Which structure monitors blood volume?

Correct Answer: A

Rationale: The JGA monitors blood volume senses pressure via JG cells (e.g., renin adjusts). Medulla oblongata controls breathing not volume. Midbrain is motor unrelated. Hypothalamus senses osmolarity not volume directly. JGA's volume role distinguishes it, key to RAAS, unlike neural or osmotic structures.

Correct Answer: B

Rationale: Alcohol is the key diuretic inhibiting ADH suppresses pituitary release (e.g., increases urine output). Water dilutes plasma stimulates ADH. Vitamin B₁₂ is metabolic not diuretic. Na influences reabsorption not ADH directly. Alcohol's ADH block distinguishes it, critical for diuresis, unlike dilution or unrelated factors.

Correct Answer: C

Rationale: Proximal convoluted tubule (PCT) cells have the most mitochondria e.g., fuel Na /K ATPase for 65% reabsorption. Skeletal muscle has many less than PCT. Liver is metabolic not reabsorptive. Cardiac muscle sustains beating less dense. PCT's energy demand distinguishes it, key to reabsorption, unlike muscle or liver cells.

Correct Answer: D

Rationale: Glomerular filtrate lacks formed elements (RBCs, WBCs) and proteins (albumin) e.g., filtered by glomerular pores. pH matches plasma ~7.4. Glucose is equal reabsorbed later. Albumin/globulins alone omits cells partial. Full exclusion distinguishes it, key to filtration selectivity, unlike pH or partial differences.

Correct Answer: C

Rationale: Glomerular capillary pressure (~55 mmHg) exceeds most capillaries (~20-30 mmHg) e.g., drives GFR. It's higher than efferent (~15 mmHg) not lower. Afferent constriction lowers it not raises. Pressure drop isn't 1:1 autoregulated. High pressure distinguishes it, critical for filtration, unlike efferent or constriction effects.