Synapses and neurotransmitters

Question 1

NMJ is

Answer 1

NMJ is a specialized synapse consisting of a presynaptic neuron (a motor neuron) and the sarcolemma (membrane of the muscle fiber).

Question 2

Nt found at NMJ is

Answer 2

always ACETYLCHOLINE

Question 3

Binding of ACh at sarcolemma causes

Answer 3

NMJ is a specialized synapse consisting of a presynaptic neuron (a motor neuron) and the sarcolemma (membrane of the muscle fiber).

Question 4

Neurotransmitters are released at the synapse when ____________

Answer 4

when the intracellular Ca2+ reaches a certain level.

The increase in intracellular Ca2+ level is caused by Ca2+ influx which is a result of membrane depolarization

Question 5

Name the major neurotransmitters in the CNS
Excitatory - 4
Inhibitory - 2
Both - 3

Answer 5

Excitatory

1. Glutamate
2. Epin
3. Ne
4. Substance P

Inhibitory

1. GABA
2. Opioids

Both

1. Acetylcholine
2. Serotonin
3. Dopamine

Question 6

Excitatory neurotransmitters cause _____1______ while inhibitory neurotransmitters ____2_______

Answer 6

1. membrane depolarization

2. do not cause depolarization/cause hyperpolarization in the postsynaptic neurons.

Question 7

Dopamine and serotonin can be excitatory or inhibitory depending on _______________

Answer 7

the subtypes of receptors that they bind to on the postsynaptic membrane.

Question 8

Name the different types of neurotransmitters:

Answer 8

1. ACh
2. monoamines eg serotonin, ne, ep, dopamine, histamine
3. Amino acids eg. Glutamate, glycine, GABA
4. Purines eg. adenosine
5. Gases eg. Nitric oxide
6. peptides eg opioids

Question 9

___________ is the most common excitatory neurotransmitter in the BRAIN.

Answer 9

Glutamate

Question 10

Glutamate is synthesized in the neuron from glutamine. Glutamine is supplied by __________

Answer 10

the astrocytes nearby.

Question 11

Glutamate

Two types of receptor: ionotropic and metabotropic. Explain them both

Answer 11

Ionotropic receptor mediates the effect of glutamate faster than metabotropic receptor as it is ion channel compared to metabotropic receptor which requires a second messenger system

It is conceivable that the ionotropic glutamate receptors are associated with cation channels since it is excitatory. Binding of glutamate to these receptors causes cation influx that will eventually lead to membrane depolarization.

Question 12

Glutamate

Explain the types of ionotropic glutamate receptors, and their effect.

Answer 12

3 types of ionotropic glutamate receptors

1. NMDA
2. AMPA
3. Kainate

All are fast and excitatory - Ca+ Na+ channels

Question 13

Glutamate

Explain the types of Metabotropic (G protein coupled) glutamate receptors, and their effect.

Answer 13

3 types of metabotropic glutamate receptors

1. group I - slow excitatory - mGlu1,5
2. group II - slow inhibitory - mGlu2,3
3. group III - slow inhibitory - mGlu4,6,7,8

Question 14

Glutamate and its receptors play important role in _______ and _________

Answer 14

synaptic plasticity and excitotoxicity.

Question 15

Excessive glutamate in the synaptic cleft can be caused due to _________.

Answer 15

due to dysfunction in the uptake mechanism or excessive release of glutamate from the neuron as a result of neuronal death.
Glutamate in the synaptic cleft continuously stimulate the postsynaptic neurons by binding to the glutamate receptor, leading to more neuronal death by excitotoxicity.

Question 16

How is glutamate formed?

Answer 16

1. Glutamate is absorbed by astrocyte
2. converted to glutamine
3. it is taken up by neuron
4. converted to glutamate

Question 17

GABA and glycine difference

Answer 17

GABA in brain

Glycine in spinal cord

Question 18

__________ and __________ are the most common inhibitory neurotransmitters in the brain and spinal cord, respectively.

Answer 18

GABA and glycine

Question 19

GABA is synthesized from _________

Answer 19

glutamate

using the enzyme Glutamate decarboxylase

Question 20

GABA and glycine

Two types of receptor: ionotropic and metabotropic. Explain their speeds and

Answer 20

Ionotropic receptor mediates the effect of GABA and glycine faster than metabotropic receptor.

Question 21

Ionotropic GABA receptors are associated with ________ since it is _________

Answer 21

anion channels since it is inhibitory.

Binding of glutamate to these receptors causes anion influx that will hyperpolarize the membrane, making it harder for the neuron to depolarize.
GABAA and GABAC receptors are associated with chloride channel. GABAB receptors, when activated, inhibits Ca2+ channels and opens K+ channels, resulting in hyperpolarization of the membrane.

Question 22

What is the difference between ionotropic receptors of excitatory and inhibitory nt’s?

Answer 22

excitiatory - associated with CATION channels - causing depolarization

inhibitory - associated with ANION channels - causing hyperpolarization

Question 23

Benzodiazepine binds to

Answer 23

Benzodiazepine binds to GABAA receptor to cause hyperpolarization in the neuron to produce its sedative effect.

Question 24

What are the 3 main GABA channels?

Answer 24

1. GABA-A : Cl- influx, IONOTROPIC
2. GABA-B : Inhibit Ca2+, open K+. METABOTROPIC
3. GABA-C : Cl- influx, IONOTROPIC

GABA-A and GABA-C receptors are associated with chloride channel, leading to hyperpolarization of neuron.

GABA-B receptors, when activated, results in hyperpolarization of the membrane.

Question 25

Difference between ionotropic and metabotropic receptors?

Answer 25

Ionotropic: faster, ligand/nt binds, - for excitatory Ca2+ in, Na+ in - for inhibitory Cl- in Metabotropic: slower, second messenger system (proteins/genes/ca affect ionotropic receptors)

Question 26

GABA-A receptor has 6 binding sites for:

Answer 26

- barbiturates - benzodiazepines - GABA - steroids - picrotoxin - chlorine have similar effects if they bind to the same receptor

Question 27

Acetylcholine is synthesized from

Answer 27

acetyl CoA and choline.

Question 28

Acetylcholine is the only neurotransmitter released by the _______ and _________

Answer 28

preganglionic neuron at the ganglia and the only neurotransmitter released at the neuromuscular junction.

Question 29

Acetylcholine has two types of receptor: ionotropic and metabotropic. what are they called specifically?

Answer 29

ionotropic = nicotinic metabotropic = muscarinic

Question 30

Acetylcholine | What are the different types of nicotinic and muscarinic receptors, and what are their effects?

Answer 30

Nicotinic - N1(NMJ) and N2(CNS) - EXCITATORY. (Associated with cation channels) Muscarinic - M1,M2,M3,M4,M5 - EXCITATORY OR INHIBITORY

Question 31

Serotonin is synthesized from

Answer 31

tryptophan

Question 32

Serotonin has 2 types of receptors - ionotropic and metabotropic. Name them all and their effects.

Answer 32

General names: 5HT1 to 5HT7. All metabotropic except for 3. All excitatory except for 1 amd 5. **inhibitory ones decrease cAMP in cell. ** To cause membrane depolarization, the intracellular cAMP level should increase and vice versa.

Question 33

Which of the serotonin receptors are antidepressants and antiemetic?

Answer 33

Antiemetic - 3. | Antidepressants - 2,6,7.

Question 34

Dopamine is synthesized from

Answer 34

L-tyrosine.

Question 35

All of dopamine's receptors are ____________.

Answer 35

metabotropic. Dopamine can be excitatory or inhibitory. D1-like receptor family (D1 and D5 receptors) are excitatory (G alpha S protein), D2-like receptor family is inhibitory (G alpha i protein).

Question 36

Dopamine is an important neurotransmitter in the | __________ and __________.

Answer 36

reward center (addiction) and for motor control (Parkinson’s disease). In Parkinson’s disease, dopamine is low. Medication to increase it (increase synthesis, increase exocytosis) or maintaining (prevent breakdown or reuptake) the dopamine level

Question 37

Serotonin syndrome - explain the mechanism

Answer 37

Due to increase in serotonin, causes over excitation. Causes: SSRI + MAOI, cocaie, triptans, etc. Signs/symptoms: mental status changes, autonomic instability - shes hot and wet!

Question 38

Norepinephrine is synthesized from

Answer 38

dopamine.

Question 39

All norepinephrine receptors are

Answer 39

metabotropic

Question 40

What are the different types of receptors of norepinephrine?

Answer 40

alpha1,2 and beta1,2. Except for α1 receptor which is linked to phospholipase C, the rest are linked to adenylyl cyclase. Except for α2 receptor which is coupled to inhibitory G protein, the rest are coupled to stimulatory G proteins. Except for β2 receptor which has higher affinity for ep>ne, the rest have the same affinity for both.

Question 41

general rule for ne-receptors

Answer 41

1's = alpha1 and beta 1= excitatory, cause more vasoconstriction, increased heart rate 2's = inhibitory, cause muscle relaxation, alpha's present in blood vessels, and bronchioles beta's present in heart.