BIOL 252 Human Anatomy & Physiology II w/Lab |
Module 9 Exam Review and Answers -Summary |
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1. A researcher is investigating a novel hormone that decreases plasma calcium concentration.
Which of the following mechanisms would most directly achieve this effect?
A. Increasing osteoclast activity in bone
B. Decreasing renal calcium reabsorption in the distal tubule
C. Increasing intestinal calcium absorption via vitamin D
D. Stimulating calcitonin secretion from parafollicular cells
Answer: B
Rationale: Decreasing renal calcium reabsorption directly lowers plasma calcium. Osteoclast activity
increases plasma calcium (A). Intestinal absorption increases plasma calcium (C). Calcitonin lowers
calcium but is not the hormone being investigated; the question asks for the mechanism of a hypothetical
hormone, and decreasing reabsorption is a direct renal effect.
2. In a patient with chronic obstructive pulmonary disease (COPD), arterial blood gas analysis
reveals pH 7.32, PaCO2 65 mm Hg, HCO3- 32 mEq/L. Which of the following best describes the
acid-base status?
A. Uncompensated respiratory acidosis
B. Partially compensated respiratory acidosis
C. Fully compensated respiratory acidosis
D. Metabolic alkalosis with respiratory compensation
Answer: B
Rationale: The pH is acidic (7.32), PaCO2 elevated (65) indicating respiratory acidosis. HCO3- is
elevated (32) suggesting metabolic compensation. Since pH is still below 7.35, compensation is partial,
not full. Metabolic alkalosis (D) is incorrect because primary disturbance is respiratory.
3. During a cardiac catheterization, a pressure tracing from the left ventricle shows a steep rise
during isovolumetric contraction. Which of the following events is directly responsible for this
pressure increase?
A. Opening of the aortic valve
B. Rapid influx of calcium into cardiomyocytes
C. Cross-bridge cycling between actin and myosin
D. Closure of the mitral valve
Answer: C
Rationale: Isovolumetric contraction occurs when ventricular pressure rises rapidly while both AV and
semilunar valves are closed. The pressure increase is due to cross-bridge cycling generating force.
Calcium influx (B) triggers contraction but does not directly cause pressure; cross-bridge cycling does.
Page 1
,Valve opening (A) or closure (D) are not the direct cause of pressure rise.
4. A patient with a deficiency in intrinsic factor would most likely have impaired absorption of
which vitamin, and what hematological consequence would ensue?
A. Vitamin B12 deficiency leading to macrocytic anemia
B. Folate deficiency leading to macrocytic anemia
C. Vitamin B12 deficiency leading to microcytic anemia
D. Iron deficiency leading to microcytic anemia
Answer: A
Rationale: Intrinsic factor is required for absorption of vitamin B12 in the ileum. Deficiency causes
pernicious anemia, characterized by macrocytic (megaloblastic) anemia. Folate (B) also causes
macrocytic anemia but is not dependent on intrinsic factor. Microcytic anemia (C, D) is associated with
iron deficiency or thalassemia, not B12 deficiency.
5. In the nephron, which of the following segments is the primary site where the concentration of
urea in the tubular fluid is highest at the end of the segment?
A. Proximal convoluted tubule
B. Thick ascending limb of loop of Henle
C. Cortical collecting duct
D. Inner medullary collecting duct
Answer: D
Rationale: Urea is reabsorbed in the inner medullary collecting duct via UT-A1 transporters,
contributing to the medullary osmotic gradient. At the end of this segment, tubular fluid urea
concentration is high due to prior water reabsorption and urea recycling. Proximal tubule (A) reabsorbs
urea passively. Thick ascending limb (B) is impermeable to urea. Cortical collecting duct (C) has
variable permeability but not as high concentration as inner medulla.
6. Which of the following correctly describes the role of the lymphatic system in maintaining fluid
homeostasis?
A. It returns approximately 3 L of interstitial fluid to the bloodstream daily via the thoracic duct
B. It produces erythrocytes and platelets to maintain blood volume
C. It actively pumps lymph using peristaltic contractions of lymphatic vessels
D. It filters all lymph through the spleen before returning to the venous system
Answer: A
Rationale: The lymphatic system returns about 3 L of fluid daily (the exact amount varies but is
significant) to the bloodstream, preventing edema. Erythropoiesis (B) occurs in bone marrow, not
lymphatic system. Lymphatic vessels have external compression and intrinsic contractions, but not true
peristalsis (C). Lymph is filtered through lymph nodes, not the spleen; spleen filters blood (D).
7. A drug that inhibits carbonic anhydrase in the renal proximal tubule would have which of the
following effects on urine composition?
A. Increased pH and increased bicarbonate excretion
Page 2
, B. Decreased pH and increased bicarbonate reabsorption
C. Increased pH and decreased bicarbonate excretion
D. Decreased pH and decreased bicarbonate excretion
Answer: A
Rationale: Carbonic anhydrase inhibition in the proximal tubule reduces H+ secretion and bicarbonate
reabsorption, leading to bicarbonate excretion in urine. Loss of bicarbonate causes metabolic acidosis,
but urine becomes alkaline (increased pH) due to excess bicarbonate. Thus, urine pH increases and
bicarbonate excretion increases.
8. During the follicular phase of the ovarian cycle, which of the following hormonal changes is
primarily responsible for the selection and dominance of one follicle?
A. A surge in luteinizing hormone (LH) from the anterior pituitary
B. A gradual rise in follicle-stimulating hormone (FSH) and increasing estradiol from the granulosa cells
C. A sharp decline in inhibin B levels
D. A decrease in gonadotropin-releasing hormone (GnRH) pulse frequency
Answer: B
Rationale: During the follicular phase, FSH stimulates follicular growth and granulosa cells produce
estradiol. Rising estradiol exerts negative feedback on FSH, causing lower FSH levels; the dominant
follicle is more sensitive to FSH and continues to grow. The LH surge (A) occurs at ovulation, not during
selection. Inhibin B (C) decreases FSH but does not directly select a follicle. GnRH pulse frequency
increases, not decreases (D).
9. A patient with a tumor secreting excess aldosterone would likely exhibit which of the following
sets of laboratory findings?
A. Hypernatremia, hypokalemia, metabolic alkalosis, low plasma renin
B. Hyponatremia, hyperkalemia, metabolic acidosis, high plasma renin
C. Hypernatremia, hyperkalemia, metabolic acidosis, low plasma renin
D. Hyponatremia, hypokalemia, metabolic alkalosis, high plasma renin
Answer: A
Rationale: Aldosterone increases Na+ reabsorption (leading to hypernatremia) and K+ excretion
(hypokalemia), and H+ excretion (metabolic alkalosis). Excess aldosterone suppresses renin via
negative feedback, so plasma renin is low. Options B, C, D describe opposite or mixed patterns
inconsistent with aldosterone excess.
10. Which of the following best explains why the partial pressure of oxygen (PO2) in systemic
venous blood is lower than in alveolar air, even though hemoglobin is nearly fully saturated?
A. The oxygen-hemoglobin dissociation curve is sigmoidal, and at high PO2, small changes in PO2 cause large
changes in saturation
B. Venous blood has a higher PCO2 and lower pH, shifting the dissociation curve to the right and decreasing
PO2
C. The majority of oxygen in venous blood is dissolved in plasma, not bound to hemoglobin
D. Hemoglobin's affinity for oxygen is lower in venous blood due to increased 2,3-BPG levels, causing release
of oxygen and lowering PO2
Page 3
Module 9 Exam Review and Answers -Summary |
LockDown Browser | Portage Learning
1. A researcher is investigating a novel hormone that decreases plasma calcium concentration.
Which of the following mechanisms would most directly achieve this effect?
A. Increasing osteoclast activity in bone
B. Decreasing renal calcium reabsorption in the distal tubule
C. Increasing intestinal calcium absorption via vitamin D
D. Stimulating calcitonin secretion from parafollicular cells
Answer: B
Rationale: Decreasing renal calcium reabsorption directly lowers plasma calcium. Osteoclast activity
increases plasma calcium (A). Intestinal absorption increases plasma calcium (C). Calcitonin lowers
calcium but is not the hormone being investigated; the question asks for the mechanism of a hypothetical
hormone, and decreasing reabsorption is a direct renal effect.
2. In a patient with chronic obstructive pulmonary disease (COPD), arterial blood gas analysis
reveals pH 7.32, PaCO2 65 mm Hg, HCO3- 32 mEq/L. Which of the following best describes the
acid-base status?
A. Uncompensated respiratory acidosis
B. Partially compensated respiratory acidosis
C. Fully compensated respiratory acidosis
D. Metabolic alkalosis with respiratory compensation
Answer: B
Rationale: The pH is acidic (7.32), PaCO2 elevated (65) indicating respiratory acidosis. HCO3- is
elevated (32) suggesting metabolic compensation. Since pH is still below 7.35, compensation is partial,
not full. Metabolic alkalosis (D) is incorrect because primary disturbance is respiratory.
3. During a cardiac catheterization, a pressure tracing from the left ventricle shows a steep rise
during isovolumetric contraction. Which of the following events is directly responsible for this
pressure increase?
A. Opening of the aortic valve
B. Rapid influx of calcium into cardiomyocytes
C. Cross-bridge cycling between actin and myosin
D. Closure of the mitral valve
Answer: C
Rationale: Isovolumetric contraction occurs when ventricular pressure rises rapidly while both AV and
semilunar valves are closed. The pressure increase is due to cross-bridge cycling generating force.
Calcium influx (B) triggers contraction but does not directly cause pressure; cross-bridge cycling does.
Page 1
,Valve opening (A) or closure (D) are not the direct cause of pressure rise.
4. A patient with a deficiency in intrinsic factor would most likely have impaired absorption of
which vitamin, and what hematological consequence would ensue?
A. Vitamin B12 deficiency leading to macrocytic anemia
B. Folate deficiency leading to macrocytic anemia
C. Vitamin B12 deficiency leading to microcytic anemia
D. Iron deficiency leading to microcytic anemia
Answer: A
Rationale: Intrinsic factor is required for absorption of vitamin B12 in the ileum. Deficiency causes
pernicious anemia, characterized by macrocytic (megaloblastic) anemia. Folate (B) also causes
macrocytic anemia but is not dependent on intrinsic factor. Microcytic anemia (C, D) is associated with
iron deficiency or thalassemia, not B12 deficiency.
5. In the nephron, which of the following segments is the primary site where the concentration of
urea in the tubular fluid is highest at the end of the segment?
A. Proximal convoluted tubule
B. Thick ascending limb of loop of Henle
C. Cortical collecting duct
D. Inner medullary collecting duct
Answer: D
Rationale: Urea is reabsorbed in the inner medullary collecting duct via UT-A1 transporters,
contributing to the medullary osmotic gradient. At the end of this segment, tubular fluid urea
concentration is high due to prior water reabsorption and urea recycling. Proximal tubule (A) reabsorbs
urea passively. Thick ascending limb (B) is impermeable to urea. Cortical collecting duct (C) has
variable permeability but not as high concentration as inner medulla.
6. Which of the following correctly describes the role of the lymphatic system in maintaining fluid
homeostasis?
A. It returns approximately 3 L of interstitial fluid to the bloodstream daily via the thoracic duct
B. It produces erythrocytes and platelets to maintain blood volume
C. It actively pumps lymph using peristaltic contractions of lymphatic vessels
D. It filters all lymph through the spleen before returning to the venous system
Answer: A
Rationale: The lymphatic system returns about 3 L of fluid daily (the exact amount varies but is
significant) to the bloodstream, preventing edema. Erythropoiesis (B) occurs in bone marrow, not
lymphatic system. Lymphatic vessels have external compression and intrinsic contractions, but not true
peristalsis (C). Lymph is filtered through lymph nodes, not the spleen; spleen filters blood (D).
7. A drug that inhibits carbonic anhydrase in the renal proximal tubule would have which of the
following effects on urine composition?
A. Increased pH and increased bicarbonate excretion
Page 2
, B. Decreased pH and increased bicarbonate reabsorption
C. Increased pH and decreased bicarbonate excretion
D. Decreased pH and decreased bicarbonate excretion
Answer: A
Rationale: Carbonic anhydrase inhibition in the proximal tubule reduces H+ secretion and bicarbonate
reabsorption, leading to bicarbonate excretion in urine. Loss of bicarbonate causes metabolic acidosis,
but urine becomes alkaline (increased pH) due to excess bicarbonate. Thus, urine pH increases and
bicarbonate excretion increases.
8. During the follicular phase of the ovarian cycle, which of the following hormonal changes is
primarily responsible for the selection and dominance of one follicle?
A. A surge in luteinizing hormone (LH) from the anterior pituitary
B. A gradual rise in follicle-stimulating hormone (FSH) and increasing estradiol from the granulosa cells
C. A sharp decline in inhibin B levels
D. A decrease in gonadotropin-releasing hormone (GnRH) pulse frequency
Answer: B
Rationale: During the follicular phase, FSH stimulates follicular growth and granulosa cells produce
estradiol. Rising estradiol exerts negative feedback on FSH, causing lower FSH levels; the dominant
follicle is more sensitive to FSH and continues to grow. The LH surge (A) occurs at ovulation, not during
selection. Inhibin B (C) decreases FSH but does not directly select a follicle. GnRH pulse frequency
increases, not decreases (D).
9. A patient with a tumor secreting excess aldosterone would likely exhibit which of the following
sets of laboratory findings?
A. Hypernatremia, hypokalemia, metabolic alkalosis, low plasma renin
B. Hyponatremia, hyperkalemia, metabolic acidosis, high plasma renin
C. Hypernatremia, hyperkalemia, metabolic acidosis, low plasma renin
D. Hyponatremia, hypokalemia, metabolic alkalosis, high plasma renin
Answer: A
Rationale: Aldosterone increases Na+ reabsorption (leading to hypernatremia) and K+ excretion
(hypokalemia), and H+ excretion (metabolic alkalosis). Excess aldosterone suppresses renin via
negative feedback, so plasma renin is low. Options B, C, D describe opposite or mixed patterns
inconsistent with aldosterone excess.
10. Which of the following best explains why the partial pressure of oxygen (PO2) in systemic
venous blood is lower than in alveolar air, even though hemoglobin is nearly fully saturated?
A. The oxygen-hemoglobin dissociation curve is sigmoidal, and at high PO2, small changes in PO2 cause large
changes in saturation
B. Venous blood has a higher PCO2 and lower pH, shifting the dissociation curve to the right and decreasing
PO2
C. The majority of oxygen in venous blood is dissolved in plasma, not bound to hemoglobin
D. Hemoglobin's affinity for oxygen is lower in venous blood due to increased 2,3-BPG levels, causing release
of oxygen and lowering PO2
Page 3
