The act of defecation is dependent on: a) increased activity of the sympathetic supply to the rectum and anal canal. b) increased parasympathetic activity to the rectum and anal ca... The act of defecation is dependent on: a) increased activity of the sympathetic supply to the rectum and anal canal. b) increased parasympathetic activity to the rectum and anal canal. c) decreased parasympathetic activity to the rectum and anal canal. d) decreased activity of the sympathetic fibres to the myenteric plexus. Vagotomy results in: a) slowing of the heart rate. b) rapid emptying of the gastric contents in the duodenum. c) decreased gastric acid secretion. d) decreased sweat secretion. The preganglionic sympathetic nerves that innervate the eye have their neurons located in the: a) mid-brain. b) ciliary ganglion. c) thoracic segment 1 and 2 of the spinal cord. d) Superior cervical ganglion. Administration of prostigmine, a drug that inhibits acetylcholine esterase, would be expected to: a) increase the secretion of gastric juice. b) cause retention of urine. c) produce dilatation of the pupil. d) inhibit salivary secretion. Administration of physostigmine, a drug that inhibits acetylcholinesterase, would be expected to produce all the following EXCEPT: a) an increase of gastric secretion. b) an increase of adrenaline secretion from adrenal medulla. c) inhibition of micturition. d) slowing of the heart. Alpha-adrenergic receptors: a) are stimulated by noradrenaline only. b) are involved in the vasoconstriction response in skin to noradrenaline. c) cause sweat secretion when body temperature rises. d) are involved in increasing cardiac contractility in response to noradrenaline.
Understand the Problem
The question set is focused on autonomic physiology, specifically related to defecation, vagotomy, sympathetic nerves, and the effects of certain drugs on autonomic responses.
Answer
Defecation: increased parasympathetic activity, Vagotomy: decreased gastric acid, Sympathetic nerves: thoracic T1-2, Prostigmine: increases gastric juice, Physostigmine exception: adrenaline secretion, Alpha receptors: vasoconstriction.
The act of defecation is dependent on: increased parasympathetic activity to the rectum and anal canal. Vagotomy results in: decreased gastric acid secretion. The preganglionic sympathetic nerves that innervate the eye have their neurons located in: thoracic segment 1 and 2 of the spinal cord. Administration of prostigmine would be expected to: increase the secretion of gastric juice. Administration of physostigmine would produce all the following EXCEPT: an increase of adrenaline secretion from adrenal medulla. Alpha-adrenergic receptors are involved in the vasoconstriction response in skin to noradrenaline.
Answer for screen readers
The act of defecation is dependent on: increased parasympathetic activity to the rectum and anal canal. Vagotomy results in: decreased gastric acid secretion. The preganglionic sympathetic nerves that innervate the eye have their neurons located in: thoracic segment 1 and 2 of the spinal cord. Administration of prostigmine would be expected to: increase the secretion of gastric juice. Administration of physostigmine would produce all the following EXCEPT: an increase of adrenaline secretion from adrenal medulla. Alpha-adrenergic receptors are involved in the vasoconstriction response in skin to noradrenaline.
More Information
Defecation primarily involves the parasympathetic nervous system, which helps relax the anal sphincters for bowel movements. Vagotomy reduces gastric secretions due to interruption of vagal supply. Prostigmine enhances cholinergic effects, increasing secretions. Alpha-adrenergic receptors typically mediate vasoconstriction, especially notable in skin.
Tips
A common mistake is confusing the roles of sympathetic and parasympathetic systems. Remember, parasympathetic is often 'rest and digest,' while sympathetic is 'fight or flight.'
Sources
- Parasympathetic extrinsic reflex: role in defecation mechanism - pubmed.ncbi.nlm.nih.gov
- Neurogastroenterology: Basic Science - gastrojournal.org
- Defecation Reflex - homework.study.com
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