SCI 221 Exam 3 V3 | SCI 221 Human
Physiology with Intervention Skill-Based
(ISB) Experiential Learning | Q&A with
Rationale (SCI221 Exam 3) | Nightingale
College
1. Which hormone is primarily responsible for the reabsorption of water in the distal
convoluted tubule and collecting duct?
A. Aldosterone
B. Cortisol
C. Atrial Natriuretic Peptide (ANP)
D. Antidiuretic Hormone (ADH)
Correct Answer: D
Rationale: Antidiuretic Hormone, also known as vasopressin, acts on the kidneys to
increase water permeability in the collecting ducts. By inserting aquaporin channels into
the apical membrane, it allows water to move from the filtrate back into the bloodstream.
This physiological response is essential for maintaining blood pressure and plasma
osmolarity during dehydration.
2. The Juxtaglomerular Apparatus (JGA) releases renin in response to which of the following
stimuli?
A. Increased blood pressure in the afferent arteriole
,B. High sodium concentration at the macula densa
C. Parasympathetic nervous system activation
D. Decreased blood pressure or decreased sodium levels
Correct Answer: D
Rationale: Renin is released when the juxtaglomerular cells sense a drop in renal
perfusion pressure or low sodium delivery to the macula densa. Once released, renin
initiates the RAAS cascade by converting angiotensinogen into angiotensin I. This
mechanism serves as a primary regulatory pathway for long-term blood pressure control
and electrolyte balance.
3. In the process of cellular respiration, where does the Krebs Cycle (Citric Acid Cycle) occur?
A. Cytosol
B. Mitochondrial Matrix
C. Inner Mitochondrial Membrane
D. Ribosomes
Correct Answer: B
Rationale: The Krebs Cycle takes place within the mitochondrial matrix where acetyl-CoA
is oxidized to produce CO2 and electron carriers. These carriers, NADH and FADH2,
subsequently donate electrons to the electron transport chain. This cycle is a central hub
for metabolism, integrating carbohydrate, lipid, and protein breakdown products.
,4. Which hormone triggers ovulation in the female reproductive cycle?
A. Follicle-Stimulating Hormone (FSH)
B. Estrogen
C. Progesterone
D. Luteinizing Hormone (LH)
Correct Answer: D
Rationale: A sharp surge in Luteinizing Hormone (LH) is the critical signal that causes the
mature Graafian follicle to rupture. This process releases the secondary oocyte into the
fallopian tube for potential fertilization. Following ovulation, the remaining follicular cells
transform into the corpus luteum under the continued influence of LH.
5. Which cell type in the stomach is responsible for the secretion of hydrochloric acid (HCl)?
A. Chief cells
B. Parietal cells
C. G cells
D. Mucous neck cells
Correct Answer: B
Rationale: Parietal cells utilize a proton pump to transport hydrogen ions into the stomach
lumen in exchange for potassium. This secretion creates a highly acidic environment
necessary for denaturing proteins and activating pepsinogen into pepsin. Additionally,
, these cells secrete intrinsic factor, which is vital for the absorption of vitamin B12 in the
ileum.
6. What is the primary function of the Loop of Henle in the nephron?
A. To secrete metabolic wastes like urea
B. To perform the majority of glucose reabsorption
C. To establish a hypertonic medullary osmotic gradient
D. To filter large proteins out of the blood
Correct Answer: C
Rationale: The Loop of Henle uses a countercurrent multiplier system to create a high
solute concentration in the renal medulla. The descending limb is permeable to water,
while the ascending limb actively pumps out salts like NaCl. This gradient is crucial because
it allows the collecting duct to concentrate urine effectively when ADH is present.
7. Which of the following conditions is most likely to cause Respiratory Acidosis?
A. Hyperventilation during a panic attack
B. Severe diarrhea leading to bicarbonate loss
C. Hypoventilation due to COPD or drug overdose
D. Excessive ingestion of antacids
Correct Answer: C
Physiology with Intervention Skill-Based
(ISB) Experiential Learning | Q&A with
Rationale (SCI221 Exam 3) | Nightingale
College
1. Which hormone is primarily responsible for the reabsorption of water in the distal
convoluted tubule and collecting duct?
A. Aldosterone
B. Cortisol
C. Atrial Natriuretic Peptide (ANP)
D. Antidiuretic Hormone (ADH)
Correct Answer: D
Rationale: Antidiuretic Hormone, also known as vasopressin, acts on the kidneys to
increase water permeability in the collecting ducts. By inserting aquaporin channels into
the apical membrane, it allows water to move from the filtrate back into the bloodstream.
This physiological response is essential for maintaining blood pressure and plasma
osmolarity during dehydration.
2. The Juxtaglomerular Apparatus (JGA) releases renin in response to which of the following
stimuli?
A. Increased blood pressure in the afferent arteriole
,B. High sodium concentration at the macula densa
C. Parasympathetic nervous system activation
D. Decreased blood pressure or decreased sodium levels
Correct Answer: D
Rationale: Renin is released when the juxtaglomerular cells sense a drop in renal
perfusion pressure or low sodium delivery to the macula densa. Once released, renin
initiates the RAAS cascade by converting angiotensinogen into angiotensin I. This
mechanism serves as a primary regulatory pathway for long-term blood pressure control
and electrolyte balance.
3. In the process of cellular respiration, where does the Krebs Cycle (Citric Acid Cycle) occur?
A. Cytosol
B. Mitochondrial Matrix
C. Inner Mitochondrial Membrane
D. Ribosomes
Correct Answer: B
Rationale: The Krebs Cycle takes place within the mitochondrial matrix where acetyl-CoA
is oxidized to produce CO2 and electron carriers. These carriers, NADH and FADH2,
subsequently donate electrons to the electron transport chain. This cycle is a central hub
for metabolism, integrating carbohydrate, lipid, and protein breakdown products.
,4. Which hormone triggers ovulation in the female reproductive cycle?
A. Follicle-Stimulating Hormone (FSH)
B. Estrogen
C. Progesterone
D. Luteinizing Hormone (LH)
Correct Answer: D
Rationale: A sharp surge in Luteinizing Hormone (LH) is the critical signal that causes the
mature Graafian follicle to rupture. This process releases the secondary oocyte into the
fallopian tube for potential fertilization. Following ovulation, the remaining follicular cells
transform into the corpus luteum under the continued influence of LH.
5. Which cell type in the stomach is responsible for the secretion of hydrochloric acid (HCl)?
A. Chief cells
B. Parietal cells
C. G cells
D. Mucous neck cells
Correct Answer: B
Rationale: Parietal cells utilize a proton pump to transport hydrogen ions into the stomach
lumen in exchange for potassium. This secretion creates a highly acidic environment
necessary for denaturing proteins and activating pepsinogen into pepsin. Additionally,
, these cells secrete intrinsic factor, which is vital for the absorption of vitamin B12 in the
ileum.
6. What is the primary function of the Loop of Henle in the nephron?
A. To secrete metabolic wastes like urea
B. To perform the majority of glucose reabsorption
C. To establish a hypertonic medullary osmotic gradient
D. To filter large proteins out of the blood
Correct Answer: C
Rationale: The Loop of Henle uses a countercurrent multiplier system to create a high
solute concentration in the renal medulla. The descending limb is permeable to water,
while the ascending limb actively pumps out salts like NaCl. This gradient is crucial because
it allows the collecting duct to concentrate urine effectively when ADH is present.
7. Which of the following conditions is most likely to cause Respiratory Acidosis?
A. Hyperventilation during a panic attack
B. Severe diarrhea leading to bicarbonate loss
C. Hypoventilation due to COPD or drug overdose
D. Excessive ingestion of antacids
Correct Answer: C
