Adrenergic effects

Question 1

What are sympathomimetics?

Answer 1

Drug that recreates the stimulation of a sympathetic nerve

Either they’re directly acting or they act indirectly by boosting the level of noradrenaline

Question 2

What is isoprenaline?

Answer 2

• Isoprenaline is a synthetic chemical which was developed for research purposes

Question 3

Potency in alpha and beta adrenergic receptors

Answer 3

• In Alpha, noradrenaline more potent than adrenaline which is more potent than isoprenaline
• In Beta, isoprenaline more potent than adrenaline which is more potent than noradrenaline

Question 4

What are all adrenoreceptors examples of?

Answer 4

All adrenoreceptors are examples of GPCR

Question 5

REFER TO NOTES FOR RECEPTORS AND THERE EFFECTS

Answer 5

1

Question 6

What do alpha 1 adrenoreceptor contract?

Answer 6

• Contract vascular smooth muscle

Question 7

What do alpha 1 adrenoreceptor increase?

Answer 7

Increase total peripheral resistance

Question 8

What do alpha 1 adrenoreceptors look like?

Answer 8

Looks like beads on strings-Varicosities

Question 9

What do varicosities spray out?

Answer 9

Varicosities spray out transmitter

Question 10

Pathway of alpha 1 adrenoreceptor?

Answer 10

• IP3 binds to its own receptor which is a Ca2+ channel thus causing the release of Ca2+ from the internal calcium stores
• DAG tends to stay in the lipid phase and can activate ion channels itself or activate PKC

Question 11

What other tissues are alpha 1 adrenoreceptors found in?

Answer 11

• Are found in other tissue:
○ Leading to contraction of the seminal vesicles
○ Contraction of Iris muscle which results in diluted pupils
Contraction of pilomotor muscle which controls hair

Question 12

Main role of alpha 2 adrenoreceptor?

Answer 12

Main role is the inhibition of neurotransmitter release

Question 13

Mechanism of adrenoreceptor 2

Answer 13

• Negative feedback mechanism which tends to be a receptor located on the nerve terminals or the varicosities
○ Decreased likely hood of the Ca2+ ion channel being opened and it becomes less sensitive to voltage
○ Adenylate cyclase becomes inhibited so the cAMP goes down and PKA goes down
○ The beta subunits stimulate some potassium channels so a cell becomes calmer. Potassium leaves a cell and the membrane potential becomes more negative
This is where the neurone can be hyperpolarised, reducing the activity of the Ca2+ channels

Question 14

Beta 1 adrenoreceptors

Answer 14

• Sympathetic innervation is throughout the heart
• Innervation of the SAN, AVN, atria and ventricles
An increase in heart rate

Question 15

What happens when sympathetic nerve stimulated?

Answer 15

○ When the sympathetic nerve is stimulated, it depolarised the action potential and it becomes briefer
Results in a larger but shorter contraction which is more powerful

Question 16

Beta 1 adrenoreceptor mechanism

Answer 16

• There is an increase in cAMP which interacts with a pacemaker channel in the SAN
More calcium released but also more calcium uptake

Question 17

Beta 1/2 adrenoreceptor

Answer 17

• Increases cardiac muscle function
• Beta 2 adrenoreceptor relaxes vascular smooth muscle:
○ Especially airways
○ Skeletal muscle vasculature
○ Coronary and cerebral blood vessels
• PKA inhibits the go mechanism in smooth muscles

Question 18

What do beta 1 blocker do

Answer 18

• Reduce arrhythmia

Less renin production in kidneys

Question 19

What are the main uses of adrenoreceptor blockers

Answer 19

• Eye drops
• Heart 
• Kidneys
• Urination
  Adrenal gland tumour