Adrenoreceptors

Question 1

What are adrenoceptors?

Answer 1

Specific cell membrane receptors in the sympathetic nervous system

Question 2

What do sympathetic nerves release?

Answer 2

Noradrenaline

Question 3

What are the two groups of adrenoceptors?

Answer 3

Alpha

Beta

Question 4

What is the most potent agonist for the adrenoceptors?

Answer 4

Alpha 1: noradrenaline
Alpha 2: adrenaline
Beta 1: isoprenaline
Beta 2: isoprenaline
Beta 3: isoprenaline

Question 5

What is the structure of an adrenoceptor?

Answer 5

G-protein coupled receptor
Integral membrane protein
Single polypeptide chain
Extracellular N-terminus
Intracellular C-terminus
7 transmembrane alpha helices
Binding site buried within the plane of the membrane

Question 6

What are alpha1 adrenoceptors couple to?

Answer 6

G protein Gq
Activates phospholipase C-beta
PLC acts on PIP2
Two products
IP3 and DAG
Ca2+ triggered release
Activation of protein kinase C

Question 7

What do alpha2 adrenoceptors do?

Answer 7

Inhibit adenylyl cyclase

Decrease phosphorylation of intracellular proteins

Question 8

What is Yohimbine?

Answer 8

Treatment of sexual dysfunction

Alpha2 antagonist

Question 9

What do beta adrenoceptors do?

Answer 9

Stimulate adenylyl cyclase

Question 10

What do cardiac adrenoceptors do?

Answer 10

Beta1
Increase heart rate at sino atrial node
Increase conduction velocity at AV node
Increase contractility of atria
Increase contractility and automacity of ventricles

Question 11

What is the effect of adrenoceptors on blood vessels?

Answer 11

Alpha1 contstriction

Beta2 dilation

Question 12

What is the effect of adrenoceptors on bronchi?

Answer 12

Beta2 dilation

Question 13

What is the effect of adrenoceptors on the GI tract?

Answer 13

Alpha1 and 2 contract sphincters

Beta2 relaxes

Question 14

What is the effect of adrenoceptors on the uterus?

Answer 14

Alpha1 contracts

Beta2 relaxes

Question 15

What is the effect of adrenoreceptors on the bladder detrusor?

Answer 15

Beta 2 and 3 relax

Question 16

What is the effect of adrenoreceptors on the bladder sphincter?

Answer 16

Alpha 2 contract

Question 17

What is the effect of adrenoreceptors on the Vas deferens?

Answer 17

Alpha 1 contract

Question 18

What is the effect of adrenoreceptors on the iris radial muscle?

Answer 18

Alpha 1 contract

Question 19

What is the effect of adrenoreceptors on ciliary muscle?

Answer 19

Beta 2 relax

Question 20

What is the effect of adrenoreceptors on the liver?

Answer 20

Alpha1 and beta2 glycogenolysis

Question 21

What is the effect of adrenoreceptors on adipose tissue?

Answer 21

Beta3 lipolysis, thermogenesis

Question 22

What is the effect of adrenoreceptors on skeletal muscle?

Answer 22

B2 glycogenolysis, tremor

B3 thermogenesis

Question 23

What is the effect of adrenoreceptors on pancreatic islets?

Answer 23

A2 reduced insulin secretion

Question 24

What is the effect of adrenoreceptors on salivary glands?

Answer 24

A1 potassium release

B1 amylase secretion

Question 25

What is the effect of adrenoreceptors on nerve terminals?

Answer 25

A2 inhibition of transmitter release | B2 enhance release

Question 26

What is the effect of adrenoreceptors on platelets?

Answer 26

A2 aggregation

Question 27

What is the effect of adrenoreceptors on mast cells?

Answer 27

B2 inhibition of histamine release

Question 28

What is the effect of adrenoreceptors on the brain stem?

Answer 28

A2 inhibition of sympathetic outflow

Question 29

Name agonists for the adrenoceptors

Answer 29

``` A1 phenylephrine A2 clonidine B1 dobutamine B2 salbutamol, terbutaline, salmeterol B3 mirabegron ```

Question 30

Name antagonists for the adrenoceptors

Answer 30

A1 prazosin, doxazosin A2 yohimbine, idazoxan B1 atenolol, metoprolol B2 butoxamine

Question 31

Uses of adrenaline

Answer 31

Cardiac arrest to restore cardiac rhythm Acute anaphylaxis Severe asthma

Question 32

How is adrenaline administered?

Answer 32

Intramuscularly | Subcutaneously

Question 33

What are the side effects of adrenaline?

Answer 33

Tachycardia Vasoconstriciton Hypertension Cardiac arrhythmias

Question 34

Uses of dobutamine

Answer 34

Acute heart failure

Question 35

How is dobutamine administered?

Answer 35

Intravenously

Question 36

Uses of salbutamol (terbutaline and salmaterol)

Answer 36

Asthma | Salbutamol only:Delay premature labour

Question 37

How is salbutamol administered?

Answer 37

Orally Inhaled Intravenously

Question 38

Uses of mirabegron

Answer 38

Treatment of overactive bladder syndrome

Question 39

Uses of phenylephrine

Answer 39

Nasal decongestion

Question 40

Uses of clonidine

Answer 40

Hypertension | Migraine

Question 41

Use of dexmedetomidine

Answer 41

Intravenous sedation

Question 42

What are side effects of B adrenoceptor antagonists?

Answer 42

``` Bronchoconstriction Bradycardia Hypoglycaemia Fatigue Bad dreams ```