Autonomic Receptors Flashcards
What are the two types of autonomic receptors?
Cholinergic and Adrenergic
Cholinergic - stimulated by ACh
Adrenergic - stimulated by noradrenaline and adrenaline
What are the types of Cholinergic receptors?
Nicotinic and Muscarinic
What are the Nicotinic receptors?
Nn and Nm
Where are Nicotinic receptors found?
The Adrenal Medulla
What are Cholinergic receptors?
They are stimulated by ACh
What are Adrenergic Receptors?
They are stimulated by Noradrenaline and Adrenaline
When stimulated what do Nicotinic receptors do?
They increase Na influx into cells
Where are Nn receptors found?
At autonomic junctions
Where are Nm receptors found?
In muscle
What are the Muscarinic receptors?
M1, M2 and M3
When stimulated what do Muscarinic receptors do?
They stimulate G proteins
What types of G proteins are there?
Gq, Gi and Gs
What does Gq do when stimulated?
Increase stimulation of Phospholipase C
What does Gi do when stimulated?
Inhibit adenyl cyclase
Decrease cAMP
What does Gs so when stimulated?
Stimulation of adenyl cyclase
Increase cAMP
When stimulated, what does M1 do?
- Increased acid secretion in the stomach
- Increases gland secretion in the ENS
When stimulated, what does M2 do?
- Decreases HR by increasing SA-AV node delay
When stimulated, what does M3 do?
M3 gives a “wet picture” - lots of secretions
- Contraction of visceral smooth muscle (bronchoconstriction)
- Increased secretion of Saliva
- Increases Vasodilation
- Pupil constriction
- Relaxed sphincters
- Vomiting/urination etc
What are the types of Adrenergic receptors?
Alpha, Beta and Dopamine
What are Alpha receptors?
A1 and A2
Where are M1 receptors found?
In the ENS and the CNS
Where are M2 receptors found?
In Cardiac Muscle
Where are A1 receptors found?
In the heart and vascular smooth muscle
Where are A2 receptors found?
In some vascular smooth muscle
Where are B1 receptors found?
In the heart
Where are B2 receptors found?
In respiratory and vascular smooth muscle
What is the opposite of the B1 receptor?
The M2 receptor
When stimulated, what does A1 do?
- Increases vasoconstriction through contraction of vascular smooth muscle
- Increases HR
- Increases the force of contraction of the heart
- Pupil dilation
- Constricts sphincters
When stimulated, what does A2 do?
- Inhibits noradrenaline release
When stimulated, what does B1 do?
- Increases the force of contraction of the heart (SV)
- Increases HR by decreasing the SA-AV node delay
- Increases CO (SV X HR)
When stimulated, what does B2 do?
- Bronchodilates
- Increases Vasodilation
- Inhibit histamine released from Mast cells
- Increase Renin secretion
- Increases contraction in GI sphincters
What G protein do A1 receptors act on?
Gq
What G protein do A2 receptors act on?
Gi
What G protein do B1 receptors act on?
Gs
What G protein do B2 receptors act on?
Gs
What G protein do M1 receptors act on?
Gq
What G protein do M2 receptors act on?
Gi
What G protein do M3 receptors act on?
Gq
What is the mnemonic for remembering what receptors act on what G proteins?
“Kiss Quick” = QISS QIQ
A1 - Q
A2 - I
B1 - S
B2- S
M1 - Q
M2 - I
M3- Q
What is Sympathetic Nervous System
Fight or Flight
What is Para-sympathetic Nervous System
Rest and Digest
What is the pre-ganglionic neurotransmitter for the Sympathetic Nervous System
ACh (acetylcholine)
What is the post-ganglionic neurotransmitter for the Sympathetic Nervous System
Noradrenaline
What is the pre-ganglionic neurotransmitter for the Para-sympathetic Nervous System
ACh (acetylcholine)
What is the post-ganglionic neurotransmitter for the Para-sympathetic Nervous System
ACh (acetylcholine)
What is the Autonomic Nervous System?
Both the Sympathetic and Para-sympathetic nervous systems
What part of the Autonomic nervous system are Muscarinic receptors?
Post-ganglion Para-sympathetic
What part of the Autonomic nervous system are Alpha receptors?
Post-ganglion Sympathetic
What part of the Autonomic nervous system are Beta receptors?
Post-ganglion Sympathetic
What is the exception for the Adrenal Medulla?
There is no post-ganglionic neurone. Pre-gangionic ACh stimulates Nicotinic receptors in the adrenal medulla. This then stimulates the secretion of adrenaline into the bloodstream where it acts on adrenergic receptors.
What is the length of pre-ganglionic sympathetic neurones?
Short
What is the length of post-ganglionic sympathetic neurones?
Long
What is the length of pre-ganglionic para-sympathetic neurones?
Long
What is the length of post-ganglionic para-sympathetic neurones?
Short
Where do the sympathetic nerves exit the spinal cord?
They leave at T1-L2, and pass into splanchnic nerves to supply organs.
Where do para-sympathetic nerves exit the spinal cord?
They have a cranialsacral outflow.
Exit cranial nerves : III, VII, IX, X
The Vagus nerve supplies organs of the head, neck, chest, abdomen and mid-gut.
Sacral Spinal nerves supply the organs of the hindgut, pelvis and perineum.
What is the mnemonic to remember all the receptor actions on the body?
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VC - Vasoconstriction
N - Noradrenaline inhibition
F - Force of contraction
H - Heart-rate increased
BD - Bronchodilation
VD - Vasodilation
G - Gastric acid secretion
H - Heart-rate decreased
BC - Bronchoconstriction
S - Saliva secretion
