General Organisation of the Nervous System

Question 1

Name the X2 primary divisions of the nervous system and what each contains.

Answer 1

Central
= brain
= spinal cord

Peripheral
= nerves and ganglia outside of the brain/spinal cord

Question 2

Neural tissue consists of:

1) neurons
2) supporting cells

What is the role of the neurons?

Answer 2

To transmit electrical impulses along their axons.

Question 3

Neural tissue consists of:

1) neurons
2) supporting cells

What is the role of the supporting cells?

Answer 3

To structurally support the neurons, bring nutrients and regulate the interstitial fluid.

Question 4

What can be said about a neurons capacity for cell division?

Answer 4

They have none, and have limited capacity for repair after damage also.

Question 5

What is the name of a neuronal cell body?

Neuronal cell body’s are highly branched, what are these branches called?

What is the name of the singly long projection from the cell body why terminates at other neurons?

Answer 5

Soma.

Dendrites.

Axon.

Question 6

What is the name of the connection between the axon of one neuron and the soma of another?

What is the name of the end point of the axon?

What is the name of the gap between the two structures?

Answer 6

Synapse.

Synaptic terminal = the end of the axon
(Synaptic cleft = the space between the two structures)

Question 7

What is the name given to the connection between a neuron and an effector cell?

Answer 7

The neuro-effector junction.

Question 8

What is another name for the supporting cells of the nervous system?

Answer 8

Neuroglial cells.

Question 9

How many types of glial cells are found within the CNS?

What are the called?

Answer 9

X4:

1) Astrocytes
2) Microglia
3) Ependymal cells
4) Oligodendrocytes

Question 10

What is the role of Astrocytes in the CNS?

Answer 10

They are in contact with both the neurons and capillaries and therefore work to maintain the blood-brain barrier.

They provide structural support for the CNS.

They produce scar tissue following injury.

They control interstitial environment and help recycle neurotransmitters.

Question 11

What is the role of Microglia in the CNS?

Answer 11

They are the macrophages of the CNS.

They can are not fixed in position therefore can mobilise around the CNS to move to where they are needed.

Question 12

What is the role of Ependymal cells in the CNS?

Answer 12

These line the ventricles of the brain and any structure containing CSF.

They branch inwards to connect with other glial cells, but their function is not fully known. It is suggested they may help with the monitoring of CSF composition.

Question 13

What is the role of Oligodendrocytes in the CNS?

Answer 13

These have many processes which wrap around axons to myelinate them.

X1 Oligodendrocytes can myelinate multiple axons in order to improve the neurons conduction velocity.

Question 14

How many types of glial cells are found within the PNS?

What are the called?

Answer 14

X2:

1) Schwann cells
2) Satellite cells

Question 15

What is the role of Schwann cells in the PNS?

Answer 15

These surround all axons in the PNS and either act to:

1) Structurally group up to 20 small diameter neurons (non-myelinate from Schwann cells)
2) Myelinate a single axon with a single cell (myelinating Schwann cells)

Question 16

What is the role of Satellite cells in the PNS?

Answer 16

These surround neural somas when they are grouped in ganglia for structural support, as well as regulating nutrient levels around them.

Question 17

What is a ganglion?

Answer 17

A group of neuron cell bodies in a cluster located outside of the CNS.

Question 18

What type of neurons are found in sensory ganglia?

Answer 18

Pseudo-unipolar.
= no synapses, one end is in the CNS, the other in the PNS at the receptor.
= has a soma with an axon that bifurcates into X2 that travel in opposite directions.

Question 19

What type of neurons are found in autonomic motor ganglia?

Answer 19

Multipolar
= X1 axon from the soma
= with have individual pre- and post-ganglionic neurons which synapse at the ganglia.

Question 20

What are the X2 structures protecting the brain & spinal cord?

Answer 20

1) cranium and vertebrae

2) meninges

Question 21

What are the X3 layers of the meninges from most to least superficial?

Answer 21

1) Dura mater
2) Arachnoid mater
3) Pia mater

Question 22

What further X2 layers is the dura mater split into?

Answer 22

1) periosteal layer = fuses with the inside of the skull

2) meningeal layer = deep to the periosteal layer and against the arachnoid mater

Question 23

In which space does the CSF exist?

Answer 23

The subarachnoid space.

Question 24

What is a dermotome?

Answer 24

An area of skin supplied by a single spinal nerve.

Question 25

What is a myotome?

Answer 25

A group of muscles that a single spinal nerve innervates.

Question 26

Which spinal nerves form plexuses?

Name some plexuses.

Answer 26

The anterior rami of all spinal nerves (excluding T2-T12).

• cervical
• brachial
• lumbar
• sacral

Question 27

Which is dorsal and which is ventral in terms of posterior and anterior?

Answer 27

Ventral = anterior

Dorsal = posterior

Question 28

What is the advantage of plexuses?

Answer 28

The criss-crossing and redistribution of spinal nerves to the point where each branch of a plexus contains fibres from multiple spinal nerves is a benefit as it means damage to a single nerve may cause muscle weakness but NOT paralysis.