General Organisation of the Nervous System

Question 1

Describe the two functional divisions of the peripheral nervous system

Answer 1

Autonomic - involuntary nervous system. Supplies smooth muscle, glands and viscera.
Somatic - Voluntary nervous system. Supplies skeletal muscle and carries sensation.

Question 2

What does the CNS consist of?

Answer 2

Spinal cord and brain

Question 3

What does the peripheral nervous system (PNS) consist of?

Answer 3

axons, ganglia, and supporting cells

Question 4

Name the 4 types of glial cells in the CNS

Answer 4

Astrocytes
Oligodendrocytes
Microglia
Ependymal Cells

Question 5

What is the function of an astrocyte?

Answer 5

Provides structural support to the neuron

Question 6

What is the function of oligodendrocytes?

Answer 6

Wraps axons together/myelinates neurons

Question 7

What is the function of microglia?

Answer 7

Macrophages of the brain

Question 8

What is the function of ependymal cells?

Answer 8

They line chambers of the CNS. Play a key role in production of cerebro-spinal fluid

Question 9

Name the two types of supporting cell in the PNS.

Answer 9

Schwann Cells

Satellite Cells

Question 10

What is the function of schwann cells?

Answer 10

Myelinate axons to allow saltatory conduction to occur.

Question 11

What is the function of Satellite cells?

Answer 11

Surround neurone cell bodies in ganglia. Regulate O2, CO2 and nutrient and neurotransmitter levels.

Question 12

What is a ganglia?

Answer 12

A structure containing a number of cell bodies - typically synapsing. Supported by connective tissue.

Question 13

Name the 3 layers of the meninges (coverings of the brain). Order the layers.

Answer 13

1. Dura mater - outermost layer. Collagenous tough layer with inner specialised folds to support the brain. Outer layer fused to periosteum.
2. Arachnoid mater - middle layer. Covers the surface of the brain.
3. Pia mater - innermost layer. Tightly attached to the brain by astrocytes and follows its contours.

Question 14

Where do sensory neurons have their cell bodies?

Answer 14

Outside the CNS in ganglia.

Question 15

Name 2 similarities between the somatic and autonomic nervous system.

Answer 15

1. Both initial cell bodies originate in the central nervous system.
2. Both travel via the motor/sensory root

Question 16

Name three differences between the somatic and autonomic nervous system.

Answer 16

1. Somatic - has only one neurone, Autonomic has two which synapse at ganglion.
2. Somatic nerves are fully myelinated, In motor nerves, only the first is myelinated.
3. Somatic supplies skeletal muscle, autonomic supplies glands, smooth muscle and viscera.

Question 17

Which segments of the spinal cord provide sympathetic innervation?

Answer 17

T1 to L2.

All thoracic and lumber 1 and 2.

Question 18

Where to motor neurons of the sympathetic system originate?

Answer 18

In the spinal cord.

Question 19

Where do motor neurons of the sympathetic nervous system synapse?

Answer 19

At sympathetic chain ganglia.

Some synapse further from the spinal cord e.g. in celiac ganglion for most nerves which innervate the liver/stomach.

Question 20

Other than ganglia. Where can preganglionic neurons stimulate?

Answer 20

The adrenal medullae - causes the release of neurotransmitter into the circulation

Question 21

Which segments of the spinal cord do parasympathetic neurons arise from?

Answer 21

Cranial nerves III, VII, IX and X.

Sacral spinal nerves S2,3,4

Question 22

What is the distribution of parasympathetic stimulation?

Answer 22

Head and trunk ONLY.

Question 23

What is the function of cranial nerve X (the vagus nerve)?

Answer 23

Provides innervation to all thoracic viscera and most of the GI tract.
Plexuses around the oesophagus.

Question 24

Where does the sacral nerves S2, S3 and S4 supply?

Answer 24

The genito-urinary region.