1|Page
BIOL 373 Midterm Exam 2 Study Guide |
Comprehensive Review, Practice Questions,
Detailed Answer Explanations & Latest Exam
Preparation (2025–2026)
BIOL 373 Midterm Exam 2 Study Guide
Comprehensive Review & Practice Questions (2025–2026)
EXAM COVERAGE SUMMARY
This examination covers the renal system with emphasis on: kidney structure and function
(nephron anatomy, cortical vs juxtamedullary nephrons, blood flow pathways); glomerular
filtration (filtration barriers, pressures regulating GFR, autoregulation mechanisms); tubular
reabsorption and secretion (Na+ transport mechanisms, secondary active transport, organic
anion transporters); urine concentration mechanisms (countercurrent multiplier system,
ADH/AVP regulation, aquaporins, medullary osmotic gradient); osmoregulation and fluid
balance (ECF volume regulation, plasma osmolarity, thirst mechanism); renal regulation of ions
(aldosterone, renin-angiotensin-aldosterone system, K+ homeostasis); renal clearance and GFR
measurement; and micturition control. The exam integrates these concepts through clinical
scenarios and application-based questions requiring understanding of both normal physiology
and pathological conditions.
1. A 65-year-old patient with hypertension has a GFR of 85 mL/min. If her plasma inulin
concentration is 0.5 mg/mL, what would be the expected filtration rate of inulin?
,2|Page
A) 42.5 mg/min
B) 85.5 mg/min
C) 170 mg/min
D) 42.5 mg/mL
E) 170 mL/min
42.5 mg/min Since inulin is neither reabsorbed nor secreted, its excretion rate equals filtration
rate. Using the formula Filtration rate = GFR × Plasma concentration = 85 mL/min × 0.5
mg/mL = 42.5 mg/min, this represents the amount of inulin filtered per minute into Bowman's
space.
2. A patient presents with high plasma osmolarity and low blood pressure. Which of the
following would be the primary compensatory response initiated by the hypothalamus?
A) Decreased ADH secretion
B) Increased atrial natriuretic peptide release
C) Increased vasopressin secretion and thirst stimulation
D) Decreased renin release from the JGA
E) Increased prostaglandin synthesis
Increased vasopressin secretion and thirst stimulation High plasma osmolarity is sensed by
osmoreceptors in the OVLT and subfornical organ, while low blood pressure activates
baroreceptor pathways. Both conditions synergistically stimulate vasopressin release from the
posterior pituitary and activate thirst centers in the hypothalamus to restore fluid balance.
3. A researcher is studying the countercurrent multiplier system and finds that furosemide
inhibits NKCC2 transporters. What would be the immediate effect on medullary
interstitial osmolarity?
A) Increased medullary osmolarity due to enhanced ion pumping
B) Decreased medullary osmolarity due to reduced NaCl transport from ascending limb
C) No change in medullary osmolarity but increased water reabsorption
,3|Page
D) Increased urea recycling leading to higher osmolarity
E) Complete loss of osmotic gradient throughout the kidney
Decreased medullary osmolarity due to reduced NaCl transport from ascending limb NKCC2
transporters on the apical membrane of the ascending limb actively move Na+, K+, and 2Cl-
into cells, which is essential for generating the high medullary interstitial osmolarity. Inhibiting
these transporters prevents salt accumulation in the medulla, reducing the osmotic gradient
needed for water reabsorption.
4. In a cortical nephron, what is the correct pathway of blood flow beginning at the
abdominal aorta?
A) Abdominal aorta → renal artery → efferent arteriole → glomerulus → afferent arteriole →
peritubular capillaries → renal vein
B) Abdominal aorta → renal artery → afferent arteriole → glomerulus → efferent arteriole →
peritubular capillaries → renal vein
C) Abdominal aorta → renal artery → afferent arteriole → glomerulus → efferent arteriole →
vasa recta → renal vein
D) Abdominal aorta → renal artery → glomerulus → afferent arteriole → efferent arteriole →
peritubular capillaries → renal vein
E) Abdominal aorta → renal artery → afferent arteriole → peritubular capillaries → glomerulus
→ efferent arteriole → renal vein
Abdominal aorta → renal artery → afferent arteriole → glomerulus → efferent arteriole →
peritubular capillaries → renal vein Cortical nephrons follow the conventional pathway where
blood enters the glomerulus through the afferent arteriole, exits through the efferent arteriole,
and then perfuses peritubular capillaries surrounding the proximal and distal tubules in the
cortex before returning to the venous system.
5. A patient with chronic kidney disease has damaged podocytes. Which of the following
would most likely be found in the patient's urine?
, 4|Page
A) Increased glucose due to damaged filtration slits
B) Increased plasma proteins due to impaired filtration barrier
C) Increased sodium due to reduced reabsorption
D) Increased urea due to decreased secretion
E) Increased water due to loss of aquaporins
Increased plasma proteins due to impaired filtration barrier Podocytes form the epithelial layer
of the filtration barrier with their foot processes connected by slit diaphragms containing
nephrin and podocin. Damage to these structures allows plasma proteins larger than 50 kDa to
pass through the filtration slits, resulting in proteinuria normally prevented by the negatively
charged basement membrane and slit membrane.
6. A 55-year-old male is experiencing vomiting and diarrhea. His plasma osmolarity is 310
mOsm and his blood pressure is 95/60 mmHg. Which hormone would be most elevated in
his circulation?
A) Atrial natriuretic peptide
B) Glucagon
C) Vasopressin
D) Insulin
E) Parathyroid hormone
Vasopressin Vomiting and diarrhea cause both volume depletion and hyperosmolarity through
loss of water and electrolytes. The elevated plasma osmolarity stimulates central osmoreceptors
while reduced blood pressure activates baroreceptor pathways, both triggering vasopressin
release from the posterior pituitary to conserve water and restore plasma osmolarity and blood
pressure.
7. What is the net pressure favoring filtration in the glomerular capillaries when
hydrostatic pressure is 55 mmHg, colloid osmotic pressure is 30 mmHg, and Bowman's
capsule fluid pressure is 15 mmHg?
BIOL 373 Midterm Exam 2 Study Guide |
Comprehensive Review, Practice Questions,
Detailed Answer Explanations & Latest Exam
Preparation (2025–2026)
BIOL 373 Midterm Exam 2 Study Guide
Comprehensive Review & Practice Questions (2025–2026)
EXAM COVERAGE SUMMARY
This examination covers the renal system with emphasis on: kidney structure and function
(nephron anatomy, cortical vs juxtamedullary nephrons, blood flow pathways); glomerular
filtration (filtration barriers, pressures regulating GFR, autoregulation mechanisms); tubular
reabsorption and secretion (Na+ transport mechanisms, secondary active transport, organic
anion transporters); urine concentration mechanisms (countercurrent multiplier system,
ADH/AVP regulation, aquaporins, medullary osmotic gradient); osmoregulation and fluid
balance (ECF volume regulation, plasma osmolarity, thirst mechanism); renal regulation of ions
(aldosterone, renin-angiotensin-aldosterone system, K+ homeostasis); renal clearance and GFR
measurement; and micturition control. The exam integrates these concepts through clinical
scenarios and application-based questions requiring understanding of both normal physiology
and pathological conditions.
1. A 65-year-old patient with hypertension has a GFR of 85 mL/min. If her plasma inulin
concentration is 0.5 mg/mL, what would be the expected filtration rate of inulin?
,2|Page
A) 42.5 mg/min
B) 85.5 mg/min
C) 170 mg/min
D) 42.5 mg/mL
E) 170 mL/min
42.5 mg/min Since inulin is neither reabsorbed nor secreted, its excretion rate equals filtration
rate. Using the formula Filtration rate = GFR × Plasma concentration = 85 mL/min × 0.5
mg/mL = 42.5 mg/min, this represents the amount of inulin filtered per minute into Bowman's
space.
2. A patient presents with high plasma osmolarity and low blood pressure. Which of the
following would be the primary compensatory response initiated by the hypothalamus?
A) Decreased ADH secretion
B) Increased atrial natriuretic peptide release
C) Increased vasopressin secretion and thirst stimulation
D) Decreased renin release from the JGA
E) Increased prostaglandin synthesis
Increased vasopressin secretion and thirst stimulation High plasma osmolarity is sensed by
osmoreceptors in the OVLT and subfornical organ, while low blood pressure activates
baroreceptor pathways. Both conditions synergistically stimulate vasopressin release from the
posterior pituitary and activate thirst centers in the hypothalamus to restore fluid balance.
3. A researcher is studying the countercurrent multiplier system and finds that furosemide
inhibits NKCC2 transporters. What would be the immediate effect on medullary
interstitial osmolarity?
A) Increased medullary osmolarity due to enhanced ion pumping
B) Decreased medullary osmolarity due to reduced NaCl transport from ascending limb
C) No change in medullary osmolarity but increased water reabsorption
,3|Page
D) Increased urea recycling leading to higher osmolarity
E) Complete loss of osmotic gradient throughout the kidney
Decreased medullary osmolarity due to reduced NaCl transport from ascending limb NKCC2
transporters on the apical membrane of the ascending limb actively move Na+, K+, and 2Cl-
into cells, which is essential for generating the high medullary interstitial osmolarity. Inhibiting
these transporters prevents salt accumulation in the medulla, reducing the osmotic gradient
needed for water reabsorption.
4. In a cortical nephron, what is the correct pathway of blood flow beginning at the
abdominal aorta?
A) Abdominal aorta → renal artery → efferent arteriole → glomerulus → afferent arteriole →
peritubular capillaries → renal vein
B) Abdominal aorta → renal artery → afferent arteriole → glomerulus → efferent arteriole →
peritubular capillaries → renal vein
C) Abdominal aorta → renal artery → afferent arteriole → glomerulus → efferent arteriole →
vasa recta → renal vein
D) Abdominal aorta → renal artery → glomerulus → afferent arteriole → efferent arteriole →
peritubular capillaries → renal vein
E) Abdominal aorta → renal artery → afferent arteriole → peritubular capillaries → glomerulus
→ efferent arteriole → renal vein
Abdominal aorta → renal artery → afferent arteriole → glomerulus → efferent arteriole →
peritubular capillaries → renal vein Cortical nephrons follow the conventional pathway where
blood enters the glomerulus through the afferent arteriole, exits through the efferent arteriole,
and then perfuses peritubular capillaries surrounding the proximal and distal tubules in the
cortex before returning to the venous system.
5. A patient with chronic kidney disease has damaged podocytes. Which of the following
would most likely be found in the patient's urine?
, 4|Page
A) Increased glucose due to damaged filtration slits
B) Increased plasma proteins due to impaired filtration barrier
C) Increased sodium due to reduced reabsorption
D) Increased urea due to decreased secretion
E) Increased water due to loss of aquaporins
Increased plasma proteins due to impaired filtration barrier Podocytes form the epithelial layer
of the filtration barrier with their foot processes connected by slit diaphragms containing
nephrin and podocin. Damage to these structures allows plasma proteins larger than 50 kDa to
pass through the filtration slits, resulting in proteinuria normally prevented by the negatively
charged basement membrane and slit membrane.
6. A 55-year-old male is experiencing vomiting and diarrhea. His plasma osmolarity is 310
mOsm and his blood pressure is 95/60 mmHg. Which hormone would be most elevated in
his circulation?
A) Atrial natriuretic peptide
B) Glucagon
C) Vasopressin
D) Insulin
E) Parathyroid hormone
Vasopressin Vomiting and diarrhea cause both volume depletion and hyperosmolarity through
loss of water and electrolytes. The elevated plasma osmolarity stimulates central osmoreceptors
while reduced blood pressure activates baroreceptor pathways, both triggering vasopressin
release from the posterior pituitary to conserve water and restore plasma osmolarity and blood
pressure.
7. What is the net pressure favoring filtration in the glomerular capillaries when
hydrostatic pressure is 55 mmHg, colloid osmotic pressure is 30 mmHg, and Bowman's
capsule fluid pressure is 15 mmHg?
