ANS Harvey Part 4 Flashcards
(balnk) is the only endogenous neurotransmitter acting at cholinergic receptors.
Acetylcholine (ACh)
(blank) are exogenous compounds that imitate functional responses associated with parasympathetic stimulation.
parasympathomimetics
(blank) are exogenous compounds that imitate functional responses produced by acetylcholine (ACh) at cholinergic receptors.
Cholinomimetics
(blank) are compounds that block cholinergic transmission at involving muscarinic receptors (antimuscarinics), neuronal nicotinic receptors (ganglionic blockers) or the neuromuscular junction (neuromuscular blockers).
Cholinergic Antagonists
To know what kinds of cholinomimetics responses you can get you must know what?
what type of receptor is involved
what type of cell/tissue is involved
the signaling pathway activated by receptor
whether effect is direct or indirect
Odd number receptors of cholinergic receptors are what kind of G proteins?
Gq
even number receptors of cholinergic receptors are what kind of G proteins?
Gi/o
How does Muscarine receptors 1/3/5 work?
by PLC, IP3->Ca2+ which creates smooth muscle contraction and vascular relaxation, and exocrine gland secretion
How does muscarine receptors 2/4 work?
by inhibiting AC and increasing potassium and creating relaxation, slow heart rate
What are the ways to get excitation?
Na+ in, little K/Cl out
HO do you get a nictoninc muscle receptor to work>
you increase Na+ and get skeletal muscle and nerve excitation
What kind of receptor is pentameric?
nicotinic receptors
What kind of receptor is this?
Ligand-gated ion channels
Exist as pentamers containing one or more of 5 different subunits (α β γ δ ε).
There are 9 α subunit isoforms (α1- α9) and 5 β subunit isoforms (β1- β5).
has at least two α subunits, where ACh binds.
nicotinic receptor
What are the 2 subtypes of nicotinic receptors?
Nm and Nn
What kind of receptor is this?
location – skeletal muscle
signaling mechanism – ligand gated ion channel
each channel composed of 4 different subunits: α1 β1 δ (γ or ε)
adult – (α1)2 β1 δ ε
neonatal - (α1)2 β1 δ γ
response – muscle contraction
nicotinic muscle receptor
Nm receptors increase (blank) so that you get muscle contraction.
sodium
What kind of receptor is this?
location – all sympathetic and parasympathetic ganglia, adrenal medulla, CNS
signaling mechanism – ligand gated ion channel
each channel composed of different α (8 isoforms, α2- α9) and β (4 isoforms, β2- β5) subunits in various ratios
response – neuronal excitation
Nn Nicotinic neuroganglionic receptors
What are the four receptor types of Nicotinic receptors?
muscle type, ganglion type, heteromeric type and honomeric type.
(They differ by subunit combinations)
Where are the muscle type nictonic receptors found?
neuromuscular junctions
Where are nicotinic ganglian cells found?
autonomic ganglia
Where are heteromeric and homomeric type nicotinic receptors found?
brain
What do all the types of nictonic receptors except for homomeric type have in common?
excited by increased Na and K permiability
How many muscarinic subtypes are there?
5
What receptors does this describe:
location – smooth muscle (blood vessels, airways,
eye, gut, bladder)
-endothelial cells (blood vessels)
-exocrine glands (salivary glands, sweat
glands, airways, gut)
-CNS
signaling mechanism – Gq activation of phospholipase C
response- stimulate smooth muscle contraction
- relax blood vessels - stimulate secretion
Muscarinic M1,M3,M5 receptors
What is the pathway that the muscarinic receptors use?
PLC+ PIP2-> IP3 +DAG-> Ca2+
How come muscarinic receptors 1,3,5 can constrict smooth muscle YET dilate blood vessesls?
Some blood vessels have parasympathetic innervation. In these blood vessels muscarinic receptors are there. The pathway for muscarinic receptors create NO which can diffuse from endothelial cell to vascular smooth muscle->cGMP-> inhibits contractions in the blood vessles ONLY via ENDOTHELIAL CELLS!
Can you get ACh relexation in the vascular smooth muscle if you rub of endothelial cells?
no
What receptors does this describe:
Low doses of (exogenous) ACh cause systemic vasodilation and hypotension due to activation of muscarinic receptors on vascular endothelial cells.
High doses of (exogenous) ACh cause systemic vasoconstriction and hypertension due to activation of muscarinic receptors on vascular smooth muscle cells.
M1,M3,M5 receptors
What does this describe:
location – smooth muscle (blood vessels, airways, eye, gut, bladder)
endothelial cells (blood vessels)
exocrine glands (salivary glands, sweat glands, airways, gut)
CNS
signaling mechanism – Gq activation of phospholipase C
response – stimulate smooth muscle contraction
relax blood vessels
stimulate secretion
M1, M3, and M5 receptors