nervous system.pdf

8/14/2019 nervous system.pdf

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THE NERVOUS SYSTEM

The functions of the nervous system are:

To allow the different parts of the body to work together, that is coordinate. To allow the individual to be aware of and react to its surroundings.

The things in the surroundings to which we react are called stimuli (singular: stimulus)

and the way we react is called a response.

Study the two cartoons below and identify the stimulus and the response in each case by completing

the table below.

CARTOON STIMULI RESPONSE

1.

2.

Angus dropped a brick on his foot Angus shouting and grabbing foot

Bones saw cat, Tug on the lead Bones chased the cat, Rosie is chasing after dog with leash


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THE STRUCTURE OF THE NERVOUS SYSTEM

Using the diagram identify the three main parts.

1.

2.

3.

The nervous system is often divided into two sections:

1. The Central Nervous System , often abbreviated to C.N.S.2. The Peripheral Nervous System, abbreviated to P.N.S.

Classify the parts labeled in the diagram as belonging to the central or peripheral nervous systems .

C.N.S. P.N.S.

BrainSpinal Cord

Nerves to and from the body

Brain and Spinal Cord Nerves to and from leg and arm internal organs of abdomen and chest


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THE BRAIN

The two functions of the brain are to:

1. To receive messages from the sense organs in the body and to send messages to other parts ofthe body to respond if required.

2. To store information from past experiences so we can learn remember and think. This allowshumans to speak, solve problems and be creative.

What type and number of cells are found in the brain of an adult?

Using the diagram identify the three main parts of the brain.

PART FUNCTION (job)

1.

2.

3.

Briefly describe the function of each part in the table above.

What is the cortex?

What jobs are done by different parts of the cortex?

Approximately 10 000 million nerve cells

Cerebellum Receives sensations from sense organs it is the place where thinking, remembering and problem solving occur. Places where voluntary decisions are made

Medulla Controls muscles of the body so that they work in harmony

Cerebrum Controls involuntary bodily processses like heartbeat, blood, circulation, salivation and cell respiration

Outer wrinlked part of the cerebrum

All jobs listed next to cerebrum


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SENSES, SENSE ORGANS AND THEIR SENSORY NERVES

What is the job of the five main senses in the human body?

What are (a) the sense organs?

(b) the sensory nerves?

Complete the following table by identifying the organ for each sense and name the sensory nerve.

SENSE SENSE ORGAN SENSORY NERVE

Sight ____________ nerve

Hearing ____________ nerve

Taste tastebuds

Smell _____________ nerve

Touch Contains different types of

sensory nerve endings to detect

different stimuli.

SENSORY NERVE ENDINGS IN THE SKIN

Inform us about what is happening in our surroundings

parts of the body that detect what is happening in our surroundings

Nerves that carry information from the same organs to the central nervous system

Eyes

Ears

Optic

Auditory

Tongue

Nose olfactory

Skin


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NORMAL PATH OF A NERVOUS IMPULSE

Distinguish between receptors and effectors.

Identify the receptors and effectors found in the human body.

RECEPTORS EFFECTORS

Using the diagram above to create a flow chart that shows the normal path of an electric impulse

through the body from the receptor to the effector as a person finds their keys in their pocket.

REMEMBER in flow charts to use elongated circles for the start or end of the process , rectangles to

indicate the steps in the process and diamonds for the points at which decisions are made.

Receptors receive information from the surroundings while effectors respond to the information

Sensory Organs Muscles and Glands


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Complete the following paragraph to describe the path of an electric impulse for a girl that is picking a

flower.

The girl sees the flower and the _________ nerve in her eye sends an electrical impulse to her

___________which makes a decision to pick the flower. The message is relayed down the ___________

_________ to the _________ nerves leading to the __________ in your body which allows you to pick

the flower.

REFLEX ACTIONS

What is a reflex action?

When do reflex actions normally occur?

Is the brain is informed of a reflex action?

What can happen when the brain is informed?

On paper

optic

brain spinal

cord motor muscles

A reflex action is one in which a person responds automatically without making a decision to act

When the body could be harmed

The brain is informed after the response has been made

If you have been injured you will feel pain


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Using the diagram produce a flow chart that shows the path of hthe reflex action produced when the

girl picking the rose catches her finger on a thorn.

THE NERVESInside each nerve there are bundles of tiny nerve fibres along which the the signals travel. Each of these

fibres is part of a single nerve cell or neurone. Each neurone has a nerve cell body which contains a

nucleus. Signals go into the nerve cell body along one or more fibres called dendrites and leave by

another fibre called an axon. The signals travel along these nerve fibres are in the form of tiny pulses of

electricity.

On paper


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Below is a very simple diagram of showing the path of nerve impulse travelling from a receptor to an

effector through nerve cells.

Below are more detailed diagrams of the different types of nerve cells encountered along the way.

Using the diagram identify the three types of nerve cells.

TYPE OF NERVE CELL FUNCTION (JOB)

1.

2.

3.

Describe the job of each type of nerve cell in the table above.

Using the diagrams contrast a sensory neurone with a motor neurone.

Sensory Neurones To conduct messages from the sense organs to the central nervous system

Connector Neurones To pass messages from sensory to motor neurones

Motor Neurones To conduct messages from the central nervous system to the effectors

inThe nerve cell body of a sensory neurone is at the side, but in the motor neurone it is a the end of the nerve. The nerve impulse exits the cell by the end branches in a sensory nerve and enters via these end branches in the motor neuronce. Motor nerves end at muscl


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What are:

(a) dendrites?(b) axons?

In what direction do nerve impulses travel in a nerve cell?

What is the function of the fatty sheath around the nerve cell?

What type of cell is bundled together to make:

1. sensory nerves?

2. motor nerves?

3. mixed nerves?

Where would connecting nerve cells be found?

How are the nerve cells in the brain different to nerve cells in the body?

Dandrites are fibres in neurones where the signal enters

Axons are fibres where in neurones where the signal leaves

From dendrites to axons

To stop the impulses from travelling into the adjacent nerve cells

In the spinal cord and the brain

Nerve cells in the brain are not long and thin instead they control of the cell body with lots of branches


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The following diagram shows how the nervous impulse is electrically transmitted along a nerve cell.

Look at the following animation to see a nervous impulse travelling along the nerve cell.

http://www.outreach.mcb.harvard.edu/animations /actionpotential.swf

You may have noticed that there are gaps between the nerve cells in the diagrams. Nervous impulses

are transmitted from one neurone to another across these gaps by means of special chemical

substances made in the neurone. They produce an electrical impulse in the next neurone.

NO NERVOUS IMPULSE :At rest

there is a difference in electrical

charge between inside and outside

of the nerve fibre called the

RESTING POTENTIAL

NERVOUS IMPULSE PRESENT:When

stimulated, a temporary reversal of

electric charge takes place. This

causes a minute pulse of electricity

called the ACTION POTENTIAL.
http://www.outreach.mcb.harvard.edu/animations/actionpotential.swfhttp://www.outreach.mcb.harvard.edu/animations/actionpotential.swfhttp://www.outreach.mcb.harvard.edu/animations/actionpotential.swfhttp://www.outreach.mcb.harvard.edu/animations/actionpotential.swfhttp://www.outreach.mcb.harvard.edu/animations/actionpotential.swfhttp://www.outreach.mcb.harvard.edu/animations/actionpotential.swfhttp://www.outreach.mcb.harvard.edu/animations/actionpotential.swf


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What is a synapse?

What is a neurotransmitter?

that are produced at the end of a nerve cell and travel accross the gap

to the other to set up the same signal in the next nerve cells.

Identify two common neurotransmitters.

1. actylcholine

nonadrenaline

2.

HOMEWORK: You are to find out about one of the following nervous disorders:

Multiple sclerosis

Epilepsy

Motor neurone disease

Parkinsons disease

Alzhiemers disease

and you are to write part of a script for a TV show in which the doctor is:

(a) informing a patient that they have been diagnosed with this disorder(b) explaining the disorder to the patient(c) answering the patients questions.

Asynapseisa gap between one nerve cell and the next nerve cell

A neurotransmitter are special chemicals


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