Presentation on theme: "The Nervous System KEYWORDS (Write these into your journal book and find the definition as part of your weeks homework) Gland, Hormone, Impulse, Nervous."— Presentation transcript:
1TheNervousSystemKEYWORDS (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, Synapse
2ENDOCRINE SYSTEM STARTER 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 minutesWorking Groups: Your choice of 1, 2 or 3
3STARTER continued Name the hormones – Have you thought of any others? Time: 10 seconds to add them to your list
4STARTER 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)
5I AM LEARNING TO understand how the body is controlled LEARNING OBJECTIVESI AM LEARNING TO understand how the body is controlledI 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 control’s its functions and responses through hormones (chemicals) and nerves (electrical impulses)
6Identification 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?
7CONTROL SYSTEMS There 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 bodyperipheral 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 intosomatic 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 intoParasympathetic 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.
8Say what? NERVOUS SYSTEM CNS PNS SNS ANS Parasympathetic Sympathetic Nervous 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 neuronesSNSANSParasympatheticSympatheticEndocrine 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.
10Parts of the nervous system The nervous system is made up of three main parts;The brainThe spinal cordNerve fibresIt detects stimuli such as light, sounds, temperature, pressure, pain and co-ordinates the bodies response.
11Parts of the nervous system For example;If you smell something burning…Your 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!
12Lets look at some bits more closely RECEPTORS Receptors are sensors on the body that detect stimuliThey convert stimuli into electrical signals (messages) called impulses.Eyes pick uplight wavesthrough theretinaCan you thinkof any receptors?Nose picks upchemical signalsthrough thenostrilsEar picks upsound wavesthrough theeardrum
13EFFECTORSAn effector is any part of the body that produces the response.Here are some examples of effectors:a muscle contracting to move the arma muscle squeezing saliva from the salivary glanda gland releasing a hormone into the blood
14NERVE 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).
15NEURONES There are three types of neurones Sensory 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
16Multiple-choice quiz Teacher notes This 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.
17Watch this video on synapses then draw a flow chart of the process Where 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.Watch this video on synapses then draw a flow chart of the process
18What 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
19The release of neurotransmitters When a nerve impulse arrives at the end of one neurone it triggers the release of neurotransmitter molecules from synaptic vesicles.synaptic vesicleneurotransmitter molecules
20Continuing the impulse The neurotransmitters diffuse across the synaptic cleft and bind with receptors on the next neurone, triggering another impulse.synaptic cleftnerve impulsereceptor
21The 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?
22REFLEX 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 effectorIt sends impulses from the receptorspinal cord effector…Yup it bypasses the brain!
23ANSWERSElectrical 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 theeffect or make a response.
24The sequence of a reflex arc Teacher 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.
25REFLEX ACTION 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.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.
27Inside the eye cornea protects eye surface and focuses light rays hold lens in placesuspensory ligamentsretinasenses lightlensfocuses light on retinairisregulates amount of light entering eyeciliary muscleschange shape of the lensoptic nervetransmits impulses to the brain
29PASS 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.
30NERVE PATHWAY… Have a go at completing this worksheet
31NERVE PATHWAY… answers SENSE ORGAN/ RECEPTORSenses stimuli from our surroundings.SENSORY NEURONETakes impulses from the sense organ to the relay neurone.SPINAL CORDWhere the relay neurones are found.RELAY NEURONETakes impulses to the brain and from the brain.EFFECTORThe muscle that receives the impulse from motor neurone.BRAINReceives impulses from the spinal cord and sends out new impulses.MOTOR NEURONETakes impulses from the relay neurone to the effector.
32NERVOUS SYSTEM… answers REFLEXPROTECTION GIVENBLINKINGTo eyeCOUGHINGStops us chokingSNEEZINGRemoves blockages from the nosePUPILS CHANGE SIZEProtects the retina4a) 37m55m/s= 0.67s4b) RT = d s= 20m40m/s= 0.5s4c) sensory receptor in eye – sensory neurone – relay neurone - brain – motor neurone - effector4d) i) brain, ii) takes too longiii) Stimulus sensory neuronerelay neurone motor neuroneeffector
33Glossary (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.
34Glossary (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.
35I AM LEARNING TO understand how the body is controlled LEARNING OBJECTIVESI AM LEARNING TO understand how the body is controlledI 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 control’s its functions and responses through hormones (chemicals) and nerves (electrical impulses)