Organisation of peripheral nervous system

Question 1

What comprises the CNS?

Answer 1

Brain + spinal cord

Question 2

What comprises the PNS?

Answer 2

Axons, ganglia and supporting cells

Question 3

What comprises neural tissue?

Answer 3

Neurons + supporting cells

Question 4

Describe neurons

Answer 4

Highly differentiated cells with almost no capacity for cell division + limited capacity for repair after injury.
Vary in length from a few mm to over a metre

Question 5

Neuroglial cells

Answer 5

Non-nervous cells within the CNS;
Astrocytes (maintains blood-brain barrier)
Oligodendrocytes (supports axons, myelination)
Microglia (macrophages of CNS)
Ependymal cells (lines ventricles of brain)

Question 6

Astrocytes

Answer 6

Maintains blood-brain barrier
Contains microfilaments which provide structural strength for the CNS
Stabilises structure after injury - produces scar tissue
Directs neural growth during development
Controls the interstitial environment; recycles neurotransmitters

Question 7

Microglia

Answer 7

Macrophages of brain, make up 5% of neural tissue but this can increase during infections.
Has 5 branches

Question 8

Ependymal cells

Answer 8

Lines the chambers and passageways of the CNS, which are filled with cerebrospinal fluid.
Has processes that make contact with glial cells, monitors the CSF and makes contact with other cells to regulate it.

Question 9

Oligodendrocytes

Answer 9

Myelinates axons; wraps axons together in a bundle

Question 10

Neuroglia

Answer 10

Support cells; satellite cells + Schwann cells

Question 11

Satellite cells

Answer 11

Surrounds neuron cell body in ganglia

Question 12

Schwann cells

Answer 12

Myelinates peripheral axon + helps with repair after injury

Question 13

How does the neuroglia work in PNS

Answer 13

Satellite cells support the cell body, while the Schwann cells support the axons (either by myelination, or by bundling)

Question 14

Ganglia

Answer 14

Group of nerve cell bodies which lie outside the CNS

Question 15

What are the meninges layers?

Answer 15

Dura
Arachnoid
Pia
(DAP/PAD)

Question 16

Dura

Answer 16

Tough and fibrous; 2 layers outermost of which fuses with periosteum and lines cranial cavity. Venous sinuses run in the gap between the two layers.

Question 17

Arachnoid

Answer 17

Covers surface of brain, superficial to subarachnoid space, which is filled with CSF - contains a network of collagen and elastic fibres which link it to the pia matter..

Question 18

Pia

Answer 18

Tightly attached to the brain by astrocytes; follows contours of the brain

Question 19

Where is supplied by the somatic nervous system

Answer 19

Body wall, skin and skeletal muscle

Question 20

What differs between the motor and sensory ganglia?

Answer 20

Sensory have no synapses; motor always has synapses

Question 21

What is a plexus

Answer 21

redistribution of nerve fibres like a tree.