Neuro phys 3

Question 1

Where are GABA receptors normally located?

Answer 1

most inhibitory synapses within the brain are GABA (most common within local circuit neurons and in cerebellum)

Question 2

What is GABA synthesised from?

Answer 2

main precursor is glucose

it is synthesised from glutamate

Question 3

How is GABA removed from the terminal?

Answer 3

Removed from the synaptic cleft by Na+ dependant co transporters

Question 4

What are the three different types of GABA receptors and which one’s are ionotropic and which one’s are metabotropic?

Answer 4

ionotropic = A + C
metabotropic = B

Question 5

What are the two binding sites of GABA(A) receptors for?

Answer 5

barbiturates and benzodiazepins

Question 6

Where are the caetecholamines from?

Answer 6

regulate many brain functions

active within the peripheral nervous system

Question 7

What is the basic pathway for the synthesis of caetecholamines?

Answer 7

Tyrosine -> Dopamine -> Norepinephrine -> Epinephrine

Question 8

What is the general pathway that is involved in dopamine transmission?

Answer 8

1. Dopamine is loaded into vesicles
2. Released in synapse occupying D1 or D2 receptors
3. Synaptic re-uptake occurs by both presynaptic (DAT) and postsynaptic terminals
4. Dopamine that diffuses out enters blood and is metabolised by both hepatic MAO and compt

Question 9

What type(s) of receptors are involved in dopamine transmission?

Answer 9

exclusively metabotropic transmission

Question 10

What is the function of norepinephrine?

Answer 10

Neurotransmitter in the brainstem nucleus that projects to forebrain areas

Question 11

How is norepinephrine cleared from the synapse?

Answer 11

Cleared from synaptic cleft by pre and postsynaptic uptake and diffusion, the diffused portion is metabolised by MAO and COMT

Question 12

What are the five types of adrenergic receptor? Give an example and the action

Answer 12

a1- smooth muscles of the blood vessels- contraction
a2- adipose tissue- inhibits lipolysis
b1- myocardium- increases strength of contraction
b2- smooth muscle of bronchioles- relaxation
b3- adipose tissue- stimulates lipolysis

Question 13

What molecule is serotonin synthesised from?

Answer 13

synthesised from tryptophan

Question 14

How is the action of serotonin terminated?

Answer 14

SERT (serotonoin reuptake transporter)

Question 15

What type of transporter are the majority of 5-HT?

Answer 15

majority of serotonin transporters are metabotropic

Question 16

What are the five different types of neuropeptides and provide an examples of each one?

Answer 16

1. Brain/gut neuropeptides- substance P
2. Opiod peptides- endorphins
3. Pituaritary peptides- eg. oxytocin
4. Hypothalmic releasing hormones- GnRH
5. Miscellaneous- angiotensin 2

Question 17

What is nitrogen oxide?

Answer 17

Lipid soluble gas with a very short half life (seconds)

Question 18

What are the steps involved in the synthesis of NO?

Answer 18

Enzyme nitric oxide synthase (NOS) converts arginine to citrulline, generating NO
NO stimulates soluble guanylate cyclase, resulting in cGMP formation
cGMP mediates many of the physiological effects of NO

Question 19

What are the differences between NO and the various other neurotransmitters?

Answer 19

1. Not stored in vesicles- generated as needed
2. Not released by Ca2+ dependant exocytosis- it is freely permeable across the membrane
3. Decays spontaneously
4. Does not interact with specific receptors (action confined to post synaptic membrane)
5. Acts as a retrograde messenger- regulates function of axon terminals presynaptic to neuron in which produced