The Nervous System

Question 1

Define ganglia.

Answer 1

A collection of cell bodies outside of the CNS.

Question 2

What are the different cell types that make up neural tissue?

Answer 2

Neurons - do not undergo cell division, highly specialised, longest cells in the body, limited capacity to self-repair

Neuroglia - support the neuron, regulation of interstitial fluid and nutrient supply

Question 3

What is another name for the cell body of a neuron?

Answer 3

The Soma

Question 4

What is the difference between axosomatic synapses and axodendritic synapses.

Answer 4

axosomatic synapses connect at the soma/cell body

axodendritic synapses connect to a point along the body of the dendrite

Question 5

What are the 4 types of glial cells found in the CNS?

Answer 5

1. Astrocytes - acts as a BBB and provide structural support to maintain neuronal cell structure. Form scar tissue after injury and recycling of neurotransmitters
2. Oligodendrocytes - myelination of segments of multiple axons
3. Microglia - from macrophage lineage, clearance of infection and pathogens by phagocytosis - make up 5% of all glial cells (at rest)
4. Ependymal cells - closely connected epithelial-like cells that line cavities and ventricles containing CSF. They extend processes to allow them to communicate with astrocytes.

Question 6

What are the 2 cell types found in the PNS?

Answer 6

1. Schwann cells - surround all axons, myelinate peripheral axons and participate in repair process after injury
2. Satellite cells - surround neuronal cell bodies in ganglia to regulate gaseous, nutrient and neurotransmitter levels.

Question 7

What are the 3 layers of the meninges?

Answer 7

Dura mater - outer layer is fused with the periosteum; inner layer has specialised folds to support the brain; venous sinuses run in gaps between the two layers

Arachnoid mater - CSF fluid fills the sub-arachnoid space

Pia mater - tightly attached to the brain by astrocytes

Question 8

What are the subdivisions of nerves of the PNS?

Answer 8

Somatic nerves - motor and sensory of the body wall, skeletal muscle and skin

Nerves of special sensation - sight, smell, taste, hearing,
balance

Autonomic nerves - motor and sensory to smooth muscle of internal organs and tissues

Question 9

True or False: All sensory axons whether somatic or autonomic have their cell bodies outside the CNS in ganglia where there are no synapses.

Answer 9

True

Question 10

True or False: All motor ganglia belong to the autonomic nervous system and always contain synapses.

Answer 10

True

Question 11

Between which lumbar vertebrae can CSF be extracted without impinging on any spinal nerves?

Answer 11

L2 and L3

Question 12

What are dermatomes?

Answer 12

Dermatomes are segments/regions of the body supplied by specific spinal nerves.

Question 13

Which nerves innervate the diaphragm?

Answer 13

C3,4,5

‘C3,4,5 - keep the diaphragm alive’

Question 14

True or False: Each limb muscle receives its nerve supply from more than one spinal nerve.

Answer 14

True

This means that destruction of a single spinal nerve may cause weakening but does not paralyse any limb muscle.