1. Which hormone is primarily responsible for the regulation of fluid balance through its effect on renal tubular reabsorption of water? A) Aldosterone B) Antidiuretic hormone (ADH) C) Atrial natriuretic peptide (ANP) D) Renin Answer: B) Antidiuretic hormone (ADH) Rationale: ADH, also known as vasopressin, is produced by the hypothalamus and released by the posterior pituitary gland. It acts on the kidneys to increase water reabsorption, thus playing a key role in regulating fluid balance. 2. In the context of renal physiology, what is the primary function of the loop of Henle? A) Filtration of blood plasma B) Reabsorption of glucose and amino acids C) Concentration of urine D) Secretion of hydrogen ions Answer: C) Concentration of urine Rationale: The loop of Henle is a segment of the nephron that creates a concentration gradient in the medulla of the kidney. This gradient allows for the reabsorption of water from the collecting ducts, leading to the concentration of urine. 3. A patient presents with hypokalemia. Which renal system response is expected to occur? A) Increased reabsorption of potassium in the distal tubules B) Decreased secretion of potassium in the distal tubules C) Increased excretion of sodium in the proximal tubules D) Decreased reabsorption of bicarbonate in the proximal tubules Answer: A) Increased reabsorption of potassium in the distal tubules Rationale: Hypokalemia, or low serum potassium levels, triggers the kidneys to conserve potassium. This is achieved by increasing the reabsorption of potassium in the distal tubules. 4. What is the primary driving force for the filtration process in the glomeruli of the kidneys? A) Oncotic pressure