Stroke volume is determined by

Correct Answer: A

Rationale: Stroke volume (SV) is the blood pumped per beat, influenced by preload (ventricular filling). 'Preload,' is correct, per Frank-Starling law (e.g., Costanzo's Physiology). 'Postload,' is a misnomer; afterload resists SV. 'Cardiac output,' is SV × HR, not a determinant. 'Cardiac overload,' is vague. Preload's direct effect on SV makes A the accurate answer.

Correct Answer: B

Rationale: Human gestation averages 280 days (40 weeks) from the last menstrual period (LMP). '280 days,' is correct, per obstetrics texts like Williams Obstetrics, a standard clinical estimate. '250 days,' is about 36 weeks, preterm. '300 days,' (43 weeks) and '320 days,' (46 weeks) exceed typical full-term. The 280-day norm, aligning with fetal development, makes B the precise answer, widely accepted in medical practice.

Correct Answer: B

Rationale: The nephron is the kidney's structural and functional unit, filtering blood and forming urine. 'Nephron,' is correct, per physiology texts like Vander, encompassing glomerulus and tubules. 'Glomerulus,' is part of the nephron. 'Renal artery,' supplies blood. 'Bowman's capsule,' encases the glomerulus within the nephron. The nephron's comprehensive role in filtration, reabsorption, and excretion makes B the precise answer.

Correct Answer: D

Rationale: Accessory digestive organs aid digestion outside the alimentary canal. 'Kidney,' is correct as the exception, filtering blood, not digesting, per physiology (e.g., Guyton). 'Liver,' produces bile. 'Pancreas,' secretes enzymes. 'Gall bladder,' stores bile. Kidney's excretory role distinguishes D as the accurate answer.

Correct Answer: C

Rationale: The peripheral nervous system (PNS) includes nerves outside the CNS. 'Spinal cord,' is correct as the exception, part of the CNS, per anatomy (e.g., Tortora). 'Cranial nerves,' and 'Spinal nerves,' are PNS. 'Autonomic nervous system,' is PNS's involuntary arm. Spinal cord's CNS role makes C the accurate answer.