Autonomic Pharmacology Flashcards
Which direction do efferent signals go?
Away from the CNS
What is somatic efferent?
Voluntary contraction
Neurones leaving spinal cord and innervating muscle
What direction do afferent signals go?
Towards the CNS
What is somatic afferent?
Nerves supplying skin, joints, muscles
What are the myenteric plexus and submucosal plexus part of and where do they supply?
They are part of the enteric nervous system, a mesh-like system of neutrons which governs the function of the GI system
What is a ganglion?
A collection of nerve cell bodies that lie outside the CNS
Where do preganglionic neurones of the sympathetic system originate from?
From the thoracolumbar region of the spinal cord: T1 to L2
What is the sympathetic neurotransmitter:
A) pre-ganglionic
B) post-ganglionic
A) Acetycholine
B) Noradrenaline
What does parasympathetic originate from?
Craniosacral (CN III, VII, IX, X)
What is a G-protein made up of?
3 polypeptide subunits (alpha, beta and gamma)
Where is the binding site on the G-protein and what can it hold?
The guanine nucleotide binding site is in the alpha subunit and can hold GDP or GTP
When there is no signal, what is the state of the receptor, G-protein and effector?
Receptor: unoccupied
G-protein: GDP bound to alpha subunit
Effector: not modulated
What happens when an agonist activates the receptor?
G-protein couples with the receptor; GDP diossicates from, and GTP binds to, the alpha subunit
What happens when GTP binds to the alpha subunit
G-protein dissociates into separate alpha and beta-gamma subunits; G-protein alpha subunit combines with and modifies the activity of the effector
How is the signal turned off?
the alpha subunit acts as a GTPase enzyme to hydrolyse gap to GDP and Pi
How is the G-protein cycle completed?
The G-protein alpha-subunit recombines with the beta-gamma subunit
What are the receptors for the parasympathetic system and what G protein does each one couple to?
M1 - Gq
M2 - Gi
M3 - Gq
What is the transmitter for the parasympathetic system?
Acetylcholine
What does stimulation of M1 receptor do?
Increase stomach acid secretion due to stimulation of phospholipase C
What does stimulation of M2 receptor do?
Decreases HR, opening of K+ channels, inhibition of adenyl cyclase: Decreased cAMP
What does stimulation of M3 receptor do?
Contraction of airways + relaxation of vasculature
What are the receptors for the sympathetic system and what G protein does each one couple to?
B1 - Gs
B2 - Gs
A1 - Gq
A2 - Gi
What does stimulation of B1 receptor do?
Causes increased heart rate and force
What does stimulation of B2 receptor do?
Relaxation of airways and vasculature
