Adrenergic effects

Question 1

What are the nerve fibres like in the sympathetic nervous system

Answer 1

There are short pre-ganglionic nerve fibres and long post-ganglionic nerve fibres

Question 2

What receptors do sympathetic nerves have

Answer 2

nicotinic acetylcholine receptors

Question 3

What is the main neurotransmitter in the sympathetic nervous system and where does it act

Answer 3

Noradrenaline

It acts on the adrenergic G coupled receptors

Question 4

How is DOPA (dihydroxyphenylalanine) made

Answer 4

Tyrosine is converted to DOPA by the action of tyrosine hydroxylase
This is the rate determining step

Question 5

How is dopamine made

Answer 5

DOPA is converted to dopamine by the action of DOPA decarboxylase

Question 6

What is dopamine used for

Answer 6

Its a neurotransmitter in the brain

Its involved in many pathways especially reward-motivated behaviour

Question 7

How is noradrenaline made

Answer 7

Dopamine is converted to noradrenaline by the action of dopamine beta-hydroxylase

Question 8

Where and how is adrenaline made

Answer 8

In the adrenal medulla, noradrenaline is converted to adrenaline by the action of phenylethanolamine N-methyltransferase (PNMT)

Question 9

What is sympathomimetics

Answer 9

A drug that mimics or looks like you’ve stimulated the sympathetic nerves

Question 10

What is indirect sympathomimetics

Answer 10

These drugs overstimulate the sympathetic nervous system

Question 11

What is direct sympathomimetics

Answer 11

When the drug is an agonist which will bind to the receptor taking the place

Question 12

What is isoprenaline

Answer 12

A synthetic stimulator

Question 13

What is the order in sensitivity of stimulators on alpha receptors

Answer 13

1. Noradrenaline
2. Adrenaline
3. Isoprenaline

Question 14

What is the order in sensitivity of stimulators on beta receptors

Answer 14

1. Isoprenaline
2. Adrenaline
3. Noradrenaline

Question 15

What type of receptor is an alpha 1 receptor

Answer 15

Gq protein coupled receptor

Question 16

What happens when alpha 1 receptors are activated

Answer 16

Phospholipase C is activated
Splits PIP2 into IP3 and DAG
IP3 causes calcium release from smooth ER
DAG causes kinase C production

Question 17

What are the physical outcomes of alpha 1 receptor stimulation

Answer 17

Vascular smooth contraction; vasoconstriction in blood vessels
Contraction of seminal vesicles; iris muscle (pupil dilation) and pilomotor muscle

Question 18

What are alpha 1 agonists

Answer 18

Phenylephrine and oxymetazoline

Question 19

What are alpha 1 antagonists

Answer 19

Prazosin, doxazosin and tamsulosin

Question 20

What type of receptor is an alpha 2 receptor

Answer 20

Gi protein coupled receptor

Question 21

What happens when alpha 2 receptors are activated

Answer 21

Inhibits adenylate cyclase

therefore decreases cAMP production so protein kinase A production reduced

Question 22

What are the physical outcomes of alpha 2 receptor stimulation

Answer 22

Inhibition of transmitter release from sympathetic nerves
The likely hood of the calcium channels on the adrenergic neurone opening is less even if depolarisation occurs since there is a lack of protein kinase A

Question 23

What are alpha 2 agonists

Answer 23

Clonidine

Question 24

What are alpha 2 antagonists

Answer 24

Yohimbine

Question 25

What type of receptor is a beta 1 receptor

Answer 25

Gs protein coupled receptor

Question 26

What happens when beta 1 receptors are stimulated

Answer 26

Activates adenylate cyclase therefore increases cAMP production so protein kinase A production is increased

Question 27

What are the physical outcomes of beta 1 receptor stimulation

Answer 27

Positive chronotropy - Heart rate increases Positive inotropy - Force increases Positive lusitropy - Rate of relaxation increases Positive dromotropy - Conduction velocity of atrioventricular node increases

Question 28

What does cAMP do after beta 1 stimulation

Answer 28

Will interact with a pacemaker channel in the SAN that open up by hyperpolarisation

Question 29

What does protein kinase A do after beta 1 stimulation

Answer 29

Makes calcium channels have a higher sensitivity to voltage therefore there is a larger influx of calcium ions Stimulates potassium channels so the action potential depolarises quicker therefore there is a shorter action potential Will affect calcium release channels, increases the uptake of calcium back into the sarcoplasmic reticulum - contraction is bigger but briefer

Question 30

Where is the juxta glomerular apparatus (JGA) located

Answer 30

Between afferent and efferent renal arteries

Question 31

What does the JGA do

Answer 31

1. Increases renin release 2. Renin converts inactive angiotensinogen to active angiotensin I 3. This is turned into angiotensin II

Question 32

What are the effects of angiotensin II

Answer 32

1. Contracts vascular smooth muscle itself 2. Increases the release of noradrenaline from sympathetic nerves 3. Stimulates aldosterone which reabsorbs more water so you have an increase in circulating volume

Question 33

What type of receptor is a beta 2 receptor

Answer 33

Gs protein coupled receptor

Question 34

What happens when beta 2 receptors are stimulated

Answer 34

1. Increased cAMP production | 2. Increased K+ channel activity and decreased Ca release

Question 35

What are the physical outcomes of beta 2 receptor stimulation

Answer 35

1. Vascular dilation/airway relaxation | 2. Decreased myosin light chain kinase and decreased contraction

Question 36

What are beta 2 agonists

Answer 36

Salbutamol, salmeterol and clenbuterol

Question 37

What are beta 2 antagonists

Answer 37

Propanolol

Question 38

What type of receptor is a beta 3 receptor

Answer 38

Gs protein coupled receptor

Question 39

What are beta 3 agonists

Answer 39

Mirabegron

Question 40

What are the physical outcomes of beta 3 receptor stimulation

Answer 40

Enhancement of lipolysis in adipose tissue

Question 41

Whats the treatment of an overreactive bladder

Answer 41

The beta 3 agonist mirabegron

Question 42

What is a nasal decongestant

Answer 42

The alpha 1 agonist phenylephrine and ephedrine

Question 43

Use of adrenoreceptor blockers 1. Heart 2. Kidneys 3. Eye drops

Answer 43

1. Atenolol 2. Atenolol, less renin production 3. Timolol