Structure and Function of the Nervous system

Question 1

What are the two types of interneurones and their functions?

Answer 1

Local interneurones: These form circuits with nearby neurones and analyse small pieces of information.

Relay Neurones: These connect Local circuits.

Question 2

What is the cell body of a neurone called?

Answer 2

The Soma.

Question 3

When an action potential reaches the terminal dendrites, what happens?

Answer 3

Each branch receives a full action potential.

Question 4

What are the three ‘Structural Classes’ of neurone?

Answer 4

Multipolar neurones.

Bipolar neurones.

Unipolar neurones.

Question 5

What are the characteristics of multipolar neurones?

Answer 5

These have one axon and several dendrite ‘trunks’.

Question 6

What are the characteristics of unipolar neurones?

Answer 6

These have a short stretch of axon leading from the soma which divides into two long branches.

Question 7

What are the characteristics of bipolar neurones?

Answer 7

These have one axon and one dendritic tree.

Question 8

Which of the ‘structural classes’ of neurones are often sensory neurones?

Answer 8

Unipolar and Bipolar.

Question 9

What is axoplasmic transport?

Answer 9

This is the process by which substances are transported along the axon.

Question 10

What are the two types of axoplasmic transport?

Answer 10

Anterograde transport - movement of substances along the axon towards the synaptic knobs. This is mediated by the transport protien kinesin.

Retrograde transport - The opposite of anterograde transport; occurs at about 1/2 of the speed and is mediated by dynein.

Question 11

What are the five Classes of Glial Cells?

Answer 11

Astrocytes, Microglia, Oligodendroglia, Satellite Cells ans Schwann Cells.

Question 12

What are the functions of Astrocytes?

Answer 12

These Cells provide structural support, clean up debris, provide neurones with nutrients and other essential substances and help regulate CSF composition.

Question 13

Outline the role of astrocytes in assisting the metabolism of neurones.

Answer 13

These Cells produce lactate through anaerobic-style glycolysis which is then transported to the neurones to be used in aerobic respiration. This allows neurones to have a higher metabolic rate. They also store glycogen for use in periods of high neuronal activity.

Question 14

Describe the function of astrocytes in ‘tissue maintenance’

Answer 14

Astrocytes break down dead or dying neurones and other debris in the brain through phagocytosis, reproducing to achieve numbers sufficient for the task. Once the neurones have been disposed they replicate and fill the empty space producing scar tissue.

Question 15

What is the function of microglia?

Answer 15

These cells are neuronal macrophages and patrol the brain looking for pathogens. Like astrocytes they move by amoeboid locomotion. They also have a role in the inflammatory response in the brain.

Question 16

What is the function of Oligodendroglia?

Answer 16

These cells provide myelination within the CNS and provide structural support. Each oligodendroglia can form around 50 segments of myelin by wrapping itself around nearby neurones.

Question 17

What is the function of Schwann Cells?

Answer 17

These form the myelin sheath around PNS neurones. They also assist in digestion of damaged neurones and provide a ‘tubular scaffold’ which can be used to repair neurones in the PNS, something that is not possible in the CNS. Furthermore the myelin in the membranes of schwann cells is different to that in oligodendroglia.

Question 18

What is the structure of the Blood Brain Barrier (BBB)?

Answer 18

This consists of the specialised endothelium of capillaries, whose cells are very tightly packed preventing movement of substances through the basement membrane without the aid of active transport.

Question 19

What is the role of the BBB?

Answer 19

The BBB makes it easier to maintain the specific CSF conditions required for correct neural function and isolates the brain from toxic compounds and substances which could interfere with proper brain function (e.g Hormones).