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PHGY 216 FINAL EXAM QUESTIONS LATEST EDITION 2026 – 2027
VERSION SOLVED QUESTIONS & ANSWERS
PHGY 216 FINAL EXAM – PRACTICE QUESTIONS
Principles of Mammalian Physiology II | Queen's University
Updated for 2025/2026 Academic Year
SECTION 1: BODY FLUID COMPARTMENTS & HOMEOSTASIS (Questions 1–25)
Question 1: What is the major cation in the intracellular fluid (ICF)?
A) Sodium
B) Chloride
C) Potassium
D) Bicarbonate
Correct Answer: C
Rationale: Potassium is the major cation in the ICF. Sodium is the major cation in the
extracellular fluid (ECF). This uneven distribution is maintained by the Na⁺-K⁺ ATPase
pump, which actively transports potassium into cells and sodium out of cells.
Question 2: Approximately what percentage of total body water is contained in the
intracellular fluid compartment?
A) 1/3
B) 1/2
C) 2/3
D) 3/4
Correct Answer: C
Rationale: The ICF contains approximately 2/3 of total body water, while the ECF
contains the remaining 1/3. The ECF is further subdivided into plasma (1/5 of ECF) and
interstitial fluid (4/5 of ECF).
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Question 3: Which of the following is TRUE regarding the composition of plasma and
interstitial fluid?
A) Plasma has lower protein concentration than interstitial fluid
B) They are identical except that plasma contains more protein
C) Interstitial fluid contains more sodium than plasma
D) They are completely identical in composition
Correct Answer: B
Rationale: At the capillary level, water and small solutes freely exchange, but plasma
proteins are too large to pass through the capillary wall. Therefore, plasma and
interstitial fluid are chemically identical EXCEPT that plasma contains significantly
more protein.
Question 4: A patient presents with severe vomiting over 24 hours. Which fluid
compartment would show the most immediate change in volume?
A) Intracellular fluid
B) Extracellular fluid
C) Transcellular fluid
D) Cerebrospinal fluid
Correct Answer: B
Rationale: Fluid losses from vomiting originate from the ECF (plasma and interstitial
fluid). The ICF is not directly affected initially because the cell membrane is not directly
permeable to water. After ECF volume decreases, osmotic gradients may cause shifts
from ICF to ECF.
Question 5: Which of the following is an example of a transcellular fluid?
A) Blood plasma
B) Interstitial fluid
C) Cerebrospinal fluid
D) Lymph
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Correct Answer: C
Rationale: Transcellular fluids are specialized fluids contained within epithelial-lined
spaces. Examples include cerebrospinal fluid, synovial fluid, pleural fluid, peritoneal
fluid, and the aqueous humor of the eye.
Question 6: A patient is diagnosed with SIADH (Syndrome of Inappropriate Antidiuretic
Hormone), leading to excessive water retention without proportional sodium retention.
Which of the following will result?
A) ECF becomes hypotonic (dilute)
B) ECF becomes hypertonic (concentrated)
C) Red blood cells shrink
D) No change in ECF osmolarity
Correct Answer: A
Rationale: In SIADH, excessive ADH/vasopressin causes water retention without
corresponding sodium retention. Since water is retained but sodium is not, the ECF
becomes dilute (hypotonic). Water then moves into cells down the osmotic gradient,
causing cellular swelling.
Question 7: What is the primary regulator of ECF osmolarity?
A) Sodium balance only
B) Water balance
C) Potassium balance
D) Calcium balance
Correct Answer: B
Rationale: ECF osmolarity is primarily regulated by water balance, not salt balance. The
hypothalamus contains osmoreceptors that detect changes in ECF osmolarity and
trigger appropriate responses (thirst and ADH secretion).
Question 8: How does hypertonicity of the extracellular fluid affect cells?
A) Water moves into cells, causing them to swell
B) Water moves out of cells, causing them to shrink
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C) There is no effect on cells
D) Cells actively pump water in
Correct Answer: B
Rationale: Hypertonicity of the ECF causes water to move out of the cells (ICF) into the
ECF until osmotic pressure is equalized. This causes the cells to shrink and can be
caused by insufficient water intake.
Question 9: What is the role of hypothalamic osmoreceptors in the regulation of water
balance?
A) They detect changes in blood glucose
B) They monitor ECF osmolarity and trigger ADH secretion and thirst
C) They regulate sodium reabsorption in the kidney
D) They control blood pressure directly
Correct Answer: B
Rationale: Hypothalamic osmoreceptors monitor the osmolarity of the fluid
surrounding them and counteract fluctuations in water balance. If osmolarity increases,
vasopressin secretion and thirst are stimulated, which increases water absorption and
water intake.
Question 10: Which of the following is TRUE regarding the distribution of body water?
A) Total body water is approximately 60% of body weight in adult males
B) Total body water is approximately 80% of body weight in adult males
C) Total body water is approximately 40% of body weight in adult males
D) Total body water is approximately 90% of body weight in adult males
Correct Answer: A
Rationale: Total body water is approximately 60% of body weight in adult males
(approximately 50% in females due to higher body fat). The ICF contains about 2/3 of
this water, and the ECF contains about 1/3.
Question 11: The primary mechanism by which water moves between fluid
compartments is:
PHGY 216 FINAL EXAM QUESTIONS LATEST EDITION 2026 – 2027
VERSION SOLVED QUESTIONS & ANSWERS
PHGY 216 FINAL EXAM – PRACTICE QUESTIONS
Principles of Mammalian Physiology II | Queen's University
Updated for 2025/2026 Academic Year
SECTION 1: BODY FLUID COMPARTMENTS & HOMEOSTASIS (Questions 1–25)
Question 1: What is the major cation in the intracellular fluid (ICF)?
A) Sodium
B) Chloride
C) Potassium
D) Bicarbonate
Correct Answer: C
Rationale: Potassium is the major cation in the ICF. Sodium is the major cation in the
extracellular fluid (ECF). This uneven distribution is maintained by the Na⁺-K⁺ ATPase
pump, which actively transports potassium into cells and sodium out of cells.
Question 2: Approximately what percentage of total body water is contained in the
intracellular fluid compartment?
A) 1/3
B) 1/2
C) 2/3
D) 3/4
Correct Answer: C
Rationale: The ICF contains approximately 2/3 of total body water, while the ECF
contains the remaining 1/3. The ECF is further subdivided into plasma (1/5 of ECF) and
interstitial fluid (4/5 of ECF).
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Question 3: Which of the following is TRUE regarding the composition of plasma and
interstitial fluid?
A) Plasma has lower protein concentration than interstitial fluid
B) They are identical except that plasma contains more protein
C) Interstitial fluid contains more sodium than plasma
D) They are completely identical in composition
Correct Answer: B
Rationale: At the capillary level, water and small solutes freely exchange, but plasma
proteins are too large to pass through the capillary wall. Therefore, plasma and
interstitial fluid are chemically identical EXCEPT that plasma contains significantly
more protein.
Question 4: A patient presents with severe vomiting over 24 hours. Which fluid
compartment would show the most immediate change in volume?
A) Intracellular fluid
B) Extracellular fluid
C) Transcellular fluid
D) Cerebrospinal fluid
Correct Answer: B
Rationale: Fluid losses from vomiting originate from the ECF (plasma and interstitial
fluid). The ICF is not directly affected initially because the cell membrane is not directly
permeable to water. After ECF volume decreases, osmotic gradients may cause shifts
from ICF to ECF.
Question 5: Which of the following is an example of a transcellular fluid?
A) Blood plasma
B) Interstitial fluid
C) Cerebrospinal fluid
D) Lymph
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Correct Answer: C
Rationale: Transcellular fluids are specialized fluids contained within epithelial-lined
spaces. Examples include cerebrospinal fluid, synovial fluid, pleural fluid, peritoneal
fluid, and the aqueous humor of the eye.
Question 6: A patient is diagnosed with SIADH (Syndrome of Inappropriate Antidiuretic
Hormone), leading to excessive water retention without proportional sodium retention.
Which of the following will result?
A) ECF becomes hypotonic (dilute)
B) ECF becomes hypertonic (concentrated)
C) Red blood cells shrink
D) No change in ECF osmolarity
Correct Answer: A
Rationale: In SIADH, excessive ADH/vasopressin causes water retention without
corresponding sodium retention. Since water is retained but sodium is not, the ECF
becomes dilute (hypotonic). Water then moves into cells down the osmotic gradient,
causing cellular swelling.
Question 7: What is the primary regulator of ECF osmolarity?
A) Sodium balance only
B) Water balance
C) Potassium balance
D) Calcium balance
Correct Answer: B
Rationale: ECF osmolarity is primarily regulated by water balance, not salt balance. The
hypothalamus contains osmoreceptors that detect changes in ECF osmolarity and
trigger appropriate responses (thirst and ADH secretion).
Question 8: How does hypertonicity of the extracellular fluid affect cells?
A) Water moves into cells, causing them to swell
B) Water moves out of cells, causing them to shrink
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C) There is no effect on cells
D) Cells actively pump water in
Correct Answer: B
Rationale: Hypertonicity of the ECF causes water to move out of the cells (ICF) into the
ECF until osmotic pressure is equalized. This causes the cells to shrink and can be
caused by insufficient water intake.
Question 9: What is the role of hypothalamic osmoreceptors in the regulation of water
balance?
A) They detect changes in blood glucose
B) They monitor ECF osmolarity and trigger ADH secretion and thirst
C) They regulate sodium reabsorption in the kidney
D) They control blood pressure directly
Correct Answer: B
Rationale: Hypothalamic osmoreceptors monitor the osmolarity of the fluid
surrounding them and counteract fluctuations in water balance. If osmolarity increases,
vasopressin secretion and thirst are stimulated, which increases water absorption and
water intake.
Question 10: Which of the following is TRUE regarding the distribution of body water?
A) Total body water is approximately 60% of body weight in adult males
B) Total body water is approximately 80% of body weight in adult males
C) Total body water is approximately 40% of body weight in adult males
D) Total body water is approximately 90% of body weight in adult males
Correct Answer: A
Rationale: Total body water is approximately 60% of body weight in adult males
(approximately 50% in females due to higher body fat). The ICF contains about 2/3 of
this water, and the ECF contains about 1/3.
Question 11: The primary mechanism by which water moves between fluid
compartments is:
