cholinergic drugs

Question 1

explain what the cholinergic nervous system is and how it functions.

Answer 1

• part of the nervous system that uses acetylcholine as its primary neurotransmitter
• transmits signals between nerve cells and between nerve cells and muscles
• mainly involved in the parasympathetic ans

receptors:
- nicotinic
- muscarinic

Question 2

what are the 2 types of nicotinic receptor?

Answer 2

• in neuromuscular junctions
• in autonomic ganglia

Question 3

outline the nicotinic receptors in neuromuscular junctions.

Answer 3

• ionotropic
• activated by acetylcholine
• ion channels open in muscle
• Na influx - depolarisation
• muscle contraction
• acetylcholine then gets broken down by acetylcholinesterase

Question 4

muscarinic receptors

Answer 4

• activated by acetylcholine
• parasympathetic ns
• GPCRs
• 5 subgroups: M1-5

Question 5

outline the nicotinic ganglion receptors

Answer 5

• ionotropic
• acetylcholine binds from pre-synaptic neurons which the receptor transfers to post-synaptic neurons
• fascilitates sympathetic and parasympathetic signals and responses
• when parasympathetic - the receptor releases acetylcholine
• when sympathetic the receptor releases noroepinephrine

Question 6

outline each muscarinic receptor.

Answer 6

M1 Receptors:
- Location: Predominantly CNS, particularly in - brain, gastric parietal cells, and autonomic ganglia.
- Function: learning and memory - In the stomach, they stimulate acid secretion by parietal cells.

M2 Receptors:
- Location: Mainly in the heart (particularly the atria) and in the CNS.
- Function: Mediate inhibition of heart rate (negative chronotropic effect) and reduce contractility in the heart. They also play a role in neurotransmitter release in the brain.

M3 Receptors:
- Location: smooth muscles and glands
- Function: Mediate smooth muscle contraction and glandular secretion

M4 Receptors:
- Location: CNS, particularly in regions like the striatum.
- Function: Involved in modulating dopamine release
- play a role in diseases like Parkinson’s disease and schizophrenia.

M5 Receptors:
- Location: primarily in the CNS, especially in regions associated with dopamine pathways
- Function: Not well understood, but likely involved in dopaminergic signaling and associated with cognitive and motor control functions.

Question 7

outline some therapeutic targets of nicotinic receptors.

Answer 7

myassthenia gravis:
- muscle weakness
- acetylcholinesterase inhibitors - increase acetylcholine to enhance receptor activation for muscle movement

surgical muscle relaxation:
- used during surgeries to reduced muscle movement
- depolarising agents - mimic ach causing the muscle to be constantly depolarised tho for short term paralysis
- non-depolarising blockers - compete with ach but dont activate it

ganglion:
- ganglionic blockers - hypertension

nicotine patches - help smoking cessation

Question 8

outline some therapeutic targets for muscarinic receptors.

Answer 8

lecture says:
- Treating bronchoconstriction in asthma

• Achieving normal BP in hypertensive patients
• Induction of labour / stop premature labour

Question 9

what nervous system and subsequent function type does cholinergic mediate?

Answer 9

• parasympathetic

Question 10

name the clinical uses for blocking muscarinic receptors (antagonists).

Answer 10

• reduced bronchial smooth muscle contraction - treats asthma
• reduces the overactivity of bladder muscle - treats incontinence