Cholinergic System

Question 1

How does the cholinergic system work?

Answer 1

adrenergic opposes cholinergic to maintain homeostasis

Question 2

How does Ach bind to muscarinic and nicotinic receptors?

Answer 2

Via internal rotation since Ach is a flexible molecule

Question 3

How does binding prevent CNS effects?

Answer 3

Both receptors have a permanent positive charge due to the quaternary ammonium ion. Therefore it is unable to diffuse around the body so it cannot cross the BBB reducing CNS effects.

Question 4

What receptors doe SAMAs and LAMAs act on?

Answer 4

M3 - they are muscarinic antagonists

Question 5

State which portion of a SAMA is responsible for selectivity and why? give an example.

Answer 5

Tropane the middle section between isopropyl and easter - maintains fixed distance between ester and quaternary ammonium ion, locked orientation suits muscarinic receptors
Example: Ipatropium bromide

Question 6

State which portion of a LAMA is responsible for selectivity and why? give an example.

Answer 6

Tropane the middle section between isopropyl and easter - maintains fixed distance between ester and quaternary ammonium ion
Example: Tiotropium bromide

Question 7

Describe why LAMAs are long acting

Answer 7

Snap lock mechanisms induce conformational change so it remains bound to receptor