MMT: Pharmacology of Autonomic Drugs Flashcards
try not to cry
what are the two main classes of receptors?
cholinergic and adrenergic
what are the two subdivisions of cholinergic receptors? what are their methods of action?
Muscarinic: GPCRs
Nicotinic: ion channels that are permeable to cations, particularly Na.
Which muscarinic receptors are associated with Gq? What is the significance of this?
M1, M3, M5. Since they’re associated with Gq, they all stimulate the release of calcium and thus the contraction of smooth muscle
Which muscarinic receptors are associated with Gi? What is the significance of this?
M2 and M4. They’re associated with lowering cAMP and increasing potassium efflux, which leads to hyperpolarization. They’re also associated with lowered PKA, which decreases Ca channel activity. This slows AP conduction
what are the subdivisions of adrenergic receptors?
alpha and beta
what is the method of action for adrenergic receptors?
GPCR
Describe alpha1-adrenergic receptors: general effect, what they’re coupled to, their downstream effect, and what they stimulate
They’re typically excitatory and regulate the SNS. They’re coupled to Gq and increase calcium release via IP3. they stimulate the constriction of smooth muscle.
Describe alpha2-adrenergic receptors
They’re typically inhibitory and reduce sympathetic outflow. They’re coupled to Gi. They’re present on presynaptic nerve terminals and prevent norepinephrine release via a negative-feedback mechanisms. If there is too much NE in the synaptic cleft, it acts of alpha2 receptors and prevent further NE release
Describe beta1-adrenergic receptors: general effect, their downstream effector, what they stimulate
They’re excitatory and regulate the SNS. They are coupled to Gs, and stimulate cAMP and contraction of heart muscle
describe beta2-adrenergic receptors: general effect, what they’re coupled to, their downstream effect, and what they stimulate
They’re inhibitory and regulate the SNS. they are coupled to Gs, and stimulate cAMP and relaxation of smooth muscle.
Describe how increased cAMP impacts cardiac and smooth muscle
Increases cardiac muscle contraction, but relaxes smooth muscle
SA node: sympathetic receptor and nervous system response vs parasympathetic receptor and nervous system response
Sympathetic b1 receptor, increased heart rate
Parasympathetic m2 receptor, decreased heart rate
AV node: sympathetic receptor and nervous system response vs parasympathetic receptor and nervous system response
Sympathetic b1 receptor increases conduction, parasympathetic m2 receptor decreases conduction
Atria: sympathetic receptor and nervous system response vs parasympathetic receptor and nervous system response
Sympathetic b1 receptor increases contractility, parasympathetic m2 receptor decreases contractility
ventricles: sympathetic receptor and nervous system response vs parasympathetic receptor and nervous system response
sympathetic b1 receptor increases contractility, and parasympathetic m receptor decreases contractility; actions of PSNS are almost negligible.
Blood vessels in skeletal muscle: impact of sympathetic and parasympathetic receptors
Sympathetic a1 receptors increase vasoconstriction, while sympathetic b2 receptors decrease vasoconstriction. m receptors are present, but are not innervated by the parasympathetic nervous system. Stimulating them decreases vasoconstriction
Blood vessels in skin and mucosa: impact of sympathetic and parasympathetic receptors
Sympathetic a1 receptors increase vasoconstriction
Bronchi smooth muscle: sympathetic receptor and nervous system response vs parasympathetic receptor and nervous system response
Sympathetic b2 receptors relax smooth muscle, parasympathetic m receptors increase contraction of smooth muscle
what receptors are associated with increased salivary and sweat gland secretion?
salivary: sympathetic a1 receptors and parasympathetic muscarinic receptors
sweat: sympathetic muscarinic receptors
Where are beta2 sympathetic receptors primarily found?
Blood vessels feeding skeletal muscle
Urinary bladder detrusor: impact of sympathetic and parasympathetic receptors
Sympathetic b2 and b3 receptors decrease bladder contraction, parasympathetic m receptors increase contraction
Urinary bladder trigone and sphincter: impact of sympathetic and parasympathetic receptors
Sympathetic a1 receptors contract the sphincter, parasympathetic m receptors relax the sphincter
Describe the role of sympathetic and parasympathetic nervous systems and their receptors in contracting and dilating the eye
Parasympathetic m3 receptors in the iris sphincter muscle contract the pupil, while sympathetic alpha1-AR receptors in the iris radial muscle increase pupil size
What is the ciliary body?
Composed of smooth muscle and epithelial cells that create aqueous humor to nourish the eye. It comes through the pupil and drains through the iris/cornea
Describe how the parasympathetic nervous system impacts the lenses of the eye
When m3 receptors are activated, the ciliary body is constricted which will impact the curvature of the lense, making it curve up. This lets us see things closer up vs farther away
Where does the sympathetic nervous system use muscarinic receptors, and for what purpose?
In the sweat glands to increase secretion
Describe the effect of parasympathetic receptors on salivary glands
Muscarinic receptors increase secretion
What receptors are present in autonomic ganglia? What is the impact?
Nicotinic; increased NT release for both sympathetic and parasympathetic
What receptors are present in adrenal medulla? What is the impact?
Nicotinic; increased sympathetic neurotransmitter release
Where are the main places we find baroreceptors to detect stretch?
Aortic arch and carotid sinus
Describe the effects of raised/lowered mean arterial pressure (MAP) on the SNS and PSNS
Raised MAP: increased PSNS, decreased SNS, lowered heart rate
Lowered MAP: increased SNS, lowered PSNS, raised heart rate
what is mydraisis? miosis?
mydraisis: enlarged pupil; a1 receptor
miosis: smaller pupil; M3 receptor
where does the sympthetic system have dominant tone?
arterioles, veins, sweat glands, and splits genital tract with parasympathetic. everything else has dominant parasympathetic tone!
