Neurones And Glia

Question 1

What 3 major types of glia can be found in the CNS?

Answer 1

Oligodendrocytes
Astrocytes
Microglia

Question 2

What is the role of oligodendrocytes?

Answer 2

myelination of axons in CNS

Question 3

What is the role of microglia?

Answer 3

Involved in immune response of brain and can act as antigen presenting cells.
They recognise foreign material and become activated then phagocytose things to remove debris and foreign material.

Question 4

Why is the brain said to be immune priveleged?

Answer 4

It is separated from the rest of the body by the blood brain barrier, so it is more difficult for infections to penetrate into this body space.

Question 5

Can T cells enter the CNS?

Answer 5

Yes, but CNS inhibits initiation of pro inflammatory T cell response, as rigid skull will not tolerate volume expansion

Question 6

What are the roles of astrocytes?

Answer 6

Supporting cells
Help to provide nutrition for neurones via glucose lactate shuttle as neurones cant store glycogen
Maintain ionic environment via K+ buffering
Help to form BB barrier
Hoover up excess neurotransmitters

Question 7

What is the role of the blood brain barrier?

Answer 7

Limits diffusion of substances into brain ECF
Maintains correct environment for neurones
Substances such as glucose, amino acids and potassium are transported across BBB

Question 8

How is the BBB maintained?

Answer 8

Tight junctions between endothelial cells
Basement membrane surrounding capillary
End feet of astrocyte processes

Question 9

What are the 3 main groups of neurotransmitters in the CNS?

Answer 9

Amino acids eg glutamate, GABA, glycine

Biogenic amines eg Ach, noradrenaline, dopamine, serotonin, histamine

Peptides- dynorphin, enkephalins, substance P, somatostatin,CCK, neuropeptide Y.

Question 10

What is the main excitatory neurotransmitter in the brain?

Answer 10

Glutamate

Question 11

What are the two main kinds of glutamate receptor?

Answer 11

Inotropic-mediate fast transmission

Metabotropic- GPCRs, modulatory response

Question 12

What are the major inhibitory neurotransmitters in the CNS?

Answer 12

GABA and glycine- GABA is main inhibitory transmitter in brain, glycine is main inhibitory transmitter in brain stem and spinal cord.

Question 13

Where can ACh be found?

Answer 13

In the:
Neuromuscular junction
Post ganglionic PNS
Ganglion synapse in all autonomics
Nicotinic and muscarinic receptors in brain

Question 14

Is ACh excitatory or inhibitory?

Answer 14

Mainly Excitatory

Question 15

Where do cholinergic neurones originate?

Answer 15

In nucleus basalis of forebrain and in brainstem also

Question 16

Where do cholinergic neurones project?

Answer 16

They give diffuse projections to many parts of cortex and hippocampus

There are also local cholinergic neurones in corpus striatum

Question 17

What psychological processes is Ach involved in?

Answer 17

Arousal, learning, memory and motor control.

Question 18

What are the 3 major dopamine pathways?

Answer 18

Mesocortical pathway- from mid brain to cortex involved in mood, arousal and reward

Nigrostriatal pathway- from mid brain to corpus striatum involved in motor control

Mesolimbic pathway- from midbrain to hippocampus and amygdala, involved in mood, arousal and reward.

Question 19

Where do noradrenergic neurones originate?

Answer 19

In pons and medulla in a place called the locus ceruleus.

Question 20

Where do noradrenergic neurones project?

Answer 20

They have diffuse projections throughout cortex, hypothalamus, amygdala and cerebellum.

Question 21

What neurotransmitter is thought to be lacking in depression?

Answer 21

Noradrenaline

Question 22

What is the distribution of serotonin neurones?

Answer 22

Similar to NA neurones

Question 23

What is the function of serotonin

Answer 23

Sleep/ wakefullness, mood