Lecture 7 & 8 - Cholinergic Transmission Flashcards
What is part of the autonomic nervous system
Sympathetic
Parasympathetic
Enteric
What does the autonomic nervous system do
Takes all outputs from CNS and transfers them to the rest of the body
What does the autonomic nervous not do
Motor signals
Is autonomic nervous system voluntary/involuntary
Involuntary
What are the two main neurotransmitters
Acetylcholine (Ach)
Noradrenaline (NA)
What does the autonomic nervous system
- Heartbeat
- Contraction/Relaxation of blood vessels
- Exocrine/Endocrine secretion
- Energy Metabolism
Sympathetic Activity
Increases Stress (Fight/Flight)
Parasympathetic Activity
Relaxation and After Meals
All preganglionic autonomic nerve fibres release _______ that act on ______
Ach that acts on nicotinic receptor
Most Postganglionic Sympathetic fibres release _____ that act on
NA that acts on alpha and beta adrenoceptors
Postganglionic Sympathetic fibres
(Exceptions)
Sweat and Adrenal
Sweat Glands receive signals from _____ acting on ______ receptors
Ach acting on Mus receptors
Adrenal Glands receive signals from _____ acting on ______ receptors
Ach acting on Nic receptors
All postganglionic Parasympathetic Fibres release _____ that act on ______
Ach that act on Mus receptors
Where does Cholinergic Transmission act
Sympathetic, Parasympathetic, Enteric
Skeletal + CNS
What are the two types of Ach receptors
Nicotinic Receptors
Muscarinic Receptors
What kind of receptors are Nicotinic Receptors
Ligand-Gated Ion Channel that conduct mainly Na+
What are the three types of Nicotinic Receptors
Ganglionic: Autonomic, postsynaptic
Muscle: Skeletal, postsynaptic
CNS: Brain Regions, pre- and postsynpatic
What are the M1 and M2 and M3
(Excitatory/Inhibitory)
M1 = Excitatory (Gq)
M3 = Excitatory (Gq)
M2 = Inhibitory (Gi)
M1 Receptors
Slow Excitation of Ganglia
M2 Receptors
Decreases Cardiac rate and Contraction force
M3 Receptors
Causes Gland Secretion
Contracts smooth muscle around organs (Visceral Muscle)
Vascular relaxation (NO-mediated)
Nicotinic vs Muscarinic (Time Scale)
Nicotinic takes milliseconds
Muscarinic takes seconds
What kind of effect does Cholinergics have at the Neuromuscular Junction
Ach binds nAchR
Causes neuromuscular blocks to relaxes muscles
Mechanism that drugs use to produces neuromuscular blocks
Antagonizes nAChr through competition (non-depolarizes)
Agonists that activate nAChR (depolarizes)
Non-depolarizing Agents mechanism
Competitive antagonists at motor endplate nAChR
Inhibits ACh release for any continuous stimuli
Muscle Paralysis
Depolarizing Agents mechanism
Agonist at nAChR
Persistent depolarization from agonist continuously binding
resistant to acetylcholinesterase
Initial muscle contraction followed by paralysis
Two types of Cholinesterases
Acetylcholinesterase (Synapse)
Butyrylcholinesterase (Plasma)
Uses of Anticholinesterases
Reverses non-depolarizing neuromuscular block
Treat myasthenia gravis (weakening of bone)
Anticholinesterase at NMJ
Increases muscle tension
Anticholinesterase at CNS
Excitation (mAChR) followed by depression of activity - unconsciousness, respiratory failure
How to reverse anticholinesterase depression
Atropine and Pralidoxime
