SCI 221 Exam 4 V3 | SCI 221 Human
Physiology with Intervention Skill-Based
(ISB) Experiential Learning | Q&A with
Rationale (SCI221 Exam 4) | Nightingale
College
1. What is the primary function of the juxtaglomerular apparatus (JGA) in the kidney?
A. To store urine before micturition
B. To filter large proteins out of the blood
C. To secrete erythropoietin for red blood cell production
D. To regulate blood pressure and the filtration rate of the glomerulus
Correct Answer: D
Rationale: The JGA is a specialized structure formed by the distal convoluted tubule and
the glomerular afferent arteriole. It plays a critical role in autoregulation by sensing
changes in sodium chloride concentration and blood pressure. When blood pressure drops,
the JGA releases renin to activate the RAAS system, ensuring the glomerular filtration rate
remains stable.
2. Which hormone is responsible for increasing the permeability of the collecting ducts to
water?
A. Antidiuretic Hormone
,B. Atrial Natriuretic Peptide
C. Aldosterone
D. Parathyroid Hormone
Correct Answer: A
Rationale: Antidiuretic Hormone (ADH), also known as vasopressin, is secreted by the
posterior pituitary gland. It acts on the cells of the distal tubule and collecting duct to insert
aquaporins into the apical membrane. This mechanism allows for significant water
reabsorption, which helps concentrate urine and maintain fluid balance.
3. In the context of acid-base balance, how do the kidneys respond to metabolic acidosis?
A. By decreasing the reabsorption of bicarbonate ions
B. By excreting more sodium and potassium ions
C. By lowering the respiratory rate to retain carbon dioxide
D. By increasing the secretion of hydrogen ions into the filtrate
Correct Answer: D
Rationale: During metabolic acidosis, the body has an excess of hydrogen ions or a deficit
of bicarbonate. The renal system compensates by secreting excess hydrogen ions into the
urine and synthesizing new bicarbonate ions. This process effectively raises the blood pH
back toward the physiological range of 7.35 to 7.45.
,4. Which of the following describes the ‘Renal Threshold’ for glucose?
A. The maximum amount of glucose the liver can store
B. The blood glucose concentration at which glucose begins to appear in the urine
C. The amount of glucose needed to maintain brain function
D. The rate at which the glomerulus filters glucose
Correct Answer: B
Rationale: The renal threshold represents the plasma concentration of a substance at
which the transport maximum of the nephron is exceeded. For glucose, this typically occurs
when blood levels exceed approximately 180 mg/dL. Beyond this point, the proximal
tubule can no longer reabsorb all the filtered glucose, leading to glycosuria.
5. What is the effect of aldosterone on the nephron?
A. It increases sodium reabsorption and potassium secretion
B. It decreases water reabsorption in the loop of Henle
C. It inhibits the release of renin from the JGA
D. It promotes the excretion of sodium and water
Correct Answer: A
Rationale: Aldosterone is a mineralocorticoid produced by the adrenal cortex in response
to angiotensin II or high potassium levels. It acts primarily on the late distal tubule and
, collecting duct to increase the activity of sodium-potassium pumps. Consequently, sodium
is conserved in the body while potassium is excreted into the tubular fluid.
6. Which portion of the nephron is known as the ‘diluting segment’ because it is impermeable
to water?
A. Proximal convoluted tubule
B. Descending limb of the loop of Henle
C. Thick ascending limb of the loop of Henle
D. Collecting duct
Correct Answer: C
Rationale: The thick ascending limb of the loop of Henle actively transports solutes like
sodium and chloride out of the tubule. However, because this segment is impermeable to
water, the tubular fluid becomes progressively more dilute as it ascends. This separation of
solute and water is essential for creating the medullary osmotic gradient.
7. Which hormone is primarily responsible for the ‘LH surge’ that triggers ovulation?
A. Progesterone
B. Estrogen
C. Inhibin
D. Follicle-Stimulating Hormone
Correct Answer: B
Physiology with Intervention Skill-Based
(ISB) Experiential Learning | Q&A with
Rationale (SCI221 Exam 4) | Nightingale
College
1. What is the primary function of the juxtaglomerular apparatus (JGA) in the kidney?
A. To store urine before micturition
B. To filter large proteins out of the blood
C. To secrete erythropoietin for red blood cell production
D. To regulate blood pressure and the filtration rate of the glomerulus
Correct Answer: D
Rationale: The JGA is a specialized structure formed by the distal convoluted tubule and
the glomerular afferent arteriole. It plays a critical role in autoregulation by sensing
changes in sodium chloride concentration and blood pressure. When blood pressure drops,
the JGA releases renin to activate the RAAS system, ensuring the glomerular filtration rate
remains stable.
2. Which hormone is responsible for increasing the permeability of the collecting ducts to
water?
A. Antidiuretic Hormone
,B. Atrial Natriuretic Peptide
C. Aldosterone
D. Parathyroid Hormone
Correct Answer: A
Rationale: Antidiuretic Hormone (ADH), also known as vasopressin, is secreted by the
posterior pituitary gland. It acts on the cells of the distal tubule and collecting duct to insert
aquaporins into the apical membrane. This mechanism allows for significant water
reabsorption, which helps concentrate urine and maintain fluid balance.
3. In the context of acid-base balance, how do the kidneys respond to metabolic acidosis?
A. By decreasing the reabsorption of bicarbonate ions
B. By excreting more sodium and potassium ions
C. By lowering the respiratory rate to retain carbon dioxide
D. By increasing the secretion of hydrogen ions into the filtrate
Correct Answer: D
Rationale: During metabolic acidosis, the body has an excess of hydrogen ions or a deficit
of bicarbonate. The renal system compensates by secreting excess hydrogen ions into the
urine and synthesizing new bicarbonate ions. This process effectively raises the blood pH
back toward the physiological range of 7.35 to 7.45.
,4. Which of the following describes the ‘Renal Threshold’ for glucose?
A. The maximum amount of glucose the liver can store
B. The blood glucose concentration at which glucose begins to appear in the urine
C. The amount of glucose needed to maintain brain function
D. The rate at which the glomerulus filters glucose
Correct Answer: B
Rationale: The renal threshold represents the plasma concentration of a substance at
which the transport maximum of the nephron is exceeded. For glucose, this typically occurs
when blood levels exceed approximately 180 mg/dL. Beyond this point, the proximal
tubule can no longer reabsorb all the filtered glucose, leading to glycosuria.
5. What is the effect of aldosterone on the nephron?
A. It increases sodium reabsorption and potassium secretion
B. It decreases water reabsorption in the loop of Henle
C. It inhibits the release of renin from the JGA
D. It promotes the excretion of sodium and water
Correct Answer: A
Rationale: Aldosterone is a mineralocorticoid produced by the adrenal cortex in response
to angiotensin II or high potassium levels. It acts primarily on the late distal tubule and
, collecting duct to increase the activity of sodium-potassium pumps. Consequently, sodium
is conserved in the body while potassium is excreted into the tubular fluid.
6. Which portion of the nephron is known as the ‘diluting segment’ because it is impermeable
to water?
A. Proximal convoluted tubule
B. Descending limb of the loop of Henle
C. Thick ascending limb of the loop of Henle
D. Collecting duct
Correct Answer: C
Rationale: The thick ascending limb of the loop of Henle actively transports solutes like
sodium and chloride out of the tubule. However, because this segment is impermeable to
water, the tubular fluid becomes progressively more dilute as it ascends. This separation of
solute and water is essential for creating the medullary osmotic gradient.
7. Which hormone is primarily responsible for the ‘LH surge’ that triggers ovulation?
A. Progesterone
B. Estrogen
C. Inhibin
D. Follicle-Stimulating Hormone
Correct Answer: B
