FCPS part 1 Medicine solved mcqs with explanation Q 15

Which of the followings is not caused by parasympathetic stimulation?

a) Micturation

b) Miosis

c) Increased GIT motility

d) Sweating

Correct Answer: d

Explanation:

Sweating is function of sympathetic stimulation rather than parasympathetic stimulation. In order to differentiate between parasympathetic & sympathetic effect and prevent any confusion, remember the following scenario.

You go out on a street and you are greeted to a fierce lion! In this situation you would want to:

• Have your pupils fully dilated (mydriasis), so that you can see the maximum of the lion and be prepared for an attack.
• Have you heart racing(tachycardia), so that when you start running your heart is able to meet the increased oxygen demand to the muscles
• Stop your bowel and bladder movement (urinary retentions & decreased GI motility), because you definitely don’t want to go to bathroom right now!
• Increase your metabolism and sweating for optimal temperature control so that you are not feeling cold when the lion bites you! (this is just an example to remember things)

Since you were met by a lion your response should be fright, fight or flight which is actually the sympathetic stuff. Everything opposite to this such as miosis, bradycardia, micturation & increased GI motility occur with parasympathetic stimulation.