LAB MED EXAM 3 | QUESTIONS, ANSWERS
AND DETAILED RATIONALES | COMPLETE
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Updated 2026 Questions and Answers
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,What happens to the oxygen-hemoglobin dissociation curve B) Hemoglobin's oxygen affinity increases.
when conditions cause a left shift?
Explanation: A left shift in the curve indicates an increase in hemoglobin's oxygen affinity,
A) Hemoglobin's oxygen affinity decreases. meaning it holds onto oxygen more tightly and delivers less oxygen to tissues at a given
B) Hemoglobin's oxygen affinity increases. oxygen pressure.
C) Hemoglobin delivers more oxygen to tissues.
D) The oxygen pressure required for saturation increases.
Which of the following correctly describes the oxygen- C) Hemoglobin is approximately 75% saturated.
hemoglobin dissociation curve in venous blood?
Explanation: In venous blood, where the oxygen pressure is lower than in arterial blood,
A) Hemoglobin is 100% saturated. hemoglobin is typically around 75% saturated, reflecting partial oxygen unloading to
B) Hemoglobin is 50% saturated. tissues.
C) Hemoglobin is approximately 75% saturated.
D) Hemoglobin is completely unsaturated.
What effect does a right shift in the oxygen-hemoglobin D) Oxygen affinity decreases, enhancing oxygen delivery.
dissociation curve have on oxygen delivery to tissues?
Explanation: A right shift reduces hemoglobin's oxygen affinity, meaning hemoglobin
A) Oxygen affinity increases, reducing oxygen delivery. releases oxygen more readily, which allows for increased oxygen delivery to tissues.
B) Hemoglobin becomes fully saturated.
C) There is no effect on oxygen delivery.
D) Oxygen affinity decreases, enhancing oxygen delivery.
What is the pH a measure of? C) The negative log of H+ concentration
A) The concentration of bicarbonate ions Explanation: pH is a measure of hydrogen ion concentration, expressed as the negative
B) The negative log of CO2 concentration logarithm of [H+]. This scale helps determine the acidity or alkalinity of a solution.
C) The negative log of H+ concentration
D) The concentration of carbonic acid
Which organ primarily regulates the concentration of CO2 in A) Lungs
the blood?
Explanation: The lungs control CO2 concentration in the blood through respiration. By
A) Lungs adjusting the rate and depth of breathing, the body can increase or decrease CO2 levels,
B) Kidneys which influences blood pH.
C) Liver
D) Pancreas
,Where is the bicarbonate ion [HCO3−] primarily metabolized? C) Kidneys
A) Liver Explanation: The kidneys play a key role in metabolizing and regulating bicarbonate ion
B) Lungs concentration in the blood, which is essential for maintaining acid-base balance.
C) Kidneys
D) Intestines
What compound does CO2 form when it dissolves in blood B) Carbonic acid (H2CO3)
plasma?
Explanation: CO2 dissolves in blood plasma to form carbonic acid, which is a primary
A) Bicarbonate ion (HCO3−) acid component in the blood and plays a significant role in maintaining acid-base
B) Carbonic acid (H2CO3) balance.
C) Hydrochloric acid (HCl)
D) Oxygen (O2)
Why is it difficult to directly measure the concentration of B) It dissociates quickly, so it is expressed as the CO2 to [HCO3−] ratio.
carbonic acid (H2CO3) in the blood?
Explanation: Carbonic acid is unstable and quickly dissociates in the blood, making direct
A) It is rapidly metabolized in the liver. measurement challenging. For practical purposes, its concentration is indirectly
B) It dissociates quickly, so it is expressed as the CO2 to represented by the ratio of CO2 to bicarbonate (HCO3−), which helps determine acid-
[HCO3−] ratio. base status.
C) The concentration remains constant.
D) It is only present in trace amounts.
What is the main purpose of the body's buffering systems? C) To minimize changes in pH
A) To increase acid accumulation Explanation: Buffering systems help stabilize pH by neutralizing excess acids or bases,
B) To completely remove all acids thereby maintaining a stable acid-base balance in the body.
C) To minimize changes in pH
D) To increase oxygen transport
Which of the following is the most important buffering system B) Sodium bicarbonate-carbonic acid buffer
in the body?
Explanation: The sodium bicarbonate-carbonic acid system is the primary buffer in the
A) Protein-phosphate buffer blood, playing a critical role in neutralizing excess acids and maintaining pH balance.
B) Sodium bicarbonate-carbonic acid buffer
C) Hemoglobin buffer
D) Calcium carbonate buffer
, In the sodium bicarbonate-carbonic acid buffer system, what A) Carbonic acid
is the weak acid?
Explanation: Carbonic acid (H2CO3) is the weak acid in this buffer system, which can
A) Carbonic acid dissociate to release hydrogen ions, helping to buffer pH changes.
B) Bicarbonate ion
C) Sodium bicarbonate
D) Phosphoric acid
Which component acts as the salt of the weak acid in the B) Sodium bicarbonate (NaHCO3)
sodium bicarbonate-carbonic acid buffer system?
Explanation: Sodium bicarbonate (NaHCO3) serves as the base in this buffer system,
A) Carbonic acid neutralizing excess hydrogen ions to help maintain acid-base balance.
B) Sodium bicarbonate (NaHCO3)
C) Potassium chloride
D) Hemoglobin
What is the normal pH range for arterial blood gases? A) 7.36 - 7.44
A) 7.36 - 7.44 Explanation: The normal pH range for arterial blood gases is 7.36 to 7.44, with 7.40 often
B) 7.20 - 7.30 used as the reference midpoint. This range indicates a balanced acid-base status in the
C) 7.00 - 7.50 blood.
D) 7.50 - 7.60
What is the reference PaCO₂ value for arterial blood gases? C) 40 mmHg
A) 30 mmHg Explanation: The normal range for PaCO₂ is 36 to 44 mmHg, with 40 mmHg used as the
B) 45 mmHg reference point. PaCO₂ reflects the respiratory component of acid-base balance, as it's
C) 40 mmHg regulated by the lungs.
D) 50 mmHg
According to Golden Rule #1, a change in PaCO₂ of 10 mmHg B) 0.08 units
will result in a pH change of:
Explanation: Golden Rule #1 states that a 10 mmHg increase or decrease in PaCO₂ causes
A) 0.05 units a pH shift of approximately 0.08 units. This rule helps predict how changes in CO₂ levels
B) 0.08 units impact blood pH.
C) 0.10 units
D) 0.15 units
AND DETAILED RATIONALES | COMPLETE
STUDY GUIDE
| GRADED A+ | GUARANTEED SUCCESS
Updated 2026 Questions and Answers
100% Verified Exam Prep
,What happens to the oxygen-hemoglobin dissociation curve B) Hemoglobin's oxygen affinity increases.
when conditions cause a left shift?
Explanation: A left shift in the curve indicates an increase in hemoglobin's oxygen affinity,
A) Hemoglobin's oxygen affinity decreases. meaning it holds onto oxygen more tightly and delivers less oxygen to tissues at a given
B) Hemoglobin's oxygen affinity increases. oxygen pressure.
C) Hemoglobin delivers more oxygen to tissues.
D) The oxygen pressure required for saturation increases.
Which of the following correctly describes the oxygen- C) Hemoglobin is approximately 75% saturated.
hemoglobin dissociation curve in venous blood?
Explanation: In venous blood, where the oxygen pressure is lower than in arterial blood,
A) Hemoglobin is 100% saturated. hemoglobin is typically around 75% saturated, reflecting partial oxygen unloading to
B) Hemoglobin is 50% saturated. tissues.
C) Hemoglobin is approximately 75% saturated.
D) Hemoglobin is completely unsaturated.
What effect does a right shift in the oxygen-hemoglobin D) Oxygen affinity decreases, enhancing oxygen delivery.
dissociation curve have on oxygen delivery to tissues?
Explanation: A right shift reduces hemoglobin's oxygen affinity, meaning hemoglobin
A) Oxygen affinity increases, reducing oxygen delivery. releases oxygen more readily, which allows for increased oxygen delivery to tissues.
B) Hemoglobin becomes fully saturated.
C) There is no effect on oxygen delivery.
D) Oxygen affinity decreases, enhancing oxygen delivery.
What is the pH a measure of? C) The negative log of H+ concentration
A) The concentration of bicarbonate ions Explanation: pH is a measure of hydrogen ion concentration, expressed as the negative
B) The negative log of CO2 concentration logarithm of [H+]. This scale helps determine the acidity or alkalinity of a solution.
C) The negative log of H+ concentration
D) The concentration of carbonic acid
Which organ primarily regulates the concentration of CO2 in A) Lungs
the blood?
Explanation: The lungs control CO2 concentration in the blood through respiration. By
A) Lungs adjusting the rate and depth of breathing, the body can increase or decrease CO2 levels,
B) Kidneys which influences blood pH.
C) Liver
D) Pancreas
,Where is the bicarbonate ion [HCO3−] primarily metabolized? C) Kidneys
A) Liver Explanation: The kidneys play a key role in metabolizing and regulating bicarbonate ion
B) Lungs concentration in the blood, which is essential for maintaining acid-base balance.
C) Kidneys
D) Intestines
What compound does CO2 form when it dissolves in blood B) Carbonic acid (H2CO3)
plasma?
Explanation: CO2 dissolves in blood plasma to form carbonic acid, which is a primary
A) Bicarbonate ion (HCO3−) acid component in the blood and plays a significant role in maintaining acid-base
B) Carbonic acid (H2CO3) balance.
C) Hydrochloric acid (HCl)
D) Oxygen (O2)
Why is it difficult to directly measure the concentration of B) It dissociates quickly, so it is expressed as the CO2 to [HCO3−] ratio.
carbonic acid (H2CO3) in the blood?
Explanation: Carbonic acid is unstable and quickly dissociates in the blood, making direct
A) It is rapidly metabolized in the liver. measurement challenging. For practical purposes, its concentration is indirectly
B) It dissociates quickly, so it is expressed as the CO2 to represented by the ratio of CO2 to bicarbonate (HCO3−), which helps determine acid-
[HCO3−] ratio. base status.
C) The concentration remains constant.
D) It is only present in trace amounts.
What is the main purpose of the body's buffering systems? C) To minimize changes in pH
A) To increase acid accumulation Explanation: Buffering systems help stabilize pH by neutralizing excess acids or bases,
B) To completely remove all acids thereby maintaining a stable acid-base balance in the body.
C) To minimize changes in pH
D) To increase oxygen transport
Which of the following is the most important buffering system B) Sodium bicarbonate-carbonic acid buffer
in the body?
Explanation: The sodium bicarbonate-carbonic acid system is the primary buffer in the
A) Protein-phosphate buffer blood, playing a critical role in neutralizing excess acids and maintaining pH balance.
B) Sodium bicarbonate-carbonic acid buffer
C) Hemoglobin buffer
D) Calcium carbonate buffer
, In the sodium bicarbonate-carbonic acid buffer system, what A) Carbonic acid
is the weak acid?
Explanation: Carbonic acid (H2CO3) is the weak acid in this buffer system, which can
A) Carbonic acid dissociate to release hydrogen ions, helping to buffer pH changes.
B) Bicarbonate ion
C) Sodium bicarbonate
D) Phosphoric acid
Which component acts as the salt of the weak acid in the B) Sodium bicarbonate (NaHCO3)
sodium bicarbonate-carbonic acid buffer system?
Explanation: Sodium bicarbonate (NaHCO3) serves as the base in this buffer system,
A) Carbonic acid neutralizing excess hydrogen ions to help maintain acid-base balance.
B) Sodium bicarbonate (NaHCO3)
C) Potassium chloride
D) Hemoglobin
What is the normal pH range for arterial blood gases? A) 7.36 - 7.44
A) 7.36 - 7.44 Explanation: The normal pH range for arterial blood gases is 7.36 to 7.44, with 7.40 often
B) 7.20 - 7.30 used as the reference midpoint. This range indicates a balanced acid-base status in the
C) 7.00 - 7.50 blood.
D) 7.50 - 7.60
What is the reference PaCO₂ value for arterial blood gases? C) 40 mmHg
A) 30 mmHg Explanation: The normal range for PaCO₂ is 36 to 44 mmHg, with 40 mmHg used as the
B) 45 mmHg reference point. PaCO₂ reflects the respiratory component of acid-base balance, as it's
C) 40 mmHg regulated by the lungs.
D) 50 mmHg
According to Golden Rule #1, a change in PaCO₂ of 10 mmHg B) 0.08 units
will result in a pH change of:
Explanation: Golden Rule #1 states that a 10 mmHg increase or decrease in PaCO₂ causes
A) 0.05 units a pH shift of approximately 0.08 units. This rule helps predict how changes in CO₂ levels
B) 0.08 units impact blood pH.
C) 0.10 units
D) 0.15 units
