PCB 3703 Exam 4 V1 | PCB 3703 Human Physiology |
Actual Q&A with Rationale (PCB3703 Exam 4) |
University of Central Florida
1. Which of the following Starling forces is the primary driver of glomerular filtration in a
healthy individual?
A. Bowman’s space osmotic pressure
B. Glomerular capillary hydrostatic pressure
C. Plasma oncotic pressure
D. Capsular hydrostatic pressure
Correct Answer: B
Explanation: Glomerular capillary hydrostatic pressure is the blood pressure within the
glomerular capillaries that pushes fluid into Bowman’s capsule. In a healthy kidney, this
pressure is significantly higher than the opposing forces, favoring filtration. It is regulated
by the relative diameters of the afferent and efferent arterioles.
2. A patient presents with a plasma glucose concentration of 400 mg/dL. What is the most
likely renal consequence?
A. Decreased GFR
B. Decreased clearance of PAH
C. Increased water reabsorption
D. Glucose appearing in the urine
,Correct Answer: D
Explanation: The renal threshold for glucose is typically around 180 to 200 mg/dL,
beyond which the SGLT transporters in the proximal tubule become saturated. When
plasma glucose exceeds this threshold, the transport maximum (Tm) is reached, and excess
glucose remains in the filtrate. This leads to glucosuria and osmotic diuresis, which are
hallmark signs of uncontrolled diabetes.
3. Which cell type in the distal tubule and collecting duct is primarily responsible for fine-
tuning sodium reabsorption under the influence of aldosterone?
A. Type A intercalated cells
B. Type B intercalated cells
C. Macula densa cells
D. Principal cells
Correct Answer: D
Explanation: Principal cells contain the epithelial sodium channels (ENaC) and the Na+/K+
ATPase pumps necessary for sodium reabsorption and potassium secretion. Aldosterone
acts on these cells to increase the expression and activity of these transporters. This
mechanism is crucial for maintaining long-term blood pressure and extracellular fluid
volume.
, 4. In the presence of maximum Vasopressin (ADH) secretion, where is the urine the most
concentrated?
A. At the top of the ascending limb
B. At the end of the proximal tubule
C. In the Bowman’s capsule
D. At the end of the collecting duct
Correct Answer: D
Explanation: Vasopressin facilitates the insertion of Aquaporin-2 channels into the apical
membrane of the collecting duct cells. As the filtrate moves down the collecting duct
through the high-osmolarity renal medulla, water is drawn out by osmosis. By the time the
fluid reaches the end of the collecting duct, it has equilibrated with the medullary
interstitial fluid, reaching its highest concentration.
5. Which of the following occurs during the Cephalic phase of gastric secretion?
A. Vagal stimulation increases gastrin release
B. CCK stimulates the gallbladder
C. Distension of the stomach triggers local reflexes
D. Secretin inhibits parietal cell activity
Correct Answer: A
Actual Q&A with Rationale (PCB3703 Exam 4) |
University of Central Florida
1. Which of the following Starling forces is the primary driver of glomerular filtration in a
healthy individual?
A. Bowman’s space osmotic pressure
B. Glomerular capillary hydrostatic pressure
C. Plasma oncotic pressure
D. Capsular hydrostatic pressure
Correct Answer: B
Explanation: Glomerular capillary hydrostatic pressure is the blood pressure within the
glomerular capillaries that pushes fluid into Bowman’s capsule. In a healthy kidney, this
pressure is significantly higher than the opposing forces, favoring filtration. It is regulated
by the relative diameters of the afferent and efferent arterioles.
2. A patient presents with a plasma glucose concentration of 400 mg/dL. What is the most
likely renal consequence?
A. Decreased GFR
B. Decreased clearance of PAH
C. Increased water reabsorption
D. Glucose appearing in the urine
,Correct Answer: D
Explanation: The renal threshold for glucose is typically around 180 to 200 mg/dL,
beyond which the SGLT transporters in the proximal tubule become saturated. When
plasma glucose exceeds this threshold, the transport maximum (Tm) is reached, and excess
glucose remains in the filtrate. This leads to glucosuria and osmotic diuresis, which are
hallmark signs of uncontrolled diabetes.
3. Which cell type in the distal tubule and collecting duct is primarily responsible for fine-
tuning sodium reabsorption under the influence of aldosterone?
A. Type A intercalated cells
B. Type B intercalated cells
C. Macula densa cells
D. Principal cells
Correct Answer: D
Explanation: Principal cells contain the epithelial sodium channels (ENaC) and the Na+/K+
ATPase pumps necessary for sodium reabsorption and potassium secretion. Aldosterone
acts on these cells to increase the expression and activity of these transporters. This
mechanism is crucial for maintaining long-term blood pressure and extracellular fluid
volume.
, 4. In the presence of maximum Vasopressin (ADH) secretion, where is the urine the most
concentrated?
A. At the top of the ascending limb
B. At the end of the proximal tubule
C. In the Bowman’s capsule
D. At the end of the collecting duct
Correct Answer: D
Explanation: Vasopressin facilitates the insertion of Aquaporin-2 channels into the apical
membrane of the collecting duct cells. As the filtrate moves down the collecting duct
through the high-osmolarity renal medulla, water is drawn out by osmosis. By the time the
fluid reaches the end of the collecting duct, it has equilibrated with the medullary
interstitial fluid, reaching its highest concentration.
5. Which of the following occurs during the Cephalic phase of gastric secretion?
A. Vagal stimulation increases gastrin release
B. CCK stimulates the gallbladder
C. Distension of the stomach triggers local reflexes
D. Secretin inhibits parietal cell activity
Correct Answer: A
