Alpha adrenoreceptors: a) are activated by noradrenaline only. b) are responsible for constriction of skin arterioles. c) mediate the dilatation of the bronchioles which accompanie... Alpha adrenoreceptors: a) are activated by noradrenaline only. b) are responsible for constriction of skin arterioles. c) mediate the dilatation of the bronchioles which accompanies sympathetic stimulation. d) are involved in acceleration of the heart induced by noradrenaline. All of the following organs receive their parasympathetic supply through the vagus nerves, EXCEPT: a) lungs. b) stomach. c) rectum. d) heart. Acetylcholine is released in all the following sites, EXCEPT in the: a) preganglionic nerve endings in the suprarenal medulla. b) all preganglionic parasympathetic nerve endings. c) postganglionic sympathetic nerve endings to the heart. d) Skeletal muscle motor end plate. The mechanism by which acetylcholine is inactivated is: a) the removal of one methyl group from choline. b) the addition of methyl group to choline. c) the hydrolysis of ester bond that links the choline group to the acetyl group. d) through the activity of methyl transferase. Increased sweating is mediated by increased: a) secretion of acetylcholine by the postganglionic sympathetic fibers to the skin. b) secretion of acetylcholine by the postganglionic parasympathetic fibers to the skin. c) secretion of norepinephrine by the postganglionic sympathetic fibers to the skin. d) secretion of epinephrine in the end portions of the sympathetic fibers to the skin.
Understand the Problem
The question is related to physiology and pharmacology, specifically how various neurotransmitters and receptors function in the autonomic nervous system. It addresses specific mechanisms related to adrenergic receptors, organ functions under vagal control, and the action of acetylcholine.
Answer
Alpha adrenoreceptors: b. Parasympathetic supply EXCEPT: c. Acetylcholine release EXCEPT: c. Inactivation mechanism: c. Increased sweating: a.
Alpha adrenoreceptors: b) are responsible for constriction of skin arterioles. Parasympathetic supply through vagus nerves, EXCEPT: c) rectum. Acetylcholine is released in all sites EXCEPT: c) postganglionic sympathetic nerve endings to the heart. Acetylcholine is inactivated by: c) the hydrolysis of ester bond. Increased sweating is mediated by: a) secretion of acetylcholine by the postganglionic sympathetic fibers to the skin.
Answer for screen readers
Alpha adrenoreceptors: b) are responsible for constriction of skin arterioles. Parasympathetic supply through vagus nerves, EXCEPT: c) rectum. Acetylcholine is released in all sites EXCEPT: c) postganglionic sympathetic nerve endings to the heart. Acetylcholine is inactivated by: c) the hydrolysis of ester bond. Increased sweating is mediated by: a) secretion of acetylcholine by the postganglionic sympathetic fibers to the skin.
More Information
Alpha adrenoreceptors are typically responsible for vasoconstriction. Acetylcholine is released predominantly at parasympathetic junctions, and the hydrolysis by acetylcholinesterase is its primary inactivation method. Secretion stimulating sweat is unique because sympathetic fibers use acetylcholine instead of norepinephrine.
Tips
Be aware that alpha receptors commonly cause vasoconstriction, and note the exceptionality of acetylcholine in sympathetic sweat regulation.
Sources
- Alpha & Beta Adrenergic Receptors | Overview & Difference - Lesson - study.com
- Autonomic Nervous System Anatomy - Medscape Reference - emedicine.medscape.com
- Adrenergic receptor - Wikipedia - en.wikipedia.org
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