ToB S9 - Nerves

Question 1

Describe the structure of a peripheral nerve

Answer 1

• Cell body with nucleus, dendrites, nissl substance
• Axon Hillock
• Myelinated axon with Schwann cells and Nodes of Ranvier, Terminal buttons

Question 2

What is an efferent nerve fibre?

Answer 2

Transports signals from the CNS to effectors Motor neurones

Question 3

Which cells maintain myelination in the CNS and in the PNS?

Answer 3

CNS - Oligodendrocytes (1 cell per 250 axons)

PNS - Schwann cells (1 cell per axon)

Question 4

What are the nodes of Ranvier?

Answer 4

• Gaps in the myelination of an axon
• Enable saltatory conduction

Question 5

What are the three types of connective tissue sheaths found in the nervous system?

Answer 5

Epineurium - Covers entire nerve

Perineurium - Covers fascicles of nerve fibres

Endoneurium - Covers single cell axons

Question 6

What are the consequences of demyelination?

Answer 6

Action potential must travel further along the axon as saltatory conduction is inhibited so action potential cannot jump between nodes of Ranvier

Question 7

What makes up a neurone?

Answer 7

Axon, cell body, dendrites

Can be uni-polar (sensory), bi-polar (retina of eye) or multi-polar (majority)

Question 8

What is white and grey matter?

Answer 8

White - axons

Grey - cell body

Question 9

Describe the features of a nerve cell body

Answer 9

Nissl substance, nucleus, nucleolus, dendrite

Question 10

What is the role of glial cells?

Answer 10

Support neurones, maintains homeostasis and form myelin/insulate neurones

Question 11

List the glial cells found in the CNS, PNS and both

Answer 11

CNS - astrocytes, oligodendrocytes

PNS - Schwann cells, satellite cells

Both - microglia

Question 12

Where are myelinated and unmyelinated neurones found?

Answer 12

Myelinated - Somatic

Both - Autonomic

Question 13

What are ganglia?

Answer 13

Collections of nerve cell bodies in the PNS (swelling)

Question 14

What two reciprocal components make up the autonomic nervous system?

Answer 14

Sympathetic and parasympathetic system

Question 15

What are effectors of the ANS

Answer 15

Smooth muscle, cardiac muscle, glands, visceral organs

Question 16

List the functions of the sympathetic NS

Answer 16

Involved in fight or flight response mechanism

• Increase heart rate
• Increase blood pressure
• Divert blood to muscles and heart
• Hyperventilation

Question 17

List the functions of the parasympathetic NS

Answer 17

Involved in the resting state

• Promotes sleep
• Promotes digestion
• Promotes normal bodily functions such as bladder emptying
• Reduced heart rate and force of contraction

Question 18

What neurones and receptors are involved in the sympathetic NS ?

Answer 18

Pre-ganglionic neurone - Cholinergic

Post-ganglionic receptors - nicotinic

Post ganglionic neurone - noradrenergic

Question 19

What type of neurotransmitter and receptors are involved in the parasympathetic NS?

Answer 19

Pre-ganglionic neurone - Cholinergic

Post-ganglionic receptors - nicotinic

Post ganglionic neurone - cholinergic

Question 20

What do excitatory and inhibitory neurones release?

Answer 20

Excitatory- glutamate/aspartate neurotransmitter

Inhibitory- glycine/GABA neurotransmitter

Question 21

What function do astrocytes have?

Answer 21

• Make up the blood brain barrier
• Assist in transfer of nutrients and waste

Question 22

What function do oligodendrocytes have?

Answer 22

Myelination of the central nervous system, myelinating up to 250 axons/cells

Question 23

What function do microglia have

Answer 23

Immune and inflammatory functions