Study Set Content:
Action chiefly muscarinic:
Muscarine, Pilocarpine
Action chiefly nicotinic:
Nicotine, Lobeline
released from parasympathetic nerves activates muscarinic receptors on effector cells to alter organ function directly
Acetylcholine
Acetylcholine released from parasympathetic nerves interacts with muscarinic receptors on nerve terminals to (blank) the release of their neurotransmitter
inhibit
By this mechanism, acetylcholine release and circulating muscarinic agonists indirectly alter organ function by modulating the effects of the
parasympathetic and sympathetic nervous systems and perhaps nonadrenergic, noncholinergic (NANC) systems.
Muscarinic agonists instilled into the conjunctival sac cause (blank) of the smooth muscle of the (blank)and of the(blank)
contraction, iris sphincter (miosis) , ciliary muscle (accommodation).
As a result, the iris is (blank) from the angle of the anterior chamber, and the trabecular meshwork at the base of the ciliary muscle is opened.
pulled away
Both effects facilitate aqueous humor outflow into the canal of (blank), which drains the anterior chamber.
Schlemm
The primary cardiovascular effects of muscarinic agonists are a
reduction in peripheral vascular resistance and changes in heart rate.
Intravenous infusions of minimally effective doses of acetylcholine in humans (eg, 20-50 mcg/min) cause
vasodilation
heart rate. • Intravenous infusions of minimally effective doses of acetylcholine in humans (eg, 20-50 mcg/min) cause vasodilation, resulting in a (blank) in blood pressure, often accompanied by a reflex(blank) in heart rate.
reduction, increase
Larger doses of acetylcholine produce (blank) and (blank) atrioventricular node conduction velocity in addition to (blank)
bradycardia, decrease, hypotension
The direct cardiac actions of muscarinic stimulants include the following: o an increase in a (blank) current (I K (ACh) ) in the cells of the sinoatrial and atrioventricular nodes, in Purkinje cells, and also in atrial and ventricular muscle cells;
potassium
a (blank) in the slow inward calcium current (I Ca) in heart cells;
decrease
a (blank) in the hyperpolarization-activated current (If) that underlies diastolic depolarization
reduction
Muscarinic stimulants (blank) the smooth muscle of the bronchial tree. In addition, the glands of the tracheobronchial mucosa are stimulated to secrete.
contract
This combination of effects can occasionally cause symptoms, especially in individuals with
asthma
contracts smooth muscles of bronchus as it restricts the amount air passing through it
Bronchoconstriction -
Administration of muscarinic agonists as in parasympathetic nervous system stimulation, (blank) the secretory and motor activity of the gut.
increases
• The salivary and gastric glands are (blank) stimulated;
strongly
