2.1 - Role of Neurones and Glia

Question 1

What are the 3 types of glial cells?

Answer 1

1. Astrocytes
2. Oligodendrocytes
3. Microglia

Question 2

What is the 5 roles of astrocytes?

Answer 2

• Structural support
• Helps Provides nutrition
• Remove neurotransmitters
• Maintain ionic environment by K+ buffering
• Help form BBB

Question 3

How do astrocytes help provide energy for neurones?

Answer 3

Astrocytes produce lactate which is transferred to neurones to supplement their supply of glucose

Question 4

How do astrocytes help to remove neurotransmitters? Why is this necessary?

Answer 4

Re-uptake of transmitters

Prevents excitation of neaby neurons and prevents formation of another EPSP

Question 5

How do astrocytes help to buffer K+ in brain ECF?

Answer 5

K+ excreted from neurones into ECF and then can be taken up via Na+K+ATPase, K+ channel, or Na-K-Cl cotransporter of astrocyte

Question 6

What is the function of oligodendrocytes?

Answer 6

Myelinate axons in CNS

Question 7

What cell type myelinates axons in the PNS?

Answer 7

Schwann cells

Question 8

What is the function of microglia? What germ layer is microglia derived from?

Answer 8

• Immune cells
• phagocytose debris and foreign material
• Derived from mesoderm

Question 9

How is the BBB formed?

Answer 9

Formed by the brain capillaries having tight junctions between endothelial cells, and the end feet of astrocyte processes surrounding the BV

Question 10

Whta are the 3 chemical classes of neurotransmitter in the CNS?

Answer 10

Amino acids

Biogenic amines

Peptides

Question 11

What are the excitatory and inhibitory AA neurotransmitters?

Answer 11

Excitatory - Glutamate

Inhibitory - GABA and glycine

Question 12

What are the ionotropic and metabotropic glutamate receptors? What are they permeable to?

Answer 12

Ionotropic:

• AMPA - Na and K
• Kainate - Na and K
• NMDA - NA, K, and Ca

Metabotropic:

• mGluR1-7

Question 13

What is the co-agnosist of NMDA receptors?

Answer 13

glycine

Question 14

How is long term potentiation achieved? What can go wrong?

Answer 14

NMDA receptors activated through strong, high frequency stimulation results in calcium entry into cell and up-regulation of AMPA receptors and easier depolarisation in the future.

Too much calcium however causes excitotoxicity

Question 15

Of the inhibitory AAs, which is found primarily in the brain and which is mostly in th ebrainstem and spinal cord?

Answer 15

Brain - GABA

Brainstem and spinal cord - Glycine

Question 16

How does GABA and glycine receptors cause hyperpolarisation of a cell?

Answer 16

GABA and glycine receptors have integral Cl- channels that hyperpolarise

Question 17

What is the mechanism of action of barbiturates and benzodiazepines?

Answer 17

Both enhance the response to GABA and therefore have sedative and anxiolytic effects.

Question 18

Explain how the patellar tendon reflex arc works

Answer 18

Hitting the patellar tendon results in activation of a sensory neuron in the quadriceps muscle which sends a signal to an excitatory motor synapse in the quadriceps and an inhibitory interneuron that connects to the hamstring muscle

Question 19

What are the main areas of action of ACh?

Answer 19

• Neuromuscular junction
• ganglion synapse in ANS
• postganglionic parasympathetic
• CNS neurotransmitter at nicotinic and muscarinic receptors in brain

Question 20

What are cholinergic pathways in the CNS linked to?

Answer 20

Arousal, learning & memory, motor control

Question 21

What is the cause of Alzheimer’s disease? How is AD treated?

Answer 21

degeneration of cholinergic neurones in the nucleus basalis. treated with cholinesterase inhibitors

Question 22

Name the 4 dopaminergic pathways in the CNS and what they are involved in

Answer 22

Nigrostriatal pathway - motor control

Mesocotrical and mesolimbic pathway - mood, arousal, and reward

tubero-hypophyseal pathway

Question 23

What is PD associated with and how can it be treated?

Answer 23

Parkinsons associated with loss of dopaminergic neurons

Treated with levodopa (L-DOPA) which is converted to dopamine by AADC. However, you dont want dopamine to be produced outside of the brain so levodopa is coupled with carbidopa to inhibit AADC and the production of dopamine outside brain. Since carbidopa and AADC cant cross the BBB the LNAA (large neutral amino acid transporter) takes L-DOPA across the BBB and the AADC in the brain converts it to Dopamine

Question 24

What is schizophrenia a disorder of and how can it be treated?

Answer 24

Possibly due to too much dopamine production and therefore antagonists of dopamine D2 receptors are given

Question 25

Where can NA be found?

Answer 25

postganglionic sympathetic and neurotransmitter in CNS

Question 26

What receptors does NA act through?

Answer 26

GPCR alpha and beta adrenoreceptors

Question 27

Which group of neurons in the brain does most NA in the brain come from? What is their function?

Answer 27

Locus ceruleus - nucleus in pons

Function - arousal and wakefulness.

Question 28

What is serotonin AKA?

Answer 28

5-HT

Question 29

How do tricyclic antidepressants function?

Answer 29

Inhibit uptake of NA/5-HT

Question 30

How do SSRIs work? What do they treat?

Answer 30

Treat depression and anxiety by inhibiting serotonin reuptake

Question 31

What is a MAOI and how does it work?

Answer 31

Monoamine oxidase inhibitor

MAO metabolises monoamines and therefore MAOI inhibits this breakdown