L3- neurotransmitters and neurotransmission

Question 1

§what is a cotransmitter

Answer 1

release of multiple neurotransmitters from a single synapse, eg ATP, No,enkephalins etc

Question 2

7 steps of neurotransmission

Answer 2

1. synthesis of nt
2. nt stored in vesicles
3. degredation of leaked nt
4. action potential dependent release
5. nt binds to postsynaptic receptors
6. nt binds to presynaptic autoreceptors
7. nt deactivated either by reuptake or degredation

Question 3

describe cholinergic neurotransmission

Answer 3

• Cholinergic neurons are primarily found in sympathetic system however they also innervate sweat glands and blood vessels in skeletal muscle
• Choline molecule is transported into the neuron by energy in a sodium transport system
• Once inside, choline reacts with acetyl coA to form acetylcholine ( catalysed by choline acetyltransferase)
• Acetylcholine put into presynaptic vesicle- protected from degradation
• Action potential causes voltage-gated calcium channels open allowing calcium to enter the axon
• This caused the vesicle to fuse with membrane
• Ach released from the terminal
• Ach binds to: 1. post-synaptic receptors- producing cholinergic response and 2. presynaptic receptors- inhibiting release of more Ach (-ve feedback)
• Acetyl cholinesterase terminates Ach function at synaptic cleft by breaking it down to Acetate and choline.
• choline is then used in the first step again

Question 4

noradrenergic nt

Answer 4

Exocytosis is a process for moving large molecules out of the cell to the cell exterior
In endocytosis, the material to be internalised is surrounded by an area of plasma membrane, which then buds off inside the cell to form a vesicle containing the ingested material
Tyrosine is made in the liver. Its taken into neuron by active transport
a-methyltyrosine is an endogenous inhibitor, binds to tyrosine to start NA synthesis, aided by methyldopa
NA inserted into vessicle, it fuses to wall and is released from synapse
NA binds to alpha and beta adrenergic receptors on postsynaptic cell and
Binds to 1. presynaptic receptors to recycle NA and 2. postsynaptic receptors to
Mop up the remainder of NA,

Question 5

excitatory amino acids

Answer 5

glutamate, aspartate

Question 6

inhibitory amino acids

Answer 6

GABA, glycine

Question 7

fast and slow transmission

Answer 7

fast- inotropic
slow-metabotroptic

Question 8

presynaptic modulation of synaptic transmission

Answer 8

mainy inhibits nt release

Question 9

autoreceptor

Answer 9

nt acting on its own presynaptic terminal to reduce release