Neurotransmitters

Question 1

A NT must be :

Answer 1

in presynaptic terminal
release in response to stimuli
interact on post synapotic receptor
be rapidly removed

Question 2

Amin and AA nt are ….

Answer 2

The amino acid and amine neurotransmitters are:
small molecules
stored and released from synaptic vesicles
capable of many binding to and activating both
ligand-gated channel receptors
G-protein coupled receptors

Question 3

Peptide nt are …

Answer 3

large molecules
stored in secretory granules
only activate G-protein coupled receptors

Question 4

dales principle

Answer 4

A neuron only has one neurotransmitter’

Dale classified neurons into mutually exclusive groups by the neurotransmitter they released

Question 5

glutamate ;

Answer 5

Most common excitatory transmitter in CNS
Amino acid, therefore, found in all neurons
3 glutamate receptor subtypes based on the drugs which act as selective agonists : NMDA,AMPA, kainate
Action is terminated by selective uptake into presynaptic terminals and glia

Question 6

AMPA receptor

Answer 6

AMPA receptors mediate fast excitatory transmission.

Glutamate binding to AMPA receptors triggers Na+ and K+ currents resulting in an EPSP

Question 7

NMDA receptor

Answer 7

• often co-exist with AMPA receptors
• have a voltage-dependent Mg2+ block. so therefore sodium cannot pass in. Need Vm to become more positive so Mg not as attracted and is removed so sodium and calcium can enter
• are permeable to Ca2+ as well as Na+ and K+
• Therefore their activation can have more widespread, lasting changes in the postsynaptic cell

Question 8

GABA nt

Answer 8

Not an amino acid used to synthesise proteins

Precursor is glutamate

Synthesis requires the enzyme glutamic acid decarboxylase

inhibitory in CNS

Question 9

GABA A receptor

Answer 9

is ionotropic
lets Cl- in to make more negative to suppress
can inactivtate Ca+ channels

Question 10

GABA B receptor

Answer 10

GPCR
activate kinase
phosphorylate calcium channels

Question 11

other chemicals that can bind to GABA a channels when GABA also binds

Answer 11

Ethanol has behavioural effects, addictive
Benzodiazepines e.g. diazepam, used to treat anxiety
Barbiturates are sedatives and anti-convulsants
Neurosteroids are metabolites of steroid hormones e.g. progesterone

bind at same time as GABA

Question 12

endorphins ?

Answer 12

Endorphins were discovered in 1975 and are naturally occurring small proteins or peptides, including:
endorphin, enkephalin, dynorphin

Question 13

opioid receptors ? where, types, how they work

Answer 13

are widely distributed in the CNS but concentrated in nociceptive areas
have at least 3 main types
Include mu (µ), kappa (), sigma ()

Can prevent voltage-gated calcium channels opening or increase opening of potassium channels, both hyperpolarise the cell.
Also decrease cAMP production

Question 14

where opiates act as drugs

Answer 14

Spinal - block pain signal (analgaesia)
Periaqueductal grey - regulates sensation of “pain”
Amygdala - regulates emotional component
Frontal cortex - cognitive aspects
Brain stem (medulla) - depress respiration and cough e.g. codeine reflex (may induce vomiting)

Analgesia:
- reduces perception of and emotional response to pain

Intestinal disorders:
- reduces diarrhoea; decreases dehydration

Antitussive:
- cough suppressant (codeine)

Question 15

issues with therapeutic use of opiates

Answer 15

Serious side effects:
Respiratory depression
Sedation
Constipation

Tolerance develops – reduced clinical effect

Dependence develops – leads to withdrawal symptoms

Relieve dull visceral pain better than sharp pain