General organisation of nervous system

Question 1

What are the two divisions of the nervous system?

Answer 1

CNS = brain + spinal cord
PNS = axons + ganglia + supporting cells

Question 2

What are support cells important for?

Answer 2

Physical support, regulating the interstitial fluid and providing nutrients

Question 3

Nerve cells

Answer 3

Highly differentiated w/ almost no capacity for cell division
Limited capacity to repair themselves after injury
Vary in length

Question 4

Describe neurons

Answer 4

Multipolar neuron has a cell body - numerous dendrites, highly branched.
Synapses on dendrites and cell body are ways that neurons communicate with each other
Cell body contains RER which produces material to be transported along the nerve cells

Question 5

What are the types of support cells?

Answer 5

Astrocytes
Microglia
Oligodendrocytes
Ependymal cells

Question 6

What do astrocytes do?

Answer 6

Maintains blood-brain barrier
Contains microfilaments which give structural strength to CNS
stabilises structure after injury - scar tissue
Directs neural growth during development
Controls the interstitial environment

Question 7

Microglia

Answer 7

5 branches
macrophages of neural tissue
5% of tissue but this can increase during infection

Question 8

Ependymal cells

Answer 8

Line chambers and passageways of the CNS which are filled with CSF
Has processes which make contact with glial cells - monitors CSF and makes contact with supporting cells to regulate the CSF

Question 9

Oligodendrocytes

Answer 9

Myelinates axons or bundles them together

Question 10

Neuroglia in peripheral nervous system

Answer 10

Schwann cells - myelinates peripheral axons, participates in repair process after injury.
Satellite cells, surrounds neuron cell bodies in ganglia
In peripheral nervous system the cell bodies within ganglia are supported by satellite cells while axons supported by Schwann cells

Question 11

Ganglia

Answer 11

Group of nerve cell bodies which lie outside the CNS supported by satellite cells.I

Question 12

What is the difference between sensory ganglia and motor?

Answer 12

Sensory ganglia have no synapses (pseudounipolar), motor has synapses and neurons are multipolar

Question 13

What are the layers of the meninges?

Answer 13

Pia
Arachnoid
Dura

Question 14

Describe the dura

Answer 14

Made up of 2 layers; tough and fibrous - inner layer has specialised folds which further support the brain;
outer layer fuses with periosteum and lines cranial cavity .
Venous sinuses run in gaps between two layers

Question 15

Describe the arachnoid layer

Answer 15

Covers surface of the brain; superficial to the subarachnoid space, which is filled with CSF. Contains a meshwork of collagen and elastic fibres linking to pia mater.

Question 16

Describe the pia

Answer 16

tightly attaches to the brain by astrocytes, follow contours of brain

Question 17

What do somatic nerves supply

Answer 17

Body wall, skeletal muscle + skin.

Contain motor and sensory fibres

Question 18

What do autonomic nerves supply

Answer 18

Internal organs with motor + sensory fibres

Question 19

Where do sensory neurones have their cell bodies

Answer 19

Whether autonomic or somatic, all sensory neurones have their cell bodies in ganglia outside the CNS

Question 20

Myotome

Answer 20

Area of muscle supplied by spinal nerve

Question 21

Dermotome

Answer 21

Area of skin supplied by spinal nerve

Question 22

How do nerve plexuses form

Answer 22

Anterior rami of all spinal nerves (except T2-T12) branch and rejoin plexuses - a network of rami.

Question 23

What are the plexuses

Answer 23

Cervical
Brachial
Lumbar
Sacral