Week 9 - The Nervous System

Question 1

What is the embryological derivative of:

1. Microglia?
2. Macroglia?

Answer 1

1. Bone marrow

2. Neural tissue

Question 2

List the types of neuroglia found in the central nervous system and outline the functions of each.

Answer 2

1. Astrocytes:
   - Assist in the transfer of nutrients and waste products between the neurones and blood
   - Constitute the blood brain barrier
   - Phagocytic functions
   - Physical support for neurones
2. Oligodendrocytes:
   - Myelination
   - Myelinate up to 250 different axons at a time
3. Ependyma:
   - Line the ventricles and central canal of the spinal cord for circulation of CSF
4. Microglia:
   - Immunity and inflammation

Question 3

List the types of neuroglia found in the central nervous system and outline the functions of each.

Answer 3

1. Schwann cells:
   - Insulation of peripheral nerve axons
   - Speeding of impulse conduction
   - 1 Schwann cell myelinates only 1 axon
2. Satellite cells:
   - Physical support of neurones in PNS
3. Microglia:
   - Immune and inflammatory reactions

Question 4

What is the function of dendrites?

Answer 4

Increase the surface area for contact with other cell types

Question 5

What does the cell body of a neurone contain?

Answer 5

1. Nucleus
2. Nissl Substance
3. Golgi apparatus

Question 6

What is the function of Nissl substance and Golgi apparatus in the cell body of a neurone?

Answer 6

Nissl substance: Protein synthesis

Golgi apparatus: Packaging of transmitters into vesicles

Question 7

Why do collections of cell bodies of neurones appear relatively grey under the microscope?

Answer 7

Due to their high absorption of incident light of the microscope

Question 8

What is an example of grey matter in the central nervous system?

Answer 8

Nerve nuclei

Question 9

What are ganglia?

Answer 9

Collection of nerve cell bodies in the peripheral nervous system

Question 10

What is an example of white matter in the peripheral nervous system?

Answer 10

A peripheral nerve

Question 11

What is a nerve fascicle?

Answer 11

A collection of axons with a common origin and destination bound together

Question 12

Briefly outline the processes involved in the response of a neurone to its axon being severed.

Answer 12

1. Proximal segment of the axon soon seals up the damage to prevent leakage of cell contents
2. Thus a nerve stump is formed
3. The distal segment is cut off from the nutritional support of the cell body
4. The distal segment of the axon soon dies
5. The distal segment of the axon undergoes Wallerian degeneration