Coordination

Question 1

What is coordination ?

Answer 1

Coordination is the linking of the action of receptors and effectors

Question 2

Name two coordinating systems

Answer 2

• nervous system

* endocrine system

Question 3

What are the two main parts of nervous system ?

Answer 3

•central nervous system:
brain and spinal cord
•Peripheral nervous system:
Cranial nerves and spinal nerves

Question 4

What is neurone ?

Answer 4

Neurone is the basic structure and functional units of nervous system

Question 5

What does a neurone consist ?

Answer 5

•cell body:
~ cytoplasm and nucleus
•nerve fibres :
~dendrons and axons

Question 6

What are the functions of dendrons and axons ?

Answer 6

•Dendrons:
~transmit nerve impulse towards cell body
•axons:
~transmit nerve impulse away from the cell body

Question 7

What is the layer of fatty materials surround the neurone called ? What is its function ?

Answer 7

•myelin sheath
•function:
~prevent the transmission of nerve impulse to the surroundings
~speed up the transmission of the nerve impulse

Question 8

Name types of neurones

Answer 8

•sensory neurones:
From receptors to the CNS
•motor neurones:
From CNS to effectors
•interneurones:
Connect sensory neurone to motor neurone or other interneurone

Question 9

What is the structure of sensory neurone ?

Answer 9

• long dendrons and short axons

* >——-0—-

Question 10

What is the structure of motor neurone ?

Answer 10

• long axon and short dendron

* >—-0————

Question 11

What is the structure of interneurone neurone ?

Answer 11

• short axon and short dendron

* >—0—-

Question 12

What is nerve fibres ?

Answer 12

Nerve fibres is a bundle of nerves

Question 13

What is receptors?

Answer 13

Receptors are cells which vacant detect stimuli and convert the stimuli into nerve impulse

Question 14

What is Nerve impulse ?

Answer 14

Nerve impulses are electrical impulses which travels at a high speed along the neurone

Question 15

What is synapse ?

Answer 15

Synapse is the point where the axon of one neurone joins the cell body or dendron of another neurone.

Question 16

What is the importance of synapse ?

Answer 16

• Synapse ensure the nerve impulse travels from one neurone to another neurone in one direction only.
• allow a neurone to communicate with many other neurones

Question 17

How are nerve impulse transmitted across a synapse?

Answer 17

• A nerve impulse reaches the synaptic knob at the ending of a neurone
• the nerve impulse stimulates the synaptic knob to release neurotransmitter.
• the neurotransmitter diffuse across the synaptic cleft.
• it stimulate the dendron or the cell body to generate nerve impulse.

Question 18

How does the CNS protected?

Answer 18

•the brain is protected by cranium and the spinal chord is protected by vertebral column
•the CNS is covered by three layers of membrane
•the space between the CNS is filled with cerebrospinal fluid:
~provide nutrients and oxygen to the neurone and remove waste from them,
~act as a shock absorbers to prevent it mechanical damage
~providing mechanical support to the brain and spinal cord to prevent it from collapsing

Question 19

What is the structure of cerebrum ?

Answer 19

• it is the largest part of the brain. It consists of two halves, the left and right cerebral hemispheres which are connected by nerves for communication. The left hemisphere mainly controls the right side of the body and the right hemisphere mainly controls the left side of the body.
• it is highly folded on its surface to allow it to hold more neurones in a limited space, so that coordination can be more efficient.
• The outer layer of the cerebrum is called cerebral cortex. It is made up of grey matter that consists mainly of the cell bodies of neurones. Their nuclei give a grey colour to this region.
• The inner layer of the cerebrum is made up of white matter that consists of nerve fibres. The myelin sheaths of nerve fibres are creamy white, giving a white colour to this region

Question 20

What is the function of cerebrum ?

Answer 20

•The cerebrum is the site for intelligence. It enables us to think, make decisions and have memories. It controls voluntary actions e.g. speaking and writing.
•The cerebral cortex is divided into three areas that serve different functions:
~The sensory areas receive nerve impulses from various receptors interpret them to give sensations such as sight, touch, hearing, smell a and taste.
~The motor areas send out nerve impulses to effectors to produce voluntary responses.
~The association areas integrate information from different sensory areas and relate the information to past experience. Then the brain makes decisions and sends nerve impulses to the motor areas to give a response.

Question 21

What is voluntary action ?

Answer 21

Voluntary actions are actions that are under conscious control. eg. Speaking and writing

Question 22

What is structure of cerebellum?

Answer 22

• Cerebellum is also highly folded

* outer layer is made up of grey matter, inner layer is made up of white matter.

Question 23

What is the function of cerebellum?

Answer 23

•Cerebellum coordinates the muscular movements to maintain body balance during walking,swimming and cycling

Question 24

****concepts
Incorrect:
The cerebellum controls the muscular contraction
Correct :
The cerebellum coordinates the activities of skeletal muscles for maintaining the body balance

Answer 24

Important concept **

Question 25

What is the structure medulla oblongata ?

Answer 25

* The medulla oblongata is the most posterior part of the brain that is continuous with the spinal cord. * Unlike the cerebrum and the cerebellum, its outer layer is made up of white matter and its inner layer is made up of grey matter.

Question 26

What is the function of medulla oblongata ?

Answer 26

* The medulla oblongata is the reflex centre for many reflex actions in the head, e.g. saliva secretion, swallowing and coughing * It also controls other involuntary actions. Examples of involuntary actions controlled by the medulla oblongata include breathing, heart beat and peristalsis.

Question 27

What is involuntary action ?

Answer 27

Involuntary actions occur automatically. They are not under the control of our will.

Question 28

What is the structure of spinal cord ?

Answer 28

•The spinal cord extends from the medulla oblongata of the brain. It consists of two regions: ~The outer region is made up of white matter, consisting of nerve fibres only. ~The inner H-shaped region is made up of grey matter, consisting mainly of the cell bodies of neurones. At the centre of the matter is the central canal which is filled with cerebrospinal fluid.

Question 29

How does the spinal nerve attached to the spinal cord ?

Answer 29

* The dorsal root contains sensory neurones which transmit nerve impulses from the receptors to the spinal cord. The cell bodies of e sensory neurones group together outside the spinal cord to form a swelling called the dorsal root ganglion. * The ventral root contains motor neurones which transmit nerve impulses from the spinal cord to the effectors. There is no swelling in the ventral root because the cell bodies of the motor neurones are located in the grey matter of the spinal cord.

Question 30

What is the function of spinal cord ?

Answer 30

* it relays nerve impulse between the brain and other parts of body * it is also a reflex center for many reflex actions involving the trunk and limbs

Question 31

What is the characteristic of reflex action ?

Answer 31

* rapid * inborn * involuntary * stereotype response

Question 32

What is the significance of rapid response of reflex action ?

Answer 32

•avoid danger and provide immediate protection

Question 33

Give examples of reflex action involve in spinal cord

Answer 33

* withdrawal action | * knee jerk action

Question 34

Give examples of reflex action involve in medulla oblongata

Answer 34

* saliva secretion * swallowing * coughing

Question 35

What is the mechanism of the withdrawal action ?

Answer 35

* The hand touches a sharp object. * Pain receptors in the skin are stimulated and they generate nerve impulses * Nerve impulses travel along the sensory neurone to the spinal cord. * Nerve impulses travel along the interneurone and the motor neurone to the arm muscle. * The arm muscle (effector) contracts. * The hand withdraws to prevent damage.

Question 36

In the withdrawal reflex, nerve impulses travel from the receptor to the effector. This reflex does not involve the cerebrum. Why we can feel the pain ?

Answer 36

we can feel the pain because nerve impulses are transmitted to the brain via another nervous pathway. The withdrawal reflex is so fast that the hand has already withdrawn before the nerve impulses reach the brain and give us a sense of pain. This protects the body from damage.

Question 37

What is the function of knee jerk reflex ?

Answer 37

Helps to maintain posture and balance

Question 38

What is the mechanism of knee jerk reflex ?

Answer 38

* The tendon just below the knee cap is tapped * Stretch receptor in the upper leg muscle is stimulated. * Nerve impulses travel along the sensory neurone. * Nerve impulses travel along the motor neurone to the leg muscle. * The leg muscle (effector) contracts * The leg kicks.

Question 39

What is reflex arc ?

Answer 39

Reflex arc is the nervous pathway that brings about a reflex action

Question 40

******concepts Incorrect: Reflex action are involuntary actions because they don’t involve the brain Correct: Reflex actions are involuntary actions because they do not involve the cerebrum. Some reflex actions, e.g. saliva secretion, swallowing and coughing, involve the medulla oblongata of the brain.

Answer 40

Important

Question 41

What is voluntary action ?

Answer 41

A voluntary action is action that under conscious control of the cerebrum

Question 42

There is a time lag between when the person withdrew his hand and when he felt pain. Why?

Answer 42

* The pathway through which the nerve impulses travel to the cerebrum is longer than the reflex arc. * More synapses are involved.

Question 43

Why were the tests conducted with X and Y is blindfolded ?

Answer 43

To avoid the reflex actions (if any) from being affected by voluntary

Question 44

How are voluntary actions brought about?

Answer 44

* After detecting a stimulus, the receptor generates nerve impulses which are transmitted to the CNS. (Some voluntary actions are initiated by the cerebrum without involving any stimuli) * The information is processed and integrated in the cerebrum which then generates other nerve impulses. * These nerve impulses are transmitted to the effector to produce a response

Question 45

What are the features of the response controlled by cerebrum ?

Answer 45

* the response can be controlled voluntary * they are not stereotyped * they need to be learnt