Anticholinergics cause all except?
**Core Concept**
Anticholinergics, also known as antimuscarinics, are a class of drugs that block the action of the neurotransmitter acetylcholine at muscarinic receptors in the central and peripheral nervous system. This results in a decrease in parasympathetic tone and an increase in sympathetic tone, leading to various physiological effects.
**Why the Correct Answer is Right**
The correct answer is an exception to the effects of anticholinergics. Anticholinergics cause mydriasis (dilation of the pupils) due to the blockade of muscarinic receptors in the eye, which normally stimulate the contraction of the iris sphincter muscle. They also cause decreased salivation, bronchodilation, and increased heart rate due to the blockade of muscarinic receptors in the salivary glands, bronchial smooth muscle, and sinoatrial node, respectively.
**Why Each Wrong Option is Incorrect**
**Option A:** Increased gut motility - This is incorrect because anticholinergics actually cause decreased gut motility by blocking muscarinic receptors in the gastrointestinal tract, leading to constipation.
**Option B:** Increased bladder contractility - This is incorrect because anticholinergics cause decreased bladder contractility by blocking muscarinic receptors in the bladder detrusor muscle, leading to urinary retention.
**Option C:** Increased sweating - This is incorrect because anticholinergics cause decreased sweating by blocking muscarinic receptors in the sweat glands.
**Clinical Pearl / High-Yield Fact**
Anticholinergics can cause anticholinergic toxicity, a condition characterized by confusion, delirium, hallucinations, and tachycardia, especially in the elderly and in patients with impaired renal function.
**Correct Answer: A. Increased gut motility. Increased gut motility is not a typical effect of anticholinergics.