Cholinergic Physiology Flashcards Preview

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Flashcards in Cholinergic Physiology Deck (10):
1

Ach Funtcions

Somatic efferents at NMJ
Pre-synaptic neurons in parasympathetic and sympathetic ganglia
Post-ganglionic neurons in parasympathetic system to activate smooth muscle and glands

2

Nicotinic Receptors

Fast acting & Ionotropic
Located at NMJ and autonomic ganglia to cause muscle contraction and post-synaptic firing respectively
Three types: Muscular, Ganglionic, CNS

3

Muscarinic Receptors

Slow acting and metabotropic
Located on effector tissue
5 subtypes: M1-M5
Odd numbers act through Gq to activate Inositol Phosphate
Even numbers act through Gi to inhibit Adenylate Cyclase
All post-synaptic, evens are pre too

4

Muscarinic Subtypes

M1(Neural): Excitatory in CNS and glandular tissue
M2(Cardiac): Inhibitory in cardiac muscle
M3(Glandular and Smooth Muscle): Excitatory of these
M4(CNS): Inhibitory in CNS
M5(CNS): Excitatory in CNS

5

Ach Synthesis

Choline is taken into nerve terminal via Choline Transporter
Choline Acetyltransferase adds and Acetyl group from AcetylCoA to choline to form Ach

6

Ach Storage

Synthesised Ach is pumped into vesicles for storage by vesicular Ach transporter

7

Ach Release

Depolerisation of the nerve terminal causes Ca influx.
This causes fusion of storage vesicles to the membrane and release of Ach by exocytosis

8

Ach Degradation

Cholinesterase enzymes break Ach into Choline and Acetate

9

Ach Reuptake

Choline is recycled and taken into nerve terminal once again by Choline transporter where it is made into Ach again

10

Pre-Synaptic Modulation

Inhibitory M2: Ach release stimulates these receptors which inhibit Ach release
Adrenergic Receptors: Sometimes present on pre-synaptic terminals. They are inhibitory and dampen parasympathetic transmission during sympathetic input