Nervous System

Question 1

What are the parts of Central Nervous System? (CNS)

Answer 1

Brain and Spinal Cord containing relay neurones

Question 2

What is the function of the CNS?

Answer 2

Spine: Transmits nerve signals from sensory to motor neurones by relay neurones

Brain: Transmits signals from brain to effectors

Question 3

What are the parts of the Somatic Nervous System? (SNS)

Answer 3

Sensory neurones from sensory receptors and senses to CNS

Motor neurones from CNS to skeletal muscles

Question 4

What is the function of the SNS?

Answer 4

Voluntary actions controlled by CNS
OR
Involuntary reflex actions (Receptors -> CNS -> Effectors)

Question 5

What is the parts of the Autonomic Nervous System? (ANS)

Answer 5

Sensory neurones found in organs from sensory receptor to CNS

Motor neurones from CNS to smooth muscle , heart and glands

Question 6

What is the function of the ANS?

Answer 6

Controls involuntary actions (Heart contractions)

Question 7

Parts of a Neurone

Answer 7

• Cell Body
• Dendron and extending Dendrites
• Axon and axon terminals
• Myelin Sheaths
• Node of Ranvier

Question 8

Describe the pathway of Voluntary actions

Answer 8

Impulses produced by brain -> Relay Neurone in spinal cord -> Motor neurone -> Effector

Question 9

Describe the pathway of reflex arc

Answer 9

Receptors -> sensory neurones -> CNS (brain or spinal cord) -> relay Neurones (may not be involved) -> motor neurones -> effector

Question 10

Differences in Voluntary and Reflex Action

Answer 10

• Involvement of Sensory neurone
• Involvement of brain
• Where the nerve impulse starts
• Control of action
• Time taken

Question 11

Heat withdrawal reflex

Answer 11

Heat Stimulus -> Receptors -> Sensory Neurones -> Relay Neurones in CNS (Spinal Cord) -> Motor Neurones -> Effector (Arm Muscles)

Question 12

Knee-jerk Reflex

Answer 12

Stimulus -> Receptor of Sensory neurone -> Sensory Neurone -> CNS (Spinal Cord) -> Motor Neurone -> Effector (Upper thigh muscle)

NO relay neurone

Question 13

Sequence of neural circuits

Answer 13

1. sensory receptor
2. Transmits nerve impulses to relay neurone in CNS
3. Relay neurones receive nerve impulses
4. Transmit nerve impulses to motor neurones
5. Motor neurones transmit nerve impulses from CNS to effectors

Question 14

How do myelin sheath and Node of Ranvier work together?

Answer 14

• Myelin sheath provides insulation to the axon
• Node of Ranvier in between myelin sheaths allows electrical impulse to ‘jump’
  Together they increase speed of nerve impulse transmission