Chemistry And Physiology Of The Synapse

Question 1

2 different ways in which acetylcholine can affect activation?

Answer 1

In heart, metabotropic ACHR, G protein, K channel, leading to hyperpolarisation

In skeletal muscle- Nicotinic AchR, Na ion Channel, depolarisation

Question 2

Define kinetics?

Answer 2

Rate of transmitter binding and channel gating determine the duration of their effects

Question 3

Which are the ionotropic receptors?

Answer 3

GABA Glutamate, Aceytcholine, seretonin and ATP

Question 4

What are the glutamate receptors?

Answer 4

NMDA, AMPA and Kai ate

Question 5

Features of AMPA and kainate?

Answer 5

Fast opening channels permeable to Na and K

Responsible for early state EPSP

Question 6

Features of NMDA?

Answer 6

Slow opening channel
permeable to Ca, Na and K
But need extracellular glycine as cofactors to open the channel
Gated by Membrane voltage Mg ion plugs the pore at resting membrane potential

Responsible for late phase EPSP

Only activated in an already depolarised membrane in presence of glutamate

Question 7

Why are NMDA receptors special?

Answer 7

Influx of ca and Na, can cause changes such as neuroplasticity- which can help with long term memory formation

Question 8

NMDA and schizophrenia?

Answer 8

Blockage can cause symptoms such as hallucinations

Question 9

Which drugs bind in NMDA pore?

Answer 9

MK.801 and phencyclidine PCP angel dust

Question 10

When does glutamate excitotoxicity happen?

Answer 10

After cardiac arrest, stoke oxygen deficiency and repeated intense seizures status epilepticus

Question 11

G protein coupled domains have how many transmembrane domain protein?

Answer 11

7

Question 12

How does norepinephrine bind?

Answer 12

Binds to B adrenergic receptor, causing gs to activate adenylyl cyclase increase in CAMP which activates protein Kinase A which increases protein phosphorylation

Question 13

How does Glutamate cause activity through metabotropic receptors?

Answer 13

Binds to mGLuR, and the Gq activates phospholipase C which activates diacylglycerol and IP3. DAG activates protein kinase C and IP3 activates Ca release, both cause increase protein phosphorylation and activate calcium binding proteins

Question 14

How does dopamine cause affect?

Answer 14

Gi then prevents adenyltl cyclase, so no CAMP, not protein kinase A hence decreased phosphorylation of proteins

Question 15

G proteins work how?

Answer 15

They are bound to GDP in rest state.

When a ligand binds the GDP switches to GTP and the heteromer splits, Galpha and GBeta gamma

Alpha subunit can convert GTP to GDP stopping the signal

Question 16

How many alpha beta and gamma subunits are there?

Answer 16

Alpha 20
Beta 5
Gamma 12

Question 17

What does By subunit do?

Answer 17

Activates K channel directly e.g in heart and GABA receptor

Question 18

What does phospholipase C do?

Answer 18

Convert PIP2 to IP3 and diacylglycerol

Question 19

Protein kinase and phosphates role?

Answer 19

Kinase adds on phosphate group

Phosphates takes off phosphate group

Question 20

Autoreceptors?

Answer 20

Regulate release of transmitter by modulating its synthesis storage release or reuptake, e.g phosphorylation of tyrosine hydroxylase

Question 21

Heteroreceptors?

Answer 21

Regulate synthesis and release of transmitter other than their own ligand NE can influence the release of Ach by modulating a-adrenergic receptors

Question 22

Metabotropic receptor examples?

Answer 22

Glutamate: Gq- 1 and 5
Gi 2 and 3
Gi 4 6 7 8
GABA B
Muscarinic acetylcholine
Dopamine
Noradrenergic/adrenergic
Seretonin 
Neuropeptides

Question 23

Enzyme linked receptors?

Answer 23

Receptor tyrosine kinases
Transmembrane protein with intrinsic tyrosine kinase activity activated by neurotrophic binding NGF and BDNF

Autophosphorylate