Download - The Nervous System
GCSE Biology 1A Human Biology
KEYWORDSKEYWORDS (Write these into your journal book and find the definition as part of your weeks homework)
Gland, Hormone, Impulse, Nervous system, Effector, Stimulus, Gland, Hormone, Impulse, Nervous system, Effector, Stimulus, Receptor, Neurone, SynapseReceptor, Neurone, Synapse
GCSE Biology 1A Human Biology
Name the hormones – Using Figure 2 on page 24 of the Student Book, write down the names of the hormones secreted by the glands shown on the diagram.
Time: 10 minutes
Working Groups: Your choice of 1, 2 or 3
STARTER
GCSE Biology 1A Human Biology
STARTER continued
Name the hormones – Have you thought of any others?
Time: 10 seconds to add them to your list
GCSE Biology 1A Human Biology
STARTER answersPituitary gland – FSH, LH (stimulates the release and maturity of
follicles during menstruation)Thyroid gland – Thyroxine (regulates the rate of metabolism)Adrenal gland - corticosteroids and catecholamines including
cortisol and adrenaline and small amounts of testosterone (regulates stress levels)
Pancreas – peptides (regulates the production of shorter active digestive enzymes)
Ovary – oestrogen, progesterone and small amounts of testosterone (regulates the growth of eggs and stabilises the growing foetus during pregnancy)
Testis – testosterone (plays a key role in the health and well-being of the man)
GCSE Biology 1A Human Biology
I AM LEARNING TO understand how the body is controlled
I WILL LEARN THAT•The nervous system enables humans to react to their surroundings and coordinate their behaviour. • Receptors detect stimuli which include light, sound, changes in position, chemicals, touch, pressure, pain and temperature. • Information from receptors passes along cells (neurones) in nerves to the brain. The brain coordinates the response.• Many processes in the body are coordinated by chemical substances called hormones. Hormones are secreted by glands and are transported to their target organs by the bloodstream.
I CANExplain how the body control’s its functions and responses through hormones (chemicals) and nerves (electrical impulses)
LEARNING OBJECTIVES
GCSE Biology 1A Human Biology
Identification of the density of nerve endingsIdentification of the density of nerve endings –
AIM: To investigate the sensitivity of different areas of the skin.Method:1. Working in pairs, one student looks in a different direction,
while another student touches them on the back of the hand with either one or two pieces of blunt pencil about 1 cm apart.
2. The blindfolded student has to say whether it was one point or two points that touched them.
3. Place a cross on the hand for each point felt.Results:Map the density of sensory receptors by drawing it into your book.Conclusion:Are the receptors in groups? Or randomly placed? What can you
say about the density of the receptors identified?
GCSE Biology 1A Human Biology
CONTROL SYSTEMSCONTROL SYSTEMSThere are two main control systems in your body.1.1. Nervous systemNervous system – which has two main sections
• central or CNScentral or CNS that is made up of the spinal cord and brain and functions to coordinate all actions of the body
• peripheral or PNSperipheral or PNS that is made up of the bodies nerves and functions to connect the CNS to the rest of the body through neurones. PNS is further divided into – somatic or SNSsomatic or SNS which is associated with the voluntary control of body movements
and is made up of all neurones, sense organs, skin, skeletal muscles– Autonomic or ANSAutonomic or ANS which is associated with the involuntary control of body
movements such as reflex and controls such things as heart rate, body temperature, digestion etc. The ANS is further divided into » Parasympathetic nervous systemParasympathetic nervous system works in actions that do not require a fast
response (fight or fight response)» Sympathetic nervous systemSympathetic nervous system works in actions that do require a fast response
(rest and digest response)
2.2. Endocrine systemEndocrine system – which is a system of glands that release a number of signalling chemicals known as hormones.
GCSE Biology 1A Human Biology
Say what?Say what? NERVOUS SYSTEMNERVOUS SYSTEM
CNSCNS PNSPNS
ANSANS SNSSNS
ParasympatheticParasympathetic SympatheticSympathetic
Nervous systemNervous system releases electrical impulses that are quick but the effects are short lived and it involves the CNS (either just spinal cord or both spinal cord and brain) messages are carried by neurones
Endocrine systemEndocrine system releases chemical signals that are slow to react but the effects are long lasting. This does not involve the CNS. Messages are carried by the blood.
GCSE Biology 1A Human Biology
Parts of the nervous systemParts of the nervous system
The nervous systemnervous system is made up of three main parts;
• The brain• The spinal cord• Nerve fibres
It detects stimulistimuli such as light, sounds, temperature, pressure, pain and co-ordinates the bodies response.
GCSE Biology 1A Human Biology
Parts of the nervous systemParts of the nervous system
For example;
If you smell something burning…
• Your nose (receptorreceptor) detects the stimulusstimulus (smell)
• Nerve fibresNerve fibres send the message to the brainbrain
• Your brainbrain then sends a message to move your body away or to put out the fire!
SIMPLES RIGHT!SIMPLES RIGHT!
GCSE Biology 1A Human Biology
Lets look at some bits more closelyLets look at some bits more closelyRECEPTORSRECEPTORS
• Receptors are sensors on the body that detect stimuli
• They convert stimuli into electrical signalselectrical signals (messages) called impulses.
GCSE Biology 1A Human Biology
EFFECTORSEFFECTORSAn effectoreffector is any part of the body that produces the responseresponse.
Here are some examples of effectors:
• a muscle contracting to move the arm • a muscle squeezing saliva from the salivary gland • a gland releasing a hormonehormone into the blood
GCSE Biology 1A Human Biology
NERVE FIBRESNERVE FIBRES• Nerve fibres are bundles of nerve cells (neurones)(neurones)
that pass on electrical signals (impulses)(impulses) to the brain.
• From the brain, nerve fibres send impulses to effectorseffectors (muscles).
GCSE Biology 1A Human Biology
NEURONESNEURONESThere are three types of neuronesThere are three types of neurones1.1. Sensory neuroneSensory neurone – carries impulses from the receptors to the
spinal cord.2.2. Relay NeuroneRelay Neurone – carries impulses to and from the spinal cord
and the brain3.3. Motor NeuroneMotor Neurone – carries impulses from the brain to the effector
GCSE Biology 1A Human Biology
SYNAPSESSYNAPSESWhere two neuronesneurones meet, there is a tiny gap called
a synapsesynapse. Signals cross this gap using chemicalschemicals. One neuroneneurone releases the chemical into the gap. The chemicalchemical diffuses across the gap and makes the
next neuroneneurone transmit an electrical signal.
http://www.bbc.co.uk/schools/gcsebitesize/science/aqa/human/thenervoussystemrev2.shtml
Watch this video on synapses then draw a flow chart of the processWatch this video on synapses then draw a flow chart of the process
GCSE Biology 1A Human Biology
What is a synapse?A synapse is a junction between two neurones across which electrical signals pass. The human body contains up to 500 trillion synapses.
presynaptic cell
postsynaptic cell
GCSE Biology 1A Human Biology
The release of neurotransmittersWhen a nerve impulse arrives at the end of one neurone it triggers the release of neurotransmitter molecules from synaptic vesicles.
synaptic vesicle
neurotransmitter molecules
GCSE Biology 1A Human Biology
Continuing the impulseThe neurotransmitters diffuse across the synaptic cleft and bind with receptors on the next neurone, triggering another impulse.
nerve impulse
receptor
synaptic cleft
GCSE Biology 1A Human Biology
The stick drop test!The stick drop test!METHOD:METHOD:1. Working in pairs, one student holds a metre rule vertically at the zero end, between
the thumb and forefinger of another student, so that the 50 cm mark is level with the top of the forefinger.
2. Without warning, the first student drops the rule and the second student attempts to catch it between the thumb and forefinger, noting the distance on the ruler just above the forefinger.
3. Repeat several times, so that a mean can be calculated. 4. Then change around so that everyone gets a turn. Write a report of the experiment.
CONCLUSION AND DISCUSSION: CONCLUSION AND DISCUSSION: What was the accuracy of the measurements, the calculation of means and the control
of variables?
Identify the parts of the body involved. What senses are being used? Can we train ourselves to react more quickly? Does practice make perfect?
Can we alter reflex actions? – think of a situations where it is possible to alter the automatic response (not dropping a hot object, deliberately breathing more slowly, etc.). Are there some reflex actions over which we have no control?
GCSE Biology 1A Human Biology
REFLEX ARCREFLEX ARC• When your body needs to react to something very
quickly (to protect itself) it uses a reflex arcreflex arc (spinal reflex).
• Instead of sending impulses from the receptorSpinal cord brain spinal cord effector
• It sends impulses from the receptor spinal cord effector…Yup it bypasses the brain!
http://www.bbc.co.uk/schools/gcsebitesize/science/aqa/human/thenervoussystemrev3.shtml
GCSE Biology 1A Human Biology
ANSWERSANSWERS
• Electrical impulses along neurones, chemical (neurotransmitters) across the synapse.
• The microscopic gap between two neurones.• By chemicals called neurotransmitters.• To pass the impulse onto the correct motor
neurone.• Glands or muscle that produce the effect or make a response.
GCSE Biology 1A Human Biology
REFLEX ACTIONREFLEX ACTION
The way the iris in our eye adjusts the size of the pupil in response to bright or dim light is also a reflex action.
http://www.bbc.co.uk/schools/gcsebitesize/science/aqa/human/thenervoussystemrev3.shtml
In bright light
In dim light
•Radial muscles of the iris relax.
•Circular muscles of the iris contract.
•Less light enters the eye through the contracted pupil.
•Radial muscles of the iris contract.
•Circular muscles of the iris relax.
•More light enters the eye through the dilated pupil.
GCSE Biology 1A Human Biology
Inside the eye
lensfocuses lighton retina
irisregulates amountof light entering eye
ciliary muscleschange shape of the lens
optic nervetransmits impulses to the brain
corneaprotects eye surface and focuses light rays
retinasenses lighthold lens in place
suspensory ligaments
GCSE Biology 1A Human Biology
PASS THE ZAPPASS THE ZAP• Some volunteers get an A4 sheets on which
the names of parts of the reflex pathway are to be written.
• The students should then arrange themselves in the correct order.
• Using a lightning-shaped zap, each student is to talk through their bit of the process as the impulse (zap) gets passed to them.
GCSE Biology 1A Human Biology
NERVE PATHWAY… NERVE PATHWAY… Have a go at completing this worksheetHave a go at completing this worksheet
GCSE Biology 1A Human Biology
NERVE PATHWAY… NERVE PATHWAY… answersanswers
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GCSE Biology 1A Human Biology
NERVOUS SYSTEM… NERVOUS SYSTEM… answersanswers
REFLEX PROTECTION GIVEN
BLINKINGBLINKING To eye
COUGHINGCOUGHING Stops us choking
SNEEZINGSNEEZING Removes blockages from the nose
PUPILS CHANGE SIZEPUPILS CHANGE SIZE Protects the retina
4a) 37m 55m/s = 0.67s4b) RT = d
s = 20m
40m/s = 0.5s
4c) sensory receptor in eye – sensory neurone – relay neurone - brain – motor neurone - effector
4d) i) brain, ii) takes too long
iii) Stimulus sensory neurone
relay neurone motor neurone
effector
GCSE Biology 1A Human Biology
Glossary (1/2)accommodation – The reflex reaction that keeps the
lens the right shape to focus light on the retina.
CNS – The central nervous system, consisting of the brain and spinal cord.
iris – The part of the eye that limits the amount of light entering the eye.
lens – The part of the eye that focuses light on the retina.
motor neurone – A neurone that carries electrical impulses from the CNS to muscles and glands.
neurone – A specialized cell that carries electrical impulses.
GCSE Biology 1A Human Biology
Glossary (2/2)
neurotransmitter – A chemical that diffuses across synapses to continue an impulse in a connecting neurone.
reaction time – The time taken to respond to a stimulus.
reflex – A fast, automatic protective response.
retina – The part of the eye that contains light receptors.
sensory neurone – A neurone that carries electrical impulses from sense organs to the CNS.
synapse – The gap between two connecting neurones.
GCSE Biology 1A Human Biology
I AM LEARNING TO understand how the body is controlled
I WILL LEARN THAT•The nervous system enables humans to react to their surroundings and coordinate their behaviour. • Receptors detect stimuli which include light, sound, changes in position, chemicals, touch, pressure, pain and temperature. • Information from receptors passes along cells (neurones) in nerves to the brain. The brain coordinates the response.• Many processes in the body are coordinated by chemical substances called hormones. Hormones are secreted by glands and are transported to their target organs by the bloodstream.
I CANExplain how the body control’s its functions and responses through hormones (chemicals) and nerves (electrical impulses)
LEARNING OBJECTIVES