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The Nervous System. 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, Synapse. STARTER. ENDOCRINE SYSTEM.

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The Nervous System

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The nervous system

The

Nervous

System

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, Synapse


Starter

STARTER

ENDOCRINE SYSTEM

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 continued

STARTER continued

Name the hormones – Have you thought of any others?

Time: 10 seconds to add them to your list


Starter answers

STARTER answers

Pituitary 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)


The nervous system

LEARNING OBJECTIVES

  • 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 CAN

  • Explain how the body control’s its functions and responses through hormones (chemicals) and nerves (electrical impulses)


The nervous system

  • Identification 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?


Control systems

CONTROL SYSTEMS

There are two main control systems in your body.

  • Nervous system – which has two main sections

    • central 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 muscles

      • Autonomic 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.


  • Say what

    NERVOUS SYSTEM

    Say what?

    CNS

    PNS

    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 neurones

    SNS

    ANS

    Parasympathetic

    Sympathetic

    Endocrine 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.


    The nervous system

    NERVOUS

    SYSTEM


    Parts of the nervous system

    Parts of the nervous system

    The nervous system is made up of three main parts;

    • The brain

    • The spinal cord

    • Nerve fibres

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


    Parts of the nervous system1

    Parts 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 brain

    • Your brain then sends a message to move your body away or to put out the fire!

      SIMPLES RIGHT!


    Lets look at some bits more closely receptors

    Lets look at some bits more closelyRECEPTORS

    • Receptors are sensors on the body that detect stimuli

    • They convert stimuli into electrical signals (messages) called impulses.

    Eyes pick up

    light waves

    through the

    retina

    Can you think

    of any receptors?

    Nose picks up

    chemical signals

    through the

    nostrils

    Ear picks up

    sound waves

    through the

    eardrum


    Effectors

    EFFECTORS

    An 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


    Nerve fibres

    NERVE FIBRES

    • Nerve 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).


    Neurones

    NEURONES

    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 brain

    • Motor Neurone – carries impulses from the brain to the effector


    Multiple choice quiz

    Multiple-choice quiz


    Synapses

    SYNAPSES

    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.

    http://www.bbc.co.uk/schools/gcsebitesize/science/aqa/human/thenervoussystemrev2.shtml

    Watch this video on synapses then draw a flow chart of the process


    What is a synapse

    presynaptic cell

    postsynaptic cell

    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.


    The release of neurotransmitters

    synaptic vesicle

    neurotransmitter molecules

    The release of neurotransmitters

    When a nerve impulse arrives at the end of one neurone it triggers the release of neurotransmitter molecules from synaptic vesicles.


    Continuing the impulse

    synaptic cleft

    nerve impulse

    receptor

    Continuing the impulse

    The neurotransmitters diffuse across the synaptic cleft and bind with receptors on the next neurone, triggering another impulse.


    The stick drop test

    The 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?


    Reflex arc

    REFLEX ARC

    • When 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 receptor

      Spinal cord brain spinal cord effector

    • It sends impulses from the receptor

      spinal cordeffector…Yup it bypasses the brain!

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


    The nervous system

    ANSWERS

    • 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

    The sequence of a reflex arc


    Reflex action

    REFLEX 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


    The iris reflex

    The iris reflex


    Inside the eye

    Inside the eye

    cornea

    protects eye surface and focuses light rays

    suspensory ligaments

    hold lens in place

    lens

    focuses lighton retina

    retina

    senses light

    iris

    regulates amountof light entering eye

    ciliary muscles

    optic nerve

    transmits impulses to the brain

    change shape of the lens


    Reflex action1

    REFLEX ACTION


    Pass the zap

    PASS 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.


    Nerve pathway have a go at completing this worksheet

    NERVE PATHWAY… Have a go at completing this worksheet

    effector

    Sense organ/

    receptor


    Nerve pathway answers

    NERVE PATHWAY… answers

    SENSE ORGAN/ RECEPTOR

    Senses stimuli from our surroundings.

    SENSORY NEURONE

    Takes impulses from the sense organ to the relay neurone.

    SPINAL CORD

    Where the relay neurones are found.

    RELAY NEURONE

    Takes impulses to the brain and from the brain.

    EFFECTOR

    The muscle that receives the impulse from motor neurone.

    BRAIN

    Receives impulses from the spinal cord and sends out new impulses.

    MOTOR NEURONE

    Takes impulses from the relay neurone to the effector.


    Nervous system answers

    NERVOUS SYSTEM… answers

    4c) sensory receptor in eye – sensory neurone – relay neurone - brain – motor neurone - effector

    4a) 37m

    55m/s

    = 0.67s

    4b) RT = ds

    = 20m

    40m/s

    = 0.5s

    4d) i) brain, ii) takes too long

    iii) Stimulussensory neurone

    relay neuronemotor neurone

    effector


    Glossary 1 2

    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.


    Glossary 2 2

    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 thatcarries electrical impulses from sense organs to the CNS.

    • synapse– The gap between two connecting neurones.


    The nervous system

    LEARNING OBJECTIVES

    • 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 CAN

    • Explain how the body control’s its functions and responses through hormones (chemicals) and nerves (electrical impulses)


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