Cholinergics

1
Cholinergics
2
Nerve Transmission
Peripheral nervous system
CNS
Brain
Peripheral nerves
Muscle
Heart
Gastro- intestinal tract (GIT)
Spinal cord
3
Nerve Transmission
Peripheral nervous system
Ach (N)
NA
Ach (N)
Ach (N)
Synapse
Ach (M)
Ach (N)
4
Nerve Transmission
Synapses
Release of neurotransmitters
Receptor binding and new signal
5
Neurotransmitter
Acetylcholine (Ach)
6
Transmission process
Signal in nerve 1
7
Transmission process
Vesicles fuse with membrane and release Ach
8
Transmission process
9
Transmission process

• Receptor binds Ach
• Induced fit triggers 2o message
• Triggers firing of nerve 2
• Ach undergoes no reaction

10
Transmission process

• Ach departs receptor
• Receptor reverts to resting state
• Ach binds to acetylcholinesterase

11
Transmission process
Ach hydrolysed by acetylcholinesterase
12
Transmission process
Choline binds to carrier protein
13
Transmission process
Choline transported into nerve
14
Transmission process
Ach resynthesised
15
Transmission process
Ach resynthesised
16
Transmission process
Ach repackaged in vesicles
17
Cholinergic receptors

• Receptor types
• Not all cholinergic receptors are identical
• Two types of cholinergic receptor - nicotinic and
  muscarinic
• Named after natural products showing receptor
  selectivity

Activates cholinergic receptors at nerve
synapses and on skeletal muscle
Activates cholinergic receptors on smooth muscle
and cardiac muscle
Acetylcholine is natural messenger for both
receptor types
18
Peripheral nervous system
Ach (N)
NA
Ach (N)
Ach (N)
Synapse
Ach (M)
Ach (N)