Neurotransmitters

Question 1

What are neurotransmitters?

Answer 1

• Chemicals that transmit signals from a neuron to an adjacent cell (nerve, muscle, organ, gland)
• Can stimulate or inhibit target cell
• Synaptic transmission is virtually always unidirectional
• Activate receptor to react
• Many work at multiple sites - action detected by receptor rather than neurotransmitter

Question 2

Which neurotransmitter normally acts on blood vessels?

Answer 2

Noradrenaline

Question 3

Which enzyme regulates presynaptic store of catecholamines?

Answer 3

Monoamine oxidase

Question 4

What do monoaminoxidases do?

Answer 4

Break down caracholamines in pre-synapse

Question 5

Into which class does the Beta 1 receptor fall?

Answer 5

G-protein linked

Question 6

What is the main role of the alpha 2 receptors in the PNS?

Answer 6

Terminating presynaptic NA release

Question 7

What does serotonin do?

Answer 7

• 13 receptor sub-types in multiple sites, regulating processes and other neurotransmitters and hormones
• Some broken down by monoamine oxidase but a lot taken back up and re-used
• Antidepressants SSRIs - selective serotonin re-uptake inhibitors
• Medications block receptor
• Longer stays in synapse, better chance of signal getting through = increased mood

Question 8

Effects of 5-HT

Answer 8

• CNS: mood, memory, aggression, appetite, sleep, addiction
• Gut: motility, emesis (5-HT3)
• CVS: vasoconstriction, HR
• Blood: platelet activation

Question 9

When ACh binds at the NMJ postsynaptic receptor, what ion influx generates AP at end plate?

Answer 9

Na+

Question 10

Main peripheral neurotransmitters and receptors

Answer 10

• Nicotinic receptors: neuromuscular junction (N2) and autonomic ganglia (N1)
• Muscarinic receptors: parasympathetic post-ganglionic (M1, M2…), sympathetic = sweating

Question 11

What are the two types of noradrenaline?

Answer 11

• Sympathetic post-ganglionic (alpha1, beta1)

- Presynaptic inhibitory (alpha2)

Question 12

Function of ACh

Answer 12

Motor function regulation (basal ganglia vs dopamine), emotion, arousal

Question 13

Function of dopamine

Answer 13

Motor function regulation (basal ganglia vs ACh), memory, emesis, regulation of hormone release (GH, prolactin)

Question 14

Function of noradrenaline

Answer 14

Memory, arousal, circadian rhythm, endorphin release in spinal cord (inhibits nociception)

Question 15

Function of serotonin

Answer 15

Mood, memory, appetite, sleep, endorphin release in spinal cord (inhibits nociception)

Question 16

Function of GABA

Answer 16

Main inhibitory neurotransmitter, GABAa (Cl- channel linked) and GABAb (GPCR)

Question 17

Function of glutamate

Answer 17

Excitatory neurotransmitter, NMDA, KA, AMPA sub-types

Question 18

Functions of endorphins/enkephalins

Answer 18

Inhibits nociception in dorsal horn of spinal cord

Question 19

Function of substance P

Answer 19

Amplifies nociception in dorsal horn of spinal cord

Question 20

What is the triad of Parkinson’s disease?

Answer 20

Tremor, rigidity, bradykinesia

Question 21

Treatment for Parkinson’s

Answer 21

Treatment revolves around boosting dopamine action either by giving more dopamine substrate (L-DOPA) or blocking dopamine breakdown (with COMT or MAO inhibitors) or by using dopamine receptor agonists