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

GCSE Biology 1A

Human Biology

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.

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Time: 10 minutes

Working Groups: Your choice of 1, 2 or 3

GCSE Biology 1A

Human Biology

I AM LEARNING TO understand how the body is controlled

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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.

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I CAN

Explain 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 endings –

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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?

GCSE Biology 1A

Human Biology

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.

GCSE Biology 1A

Human Biology

Say what?

NERVOUS SYSTEM

CNS

PNS

ANS

SNS

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 neurones

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.

GCSE Biology 1A

Human Biology

GCSE Biology 1A

Human Biology

Parts of the nervous system

The nervous system is made up of three main parts;

• The brain
• The spinal cord
• Nerve fibres

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

GCSE Biology 1A

Human Biology

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!

GCSE Biology 1A

Human Biology

Lets look at some bits more closely�RECEPTORS

• Receptors are sensors on the body that detect stimuli
• They convert stimuli into electrical signals (messages) called impulses.

GCSE Biology 1A

Human Biology

EFFECTORS

An effector is any part of the body that produces the response.

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Here are some examples of effectors:

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• a muscle contracting to move the arm
• a muscle squeezing saliva from the salivary gland
• a gland releasing a hormone into the blood

GCSE Biology 1A

Human Biology

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).

GCSE Biology 1A

Human Biology

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

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GCSE Biology 1A

Human Biology

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

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Watch 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.

GCSE Biology 1A

Human Biology

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.

GCSE Biology 1A

Human Biology

Continuing the impulse

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

GCSE Biology 1A

Human Biology

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.

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CONCLUSION AND DISCUSSION:

What was the accuracy of the measurements, the calculation of means and the control of variables?

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Identify the parts of the body involved. What senses are being used? Can we train ourselves to react more quickly? Does practice make perfect?

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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 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

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• 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

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GCSE Biology 1A

Human Biology

ANSWERS

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• 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 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

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GCSE Biology 1A

Human Biology

REFLEX ACTION

GCSE Biology 1A

Human Biology

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.

GCSE Biology 1A

Human Biology

Glossary (1/2)

• 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 CAN

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

LEARNING OBJECTIVES

GCSE Biology 1A

Human Biology