Dr Gawad Physiology Course Online Exams - Parasympathetic Nervous System, Chemical Transmitters
13 MCQs (Only one correct answer)
Each MCQ: 1 mark, Total mark: 13 (you will get the results immediately with correction by the web)
Allowed time: 16 minGood Luck
- 1.
About the vagus nerve, all the following is true except:
- A.
(A) It contains afferent and efferent fibres.
- B.
(B) It contains parasympathetic pregang fibres.
- C.
(C) It produces micturition.
- D.
(D) It causes increased peristaltic movement of the intestinal wall.
Correct Answer
C. (C) It produces micturition.Explanation
The vagus nerve is a cranial nerve that contains both afferent (sensory) and efferent (motor) fibers. It is responsible for many parasympathetic functions, including regulating heart rate, stimulating digestive processes, and promoting peristaltic movement of the intestinal wall. However, it does not directly produce micturition (urination). Micturition is controlled by the sacral nerves and the parasympathetic nervous system, but not the vagus nerve.Rate this question:
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- 2.
Stimulation of the pelvic nerve (sacral autonomic) produces :
- A.
(A) Relaxation of the wall of rectum and contraction of the internal anal sphincter.
- B.
(B) V.C. of the blood vessels in the external genitalia causing erection of penis.
- C.
(C) Contraction of the bladder wall and relaxation of the internal urethral sphincter.
- D.
(D) Contraction of smooth muscles in the male sexual passages causing ejaculation.
- E.
(E) Relaxation of the external urethral and anal sphincters.
Correct Answer
C. (C) Contraction of the bladder wall and relaxation of the internal urethral spHincter.Explanation
Stimulation of the pelvic nerve (sacral autonomic) leads to contraction of the bladder wall and relaxation of the internal urethral sphincter. This allows for the emptying of the bladder during urination.Rate this question:
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- 3.
Concerning the pelvic nerve, all the following is true except:
- A.
(A) It is the nerve of erection (= nervus erigenes).
- B.
(B) It is motor to the urinary bladder and distal half of the large intestine.
- C.
(C) It is inhibitory to both the internal anal and urethral sphincters.
- D.
(D) It has no postganglionic nerve fibres.
Correct Answer
D. (D) It has no postganglionic nerve fibres.Explanation
The correct answer is (D) It has no postganglionic nerve fibers. The pelvic nerve is responsible for motor innervation to the urinary bladder and distal half of the large intestine. It is also inhibitory to both the internal anal and urethral sphincters. However, it does have postganglionic nerve fibers, which are responsible for transmitting signals from the ganglia to the target organs.Rate this question:
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- 4.
The parasympathetic nerves :
- A.
(A) Are important in emergency conditions.
- B.
(B) Play important functions in the skin and skeletal muscles.
- C.
(C) Tend to have longer postganglionic fibres than pregang fibres.
- D.
(D) Are catabolic in their actions.
- E.
(E) Mainly exert opposite effects to those of the sympathetic nerves.
Correct Answer
E. (E) Mainly exert opposite effects to those of the sympathetic nerves.Explanation
The parasympathetic nerves mainly exert opposite effects to those of the sympathetic nerves. This means that while the sympathetic nerves prepare the body for "fight or flight" responses in emergency conditions, the parasympathetic nerves work to promote relaxation and rest. They are responsible for functions such as slowing heart rate, constricting pupils, stimulating digestion, and promoting salivation. Overall, the parasympathetic nervous system helps to maintain homeostasis and conserve energy.Rate this question:
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- 5.
An injury to the first 4 sacral segments of the spinal cord produces :
- A.
(A) Hyperglycaemia.
- B.
(B) V.D. in the cutaneous blood vessels.
- C.
(C) Disturbance of sweat secretion.
- D.
(D) Lack of erection of the penis in males and clitoris in females.
- E.
(E) Relaxation of the internal anal and urethral sphincters.
Correct Answer
D. (D) Lack of erection of the penis in males and clitoris in females.Explanation
An injury to the first 4 sacral segments of the spinal cord can cause a lack of erection of the penis in males and clitoris in females. This is because these segments are responsible for controlling the parasympathetic nerves that are involved in the erectile response. When these segments are injured, the signals from the brain to the genital organs are disrupted, leading to the inability to achieve an erection in males and clitoral engorgement in females.Rate this question:
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- 6.
The functions of Parasympathetic innervations to the salivary glands is:
- A.
(A) V. C. and secretion.
- B.
(B) V.D. and secretion.
- C.
(C) V.D. and inhibition of secretion.
- D.
(D) Secretion of scanty viscous saliva.
Correct Answer
B. (B) V.D. and secretion.Explanation
Parasympathetic innervations to the salivary glands refer to the signals sent by the parasympathetic nervous system to stimulate the salivary glands. The parasympathetic nervous system is responsible for rest and digest activities, including the production of saliva. "V.D." refers to vasodilation, which is the widening of blood vessels, and "secretion" refers to the release of saliva. Therefore, option (B) correctly states that parasympathetic innervations to the salivary glands include vasodilation and secretion.Rate this question:
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- 7.
Which of the following may be produced by parasympathetic stimulation:
- A.
(A) Acceleration of the heart.
- B.
(B) Relaxation of the GIT wall
- C.
(C) V.D. of coronary artery.
- D.
(D) Dilatation of the pupil.
- E.
(E) Contraction of the urinary bladder wall.
Correct Answer
E. (E) Contraction of the urinary bladder wall.Explanation
Parasympathetic stimulation is responsible for promoting rest and relaxation in the body. It is known as the "rest and digest" response. The parasympathetic nervous system controls various bodily functions, including the contraction of the urinary bladder wall. When the bladder is stimulated by the parasympathetic nervous system, it contracts, leading to the expulsion of urine from the body. Therefore, the correct answer is (E) Contraction of the urinary bladder wall.Rate this question:
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- 8.
About acetylcholine, all the following is true except:
- A.
(A) It is synthesized & released by some sympath postgang nerve fibres.
- B.
(B) It is the chemical transmitter released by all pregang nerve fibres.
- C.
(C) It is not related to accommodation
- D.
(D) It is liberated by all parasympathetic postganglionic nerve fibres.
Correct Answer
C. (C) It is not related to accommodationExplanation
Acetylcholine is a neurotransmitter that is synthesized and released by some sympathetic postganglionic nerve fibers and all parasympathetic postganglionic nerve fibers. It is also the chemical transmitter released by all preganglionic nerve fibers. However, acetylcholine is related to accommodation, which is the process by which the eye changes its focus to see objects at different distances. Therefore, the correct answer is (C) It is not related to accommodation.Rate this question:
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- 9.
All the following statements are correct except :
- A.
(A) Stimulation of the greater splanchnic nerve causes adrenomedullary secretion
- B.
(B) Acetylcholine is normally present at low concentrations in the blood.
- C.
(C) Intravenous injection of acetylcholine does not cause exactly the same effects as parasympathetic stimulation.
- D.
(D) The dilator pupillae muscle contains alpha adrenergic receptors.
- E.
(E) Stimulation of the postganglionic nerve fibres arising from the collateral ganglia causes secretion from the adrenal (suprarenal) medulla.
Correct Answer
E. (E) Stimulation of the postganglionic nerve fibres arising from the collateral ganglia causes secretion from the adrenal (suprarenal) medulla. -
- 10.
The nicotine-like action of acetylcholine is present in :
- A.
(A) All preganglionic nerve endings.
- B.
(B) The sympathetic postganglionic supply to the blood vessels in skeletal muscles.
- C.
(C) The parasympathetic postganglionic supply to the heart.
- D.
(D) The sympathetic postganglionic supply to the sweat glands.
- E.
(E) The parasympathetic postganglionic supply to the GIT.
Correct Answer
A. (A) All preganglionic nerve endings.Explanation
The correct answer is (A) All preganglionic nerve endings. Acetylcholine is a neurotransmitter that is released at the synapses of preganglionic neurons in both the sympathetic and parasympathetic divisions of the autonomic nervous system. It acts on nicotinic receptors, which are named after nicotine because they are also activated by nicotine. Therefore, the nicotine-like action of acetylcholine is present in all preganglionic nerve endings.Rate this question:
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- 11.
The alpha adrenergic receptors :
- A.
(A) Are not stimulated by epinephrine.
- B.
(B) When stimulated they reduce the gastrointestinal motility.
- C.
(C) Are blocked by propranolol.
- D.
(D) increase heart rate.
Correct Answer
B. (B) When stimulated they reduce the gastrointestinal motility.Explanation
Alpha adrenergic receptors, when stimulated, cause constriction of blood vessels and reduction in gastrointestinal motility. Epinephrine stimulates both alpha and beta adrenergic receptors. Propranolol is a non-selective beta blocker that blocks beta adrenergic receptors, not alpha adrenergic receptors. Therefore, the correct answer is (B) When stimulated they reduce the gastrointestinal motility.Rate this question:
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- 12.
A drug which blocks the beta adrenergic receptors causes :
- A.
(A) Dilatation of the bronchial muscle.
- B.
(B) Relaxation of the sphincters in the alimentary canal.
- C.
(C) Fall in the cardiac output.
- D.
(D) None of the above
Correct Answer
C. (C) Fall in the cardiac output.Explanation
Blocking beta adrenergic receptors inhibits the action of adrenaline and noradrenaline, which are responsible for increasing heart rate and contractility. Therefore, when these receptors are blocked, the heart rate and contractility decrease, leading to a fall in cardiac output. This is why the correct answer is (C) Fall in the cardiac output.Rate this question:
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- 13.
The alpha adrenergic receptors mediate all the following except :
- A.
(A) Vasoconstriction.
- B.
(B) Pupil dilatation.
- C.
(C) Spleen contraction.
- D.
(D) Relaxation of intestinal wall.
- E.
(E) increased cardiac activity.
Correct Answer
E. (E) increased cardiac activity.Explanation
Alpha adrenergic receptors are responsible for vasoconstriction, pupil dilatation, spleen contraction, and relaxation of the intestinal wall. However, they do not mediate increased cardiac activity. This is because alpha adrenergic receptors primarily cause constriction of blood vessels, which leads to increased blood pressure, but they do not directly affect the heart's activity.Rate this question:
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Mar 21, 2023Quiz Edited by
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Oct 30, 2016Quiz Created by
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