PowerPoint Presentation

TheNervousSystem

KEYWORDS (Write these into your journal book and find the definition as part of your weeks homework)Gland, Hormone, Impulse, Nervous system, Effector, Stimulus, Receptor, Neurone, Synapse1STARTERName 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 minutesWorking Groups: Your choice of 1, 2 or 3ENDOCRINE SYSTEM2STARTER continuedName the hormones Have you thought of any others?

Time: 10 seconds to add them to your list3STARTER 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)4 I AM LEARNING TO understand how the body is controlled

I WILL LEARN THATThe 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 controls its functions and responses through hormones (chemicals) and nerves (electrical impulses)LEARNING OBJECTIVES5Identification of the density of nerve endings

AIM: To investigate the sensitivity of different areas of the skin.Method: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. The blindfolded student has to say whether it was one point or two points that touched them. 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?6CONTROL SYSTEMSThere are two main control systems in your body.Nervous system which has two main sectionscentral or CNS that is made up of the spinal cord and brain and functions to coordinate all actions of the body peripheral 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 SNS which is associated with the voluntary control of body movements and is made up of all neurones, sense organs, skin, skeletal musclesAutonomic 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 system works in actions that do not require a fast response (fight or fight response)Sympathetic nervous system works in actions that do require a fast response (rest and digest response)Endocrine system which is a system of glands that release a number of signalling chemicals known as hormones.7Say what?NERVOUS SYSTEMCNSPNSANSSNSParasympatheticSympatheticNervous 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 neuronesEndocrine 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.8NERVOUSSYSTEM9Parts of the nervous systemThe nervous system is made up of three main parts;The brainThe spinal cordNerve fibres

It detects stimuli such as light, sounds, temperature, pressure, pain and co-ordinates the bodies response.

10Parts of the nervous systemFor example;If you smell something burningYour nose (receptor) detects the stimulus (smell)Nerve fibres send the message to the brainYour brain then sends a message to move your body away or to put out the fire! SIMPLES RIGHT!

11Lets look at some bits more closelyRECEPTORSReceptors are sensors on the body that detect stimuliThey convert stimuli into electrical signals (messages) called impulses.Can you think of any receptors?

Ear picks up sound waves through the eardrumNose picks upchemical signalsthrough thenostrilsEyes pick uplight wavesthrough theretina12EFFECTORSAn effector is any part of the body that produces the response.

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 hormone into the blood

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NERVE FIBRESNerve fibres are bundles of nerve cells (neurones) that pass on electrical signals (impulses) to the brain.From the brain, nerve fibres send impulses to effectors (muscles).14NEURONESThere are three types of neuronesSensory neurone carries impulses from the receptors to the spinal cord.Relay Neurone carries impulses to and from the spinal cord and the brainMotor Neurone carries impulses from the brain to the effector

15Multiple-choice quiz

16Teacher notesThis multiple-choice quiz could be used as a plenary activity to assess students understanding of electrical signals. The questions can be skipped through without answering by clicking next. Students could be asked to complete the questions in their books and the activity could be concluded by the completion on the IWB. SYNAPSESWhere two neurones meet, there is a tiny gap called a synapse. Signals cross this gap using chemicals. One neurone releases the chemical into the gap. The chemical diffuses across the gap and makes the next neurone 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 process17

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 cellpostsynaptic cell

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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 vesicleneurotransmitter molecules

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Continuing the impulseThe neurotransmitters diffuse across the synaptic cleft and bind with receptors on the next neurone, triggering another impulse.nerve impulsereceptorsynaptic cleft

20The stick drop test!METHOD: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. 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. Repeat several times, so that a mean can be calculated. Then change around so that everyone gets a turn. Write a report of the experiment.

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? 21REFLEX ARCWhen your body needs to react to something very quickly (to protect itself) it uses a reflex arc (spinal reflex). Instead of sending impulses from the receptorSpinal cord brain spinal cord effector

It sends impulses from the receptor spinal cordeffectorYup it bypasses the brain!http://www.bbc.co.uk/schools/gcsebitesize/science/aqa/human/thenervoussystemrev3.shtml

22ANSWERS

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.

The sequence of a reflex arc

24Teacher notesThis ordering activity could be used as a plenary or revision exercise on reflex arcs. Mini-whiteboards could be used to make this a whole-class exercise.REFLEX ACTIONThe way the iris in our eye adjusts the size of the pupil in response to bright or dim light is also a reflex action.In bright lightIn dim lightRadial 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.

http://www.bbc.co.uk/schools/gcsebitesize/science/aqa/human/thenervoussystemrev3.shtml

25The iris reflex

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Inside the eyelensfocuses lighton retinairisregulates amountof light entering eyeciliary muscleschange shape of the lensoptic nervetransmits impulses to the braincorneaprotects eye surface and focuses light raysretinasenses lighthold lens in placesuspensory ligaments

27REFLEX ACTION

28PASS THE ZAPSome 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. 29

effectorSense organ/receptorNERVE PATHWAY Have a go at completing this worksheet30NERVE PATHWAY answersSENSORY NEURONETakes impulses from the sense organ to the relay neurone.RELAY NEURONETakes impulses to the brain and from the brain.MOTOR NEURONETakes impulses from the relay neurone to the effector.BRAINReceives impulses from the spinal cord and sends out new impulses.SENSE ORGAN/ RECEPTORSenses stimuli from our surroundings.EFFECTORThe muscle that receives the impulse from motor neurone.SPINAL CORDWhere the relay neurones are found.31NERVOUS SYSTEM answersREFLEXPROTECTION GIVENBLINKINGTo eyeCOUGHINGStops us chokingSNEEZINGRemoves blockages from the nosePUPILS CHANGE SIZEProtects the retina4a) 37m 55m/s = 0.67s4b) RT = d s = 20m 40m/s = 0.5s4c) sensory receptor in eye sensory neurone relay neurone - brain motor neurone - effector4d) i) brain, ii) takes too long iii) Stimulussensory neurone relay neuronemotor neurone effector32Glossary (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.

33Glossary (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.

34 I AM LEARNING TO understand how the body is controlled

I WILL LEARN THATThe 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 controls its functions and responses through hormones (chemicals) and nerves (electrical impulses)LEARNING OBJECTIVES35