction happens reaction happens twice per glucose, twice per glucose,

so 2 Acetyl are so 2 Acetyl are made.made.

Taken up byTaken up by HydrogenHydrogenacceptors.acceptors.

Inside MatrixInside Matrix

The Krebs CycleThe Krebs CycleAcetyl Acetyl (2C) Co-enzyme A(2C) Co-enzyme A

6C Compound6C Compound

5C Compound5C Compound

4C Compound4C Compound

COCO22

2H2H

COCO22

ATPATP

2H2H

2H2H

2H2H

NADNAD

Reduced NADReduced NAD

NADNAD

Reduced NADReduced NAD

NADNAD

Reduced NADReduced NAD

FADFAD

Reduced FADReduced FAD

Each molecule of the 2C Acetyl coenzyme A from the link reaction is used to Each molecule of the 2C Acetyl coenzyme A from the link reaction is used to generate:generate:•three molecules of reduced NADthree molecules of reduced NAD•one molecule of reduced FADone molecule of reduced FAD•two molecules of COtwo molecules of CO22•one molecule of ATP by substrate-level phosphorylation one molecule of ATP by substrate-level phosphorylation (synthesised directly from the (synthesised directly from the energy released by reorganising chemical bonds)energy released by reorganising chemical bonds)..•one molecule of a 4-carbon compound which is regenerated to accept an acetyl one molecule of a 4-carbon compound which is regenerated to accept an acetyl group and start the cycle again.group and start the cycle again.

As each glucose molecule makes 2 pyruvate = 2 Acetyl = 2 turns around carbon As each glucose molecule makes 2 pyruvate = 2 Acetyl = 2 turns around carbon cycle.cycle.

Oxidative phosphorylation, Oxidative phosphorylation, chemiosmosis and the electron chemiosmosis and the electron transport chaintransport chainVast majority of ATP generated in aerobic respiration comes from the electron transport chain...Vast majority of ATP generated in aerobic respiration comes from the electron transport chain...

electronelectroncarriercarrier

electronelectroncarriercarrier

electronelectroncarriercarrier

HH++ HH++ HH++

NADNADReduced Reduced NADNAD HH22OO

½O½O 2H2H++

ADP+PADP+Pii ATPATP

Inte

rmem

bran

e Sp

ace

Inte

rmem

bran

e Sp

ace

inne

r in

ner

mit

ocho

ndri

am

itoc

hond

ria

l mem

bran

el m

embr

ane

mit

ocho

ndri

alm

itoc

hond

rial

mat

rix

mat

rix

Reduced NAD Reduced NAD (coenzyme) (coenzyme)

carries Hcarries H++ and and ee-- to e.t.c. on to e.t.c. on

inner inner mitochondrial mitochondrial membrane.membrane.

11

1122

33 44

5566

Electrons pass from one Electrons pass from one electron carrier to the next in a electron carrier to the next in a series of redox reactions; the series of redox reactions; the

carrier is reduced when it carrier is reduced when it receives the electrons and receives the electrons and

oxidised when it passes them oxidised when it passes them on.on.

22 Protons (HProtons (H++) move across the ) move across the inner membrane mitochondrial inner membrane mitochondrial

membrane creating high Hmembrane creating high H++ concentrations in the concentrations in the

intermembrane space.intermembrane space.

33

HH++ diffuse back into the diffuse back into the matrix down electrochemical matrix down electrochemical

gradient.gradient.

44

HH++ diffusion allows ATPase diffusion allows ATPase to catalyse ATP to catalyse ATP

synthesissynthesis

55

Electrons & HElectrons & H++ ions ions recombine to form hydrogen recombine to form hydrogen atoms which then combine atoms which then combine

with oxygen to create water. with oxygen to create water. If supply of oxygen stops, If supply of oxygen stops,

e.t.c. and ATP synthesis will e.t.c. and ATP synthesis will also stop.also stop.

66

Majority of ATP generated by aerobic respiration comes from the activity of the e.t.c. Majority of ATP generated by aerobic respiration comes from the activity of the e.t.c. in the cristae (inner membrane of the mitochondria)in the cristae (inner membrane of the mitochondria)

Aerobic respiration -Aerobic respiration -The overall reaction can be summarised as The overall reaction can be summarised as

1) splitting and oxidation of a respiratory substance (glucose) to 1) splitting and oxidation of a respiratory substance (glucose) to release COrelease CO22 as a waste product. as a waste product.

2) reuniting hydrogen with oxygen which releases a large amount 2) reuniting hydrogen with oxygen which releases a large amount of energy in the form of ATP.of energy in the form of ATP.

summarysummary

The diagram (right) shows how many ATP molecules are generated by substrate level phosphorylation and oxidative phosphorylation (via e.t.c.)

Control of cardiac cycleControl of cardiac cycleThe impulse to contract the heart originates from the heart The impulse to contract the heart originates from the heart itself. Hence the heart is itself. Hence the heart is myogenicmyogenic..

RARA

RVRVLVLV

LALA

sinoatrial node (SAN)

sinoatrial node (SAN)

atrio

vent

ricula

r nod

e

atrio

vent

ricula

r nod

e

(AVN)

(AVN)

non-conducti

ng layer in

non-conducti

ng layer in

heart wall b

etween atria

heart wall b

etween atria

and ventricles

and ventricles

Purkyne fibres

Purkyne fibres

Electrical impulses from the SAN Electrical impulses from the SAN spread across the atria walls, spread across the atria walls, causing contraction. causing contraction. ATRIAL ATRIAL

SYSTOLE.SYSTOLE.

11

1122

33

4444

Impulses pass to the ventricles via Impulses pass to the ventricles via the AVN after a short delay to allow the AVN after a short delay to allow

time for the atria to finish time for the atria to finish contracting.contracting.

22

Impulses pass down the Purkyne Impulses pass down the Purkyne fibres to the heart apex.fibres to the heart apex.

33

The impulses spread up through The impulses spread up through the ventricle walls causing the ventricle walls causing contraction from the apex contraction from the apex

upwards. Blood is squeezed into upwards. Blood is squeezed into arteries. arteries.

VENRTICULAR SYSTOLE.VENRTICULAR SYSTOLE.

44

After systole the heart goes into diastole, where After systole the heart goes into diastole, where the cardiac muscles relax. Returning blood fills the cardiac muscles relax. Returning blood fills

atria.atria.

Measuring electrical Measuring electrical changes in the heartchanges in the heart

Electrical currents caused by wave of depolarisation when Electrical currents caused by wave of depolarisation when the impulse spreads can be detected using an ECG.the impulse spreads can be detected using an ECG.

ECG resultsECG results

P WaveP Wave T Wave

T Wave

ST segmentST segment

Q SQ S

RR

PR intervalPR interval

1 Second1 Second

The P wave is the time of The P wave is the time of atrial systole.atrial systole.The QRS complex is the The QRS complex is the time of ventricular systole.time of ventricular systole.The T wave is causing The T wave is causing repolarisation of ventricles repolarisation of ventricles during diastoleduring diastoleYou can work out heart beat You can work out heart beat by measuring time interval by measuring time interval between 1 P wave and next between 1 P wave and next (1 cycle) and working out (1 cycle) and working out rate per minute.rate per minute.

Regulation of cardiac Regulation of cardiac outputoutput

cardiac output (dmcardiac output (dm33minmin-1-1) = stroke volume (dm) = stroke volume (dm33) x heart ) x heart rate (minrate (min-1-1) )

stroke volume stroke volume is volume of blood leaving the left ventricle with is volume of blood leaving the left ventricle with each beateach beat

the heart rate can be affected by hormones (eg adrenaline) and the heart rate can be affected by hormones (eg adrenaline) and nervous control.nervous control.

the Cardiovascular Control Centre in the medulla of the brain the Cardiovascular Control Centre in the medulla of the brain controls the sinoatrial node via nerves.controls the sinoatrial node via nerves.

the Sympathetic Nerve speeds up the heart rate in response to the Sympathetic Nerve speeds up the heart rate in response to falls in the pH in the blood due to COfalls in the pH in the blood due to CO2 2 and lactate levels rising, and lactate levels rising, increases in temperature and mechanical activity in joints.increases in temperature and mechanical activity in joints.

Impulses carried by vagus nerve (Parasympathetic) slows down Impulses carried by vagus nerve (Parasympathetic) slows down heart rate when the demand for Oheart rate when the demand for O22 and CO and CO2 2 reduces.reduces.

Regulation of ventilation Regulation of ventilation raterateventilation rate = tidal volume x number of breaths per minuteventilation rate = tidal volume x number of breaths per minute

Tidal volume - volume of air breathed in or out of lungs per breathTidal volume - volume of air breathed in or out of lungs per breath

Vital capacity - max volume of air that can be forcibly exhaled after a Vital capacity - max volume of air that can be forcibly exhaled after a max intake of airmax intake of air

The ventilation centre in the medulla controls the rate and depth of The ventilation centre in the medulla controls the rate and depth of breathing in response to impulses from chemereceptors in the medulla breathing in response to impulses from chemereceptors in the medulla and arteries which detect the pH and concentration of COand arteries which detect the pH and concentration of CO22 in the blood. in the blood.

Impulses are sent from the ventilation centre to stimulate muscles Impulses are sent from the ventilation centre to stimulate muscles involved in breathing.involved in breathing.

A small increase in COA small increase in CO22 concentration causes a large increase in concentration causes a large increase in ventilation.ventilation.

It also increases in response to impulses from the motor cortex and It also increases in response to impulses from the motor cortex and from stretch receptors in tendons and muscles involved in movement.from stretch receptors in tendons and muscles involved in movement.

We also have some voluntary control over breathing.We also have some voluntary control over breathing.

SpirometerSpirometerA person using a A person using a spriometer breathes in spriometer breathes in and out of an airtight and out of an airtight chamber causing it to chamber causing it to move up & down and move up & down and leaving a trace on a leaving a trace on a revolving drum.revolving drum.The volume of O2 absorbed in a given time by The volume of O2 absorbed in a given time by measuring differences in volume between troughs measuring differences in volume between troughs (labelled A + B) in the diagram and dividing by the (labelled A + B) in the diagram and dividing by the time between A + B.time between A + B.

HomeostasisHomeostasisHomeostasis is the maintenance of a stable internal environment. Homeostasis is the maintenance of a stable internal environment. A homeostatic system requires: A homeostatic system requires: ‣ receptors to detect the change away from the norm value receptors to detect the change away from the norm value

(stimulus)(stimulus)‣ a control mechanisms that can respond to the information. The a control mechanisms that can respond to the information. The

control mechanism uses the nervous system or hormones to control mechanism uses the nervous system or hormones to switch effectors on or offswitch effectors on or off

‣ effectors to bring about the response. Muscles and glands are effectors to bring about the response. Muscles and glands are effectors.effectors.

InputInput ReceptorsReceptors Control MechanismControl Mechanism EffectorsEffectors OutputOutput

FeedbackFeedback

Homeostasis -Homeostasis -Negative feedback helps to keep the internal environment constant. Negative feedback helps to keep the internal environment constant.

A change in the internal environment will trigger a response that A change in the internal environment will trigger a response that counteracts the change. For negative feedback to occur there must counteracts the change. For negative feedback to occur there must be a norm value (set point).be a norm value (set point).

negative feedbacknegative feedback

Conditions controlled by homeostasis fluctuate about the norm Conditions controlled by homeostasis fluctuate about the norm value.value.

norm valuenorm value

Condition is controlled by negative Condition is controlled by negative feedback.feedback.

norm valuenorm value

rise aboverise abovenormnorm

fall below fall below normnorm

change from change from norm norm

detecteddetected

effectors act to return effectors act to return the condition to the set the condition to the set

pointpoint

timetime

Homeostasis Homeostasis The increased respiration rate not only produces a lot of CO2 The increased respiration rate not only produces a lot of CO2 and/or lactate but the energy transfers also release a lot of and/or lactate but the energy transfers also release a lot of heat energy. heat energy.

It can be as much as 1C rise every 5-10 mins is the heat can’t It can be as much as 1C rise every 5-10 mins is the heat can’t be dispersed.be dispersed.

The control of core body temperature through negative The control of core body temperature through negative feedback is called thermoregulation.feedback is called thermoregulation.

Thermoreceptors in the skin detect changes in temperature, as Thermoreceptors in the skin detect changes in temperature, as well as thermoreceptors in the hypothalamus which can detect well as thermoreceptors in the hypothalamus which can detect changes in the core blood temperature.changes in the core blood temperature.

If a rise in temperature is detected above the norm value the If a rise in temperature is detected above the norm value the heat loss centre will stimulate effectors to increase heat loss heat loss centre will stimulate effectors to increase heat loss from the body (usually through skin)from the body (usually through skin)

and exerciseand exercise

Homeostasis Homeostasis This can be summarised in the diagram below:This can be summarised in the diagram below:

and exerciseand exercise

set pointset point(norm)(norm)

detected bydetected byreceptorsreceptors

heat lossheat losscentre incentre in

hypothalamushypothalamuseffectorseffectors

reactreact

set pointset point(norm)(norm)

set pointset point(norm)(norm)

detected bydetected byreceptorsreceptors

heat gainheat gaincentre incentre in

hypothalamushypothalamus

effectorseffectorsreactreact

Temperature RisesTemperature Risessendssends

impulsesimpulses sendssendsimpulsesimpulses Temperature FallsTemperature Falls

Temperature FallsTemperature Falls

sendssendsimpulsesimpulses sendssends

impulsesimpulses

Temperature RisesTemperature Rises

Heat Loss Heat Loss CentreCentre

Stimulates: Stimulates: -sweat glands to -sweat glands to secrete sweatsecrete sweat

Inhibits:Inhibits:- contraction of - contraction of

arterioles in skin arterioles in skin (dilates (dilates

capillaries)capillaries)- hair erector - hair erector

muscles.muscles.- liver (reduces - liver (reduces metabolic rate.metabolic rate.

- skeletal muscles - skeletal muscles (relax - no (relax - no shivers) shivers)

Heat Gain Heat Gain CentreCentre

Stimulates: Stimulates: -arterioles in the -arterioles in the skin to contsrictskin to contsrict

-hair erector -hair erector muscles to muscles to contractcontract

- liver to raise - liver to raise metabolic ratemetabolic rate

- skeletal muscles - skeletal muscles to contract in to contract in

shiveringshivering

Inhibits:Inhibits:- sweat glands- sweat glands

Above and below certain temperatures makes homeostasis fail. Above and below certain temperatures makes homeostasis fail.

Instead Positive feedback may occur resulting in a higher Instead Positive feedback may occur resulting in a higher temperature continuing to rise or low temperature falling still.temperature continuing to rise or low temperature falling still.

This may lead to death.This may lead to death.

Medical Technology & Medical Technology & SportSportKeyhole surgeryKeyhole surgery uses fibre optics. This makes it possible for uses fibre optics. This makes it possible for surgeons to repair damaged joints (inc. ligaments in knee) surgeons to repair damaged joints (inc. ligaments in knee) which precision and little damage. Only a small incision is made which precision and little damage. Only a small incision is made = less blood & damage to joint - recovery is much quicker.= less blood & damage to joint - recovery is much quicker.Prostheses Prostheses are artificial body parts are artificial body parts designed to help the patient regain designed to help the patient regain relatively normal function and/or relatively normal function and/or appearance. The design of prostheses appearance. The design of prostheses has improved over the years so many has improved over the years so many disabled athletes can compete at high disabled athletes can compete at high levels. (eg dynamic response feet literally levels. (eg dynamic response feet literally provide a spring in their step). Damaged provide a spring in their step). Damaged joints (eg knee) can be repaired with joints (eg knee) can be repaired with small prosthetic implants to replace small prosthetic implants to replace damaged bone ends. This restores damaged bone ends. This restores mobility and free the patient from a life of mobility and free the patient from a life of pain.pain.

Too Little ExerciseToo Little ExerciseOver prolonged periods of time, too Over prolonged periods of time, too little exercise can have side effects:little exercise can have side effects:reduced physical endurance, lung capacity, reduced physical endurance, lung capacity, stroke volume and maximum heart rate.stroke volume and maximum heart rate.increased resting heart rate. blood pressure and increased resting heart rate. blood pressure and storage of fat in the body.storage of fat in the body.increased risk of CHD, type 2 diabetes, some increased risk of CHD, type 2 diabetes, some cancers, weight gain and obesity.cancers, weight gain and obesity.impaired immune response due to lack of impaired immune response due to lack of natural killer cells.natural killer cells.increased LDL levels and reduced HDL levels.increased LDL levels and reduced HDL levels.reduced bone density = higher risk of reduced bone density = higher risk of osterperosis.osterperosis.

Too Much ExerciseToo Much ExerciseOvertraining can lead to chronic fatigue and Overtraining can lead to chronic fatigue and poor athletic performancepoor athletic performance

It can also lead to increased wear and tear on It can also lead to increased wear and tear on joints. Damage to cartilage in synovial joints joints. Damage to cartilage in synovial joints can lead to inflammations and a form of athritis. can lead to inflammations and a form of athritis. Ligaments also damage. Bursae the cushion Ligaments also damage. Bursae the cushion joint parts become inflamed and tenderjoint parts become inflamed and tenderAlso, there is correlation between intense exercise and the risk of Also, there is correlation between intense exercise and the risk of infections like colds and sore throats. It could be caused by increased infections like colds and sore throats. It could be caused by increased pathogen exposure or a suppression of the immune system.pathogen exposure or a suppression of the immune system.

There is some evidence that the number and activity of some cells of There is some evidence that the number and activity of some cells of the immune system may be decrease in post vigorous exercise the immune system may be decrease in post vigorous exercise recovery. recovery.

It may also be true that damage to muscles and release of hormones It may also be true that damage to muscles and release of hormones (eg adrenaline) during exercise may cause an inflammatory response (eg adrenaline) during exercise may cause an inflammatory response which could also suprpress the immune system.which could also suprpress the immune system.

Effect of Drugs on Effect of Drugs on GenesGenesSome drugs (eg anabolic steroids) are closely related to natural steroid Some drugs (eg anabolic steroids) are closely related to natural steroid

hormones.hormones.

They can pass directly through cell membranes and be carried into the They can pass directly through cell membranes and be carried into the nucleus bound to a receptor molecule.nucleus bound to a receptor molecule.

These hormone/receptor complexes act as transcription factors. They bind These hormone/receptor complexes act as transcription factors. They bind to the promoter region of a gene allowing RNA polymerase to start to the promoter region of a gene allowing RNA polymerase to start transcription.transcription.

As a result more protein synthesis takes place in the cells.As a result more protein synthesis takes place in the cells.

EXAMPLE: Testosterone increases protein synthesis in muscle cells, EXAMPLE: Testosterone increases protein synthesis in muscle cells, increasing the size & strength of muscle tissue. increasing the size & strength of muscle tissue.

Peptide hormones don’t enter cell directly but they bind with receptors on Peptide hormones don’t enter cell directly but they bind with receptors on the CSM which starts a process that results in the activation of a the CSM which starts a process that results in the activation of a transcription factor within the nucleus.transcription factor within the nucleus.

EXAMPLE: Erythropoietin (EPO) stimulates the production of red blood cells. EXAMPLE: Erythropoietin (EPO) stimulates the production of red blood cells. THis means that blood carries more oxygen, which is good for an athlete. THis means that blood carries more oxygen, which is good for an athlete.

Effect of Drugs on Effect of Drugs on GenesGenes

RNA polymerase

RNA polymerase

Promoter region

Promoter region (site

for RNA polymerase

(site for RNA polymerase

attachment)

attachment)

GeneGene

DNADNA

Transcription factors

Transcription factors

transcriptiontranscriptioninitiation complexinitiation complex

RNA SynthesisRNA Synthesis

Genes are switched on by successful Genes are switched on by successful formation and attachment of formation and attachment of

transcription initiation complex to transcription initiation complex to the promoter region.the promoter region.

Genes remain switched off by the failure of the Genes remain switched off by the failure of the transcription initiation complex to form and attach transcription initiation complex to form and attach to the promoter region. This is due to absence of to the promoter region. This is due to absence of protein transcription factors or action of repressor protein transcription factors or action of repressor

molecules.molecules.

Performance Enhancing Performance Enhancing Drugs & EthicsDrugs & Ethics

Some athletes feel the need to use illegal performance-enhancing Some athletes feel the need to use illegal performance-enhancing substances to pursue excellence. Others may feel the need to follow substances to pursue excellence. Others may feel the need to follow suit, in order to keep up.suit, in order to keep up.

Ethical frameworks can be used on both sides of the argument:Ethical frameworks can be used on both sides of the argument:- right and duties- right and duties- maximising the amount of good in the world- maximising the amount of good in the world- making decisions for yourself- making decisions for yourself- leading a virtuous life- leading a virtuous life

EXAMPLE - doping could be not acceptable because of athlete’s right EXAMPLE - doping could be not acceptable because of athlete’s right to a fair competition. However, it could equally be considered that to a fair competition. However, it could equally be considered that athletes have a right to exercise autonomy, to achieve their best athletes have a right to exercise autonomy, to achieve their best performance.performance.

Performance Enhancing Performance Enhancing Drugs & EthicsDrugs & Ethics

In order to maintain if something is ethical or not, a reasonable In order to maintain if something is ethical or not, a reasonable argument needs to be executed.argument needs to be executed.

Ethical Ethical Absolutists Absolutists see things as very clear cut, black and white. They see things as very clear cut, black and white. They would take one of two stances: would take one of two stances: - It is never acceptable for athletes to use such substances even if - It is never acceptable for athletes to use such substances even if legal legal or or - It is always acceptable for athletes to use any substance available to - It is always acceptable for athletes to use any substance available to them to compete effectively, even if there are health risks.them to compete effectively, even if there are health risks.

Ethical Ethical RelativistsRelativists would realise that people and circumstances may be would realise that people and circumstances may be differentdifferent- EXAMPLE It is wrong for athletes to use performance enhancing - EXAMPLE It is wrong for athletes to use performance enhancing substances but there may be some occasions when it is acceptable.substances but there may be some occasions when it is acceptable.

Topic 8Topic 8Grey MatterGrey Matter

Responding to the Responding to the EnvironmentEnvironmentAnimals have a fast acting nervous systems which Animals have a fast acting nervous systems which contain neurones (nerve cells) that carry information contain neurones (nerve cells) that carry information in the form of impulses.in the form of impulses.In mammals, sensory neurones carry impulses from In mammals, sensory neurones carry impulses from receptors to a central nervous system (CNS) which receptors to a central nervous system (CNS) which consists of the brain & spinal crd.consists of the brain & spinal crd.The CNS incorporates relay neurones, and processes The CNS incorporates relay neurones, and processes info from lots of sources and sends the via motor info from lots of sources and sends the via motor neurones to effector organs (eg. muscles and neurones to effector organs (eg. muscles and glands)glands)

The Pupil ReflexThe Pupil Reflex

The iris contains antagonistic muscles (radial and circular) which control iris size The iris contains antagonistic muscles (radial and circular) which control iris size under the influence of the autonomic nervous system (involuntary)under the influence of the autonomic nervous system (involuntary)

Radial Muscles Relax

Radial Muscles RelaxCircular muscles contract

Circular muscles contract

Radial Muscles ContractRadial Muscles Contract

Circular muscles relax

Circular muscles relax

Pupil ConstrictedPupil Constricted Pupil DilatedPupil Dilated

In bright light photoreceptors (eg In bright light photoreceptors (eg rodsrods) in the retina cause nerve ) in the retina cause nerve impulses to pass along the optic impulses to pass along the optic nerver to a group of nerve cells in the nerver to a group of nerve cells in the brain.brain.

These cells then send impulses along These cells then send impulses along the parasympathetic motor neurones the parasympathetic motor neurones to the circular muscles of the iris.to the circular muscles of the iris.

The muscles contact, reducing the The muscles contact, reducing the diameter of the pupil so less light diameter of the pupil so less light enters the eye which prevents retinal enters the eye which prevents retinal damage.damage.

In low light situations, fewer impulses In low light situations, fewer impulses reach the retina, hence fewer reach reach the retina, hence fewer reach coordinating centre in the brain.coordinating centre in the brain.

Impules are sent down sypathetic Impules are sent down sypathetic motor neurones to radial muscles of motor neurones to radial muscles of the iris.the iris.

This causes radial muscles to contract This causes radial muscles to contract and the pupil become dilated.and the pupil become dilated.

This allows more light in.This allows more light in.

Converts toConverts to

Reverts quickly in Reverts quickly in Far Red LightFar Red LightPPRR reverts slowly in the reverts slowly in the

dark dark as relatively unstableas relatively unstable

may trigger a range of

may trigger a range of

different photoperidic

different photoperidic

responsesresponses

Plant Sensitivity - Plant Sensitivity - PhotoperiodismPhotoperiodism

Plants flower and their seeds germinate in response to changes in day Plants flower and their seeds germinate in response to changes in day length. length.

The photoreceptor here is ‘Phytochrome’ (blue-green pigment), and comes in The photoreceptor here is ‘Phytochrome’ (blue-green pigment), and comes in two forms : Red(Ptwo forms : Red(PRR) and Far-red(P) and Far-red(PFRFR))

PPFRFR

Absorbs Absorbs natural (red)

natural (red) lightlight InactiveInactive ActiveActive

Plant Sensitivity - Plant Sensitivity - PhototropismPhototropism

Tropisms are growth responses in plants, where direction of growth is Tropisms are growth responses in plants, where direction of growth is determined by the direction of external stimulus. determined by the direction of external stimulus.

If a plant grows If a plant grows towards towards a stimulus, it is a positive trophic response.a stimulus, it is a positive trophic response.

In plant shoots, light and auxins have an effect:In plant shoots, light and auxins have an effect:

With illumination With illumination from all sides, an from all sides, an even distribution even distribution of auxins moves of auxins moves down from the down from the shoot tip and shoot tip and

causes elongation causes elongation of cells across the of cells across the zone of elongationzone of elongation

Auxins are broken Auxins are broken down by enzymesdown by enzymes

When light comes When light comes from just one side, from just one side, auxins move along auxins move along the shaded side of the shaded side of

the shoot, the shoot, elongating them elongating them

which bends to tip which bends to tip towards the light.towards the light.

Comparison Comparison of communication of communication and coordination methods in plants and coordination methods in plants and mammalsand mammals

Nervous Nervous system in system in mammalsmammals

Endocrine Endocrine system in system in mammalsmammals

Tropisms in Tropisms in plantsplants

Electrochemical changes giving an Electrochemical changes giving an electrical impulse. Chemical electrical impulse. Chemical

neurotransmitters used at most neurotransmitters used at most synapses.synapses.

Chemical hormones from Chemical hormones from endocrine glands carried in endocrine glands carried in

blood plasma around blood plasma around circulatory system.circulatory system.

Chemical growth substances Chemical growth substances (eg auxins) diffusing from (eg auxins) diffusing from

cell to cell. Some may go in cell to cell. Some may go in phloemphloem

rapid actingrapid acting slower actingslower acting slower actingslower actingUsually associated with Usually associated with short term changes (eg short term changes (eg

muscle contraction)muscle contraction)

Can control long term responses (eg Can control long term responses (eg growth). Some involved in growth). Some involved in

homeostasis (eg blood sugar levels). homeostasis (eg blood sugar levels). Some can be relatively fast (eg Some can be relatively fast (eg

adrenaline response)adrenaline response)

Controls long term growth Controls long term growth responses (eg cell responses (eg cell

elongation)elongation)Response is very localised Response is very localised

and specific to (eg) and specific to (eg) muscle cell or glandmuscle cell or gland

Response can be Response can be widespread or targeted widespread or targeted

to specific cells.to specific cells.

Response may be widespread but Response may be widespread but normally restricted to cells within a normally restricted to cells within a

short distance of the growth short distance of the growth substance being released.substance being released.

Structure Structure of of NeuronesNeuronesDendrites conduct impulses towards cell Dendrites conduct impulses towards cell body.body.

Axons conduct impulses away from cell Axons conduct impulses away from cell body.body.

Neurones can carry waves of action Neurones can carry waves of action potentials (electrical activity) over long potentials (electrical activity) over long distances. The membranes are polarised.distances. The membranes are polarised.

Myelin sheath wrapped is a fatty insulating Myelin sheath wrapped is a fatty insulating layer. This increases the speed of conduction layer. This increases the speed of conduction through SALTATORY CONDUCTION:through SALTATORY CONDUCTION:

Schwann cells wrap around the neurone go Schwann cells wrap around the neurone go nourish and protect it and produce myelin nourish and protect it and produce myelin sheath.sheath.

There are small gaps left uncovered called There are small gaps left uncovered called nodes of Ranvier.nodes of Ranvier.

Action potentials jump from one node of Action potentials jump from one node of Ranvier to the next, increasing conduction Ranvier to the next, increasing conduction speed.speed.

NucleusNucleus

lipid layer lipid layer made by

made by

schwannschwann

AxonAxonSchwann CellSchwann Cell

Cell BodyCell Body

DendritesDendritesNucleusNucleus

Axon

Axon

Schwann cell

Schwann cell

node of

node of Ranvier

Ranvier

Termin

Termin

al al

Branch

Branch

esesMotor NeuroneMotor Neurone

Cell BodyCell BodySchwann cell

Schwann cell

DendritesDendritesAxonAxon

Sensory NeuroneSensory Neurone

Relay NeuroneRelay Neurone

Cell Body

Cell Body

AxonAxon

DendriteDendritess

several axons held several axons held together making a together making a

movemoveNerveNerve

Transmission of a nerve Transmission of a nerve impulseimpulse

In a resting neurone, there are more sodium (NaIn a resting neurone, there are more sodium (Na++) ions ) ions outside the cell membrane than inside, and more potassium outside the cell membrane than inside, and more potassium (K(K++) inside that outside.) inside that outside.The inside of resting neurone has a negative charge in The inside of resting neurone has a negative charge in comparison, due to presence of chloride ions and -ve comparison, due to presence of chloride ions and -ve charged proteins = p.d. of about -70mV. charged proteins = p.d. of about -70mV. This is resting potential. The membrane is called ‘Polarised’.This is resting potential. The membrane is called ‘Polarised’.The sodium-potassium pump creates concentration The sodium-potassium pump creates concentration gradients across the membrane (Nagradients across the membrane (Na+ + move out, Kmove out, K+ + in).in).Potassium ion channels allow facilitated diffusion of KPotassium ion channels allow facilitated diffusion of K+ + out of out of the membrane (down concentration gradient) which creates the membrane (down concentration gradient) which creates that uneven charge.that uneven charge.

Transmission of a nerve Transmission of a nerve impulseimpulse

If a neurone cell is stimulated by an impulse, voltage If a neurone cell is stimulated by an impulse, voltage dependant Nadependant Na+ + channels open and Nachannels open and Na+ + diffuse in.diffuse in.This increases the positive charge inside the cell = charge This increases the positive charge inside the cell = charge across membrane is reversed.across membrane is reversed.The membrane now carries a p.d. of +40mV. This is the The membrane now carries a p.d. of +40mV. This is the action action potential potential and the membrane is said to be polarised.and the membrane is said to be polarised.As the charge reverses, the NaAs the charge reverses, the Na+ + channels shut and voltage-channels shut and voltage-dependant Kdependant K+ + ions channels open so more potassium ions ions channels open so more potassium ions leave the axon, which repolarises the membrane.leave the axon, which repolarises the membrane.The membrane can become hyperpolarised, when the p.d. The membrane can become hyperpolarised, when the p.d. drops below the resting potential. Voltage-dependant Kdrops below the resting potential. Voltage-dependant K+ +

channels close. Kchannels close. K+ + diffuses back into the axon to recreate the diffuses back into the axon to recreate the resting potential.resting potential.

TransmissioTransmission of a nerve n of a nerve impulseimpulseMovement of ions Movement of ions in and out of in and out of membrane during membrane during an action potential.an action potential.

Propagation of a nerve impulse along Propagation of a nerve impulse along an axonan axon

High NaHigh Na++

High KHigh K++ axonaxon

At resting potential, At resting potential, there is a positive there is a positive

charge on the charge on the outside, and outside, and

negative charge negative charge inside, which high inside, which high

Sodium Sodium concentration concentration

outside and high outside and high Potassium Potassium

concentration concentration inside.inside.

When stimulated, voltage dependant Na+ channels When stimulated, voltage dependant Na+ channels open and Na+ flow into axon = depolarisation. open and Na+ flow into axon = depolarisation. Localised electric currents are generated in the Localised electric currents are generated in the membrane. Na+ move into adjacent polarised membrane. Na+ move into adjacent polarised

(resting) region causing a change in charge across (resting) region causing a change in charge across this part of membranethis part of membrane

1st Action Potential1st Action PotentialNaNa++

NaNa++

stimulation

localised electric currentlocalised electric current

11

22

33

The change in p.d. in the membrane adjacent to the 1st The change in p.d. in the membrane adjacent to the 1st action potential initiates a second action potential.action potential initiates a second action potential.At the site of the first At the site of the first action potential, the action potential, the

voltage dependant Na+ voltage dependant Na+ ion channels close and ion channels close and voltage dependant K+ voltage dependant K+

channels open. K+ leave channels open. K+ leave the axon, repolarising the the axon, repolarising the

membrane. The membrane. The membrane is membrane is

hyperpolarisedhyperpolarised

44A 3rd action potential A 3rd action potential is initiated by the 2nd. is initiated by the 2nd.

In this way local In this way local electric currents cause electric currents cause the nerve impulse to the nerve impulse to move along the axon.move along the axon.At the site of the 1st, At the site of the 1st, K+ move back into K+ move back into

axon, restoring action axon, restoring action potential.potential.

2nd Action Potential2nd Action PotentialNaNa++

NaNa++

KK++

KK++

3rd Action Potential3rd Action PotentialNaNa++

NaNa++

KK++

KK++RefractoryRefractoryperiodperiodprogress of impulseprogress of impulse

Action potentials are all or Action potentials are all or nothing. A bigger stimulus nothing. A bigger stimulus

increases the frequency of action increases the frequency of action potentials - NOT the strength.potentials - NOT the strength.

A threshold stimulus must be A threshold stimulus must be applied to produce an action applied to produce an action

potential.potential.

Right after an action potential Right after an action potential there is a refractory period. This is there is a refractory period. This is

where a new action potential where a new action potential cannot be generated as Na+ cannot be generated as Na+

channels can’t reopen.channels can’t reopen.This ensure that action potentials This ensure that action potentials are kept as separate signals, and are kept as separate signals, and

are UNIDIRECTIONALare UNIDIRECTIONAL

SynapsesSynapsesA synapse it the point where one neurone meets another.A synapse it the point where one neurone meets another.At the tip of an axon, an impulse opens up Calcium ion (CaAt the tip of an axon, an impulse opens up Calcium ion (Ca++) channel, ) channel, then triggers the release of a chemical neurotransmitter from synaptic then triggers the release of a chemical neurotransmitter from synaptic vesicles.vesicles.The neurotransmitter can diffuse across the gap between neurones The neurotransmitter can diffuse across the gap between neurones (synaptic cleft) and bind to receptors of postsynaptic membrane.(synaptic cleft) and bind to receptors of postsynaptic membrane.If the neurotransmitter comes from a excitatory neurone, it may open If the neurotransmitter comes from a excitatory neurone, it may open Na+ channels on the post synaptic membrane which will trigger a new Na+ channels on the post synaptic membrane which will trigger a new action potential in the postsynaptic neurone.action potential in the postsynaptic neurone.Some neurotransmitters are inhibitory, and may open Chloride ion Some neurotransmitters are inhibitory, and may open Chloride ion channels on the post synaptic membrane, causing it to be channels on the post synaptic membrane, causing it to be hyperpolarised and therefore harder to get an above-threshold hyperpolarised and therefore harder to get an above-threshold response needed to trigger the new action potential.response needed to trigger the new action potential.

SynapsesSynapsesAn enzyme is often present in the synaptic cleft to An enzyme is often present in the synaptic cleft to hydrolyse the neurotransmitter to avoid the response hydrolyse the neurotransmitter to avoid the response from repeating.from repeating.The neurotransmitter may be taken back into The neurotransmitter may be taken back into presynaptic membrane to be reused.presynaptic membrane to be reused.As receptors are only on the postsynaptic membrane, As receptors are only on the postsynaptic membrane, the signal can only be unidirectional. the signal can only be unidirectional. Synapses also act as junctions and allow nerve Synapses also act as junctions and allow nerve impulses to converge or diverge because one neurone impulses to converge or diverge because one neurone can meet many others at a single synapse.can meet many others at a single synapse.

SynapsSynapseses

AxonAxon

Synaptic Vesicle

Synaptic Vesicle

NeurotransmitterNeurotransmitter

Presynaptic Presynaptic

MembraneMembrane

Postsynaptic

Postsynaptic

Membrane

Membrane

Synaptic CleftSynaptic Cleft

CaCa2+2+

NaNa++

An action potential arrivesAn action potential arrives11

11

The membrane depolarises. The membrane depolarises. Calcium ions channels open.Calcium ions channels open.

Calcium ions enter the Calcium ions enter the neurone.neurone.

22

22Calcium ions cause synaptic vesicles Calcium ions cause synaptic vesicles containing neurotransmitter to fuse containing neurotransmitter to fuse

with the presynaptic membrane.with the presynaptic membrane.

33

33Neurotransmitter is released into the synaptic cleft.Neurotransmitter is released into the synaptic cleft.44

44

Neurotransmitter binds with Neurotransmitter binds with receptors on the postsynaptic receptors on the postsynaptic membrane. Cation channels membrane. Cation channels

open. Sodium ions flow through open. Sodium ions flow through the open channels.the open channels.

55Membrane depolarises Membrane depolarises and initiates an action and initiates an action

potentialpotential

66

55 66

When released the neurotransmitter will be taken When released the neurotransmitter will be taken up across the presynaptic membrane (whole or up across the presynaptic membrane (whole or

after being broken down), or it can diffuse away & after being broken down), or it can diffuse away & be broken downbe broken down

77

77

Vision Vision & Human & Human PhotoreceptorsPhotoreceptors

Human eyes have 2 types of photoreceptor cells found in Human eyes have 2 types of photoreceptor cells found in our retinas. our retinas. 1) Cones allow colour vision in bright light and are 1) Cones allow colour vision in bright light and are clustered in the centre of the retina.clustered in the centre of the retina.2) Rods only provide black and white vision, but are much 2) Rods only provide black and white vision, but are much more sensitive than cones and work in dim light conditions.more sensitive than cones and work in dim light conditions.

Vision Vision & Human & Human PhotoreceptorsPhotoreceptors

Light energy is absorbed by rhodopsin Light energy is absorbed by rhodopsin which splits into retinal and opsin.which splits into retinal and opsin.

The opsin binds to the membrane of The opsin binds to the membrane of the outer segment of the cell and this the outer segment of the cell and this causes sodium ion channels to close.causes sodium ion channels to close.

The inner segment continues to pump The inner segment continues to pump sodium ions out of the cell and the sodium ions out of the cell and the membrane becomes hyperpolarised.membrane becomes hyperpolarised.

This means that glutamine will not be This means that glutamine will not be released across the synapse.released across the synapse.

Glutamine usually inhibits the Glutamine usually inhibits the neurones which connect the rod cells neurones which connect the rod cells to the neurones in the optic nerve.to the neurones in the optic nerve.

When there is less inhibition an action When there is less inhibition an action potential forms and is transmitted to potential forms and is transmitted to the brain.the brain.

The info from the optic nerve is The info from the optic nerve is processed by the brain in the visual processed by the brain in the visual cortex.cortex.

darkdark lightlightOuterOuterSegmentSegment

InnerInnerSegmentSegment

Na+ diffuse Na+ diffuse through open through open

cation cation channelschannelsNaNa++

NaNa++

Na+ move down Na+ move down concentration concentration

gradientgradient

Na+ actively Na+ actively pumped outpumped out

Membrane Membrane slightly slightly

depolarised -depolarised -40mV40mV

NeurotransmitteNeurotransmitter is released r is released and binds to and binds to bipolar cell bipolar cell

preventing it preventing it depolarisingdepolarising Bipolar

Bipolar NeuroneNeurone

Light breaks Light breaks down rhodopsin down rhodopsin to retinal and to retinal and

opsinopsinOpsin binds to the membrane Opsin binds to the membrane

causing a series of reactions which causing a series of reactions which result in the Na+ channels being result in the Na+ channels being

closedclosed

Na+ actively Na+ actively pumped outpumped out

Membrane Membrane hyperpolarisedhyperpolarised

No No Neurotransmitter Neurotransmitter

is releasedis releasedNaNa++

Cation channels in bipolar cell open and Cation channels in bipolar cell open and membrane becomes depolarised, membrane becomes depolarised,

generating an action potential in the generating an action potential in the optic nerve neurone.optic nerve neurone.

The CerebrumThe CerebrumThe cerebral cortex (cerebrum) is the largest The cerebral cortex (cerebrum) is the largest part of the brain.part of the brain.It’s divided into 2 hemispheres connected by a It’s divided into 2 hemispheres connected by a band of white matter called the ‘Corpus band of white matter called the ‘Corpus Callosum’. Callosum’. The cerebrum is associated with advanced The cerebrum is associated with advanced mental activity like language, memory, mental activity like language, memory, calculation, processing info from eyes & ears, calculation, processing info from eyes & ears, emotion and controlling all voluntary activities.emotion and controlling all voluntary activities.

The CerebrumThe Cerebrum

Frontal Lobe Frontal Lobe

Parietal Lobe Parietal Lobe

OccipitaOccipitall

LobeLobeTemporal Lobe Temporal Lobe

CerebullumCerebullum

Frontal Lobe Frontal Lobe Concerned with the Concerned with the

higher brain functions, higher brain functions, like decision making, like decision making, reasoning, planning & reasoning, planning &

consciousness of emotion.consciousness of emotion.Also, it’s concerned with Also, it’s concerned with forming associations and forming associations and

with ideas.with ideas.It includes the primary It includes the primary motor cortex which has motor cortex which has neurones that connect neurones that connect

directly to the spinal cord directly to the spinal cord and brain stem (and onto and brain stem (and onto

the muscles).the muscles).

Parietal Lobe Parietal Lobe Concerned with Concerned with

orientation, movement, orientation, movement, sensation, calculation, sensation, calculation,

some times of recognition some times of recognition & memory.& memory.

Occipetal Lobe Occipetal Lobe concerned with concerned with

processing info from eyes, processing info from eyes, including vision, colour, including vision, colour, shape recognition and shape recognition and

perspectiveperspective

Temporal Lobe Temporal Lobe concerned with concerned with

processing auditory info, processing auditory info, ie hearing, speech, ie hearing, speech,

recognition and also recognition and also involved in memory.involved in memory.

Next Slide for more on Next Slide for more on CerebellumCerebellum

The CerebellumThe Cerebellum

Spinal Cord

Spinal Cord

Medulla OblongataMedulla Oblongata

CerebellumCerebellum

CerebrumCerebrum

Midbra

in

Midbra

in

Pituita

ry Gland

Pituita

ry Gland

Basal GangliaBasal Ganglia

Corpus Corpus Callosum

Callosum

HypothalalmusHypothalalmus

ThalamusThalamus

HypothalamusHypothalamuscontrols thermoregulationcontrols thermoregulation

CerebellumCerebellumimportant for balance & important for balance & coordinating movementscoordinating movements

Medulla OblongataMedulla Oblongatacontrols many body controls many body

processes such as heart processes such as heart rate, breathing and blood rate, breathing and blood

pressurepressure

Critical WindowsCritical WindowsCritical Windows (or critical periods) for development are those periods of time where it is Critical Windows (or critical periods) for development are those periods of time where it is though that the nervous system needs specific stimuli in order to properly develop.though that the nervous system needs specific stimuli in order to properly develop.Evidence for critical windows have come from medical observationsEvidence for critical windows have come from medical observationsEXAMPLE: A child under 10 days who develops cataracts may suffer from permanent visual EXAMPLE: A child under 10 days who develops cataracts may suffer from permanent visual damage even if cataracts are removed at a later datedamage even if cataracts are removed at a later dateAnimal models are also used; EXAMPLE: Hubel and Wiesel used kittens and monkeys as Animal models are also used; EXAMPLE: Hubel and Wiesel used kittens and monkeys as models to investigate the critical window in visual development because of the similarity of models to investigate the critical window in visual development because of the similarity of their visual systems to that of humans.their visual systems to that of humans.The animals were deprived of stimulus of light into one eye (monocular deprivation) at The animals were deprived of stimulus of light into one eye (monocular deprivation) at different stages of development and for different lengths of time.different stages of development and for different lengths of time.It found that kittens deprived of light in 1 eye at age 4 weeks were effectively permanently It found that kittens deprived of light in 1 eye at age 4 weeks were effectively permanently blind in that eye.blind in that eye.Monocular deprivation before 3 weeks and after 3 months had NO effect.Monocular deprivation before 3 weeks and after 3 months had NO effect.

Eye deprived of light during critical periodEye deprived of light during critical period Eye that remains open during critical periodEye that remains open during critical periodAxons do not pass nerve impulses to cells in the visual Axons do not pass nerve impulses to cells in the visual

cortexcortex Axons pass nerve impulses to cells in the visual cortexAxons pass nerve impulses to cells in the visual cortex

Inactive synapses eliminatedInactive synapses eliminated Synapses used by active axons are strengthenedSynapses used by active axons are strengthenedEye has no working connection to the visual cortex and is Eye has no working connection to the visual cortex and is effectively blind, even though the cells of the retina and effectively blind, even though the cells of the retina and

optic nerve work normally when exposed to lightoptic nerve work normally when exposed to light

Synapses only present for axons coming from the light-Synapses only present for axons coming from the light-stimulated eye. So the visual cortex can only respond to stimulated eye. So the visual cortex can only respond to

this eye.this eye.

Animal Rights IssuesAnimal Rights IssuesThe use of animals in scientific study is a controversial The use of animals in scientific study is a controversial topic.topic.Animal Rights activists who hold an absolutist view think it Animal Rights activists who hold an absolutist view think it is NEVER right to used animals in medical research.is NEVER right to used animals in medical research.Medical Researchers hold a more relativist view, that Medical Researchers hold a more relativist view, that humans should keep animals well and minimise harm and humans should keep animals well and minimise harm and suffering as much as possible. The emphasis is on animal suffering as much as possible. The emphasis is on animal welfare (rights to food, drink, vets and normal behaviours). welfare (rights to food, drink, vets and normal behaviours). It’s very similar to EU law.It’s very similar to EU law.This all assumes that animals can suffer and experience This all assumes that animals can suffer and experience pleasure.pleasure.A A utilitarian utilitarian ethical framework allows certain animalsethical framework allows certain animals

Nature, Nurture & Brain Nature, Nurture & Brain developmentdevelopment

Nature: Many of our characteristics develop Nature: Many of our characteristics develop solely under the influence of our genes with solely under the influence of our genes with little help from our environment or learning (eg little help from our environment or learning (eg blood group)blood group)Nurture: Many Characteristics are learnt or Nurture: Many Characteristics are learnt or heavily influenced by our environment (eg hair heavily influenced by our environment (eg hair length)length)

Nature, Nurture & Brain Nature, Nurture & Brain developmentdevelopment

Most characteristics are determined by nature and nurture, Most characteristics are determined by nature and nurture, or nature via nurture.or nature via nurture.We are the result of a mix of genetic and environmental We are the result of a mix of genetic and environmental factors.factors.Human behaviours, attitudes and skills may have an Human behaviours, attitudes and skills may have an underlying genetic basis, but are modified (eg by underlying genetic basis, but are modified (eg by experience etc)experience etc)EXAMPLE: the chance of developing some cancers has a EXAMPLE: the chance of developing some cancers has a genetic basis where are gene (or several) interact to confer genetic basis where are gene (or several) interact to confer susceptibility to the disease with environmental factors susceptibility to the disease with environmental factors contributing to the risk of development.contributing to the risk of development.

Nature, Nurture & Brain Nature, Nurture & Brain developmentdevelopment

Evidence for the relative roles of nature and nurture in brain development come Evidence for the relative roles of nature and nurture in brain development come from a variety of different sources:from a variety of different sources:The abilities of newborn babies:The abilities of newborn babies: The innate abilities that babies exhibit suggest that genes help form The innate abilities that babies exhibit suggest that genes help form the brain & some behaviours before the baby is born.the brain & some behaviours before the baby is born.Studies of patients with damaged brain areas:Studies of patients with damaged brain areas: Some px’s who have suffered brain damage show the Some px’s who have suffered brain damage show the ability to recover some of their brain function, which demonstrates that some neurones have ability ability to recover some of their brain function, which demonstrates that some neurones have ability to change.to change.Animal experiments:Animal experiments: eg Hubel and Weisel’s experiments on critical windows for sight, suggesting eg Hubel and Weisel’s experiments on critical windows for sight, suggesting that stimulation is important in brain development.that stimulation is important in brain development.Twin Studies:Twin Studies: Identical twins obviously share all the same genes. Fraternal (non-identical) twins share Identical twins obviously share all the same genes. Fraternal (non-identical) twins share the same number as any other sibling would. Twin studies can estimate the relative contribution of the same number as any other sibling would. Twin studies can estimate the relative contribution of genes and the environment. Any differences between identical twins must be due to environmental genes and the environment. Any differences between identical twins must be due to environmental effects.effects.Identical twins raised apart in comparison to those raised together are particularly useful for study. Identical twins raised apart in comparison to those raised together are particularly useful for study. EXAMPLE: If there is a greater difference between those twins raised apart than twins raised together EXAMPLE: If there is a greater difference between those twins raised apart than twins raised together it suggests some environmental influence. However, twins raised apart may not have completely it suggests some environmental influence. However, twins raised apart may not have completely different environments and twins raised together may develop different personalities due to a desire different environments and twins raised together may develop different personalities due to a desire to be different. to be different. In general if genes have a strong influence on the development of a characteristic, then the closer In general if genes have a strong influence on the development of a characteristic, then the closer the genetic relationship, the stronger the correlation will be between individuals for that trait.the genetic relationship, the stronger the correlation will be between individuals for that trait.Cross-cultural studies:Cross-cultural studies: Investigations into the visual perceptions of groups from different cultural Investigations into the visual perceptions of groups from different cultural backgrounds support the idea that visual cures for depth perception are at least partially learnt.backgrounds support the idea that visual cures for depth perception are at least partially learnt.

HabituationHabituation

Habituation is a very simple type of learning Habituation is a very simple type of learning which involves the loss in response to a which involves the loss in response to a repeated stimulus which fails to provide any repeated stimulus which fails to provide any form of reinforcement (reward or punishment).form of reinforcement (reward or punishment).It allows animals to ignore unimportant stimuli It allows animals to ignore unimportant stimuli so they can concentrate of reinforce stimuli.so they can concentrate of reinforce stimuli.

Habituation Habituation InvestigationsInvestigations

This practical measures the This practical measures the time a snail spends time a snail spends withdrawn into its shell withdrawn into its shell when you tap its head when you tap its head (between the eyes).(between the eyes).Initially the snail tends to Initially the snail tends to hide for a significant length hide for a significant length of time, but as the tapping of time, but as the tapping continues, the time interval continues, the time interval decreases.decreases.The snail becomes The snail becomes habituated to the tap.habituated to the tap.Ethical and Safety concerns Ethical and Safety concerns need to be addressed here need to be addressed here as animals are used.as animals are used.

Core PracticalCore PracticalAnimal ModelsAnimal ModelsInvertebrates make for useful animal models for the inner working Invertebrates make for useful animal models for the inner working of the nervous system. Here, Sea Slugs have been used to of the nervous system. Here, Sea Slugs have been used to investigate habituation.investigate habituation.

Gill withdraws siphon Gill withdraws siphon when stimulated by when stimulated by

water jetwater jet

SiphonSiphon

Water JetWater Jet

After several minutes of After several minutes of repeated stimulation of repeated stimulation of the siphon the gill no the siphon the gill no

longer withdraws.longer withdraws.

SiphonSiphon

Water JetWater Jet

With repeated stimulation, CaWith repeated stimulation, Ca2+2+ channels become less responsive channels become less responsive

so less Caso less Ca2+2+ crosses the crosses the presynaptic nervepresynaptic nerve

11

Less neurotransmitter Less neurotransmitter released.released.22

There is less depolarisation There is less depolarisation of postsynaptic membrane, of postsynaptic membrane,

so no action potential is so no action potential is triggered in motor neurone.triggered in motor neurone.

33

CaCa2+2+

sensory neurone sensory neurone from siphonfrom siphon motor neurone to motor neurone to

the gillthe gill

Gill Gill withdrawalwithdrawal

GillGill

Dopamine & Parkinson’sDopamine & Parkinson’sParkinson’s disease is associated with the death of a group of dopamine Parkinson’s disease is associated with the death of a group of dopamine secreting neurones in the brain (midbrain). This results in the reduction of secreting neurones in the brain (midbrain). This results in the reduction of dopamine levels in the brain.dopamine levels in the brain.Dopamine is a neurotransmitter which is active in neurones in the frontal cortex, Dopamine is a neurotransmitter which is active in neurones in the frontal cortex, brain stem and spinal cord. It is associated with the control of movement & brain stem and spinal cord. It is associated with the control of movement & emotional responses.emotional responses.Treatments for Parkinson’s are varied, with most aiming to increase the Treatments for Parkinson’s are varied, with most aiming to increase the concentration of dopamine in the brain.concentration of dopamine in the brain.Dopamine cannot move into the brain from the bloodstream but the L-Dopa Dopamine cannot move into the brain from the bloodstream but the L-Dopa molecule, which is used to make dopamine, can which could help to relieve molecule, which is used to make dopamine, can which could help to relieve symptoms. symptoms. The symptoms of Parkinson’s are:The symptoms of Parkinson’s are:

muscle tremorsmuscle tremorsmuscle stiffness & slow movementmuscle stiffness & slow movementpoor balance and walking problemspoor balance and walking problemsdifficulties with speech and breathingdifficulties with speech and breathingdepressiondepression

Serotonin & DepressionSerotonin & DepressionSerotonin is another neurotransmitter, but this time Serotonin is another neurotransmitter, but this time it’s linked to feelings of reward & pleasure. Clinical it’s linked to feelings of reward & pleasure. Clinical depression depression (prolonged feelings of sadness, anxiety, (prolonged feelings of sadness, anxiety, hopelessness, loss of interest, restlessness, insomnia... hopelessness, loss of interest, restlessness, insomnia... etc...) etc...) is attributed to low serotonin levels. is attributed to low serotonin levels. Treatments for depression often involve drugs which Treatments for depression often involve drugs which can increase serotonin concentration in synapses.can increase serotonin concentration in synapses.EXAMPLE: Prozac is a ‘Selective Serotonin Reuptake EXAMPLE: Prozac is a ‘Selective Serotonin Reuptake Inhibitor’ (SSRI) that blocks the process which removes Inhibitor’ (SSRI) that blocks the process which removes serotonin from the synapse.serotonin from the synapse.

Drug effects on Drug effects on synapsessynapses

1)1) Some drugs affect the synthesis, or storage, of neurotransmitters. (eg L-dopa used in the Some drugs affect the synthesis, or storage, of neurotransmitters. (eg L-dopa used in the treatment of Parkinson’s disease is converted into dopamine, increasing the treatment of Parkinson’s disease is converted into dopamine, increasing the concentration of dopamine to reduce the symptoms of the disease)concentration of dopamine to reduce the symptoms of the disease)

2)2) Some drugs may affect the release of the neurotransmitter from the presynaptic Some drugs may affect the release of the neurotransmitter from the presynaptic membrane.membrane.

3)3) Some drugs may affect the interaction between the neurotransmitter and the receptors Some drugs may affect the interaction between the neurotransmitter and the receptors on the postsynaptic membraneon the postsynaptic membrane~ some may be stimulatory by binding to the receptors and opening the sodium ion ~ some may be stimulatory by binding to the receptors and opening the sodium ion channels - eg dopamine agonists (mimic dopamine due to shape, used in Parkinson’s channels - eg dopamine agonists (mimic dopamine due to shape, used in Parkinson’s treatment) bind to dopamine receptors and trigger action potentials.treatment) bind to dopamine receptors and trigger action potentials.~ some may be inhibitory, blocking the receptors on the postsynaptic membranes and ~ some may be inhibitory, blocking the receptors on the postsynaptic membranes and preventing the neurotransmitters binding.preventing the neurotransmitters binding.

4)4) Some drugs prevent the reuptake of the neurotransmitter back into the presynaptic Some drugs prevent the reuptake of the neurotransmitter back into the presynaptic membrane - eg Ecstasy (MDMA) prevents the reuptake of Serotonin. The effect is the membrane - eg Ecstasy (MDMA) prevents the reuptake of Serotonin. The effect is the maintenance of a high serotonin concentration in the synapse which brings about moods maintenance of a high serotonin concentration in the synapse which brings about moods changes in MDMA users. One of the side effects of MDMA is depression as a result of the changes in MDMA users. One of the side effects of MDMA is depression as a result of the loss of serotonin from neurones, due to lack of reuptake. Prozac is a SSRI that blocks the loss of serotonin from neurones, due to lack of reuptake. Prozac is a SSRI that blocks the reuptake of serotonin in the treatment of depression.reuptake of serotonin in the treatment of depression.

5)5) Some drugs may inhibit enzymes involved in breaking down the neurotransmitter in the Some drugs may inhibit enzymes involved in breaking down the neurotransmitter in the synaptic cleft, resulting in maintenance of a high concentration of the neurotransmitter in synaptic cleft, resulting in maintenance of a high concentration of the neurotransmitter in the synapse and therefore repeated action potentials (or inhibition) of the presynaptic the synapse and therefore repeated action potentials (or inhibition) of the presynaptic cleft.cleft.

Drug effects on Drug effects on synapsessynapses

Presynaptic membranePresynaptic membrane

Postsynaptic Postsynaptic membranemembrane

Neurotransmitter Neurotransmitter synthesis & synthesis &

storagestorage

Neurotransmitter Neurotransmitter releaserelease

Neurotransmitter receptor Neurotransmitter receptor bindingbinding

Neurotransmitter Neurotransmitter reuptakereuptake

Neurotransmitter Neurotransmitter breakdownbreakdown

Drug developmentDrug developmentWe now know that chemicals which affect membrane-bound proteins or We now know that chemicals which affect membrane-bound proteins or mimic the effect of naturally occurring neurotransmitters can have a mimic the effect of naturally occurring neurotransmitters can have a significant effect on defective or normal neural pathways. The more we significant effect on defective or normal neural pathways. The more we know about the specific proteins (and their shapes) active in cells, the know about the specific proteins (and their shapes) active in cells, the more likely we can find complementary chemicals with the same effect.more likely we can find complementary chemicals with the same effect.Traditionally most medicines come from existing plant-based chemicals. Traditionally most medicines come from existing plant-based chemicals. However, info from the human genome project could help develop However, info from the human genome project could help develop drugs that are highly specific so that they can be effective in lower drugs that are highly specific so that they can be effective in lower doses with fewer side effects. doses with fewer side effects. Pharmacogenomics links pharmaceutical expertise with the knowledge Pharmacogenomics links pharmaceutical expertise with the knowledge of the genome project. of the genome project. New drugs have to go through rigorous testing before they go to market New drugs have to go through rigorous testing before they go to market (see unit 2)(see unit 2)

Brain Imaging Brain Imaging TechniquesTechniques

Magnetic Resonance Imaging (MRI) Magnetic Resonance Imaging (MRI) scans use a scans use a strong magnetic field and radio waves to make images of strong magnetic field and radio waves to make images of soft tissues (like the brain). They align hydrogen nuclei to soft tissues (like the brain). They align hydrogen nuclei to the magnetic field. MRI scans can be used in the the magnetic field. MRI scans can be used in the diagnosis of tumours, strokes, brain injuries and diagnosis of tumours, strokes, brain injuries and infections. They can also track progress of degenerative infections. They can also track progress of degenerative diseases like Alzheimer's by comparing scans over a diseases like Alzheimer's by comparing scans over a period of time.period of time.Functional MRI (fMRI) Functional MRI (fMRI) scan are a modified MRI scan are a modified MRI technique which allows you to see the brain in action technique which allows you to see the brain in action doing live tasks, as it detects activity in the brain, doing live tasks, as it detects activity in the brain, followed by oxygen uptake in active bran areas.followed by oxygen uptake in active bran areas.Computerised axial tomography (CAT or CT)Computerised axial tomography (CAT or CT) scans scans use 1000’s of narrow collimated x-ray beams rotated use 1000’s of narrow collimated x-ray beams rotated around the px. Like MRI they only capture a snapshot in around the px. Like MRI they only capture a snapshot in time, so only look at structures and damage rather than time, so only look at structures and damage rather than functions. The resolution is worse than MRI so small functions. The resolution is worse than MRI so small structures in the brain cannot be distinguished. X-rays structures in the brain cannot be distinguished. X-rays are ionising, so have potential to harm.are ionising, so have potential to harm.

Drug development & Drug development & The Human Genome The Human Genome ProjectProject

A genome is A genome is ALL ALL the DNA of an organism. The Human the DNA of an organism. The Human Genome Project (HGP) was an international project which Genome Project (HGP) was an international project which determined the base sequence of the human genome. Many determined the base sequence of the human genome. Many new genes have been identified, inc. some which are new genes have been identified, inc. some which are responsible for inherited diseases.responsible for inherited diseases.In addition, new drug targets have been identified. Info about In addition, new drug targets have been identified. Info about a px’s genome may help Drs to prescribe the correct drug at a px’s genome may help Drs to prescribe the correct drug at the correct dose. The HGP may also allow some prevention of the correct dose. The HGP may also allow some prevention of diseases. If the genes you carry are known, then you may diseases. If the genes you carry are known, then you may understand what disease you’re at risk from.understand what disease you’re at risk from.The HGP also provides info about evolution and increases our The HGP also provides info about evolution and increases our knowledge of physiology and cell biology. knowledge of physiology and cell biology. The HGP has also noted other animals and plant’s genome.The HGP has also noted other animals and plant’s genome.

The Human Genome The Human Genome Project & Ethical IssuesProject & Ethical Issues

Here are some ethical questions about the HGP:Here are some ethical questions about the HGP:Who owns the information? Some groups have applied for Who owns the information? Some groups have applied for patents on genetic sequences, so they have ownership, or patents on genetic sequences, so they have ownership, or have to be paid for any treatments developed using the have to be paid for any treatments developed using the knowledge of that sequence.knowledge of that sequence.Who is entitled to know the information about YOUR genome Who is entitled to know the information about YOUR genome if it is sequenced? Should insurance companies know? if it is sequenced? Should insurance companies know? Employers?Employers?Will genetic screen lead to the genetic selection of humans Will genetic screen lead to the genetic selection of humans (eugenics) and designer babies?(eugenics) and designer babies?Who will pay for the development of new therapies and Who will pay for the development of new therapies and drugs? Many possible highly specialised treatments are drugs? Many possible highly specialised treatments are expensive and will only be suitable for a few people.expensive and will only be suitable for a few people.

Use of GM to make Use of GM to make drugsdrugsGM plants may be useful for the production of edible drugs (eg vaccines) that can easily be GM plants may be useful for the production of edible drugs (eg vaccines) that can easily be

transported and stored in plant products (eg bananas or potatoes).transported and stored in plant products (eg bananas or potatoes).Useful genes can be transferred into crop plants by using a vector, gene guns (pellets Useful genes can be transferred into crop plants by using a vector, gene guns (pellets coated with DNA) or a virus.coated with DNA) or a virus.Restriction enzymes are used to cut DNA at specific sequences and DNA Ligase (enzyme) Restriction enzymes are used to cut DNA at specific sequences and DNA Ligase (enzyme) can stick DNA pieces together. can stick DNA pieces together. These make it possible to insert specific DNA sequences in to the GM organism. Large These make it possible to insert specific DNA sequences in to the GM organism. Large numbers of identical GM plants can easily be produced.numbers of identical GM plants can easily be produced.

Transgenic Animals (animals with a human gene added) can be used to produce drugs that Transgenic Animals (animals with a human gene added) can be used to produce drugs that can be harvested from their milk or semen. can be harvested from their milk or semen. Liposomes and viruses are vectors used to insert genes into animal cells. Drugs produces Liposomes and viruses are vectors used to insert genes into animal cells. Drugs produces from transgenic animals include the blood clotting factors used to treat haemophilia.from transgenic animals include the blood clotting factors used to treat haemophilia.

Microorganisms such as bacteria are the most common target for genetic modification as Microorganisms such as bacteria are the most common target for genetic modification as the are relatively easy targets for gene transfer and can be grown rapidly in large the are relatively easy targets for gene transfer and can be grown rapidly in large quantities in fermenters. quantities in fermenters. The drugs made can be extracted and purified using downstream processing. Insulin to The drugs made can be extracted and purified using downstream processing. Insulin to treat type II diabetes is an eg of a drug produced from GM micro-organisms.treat type II diabetes is an eg of a drug produced from GM micro-organisms.

Genetically Modified Genetically Modified PlantsPlants Bacteria

Bacteria

Plasmid carrying desired gene & antibiotic resistance Plasmid carrying desired gene & antibiotic resistance genegene(marker gene)(marker gene) ChromosomChromosom

ee

DNA gunDNA gun

Pellets coated in DNAPellets coated in DNA

BulleBullett

oror

oror

insertion insertion of new of new genegene

Virus Virus DNADNA

genes incorporated into the genes incorporated into the plant DNA of some cells.plant DNA of some cells. incubation in growth medium, incubation in growth medium,

with antibioticwith antibiotic

only cells with the only cells with the new genes survivenew genes survive

plant growth substances plant growth substances stimulate shoot and root stimulate shoot and root

growthgrowthMicropropagation: cells grow in sterile Micropropagation: cells grow in sterile culture medium, with sucrose, amino culture medium, with sucrose, amino acids, inorganic ions and plant growth acids, inorganic ions and plant growth

substances.substances.

transgenic plant - transgenic plant - all cells contain all cells contain

new genenew geneplantlets separated plantlets separated and grown into full and grown into full

size plantssize plants

Concerns over GMOsConcerns over GMOsgenetic pollution through cross-pollinationgenetic pollution through cross-pollinationantibiotic resistance genes are used to identify GM antibiotic resistance genes are used to identify GM bacteria, which could lead to antibiotic resistance in bacteria, which could lead to antibiotic resistance in other microbesother microbesGM crops could out-compete other plants and resist GM crops could out-compete other plants and resist herbicides - Become ‘Super-weeds’. They could damage herbicides - Become ‘Super-weeds’. They could damage natural food chains, resulting in damaged environment, natural food chains, resulting in damaged environment, because they would encourage farms to use selective because they would encourage farms to use selective herbicides to kill everything but the cropherbicides to kill everything but the cropGM crops may not produce fertile seeds. This prevents GM crops may not produce fertile seeds. This prevents farmers collecting seed and replanting, so may need to farmers collecting seed and replanting, so may need to return to biotech company to buy new seeds for each return to biotech company to buy new seeds for each planting - this could increase the price.planting - this could increase the price.