Where is the juxtaglomerular apparatus located?

Correct Answer: C

Rationale: The JGA is between afferent arteriole and distal tubule macula densa/JG cells (e.g., renin release site). Loop is tubular not vascular. Medulla oblongata is brain unrelated. Collecting/PCT lacks JGA wrong. JGA's position distinguishes it, critical for GFR/BP control, unlike tubular or brain errors.

Correct Answer: D

Rationale: Skeletal system isn't directly influenced by kidneys bones respond indirectly via vitamin D (e.g., calcium). Cardiovascular is BP/volume direct. Respiratory ties to pH HCO₃⁻ effect. Endocrine involves hormones (renin) direct. Skeletal's indirect link distinguishes it, critical for system specificity, unlike directly impacted systems.

Correct Answer: A

Rationale: Glomerular capillaries have larger pores fenestrated (e.g., allow plasma filtration, not cells/proteins). Shorter length is false longer for GFR. Innervation is minimal not functional trait. Na absorption is tubular not glomerular. Pore size distinguishes it, key to filtration selectivity, unlike length, nerve, or absorption traits.

Correct Answer: C

Rationale: Nitrogen for excretion comes from protein deamination e.g., liver converts amino acids to urea. Carbohydrates yield COâ‚‚/Hâ‚‚O not nitrogen. Nitric buffer isn't a system false. Atmosphere provides Oâ‚‚ not waste N. Deamination distinguishes it, critical for nitrogen source, unlike carbs or external origins.

Correct Answer: D

Rationale: Aldosterone antagonist (e.g., spironolactone) reduces Na /water reabsorption lowers blood volume (e.g., less retention). Urine volume rises not falls. K concentration rises retained. Viscosity unchanged volume-based. Volume drop distinguishes it, key to antagonist effect, unlike urine or K missteps.