Nervous system

Question 1

What is the nervous system made up of

Answer 1

• Central nervous system
• Peripheral nervous system

Question 2

What is the central nervous system

Answer 2

• Consists of brain and spinal cord
• Functions as a coordination centre that processes information

Question 3

What is the myelin sheath

Answer 3

• Covers most long fibres
• Insulates nerve fibres
• Increases transmission speed of nerve impulses

Question 4

What is a dendron

Answer 4

• Transmits nerve impulses towards neurone cell body
• End branches are called dendrites

Question 5

What is an axon

Answer 5

• Transmits nerve impulses away from neurone cell body
• End branches are called axon terminals

Question 6

What are the Nodes of Ranvier

Answer 6

Regions where myelin sheath is absent

Question 7

What happens when nerve impulses reach the axon terminals

Answer 7

• Neurones are not physically attached to receiving cells
• There is a gap between a neurone and effector called the synapse
• Neurotransmitter is released into the synapse when nerve impulses reach the axon terminals
• Activity of receiving cells is altered

Question 8

Describe the structure and function of the sensory neurone

Answer 8

• Circular cell body
• Long dendron, short axon
• Dendron and cell body outside CNS, axon inside CNS
  Functions: Transmit nerve impulses from receptors to CNS

Question 9

Describe the structure and function of the motor neurone

Answer 9

• Irregular cell body
• Long axon, dendrites
• Cell body and dendrites inside CNS, axon outside CNS
  Functions: Transmit nerve impulses from relay neurone to effector

Question 10

Describe the structure and function of the relay neurone

Answer 10

• Circular or irregular cell body
• Whole neurone inside CNS
  Functions: Transmit nerve impulses from sensory neurone to motor neurone or to another relay neurone

Question 11

Define a reflex

Answer 11

A reflex is any immediate response to a specific stimulus that occurs without any conscious effort

Question 12

Define a simple reflex

Answer 12

Simple reflexes are built-in, unlearned responses, and they have protective functions

Question 12

Define a reflex arc

Answer 12

A reflex arc is the shortest pathway by which impulses travel from the receptor to the effector

Question 13

Define a conditioned reflex

Answer 13

Conditioned reflexes are acquired from past experiences of learning with a stimulus which was originally not effective in producing a response

Question 14

What are the types of simple reflexes

Answer 14

Spinal reflex
- Spinal cord is reflex centre

Cranial reflex
- Brain is reflex centre

Question 15

How does withdrawal reflex occur

Answer 15

• Stimulus stimulates pain receptor on finger, generating nerve impulses
• Nerve impulses travel along sensory neurone to spinal cord
• Neurotransmitters released across synapse between sensory and relay neurone
• Nerve impulses flow along relay neurone to motor neurone
• Neurotransmitters released across synapse between relay and motor neurone
• Nerve impulses leave the spinal cord along the motor neurone to the effector
• Effector is bicep muscles, which contract to cause withdrawal action

Question 16

Which neurones have myelin sheath

Answer 16

Motor
Sensory