Autonomic and endocrine system Flashcards
What does acetylcholine and noradrenaline act on?
nAChRs
mAChRs
Alpha&Beta adrenoreceptors
What are the principal neurotransmitters in ANS?
Acetylcholine
Noradrenaline
Why are sweat glands the anomaly of the sympathetic system? (in regards to ACh and NA)
The sweat glands are the target of ACh whereas the blood vessels and adrenal medulla are the target of NA
Where are muscarinic receptors found?
Postsynaptic in parasympathetic ganglion neurons and sweat glands
Which muscarinic receptors couple to Gq receptors?
M1
M3
M5
What is the effect of a Gq coupled to a muscarinic receptor?
Phospholipase C is increased ->
IP3 activates er receptors ->
Triggering release of Ca2+ into the cell ->
Causing secretion or contraction
Where are M1 receptors found?
Autonomic ganglia
Glands (salivary, lacrimal, gastric)
Cerebral cortex
Where are M3 receptors found?
Exocrine glands
Smooth muscle (GI tract, eye, airways, bladder)
Endothelium in blood vessels
Function of M3 receptor?
Regulates production of NO
Which muscarinic receptors are coupled to Gi?
M2
M4
What do M2&M4 receptors do?
Inhibit activity of adenylyl cyclase ->
Decrease the amount of cAMP ->
Causes an increase in GIRK ->
Decreases the opening of voltage gated calcium channels
Where are M2 receptors located?
Heart (atria)
CNS
Nodal tissue
Where are M4 receptors located?
CNS
Where are M5 receptors located?
CNS (substantia nigra)
Salivary glands
Iris/ciliary muscle
Functional response of M1?
Gastric secretion
CNS excitation
Functional response of M2?
Cardiac inhibition (decreased force of contraction in atria)
Neural inhibition
Central muscarinic effects
Functional response of M3 receptor?
Gastric, salivary secretion
Gastrointestinal smooth muscle contraction
Ocular accommodation
Vasodilation
Functional response of M4 receptor?
Enhanced locomotion
What happens to a cardiac action potential when ACh is applied?
Action potential will decrease and shorten
(contraction of atria is smaller)
What is the effect of Muscarine? Which receptors are these a result of ?
Nausea
Lower blood pressure (decrease in cardiac output, M2, and increased NO production, M3,)
Increased saliva (M3)
Name 2 clinical mAChR agonists
Cevimeline
Pilocarpine
Use of Cevimeline
Improves salivary and lacrimal secretions in Sjogren’s syndrome
Which receptor does Cevimeline act on?
M3
Uses of Pilocarpine
Eye drops for glaucoma
reduce pressure on optic nerve by allowing drainage
What receptor does pilocarpine act on?
Non-selective mAChR
Name a muscarinic antagonist
Atropine
Which receptor does atropine act on?
Non-selective mAChR
Effects of Atropine
Inhibition of secretion
Smooth muscle relaxant
Pupillary dilation
Increase HR
Decrease GI motility, acid secretion
CNS agitation and disorientation
Increase in body temp
What is the definition of cholinomimetic?
Drugs that act indirectly to enhance cholinergic transmission
Clinical uses of Acetylcholinesterase
To reverse action of neuromuscular blocking drugs
Alzheimer’s disease
Glaucoma
What does beta 1 adrenergic receptor affect?
Cardiovascular consequences
What does beta 2 adrenergic receptor affect?
The lungs
Used therapeutically to treat asthma
What is released by sympathetic neurons in the heart?
Noradrenaline
What is released by chromaffin cells in the heart?
Adrenaline
What is the effect of NA and A in the heart?
Increased voltage gated calcium channel opening time ->
Increase in calcium in cardiac muscle cells ->
Increase contraction
Name a bronchodilator
Salbutamol
What receptor does salbutamol act on?
B2
Is salbutamol and agonist or antagonist?
Agonist
What is a sympathomimetic drug?
A drug that mimics the effect of the sympathetic nervous system
Example of a sympathomimetic drug
Amphetamine
Catecholamine
Mechanism of sympathomimetic drugs
Competes with NA for space in the vesicles
Exocytosis is not involved
Drug for hypertension. Receptor it acts on
Prazosin
A1
Drug for heart failure. Receptor it acts on
Carvedilol
(A&B)
Drug for somatic symptoms of anxiety. Receptor it acts on.
Propanolol
(B1 & B2)
