08/05/23

BiologyBiology

New Bridge Academy Science dept.

(AQA)

08/05/23The Nervous SystemThe Nervous SystemThe NERVOUS SYSTEM enables us to react to our surroundings. It consists mainly of the brain, the spinal chord, nerve cells (“neurones”) and receptors.

Types of receptor:1) Light receptors in the eyes2) Sound receptors in the ears3) Taste receptors on the tongue4) Smell receptors in the nose5) Touch, pressure and temperature receptors in the skin6) Changes of position receptors in the ears (balance)

08/05/23Nervous ReactionsNervous ReactionsWhen we react to a stimulus our bodies use the following pattern:

Stimulus Receptor Coordinator Effector ResponseFor example, consider

a man and a camel: Oh No!

What are the stimulus, receptor, coordinator, effector and response in this situation?

08/05/23Examples of reactionsExamples of reactionsStimulus Receptor

(i.e. the thing that detects the stimulus)

Effector (i.e. the thing that will do

the reaction)

Response (i.e. action

taken)

Bright light

Sour taste

Losing balance

Sit on a drawing pin

08/05/23Types of nerve cellTypes of nerve cellNucleus Muscle strands

(effector)Cell body

1) Motor neurone 2) Sensory neurone 3) Relay neurone

Impulse Impulse

Nerve cells (neurones) are elongated with branched endings to connect to many muscles

fibres.

08/05/23Conscious actionsConscious actionsA conscious action is one where the brain makes a considered response. Here’s what happens:

Stimulus Receptor Sensory Neurone Coordinator Motor Neurone Effector Response

1) Receptors in your skin detect a stimulus

3) Here another sensory neurone carries the signal to the brain

4) The brain decides to move away the hand

5) This impulse is sent by MOTOR NEURONES to the hand muscles (the effectors) via the spinal chord…

2) The impulse is carried by SENSORY NEURONES to the spinal chord

6) Which then moves the hand away

08/05/23Reflex actionsReflex actionsSometimes conscious action is too slow to prevent harm, e.g…

In situations like this the body bypasses the brain to produce a quicker response. Here’s how it works…

08/05/23Reflex actionsReflex actions

1. Receptor

2. Sensory neurone

3. Relay neurone in the spinal chord

4. Motor neurone

5. Effector

08/05/23SynapsesSynapses

Neurones never ____ each other – there is a small gap between them called a _____. A signal is sent from one _______ to the next by a _______ transmitter across the synapse. These transmitters are then ________.

Words – chemical, synapse, neurone, touch, destroyed

08/05/23HomeostasisHomeostasisHomeostasis means “controlling internal conditions”:

Waste products that need to be removed + howCO2

Urea

Internal conditions that need controlling + howTemperature

Ion contentWater

contentBlood

glucose

Produced by respiration, removed via lungsProduced by liver breaking down amino acids,

removed by kidneys and transferred to bladder

Increased by shivering, lost by sweatingIncreased by eating, lost by sweating + urine

Increased by drinking, lost by sweating + urineIncreased and decreased by hormones

08/05/23FertilityFertility

In normal circumstances natural hormones are responsible for releasing the egg and for thickening the lining of the womb. These hormones are produced by the pituitary gland in the brain and in the ovaries.

1) …stimulate the release of eggs

2) …inhibit the release of eggs

The amount of glucose in our blood is an example of a process controlled by hormones. Hormones are “chemical messengers”, produced by glands and tranposrted by blood. Another example of a process controlled by hormones is the menstrual cycle, where hormones can...

08/05/23FertilityFertility3 hormones are involved in the menstrual cycle: oestrogen, LH and FSH. Here’s how:

Step 3: LH stimulates the release of the mature egg in the middle of the menstrual cycle

Artificial fertility:1) To INCREASE fertility FSH is given to stimulate maturation of

eggs.

2) To DECREASE fertility oestrogen is given (“The Pill”) to inhibit FSH production stopping eggs from maturing.

Step 1: FSH produced by the pituitary gland causes both an egg to mature and the ovaries to start producing oestrogen

Step 2: The rising levels of oestrogen cause the pituitary gland to stop producing FSH and produce LH instead

08/05/23Balanced dietBalanced dietA balanced diet should contain fats, proteins and carbohydrates in roughly these amounts:

It should also contain water, vitamins, minerals and fibre.

08/05/23Poor dietsPoor dietsIf we don’t have a balanced diet we may suffer form a “deficiency symptom”:

Vitamin D

Protein

Vitamin C

Vitamin A

Iron

Calcium

Anaemia

Scurvy (bleeding gums and joints)

Weak bones and teeth

Wasting of body tissue

Rickets

Poor night vision

Lack of… Causes…

08/05/23Metabolic Rate and healthMetabolic Rate and healthThe rate at which our bodies carry out chemical reactions is called the “metabolic rate”. This rate varies with:• The amount of work we do• The amount of fat in our body• Inherited factors

Condition How this affects our health

Lack of exerciseFatty dietsWarm weatherUsing cars instead of walkingPlaying XBox instead of football

08/05/23Conditions caused by increased Conditions caused by increased weightweight

Obesity is a condition caused by excess weight. This can also lead to the following diseases:

AthiritisWhat is it?

What causes it?

Heart diseaseWhat is it?

What causes it?

High blood pressureWhat is it?

What causes it?

DiabetesWhat is it?

What causes it?

08/05/23Heart diseaseHeart disease

08/05/23CholesterolCholesterolCholesterol is a fatty substance made in the liver from saturated fats in your food. The amount of it in your blood depends on your diet and inherited factors.

Cholesterol is transported in the bloodstream attached to proteins. This combination is called a “lipoprotein”:

Low density lipoproteins (LDL)

High density lipoproteins (HDL)

• “Bad” lipoproteins• Carry cholesterol to cells• High levels of LDLs cause fat to build up in the artery

• “Good” lipoproteins• Carry cholesterol back to liver• Helps prevent cholesterol building up

08/05/23Restoring the balanceRestoring the balance

Saturated fats (“bad fats”) increase cholesterol levels.

Mono-unsaturated fats and polyunsaturates may help reduce cholesterol and restore the balance between LDLs and HDLs.

08/05/23Modern diets and health Modern diets and health problemsproblems

% obesity in the UK

08/05/23DrugsDrugs

Why do people use illegal drugs?

08/05/23Cannabis: Pros and consCannabis: Pros and consIn January 2004 cannabis was changed from a class B drug to a class C drug. Some people think that Cannabis should be made legal. What are the pros and cons of cannabis?Pros:

Cons:

08/05/23SmokingSmokingCigarettes contain 3 harmful things:1. NICOTINE, which is an ___________ drug that raises the

heart beat, narrows the arteries and so causes ____ _____ _____. This leads to heart _________.

2. TAR, which coats the lining of the _______ making them less able to take in oxygen. It also contains carcinogens which cause ______________.

3. CARBON MONOXIDE, which is a _______ ____ which joins up with ____ blood cells making them incapable of transporting _____________ around the body. In pregnant women it can cause oxygen deprivation, leading to low birth ______.Words – high blood pressure, oxygen, red, addictive,

disease, poisonous gas, lungs, cancer, mass

08/05/23Tobacco and Lung CancerTobacco and Lung Cancer

Sir Richard Doll, 1912-

2005

Over 50 years I proved the link between smoking and lung cancer. I published my first findings in 1950, based on patients in

London hospitals, and then studied 40,000 doctors and proved a link in a

paper published in 1954.

Smoking has existed in Western culture since the 16th Century. However, scientists only proved the link between it and various diseases shortly after the Second World War.

08/05/23Stopping smokingStopping smokingThere are generally two methods of stopping smoking:

“Cold turkey” – stopping completely with no help

Nicotine Replacement Therapy – e.g. Patches, gum etc

What are the advantages and disadvantages of each?

08/05/23Developing new drugsDeveloping new drugsBefore a new drug can be approved it has to go through a strict testing process. Consider the example of thalidomide:Date Event

Mid 1950s

Late 1950s

Early 1960s

Mid 1960s

Animal testing using thalidomide was undertaken. Tests showed that it was safe but the tests were “inadequate” – no tests were done on pregnant animalsThalidomide prescribed to pregnant mothers to help sleep and morning sickness problems

Babies are born with birth defects and the drug was banned worldwide. Around 12,000 deformed Thalidomide babies born, 4,000 die in first year. Tests show that Thalidomide can help leprosy sufferers and it is still used today for this purpose.

08/05/23Thalidomide childrenThalidomide children

Mat Fraser, comedian and

actor

Tony Melendez, guitarist

08/05/23Drugs Research ProjectDrugs Research ProjectExplain and give examples for the following:

1) Why do people use legal drugs?

2) What are the drawbacks of legal drugs?

3) Alchohol is a legal drug. What does it do to the human body?

4) Why do people use illegal drugs?

5) What are the drawbacks of illegal drugs? What can they cause?

6) Choose one drug and discuss how it affects the human body

08/05/23MicrobesMicrobesMicrobes are micro organisms that can cause diseases. They can enter the body in a number of ways:

…or other natural openings…

They can be breathed in through the mouth or nose

They can enter through cuts or bites in the skin

08/05/23DiseaseDiseaseA disease is any condition where the body isn’t working as it should. This could be caused by a malfunction in the body (as with diabetes) or it could be caused by a type of PATHOGEN (a microbe that causes disease): VirusesBacteria

• 1/1000th mm big• Living cells (some are harmless)• Grow very quickly• Affected by antibiotics• Examples: food poisoning, tetanus, sore throats

• 1/1,000,000th mm big• Genetic info inside a protein coat• Not affected by antibiotics• Release poisons• Examples: colds, flu, polio, chicken pox

08/05/23Microbes: our defence against Microbes: our defence against themthem

Our bodies have four major defence mechanisms against invading microbes:

If our skin is cut platelets seal the wound by clotting

The breathing organs produce mucus to cover the lining of these organs and trap the microbes

The skin acts as a barrier

Our blood contains white blood cells

08/05/23Fighting diseaseFighting diseaseIf microbes enter our body they need to be neutralised or killed. This is done by WHITE BLOOD CELLS:

White blood cells do 3 things:1) They eat the microbe2) They produce antibodies to

neutralise the microbe3) The produce antitoxins to

neutralise the poisons produced by microbes

08/05/23Producing antibodiesProducing antibodies

Step 1: The white blood cell “sees” the pathogen (microbe)

Step 2: The cell produces antibodies to “fit” the pathogen

Step 3: The antibodies fit onto the pathogens and cause them to “clump”

Step 4: The pathogens are “eaten” by the white blood cells

You’re going down

08/05/23Fighting diseaseFighting diseaseNATURAL IMMUNITYThis is when antibodies are produced by a person when needed or they are passed on by the mother during pregnancy.

ARTIFICIAL IMMUNITYCan be done in two ways:1) A vaccine with dead microbes is

injected – the body is “tricked” into producing antibodies ready for the real thing. This is called PASSIVE IMMUNISATION

2) The antibodies are injected directly into the body – this is called ACTIVE IMMUNISATION.

08/05/23Using AntibioticsUsing AntibioticsAntibiotics can be used to kill bacteria. However, there

are two problems: 1) Overuse of antibiotics can lead

to bacteria becoming resistant (e.g. the MRSA “superbug”). This means that antibiotics must be used sparingly.

2) Antibiotics have no effect on a virus, like the common cold. It is difficult to kill a virus without damaging body tissue. A virus is usually allowed to “run its course”.

08/05/23A smaller example…A smaller example…Although vaccinations and antibiotics are useful in the fight against pathogens, bacteria and virii can mutate to form a new, resistant “strain”:

1) Variation – some strains of bacteria are resistant and some aren’t.

2) Competition – The non-resistant bacteria are killed by the penicillin.

3) Survival of the fittest – the resistant bacteria survive.

4) Passing on of genes – the resistant bacteria reproduce and pass on their adaptations to their offspring. This is how the bird flu virus developed.

Bacteria

Penicillin

08/05/23Using PainkillersUsing PainkillersPainkillers are drugs used to relieve the symptoms of disease but without killin the pathogens, for example:

ParacetamolAspirin

Ibuprofen

08/05/23The spread of infectionThe spread of infection

Ignaz Semmelweiss

1818-1865

Guten tag. In the mid-19th century I realised that many deaths in hospitals could be avoided by insisting on clean hands and equipment. As a result of my work deaths

in my wards fell from 12% to 1%.

More people die due to infections from hospitals than on the roads in Britain. Hospitals have been trying to improve hygiene standards:

Year Amount of hand wash solution used

(litres per 1000 patient days)

MRSA infections per 100 patients

1993 3.5 0.501995 6.9 0.481997 10.9 0.25

08/05/23VaccinationsVaccinationsSome people argue that the MMR vaccine is a good idea, others think it is a bad idea. Briefly summarise each side of the argument:

MMR vaccine

For Against