Nervous System

Question 1

Use of dendron in neurone

Answer 1

Transmit nerve impulse to cell body, the end branches of dendron are called dendrites which receive signals from other neurones

Question 2

Use of axon in neurone

Answer 2

Transmits nerve impulse away from cell body, the ends of axon are called axon terminals which transmits nervse impulses to effectors

Question 3

Function of myelin sheath

Answer 3

Presence of myelin sheath insulates nerve fibre and increases speed of transmission of nerve impulses

Question 4

What are Nodes of Ranvier

Answer 4

Regions on the neurone where myelin sheath are absent

Question 5

What happens when nerve impulse reaches axon terminals

Answer 5

Neurones are not physically attached to receiving cellls. There is a gap or junction between neurone and neurone/effector called synapse. When nerve impulse reaches AT, neurotransmitter is released into synapse which alters activity of receiving cells.

Question 6

Describe structure of sensory neurone

Answer 6

Sensory neurone has circular cell body with long dendron and short axon. The cell body and dendrites are outside CNS and axon is inside CNS

Question 7

What is function of sensory neurone

Answer 7

Sensory neurones transmit nerve impulses from receptors to the CNS

Question 8

Describe structure of relay neurone

Answer 8

Relay neurone can have irregular or circular cell body and whole neurone is found within CNS

Question 9

Describe function of relay neurones

Answer 9

Relay neurones transmit nerve impulses from sensory to motor neurones. Relay transmit nerve impulses to other relay neurones in CNS

Question 10

Describe structure of motor neurone

Answer 10

Motor neurones have irregular cell body with dendrites and long axons. Cell body and dendrites are in CNS and axon is outside CNS

Question 11

What is the function of motor neurone

Answer 11

Motor neurones transmit nerve impulses from the CNS to effectors

Question 12

Function of brain, spinal cord and nerves

Answer 12

They serrve to coordinate and regulate bodily functions by helping organisms adjust radpily to changes in their environment and emable various parts of body to coordinate with each other

Question 13

Define reflex

Answer 13

An immediate response to a specific stimulus that occurs without any conscious effort

Question 14

What are simple reflexes

Answer 14

They are built-in, unlearned responses and have protective function

Question 15

What does a reflex arc include

Answer 15

Receptor, sensory neurone, relay neurone in reflex centre and motor neurone, effector

Question 16

Describe withdrawal reflex

Answer 16

Stimulus stimulates pain receptor on finger, nerve impulse generated. Nerve impulse travels along sensory neurone to spinal cord. In spinal cord, neurotransmitters are released across synapse between sensory and relay neurones. Nerve impulse flow along relay neurone and neurotransmitters are released across synapse to motor neurone. nerve impulse leave spinal cord along motor neurone to effector, bicep muscles which contracts to cause withdrawal action