3. Neurotransmitters

Question 1

Neurotransmitters

Answer 1

chemical substances that move messages across the synapse. More than 100 substances.

Question 2

What are the functions of neurotransmitters?

Answer 2

excitatory or inhibitory depending on their receptor (there are many subtypes that may have very different responses)

Question 3

what are small-molecule neurotransmitters?

Answer 3

amino acids
monoamines
acetylcholine
Unconventional neurotrasmitters

Question 4

neuropeptides

Answer 4

pituitary peptdes
hypothalamic peptides
brain-gut peptides
opioid peptides
miscellaneous peptides

Question 5

what are the most common amino acids?

Answer 5

amino acids

Question 6

excitatory neurotransmitters that are amino acids

Answer 6

glutamate and asparate

Question 7

inhibitory neurotransmitters that are amino acids

Answer 7

Gamma-aminoburytic acid (GABA) and glycine

Question 8

how are amino acids distributed

Answer 8

widely through the CNS

Question 9

Glutamate involved in…

Answer 9

especially involved in learning through a particular receptor-type (NMDA receptors). Involved in excitoticity - prolonged depolarisation of postsynaptic cell -> neuron death

Question 10

two classes of monoamines

Answer 10

catecholamines and indolamines (based on structure)

Most of them diffusely released into extracellular fluid

Question 11

catecholamines

Answer 11

dopamine, epinephrine, norepinephrine;

All derived from one amino acid - tyrosine

Question 12

indolamines

Answer 12

Serotonin or 5-HT (melatonin)

derived from tryptophan

Question 13

two pathways of dopamine

Answer 13

two pathways are mesostriatal and mesolimbocortical

Question 14

functions of dopamine

Answer 14

reward (motivation)
pleasure, euphoria
motor function (fine tuning)
compulsion
Perservation

Question 15

Mesostriatal pathway

Answer 15

Dopamine from the substantia nigra to the striatum

Question 16

mesolimbocortical

Answer 16

from the VTA to the hippocampus, nucleus accumbens and frontal cortex

Question 17

behavioural effects of serotonin

Answer 17

mood
perception
memory
anger
aggression
fear
stress responses
appetite
addiction
sexuality
sleep
cognition

Question 18

seratonin pathway

Answer 18

Raphe nucleus to the striatum, nucleus accumbens, frontal cortex, hippocampus,

Question 19

what was the first neurotransmitter to be detected?

Answer 19

acetylcholine (ACh)

Question 20

What is acetylcholine usually referred to as?

Answer 20

the cholinergic system (i.e. acetylcholine-containing)

Question 21

what are ACh receptors usually?

Answer 21

either nicotinic or muscarinic

Question 22

nicotinic

Answer 22

ionotropic; excitatory

Question 23

muscarinic

Answer 23

metabolic; both excitatory and inhibitory

Question 24

what is Acetylcholine implied in?

Answer 24

Alzheimer’s disease; learning and memory

Question 25

what is the cholinergic system?

Answer 25

projections of cholinergic neurons from the chollinergic nuclei of the pons and midbrain to the hippocampus, thalamus and amygdala
and also from the basal forebrain to the cerebral cortex

Question 26

two kinds of unconventional neurotransmitters

Answer 26

nitric oxide, carbon monoxide

Endocannabinoids

Question 27

Nitric Oxide, carbon monoxide

Answer 27

soluble gaseous neurotransmitter
easily penetrate the cell membrane and active second messengers
involved in retrogade transmission

Question 28

endocannabinoids

Answer 28

includes anandamide - which was the first endocannabinoid to be discovered with similar properties to the main psychoactive properties of marijuana
The major effect on presynaptic neurons inhibiting synaptic transmission

Question 29

how many neuroptides are identified?

Answer 29

about 100

Question 30

what do the neuropeptides functions depend on?

Answer 30

their amino acid sequence

Question 31

5 categories of neuroptides

Answer 31

pituitary peptides
hypothalamic peptides
brain-gut peptides
opiate peptides
miscellaneous hormones

Question 32

pituitary peptides

Answer 32

those released from the pituitary gland (e.g. oxytocin; “love” hormone

Question 33

hypothalamic peptides

Answer 33

those released from the hypothalamus (e.g. CRH; corticotropin releasing hormone; anxiety)

Question 34

brain-gut peptides

Answer 34

those first identified in the gut (e.g. ghrelin; hunger hormone also thought to be involved in stress, anxiety, depression; learning etc.)

Question 35

opiate peptides

Answer 35

those that resemble the structure of active ingredient of opium (endogenously produced; (e.g. endorphins; happy hormones)

Question 36

miscellaneous hormones

Answer 36

those that dont fit any other category

Question 37

how do drugs influence synaptic transmission

Answer 37

drugs either facilitate (agonists) or inhibit (antagonist) effects of neurotransmitters. Drugs can act on various steps of neurotransmitter action either pre or post synaptically

Question 38

what are the 7 steps to neurotransmitter action

Answer 38

1. neurotransmitter molecules are synthesised from precursors under the influence of enzymes
2. neurotransmitter molecules are stored in vesicles
3. neurotransmitter molecules that leak from their vesicles are destroyed by enzymes
4. action potentials cause vesicles to fuse with the presynaptic membrane and release their neurotransmitter molecules into the synapse
5. Released neurotransmitter molecules bind with autoreceptors and inhibit subsequent neurotransmitter release
6. Released neurotransmitter molecules bind to postsynaptic receptors
7. Released neurotransmitter molecules are deactivated by either reuptake or enzymatic degradation