Neurotransmitters 4

Question 1

serotonin synthesis and breakdown

Answer 1

same as norepinephrine from tyrosine

Question 2

• produced in the pineal gland in response to the light–dark cycle level in the blood rising in a dark environment
• organizing seasonal and circadian rhythms
• melatonin may also be involved in regulating reproductive functions

Answer 2

melatonin

Question 3

melatonin neurotransmitter is also synthesized from

Answer 3

tryptophan

Question 4

within brain is produced both by mast cells and by certain neuronal fibers

Answer 4

histamine

Question 5

synthesis of histamine

Answer 5

from histidine in a single step enzyme histidine decarboxylase requires pyridoxal phosphate, and its mechanism is very similar to that of DOPA decarboxylase

Question 6

activation of the exocytotic release of histamine

Answer 6

depolarization of nerve terminals activates the exocytotic by voltage-dependent as well as a calcium-dependent mechanism

Question 7

breakdown of histamine in brain

Answer 7

deactivated by methylation, then oxidation by MAO-B, followed by an additional oxidation step.

SAM (S-adenosylmethionine) converts to through said methylation SAH (S-adenosylhomocysteine)

Question 8

breakdown of histamine in peripheral tissues

Answer 8

undergoes deamination by diamine oxidase, followed by oxidation to a carboxylic acid

no methylation like in the brain thats the big difference

Question 9

acetylcholine is synthesised from

Answer 9

acetyl CoA and choline by the enzyme 
choline acetyltransferase (ChAT).

Question 10

acetylcholine is stored in and released through

Answer 10

vesicles and later released through calcium-mediated exocytosis

Question 11

derived from the hydrolysis of phosphatidylcholine in membrane lipids

Answer 11

acetylcholine

Question 12

acetylcholine is inactivated by

Answer 12

acetylcholinesterase enzyme

products are acetic acid and choline

Question 13

the major neurotransmitter at the neuromuscular junctions

Answer 13

acetylcholine

Question 14

excitatory neurotransmitter within the central nervous system leading to the depolarization of neurons

Answer 14

glutamate

Question 15

does not readily cross the blood-brain barrier

Answer 15

glutamate

Question 16

γ-aminobutyric acid

Answer 16

gaba

Question 17

gaba

Answer 17

major inhibitory neurotransmitter in the central nervous system.

Question 18

gaba is synthesised by the

Answer 18

decarboxylation of glutamate in a single step catalyzed by the enzyme glutamic acid decarboxylase (GAD)

Question 19

glutamate is synthesised

Answer 19

de novo from glucose/α-ketoglutarate (via enzyme glutamate dehydrogenase or through transamination reactions)

Question 20

gaba is recycled in the central nervous system by

Answer 20

a series of reactions called the GABA shunt which conserves glutamate and GABA.

Question 21

uptake of gaba occurs in

Answer 21

glial cells

Question 22

transporter of glutamate between cells in the CNS

Answer 22

glutamine

Question 23

mechanism of gaba shunt in glial cells

Answer 23

glial cells produces glutamate, which is converted to glutamine and transported out of the glial cells to neurons, where it is converted back to glutamate

Question 24

lack GAD and cannot synthesise GABA

Answer 24

glial cells

Question 25

excitatory neurotransmitters

Answer 25

aspatate and glutamate

Question 26

aspatate synthesised from

Answer 26

oxaloacetate via transamination reactions

Question 27

cannot pass blood brain barrier

Answer 27

aspatate

Question 28

involved in learning and memory processes as well as motor functions

Answer 28

excitatory amino acids aka (glutamate and aspartate)

Question 29

prolonged stimulation of neurons by excitatory amino acids results in neuronal death or injury overexcitatory effects result in

Answer 29

alzheimer’s disease

Question 30

major inhibitory neurotransmitter in the spinal cord

Answer 30

glycine

Question 31

glycine is synthesised

Answer 31

in neurons synthesized de novo within the nerve terminal from serine by the enzyme serine hydroxymethyltransferase which requires folic acid

Question 32

glycine inactivation

Answer 32

via uptake by a high-affinity transporter

Question 33

controls vasodilation neurotransmission and the ability of the immune system to kill tumor cells and parasites

Answer 33

nitric oxide (NO)

Question 34

nitric oxide is synthesised from

Answer 34

arginine by nitric oxide synthase

Question 35

what in smooth muscles cells leads to the relaxation of smooth muscle and the subsequent dilation of vessels

Answer 35

cGMP activation of protein kinases

Question 36

what leads to an increased in cellular cGMP

Answer 36

nitric oxide activation of a soluble guanylate cyclase (a lyase enzyme that converts guanosine triphosphate (GTP) to cyclic guanosine monophosphate (cGMP) and pyrophosphate part of the G protein signaling cascade that is activated by low intracellular calcium levels and inhibited by high intracellular calcium levels)

Question 37

can easily cross cell membranes

Answer 37

nitric oxide because its a gas

Question 38

nitric oxide quirks

Answer 38

- not stored in vesicles - not released by calcium-dependent exocytosis (it diffuses) - no active process that terminates its action - decays spontaneously - does not interact with receptors on target cells - action is not confined to the conventional presynaptic-postsynaptic direction - retrograde messenger and regulates the function of axon terminals presynaptic to the neuron in which it is synthesised

Question 39

nitric oxide inhibitor

Answer 39

hemoglobin and other heme proteins which bind it tightly

Question 40

cofactor and coenzyme for all three NO isoforms

Answer 40

BH2 as a cofactor (Tetrahydrobiopterin (BH4, THB) | (NADPH) as a coenzyme

Question 41

any of two or more functionally similar proteins that have a similar but not identical amino acid sequence and are either encoded by different genes or by RNA transcripts from the same gene which have had different exons removed.

Answer 41

isoforms

Question 42

site : neurons and epithelial cells activated by : influx of extracellular calcium enzyme : nitric oxide syntheses (nNOS)

Answer 42

Isoform I

Question 43

site : macrophages and smooth muscle cells induced by : cytokines enzyme : inducible form of nitric oxide synthase (iNOS)

Answer 43

Isoform II

Question 44

site : endothelial cells lining and blood vessels activated by : influx of extracellular calcium enzyme : endothelial nitric oxide synthase

Answer 44

Isoform III

Question 45

function contributes to pathogen killing and has immune-regulatory effects such as inhibiting T cell activity

Answer 45

iNOS