What is the cause of the distention of the urinary bladder and what does its distension produce?

Correct Answer: B

Rationale: Distension of the urinary bladder is caused by an increase in intra-vesical pressure as urine volume rises, stretching the bladder wall. This activates stretch receptors, producing the micturition reflex: reflex contraction of the detrusor muscle and relaxation of the internal and external urethral sphincters, facilitating urination. This differs from relaxation, sphincter contraction, or pain alone, making B the correct cause and effect.

Correct Answer: B

Rationale: Fluid in the proximal convoluted tubule (PCT) is isosmotic (~300 mOsm/L), as water and solutes (e.g., Na⁺, Cl⁻) are reabsorbed proportionally via leaky epithelium and aquaporins. This maintains osmolarity similar to plasma. It's not hyperosmotic (A) or hypoosmotic (C), and ADH affects later segments (D), making B correct.

Correct Answer: C

Rationale: Respiratory alkalosis (high pH, low PCOâ‚‚) results from hyperventilation, seen in fever (A), anxiety (B), and salicylate toxicity (D) due to stimulated breathing. Laryngeal obstruction (C) restricts airflow, causing COâ‚‚ retention (respiratory acidosis, low pH, high PCOâ‚‚), not alkalosis, making C the exception.

Correct Answer: B

Rationale: Activity intolerance post-myocardial infarction reflects reduced cardiac capacity. An outcome like ambulating 50 feet without dyspnea (B) is specific, measurable, and aligns with improving tolerance. Smoking cessation (A) is unrelated, no dyspnea on exertion (C) is vague, and tolerating activity (D) lacks specificity, making B correct.

Correct Answer: D

Rationale: The parasympathetic nervous system, via pelvic nerves (S2-S4), promotes bladder emptying (D) by contracting the detrusor muscle and relaxing the internal sphincter during micturition. Blood pressure (A) is autonomic, fight-or-flight (B) is sympathetic, and voluntary control (C) is somatic, making D the correct role.