Nervous System

Question 1

In CNS, myelin is formed by ……

Answer 1

Oligodendrocytes

Question 2

In PNS, myelin is formed by ……

Answer 2

Schwann cells

Question 3

Function of Myelin

Answer 3

1. Insulates axons - which increases speed of electrical conduction
2. Allows saltatory conduction
3. Conserves energy by reducing ion exchange area

Question 4

Name 2 types of receptors at synapses. (give examples for each)

Answer 4

1. Ionotropic receptor
   - GABA-A
   - Nicotinic ACh
2. Metabotropic receptor
   - Dopamine
   - Serotonin
   - Muscarinic Ach

Question 5

Function of synapse:

Answer 5

To facilitate communication between neurones.

• Allows a neurone (nerve cell) to pass an electrical / chemical signal to another neurone or to a target effector cell

Question 6

Function of astrocytes

Answer 6

• regulate blood-brain barrier
• maintain stable chemical environment for neurones

Question 7

Function of Oligodendrocytes

Answer 7

To myelinate axons in CNS. - in order to increase conduction speed

Question 8

What are Microglia

Answer 8

Resident innate immune cells in the CNS

Question 9

Major neurotransmitters of the CNS

Answer 9

Glutamate
GABA
Dopamine
Serotonin
Acetylcholine, Ach

Question 10

How is a signal transmitted in the CNS?

Answer 10

Via synapse

1. Action potential reaches axon terminal, depolarising the presynaptic membrane
2. Voltage-gated channels open. Ca2+ influx
3. Neurotransmitter released into synaptic cleft
4. Neurotransmitter binds to receptor on post-synaptic membrane
5. Post-synaptic response occurs (either inhibitory or excitatory)
6. Signal termination

Question 11

Function of neurotransmitter:
Dopamine

Answer 11

• Movement
• Reward
• Motivation

Question 12

Function of neurotransmitter:
Serotonin

Answer 12

• Mood
• Appetite
• Sleep regulation

Question 13

Function of neurotransmitter:
norepinephrine

Answer 13

• arousal
• alertness
• stress response