Autonomic nervous system

Question 1

What are the sympathetic neurotransmitters?

Answer 1

Noradrenaline and adrenaline

Question 2

What are the adreceptors?

Answer 2

Alpha and beta receptors

Question 3

What is the parasympathetic neurotransmitter and receptor called?

Answer 3

Neurotransmitter = acetylcholine
Receptor = muscarinic

Question 4

Noradrenaline

Answer 4

Neurotransmitter released at sympathetic nerve endings onto smooth muscle
Mainly alpha stimulation
Main effect: vasoconstriction (1-): used to raise blood pressure e.g., after shock, or to reduce local blood flow e.g., in surgery

Question 5

What are the predominant adrenoceptors of .. and their effects when stimulated?
Small blood vessels
Large blood vessels
Bronchial tree
Myocardium

Answer 5

Small blood vessels - A1 - vasoconstriction
Large blood vessels - B2 - vasodilation
Bronchial tree - B2 - bronchodilation
Myocardium - B1 - Increased HR, contractility

Question 6

What adrenoceptors does noradrenaline and adrenaline have greater effect on?

Answer 6

NorA - More at alpha than beta

Adren - equal activity at alpha and beta

Question 7

How do agonists affect the sympathetic nervous system?

Answer 7

Mimic stimulation on SNS

Question 8

How do antagonists affect the sympathetic nervous system?

Answer 8

Mimic inhibiting the SNS

Question 9

Adrenaline

Answer 9

Alpha and beta stimulation
Vasoconstriction (1-): uses as for noradrenaline, also to increase duration of effect of local anaesthetics by constricting surface blood vessels (e.g., lignocaine with adrenaline)
increased heart rate (1-)
bronchodilation (2-)
e.g., Epipen®: used to raise bp, increase heart rate, bronchodilation in anaphylactic shock

Question 10

Alpha-agonists

Answer 10

Vasoconstriction

Question 11

Beta-agonists

Answer 11

Bronchodilation

Question 12

Alpha-antagonists

Answer 12

Vasodilation

Question 13

Beta-antagonists

Answer 13

Cardioprotection - reduces effects of nor/adr

Question 14

A1 agonist

Answer 14

Vasoconstriction
Noradrenaline they raise blood pressure e.g., in shock and reduce blood flow during surgery
Main use: Relieve nasal congestion by constricting nasal blood vessels (decongestants) – when inflamed e.g., during a cold, these vessels become dilated and oedematous (‘stuffed/runny nose’)
Occasionally used to produce pupil dilation (mydriasis)