Gas Exchange: Diffusion, Partial Pressures, and Oxygen-Hemoglobin Dissociation Curve

Question 1

Which of the following factors primarily influences the rate of gas exchange across the respiratory membrane?

Accepted Answer

Partial pressure gradient

Answer

Surface area of the membrane

Answer

Diffusion coefficient

Answer

Membrane thickness

Question 2

What is the main mechanism by which oxygen is transported in the bloodstream?

Accepted Answer

Bound to hemoglobin

Answer

Dissolved in plasma

Answer

Bound to albumin

Answer

Bound to bicarbonate

Question 3

What is the primary function of surfactant in the lungs?

Accepted Answer

Reduce surface tension at the air-liquid interface

Answer

Increase lung compliance and prevent alveolar collapse

Answer

Enhance gas exchange directly

Answer

Protect the airways from infection

Question 4

Which mechanism is primarily responsible for adjusting ventilation to meet metabolic demands?

Accepted Answer

Chemoreceptor reflex

Answer

Hypothalamic respiratory center

Answer

Baroreceptor reflex

Answer

Voluntary control

Question 5

Define the Bohr effect.

Accepted Answer

The decrease in oxygen-hemoglobin affinity with increasing pH

Answer

The increase in oxygen-hemoglobin affinity with increasing temperature

Answer

The displacement of oxygen from hemoglobin by carbon dioxide

Answer

The increase in carbon dioxide-hemoglobin affinity with increasing partial pressure of oxygen

Question 6

Which of the following is NOT a primary function of the respiratory system?

Accepted Answer

Maintenance of fluid balance

Answer

Gas exchange

Answer

Regulation of pH

Answer

Speech production

Question 7

The oxygen-hemoglobin dissociation curve is:

Accepted Answer

Sigmoidal

Answer

Linear

Answer

Parabolic

Answer

Hyperbolic

Question 8

Gas exchange in the lungs primarily occurs through:

Accepted Answer

Diffusion

Answer

Osmosis

Answer

Active transport

Answer

Facilitated diffusion

Question 9

Hemoglobin's primary role in gas exchange is to:

Accepted Answer

Transport oxygen from the lungs to the tissues

Answer

Transport carbon dioxide from the tissues to the lungs

Answer

Regulate the partial pressure of gases in the blood

Answer

Facilitate the diffusion of gases across cell membranes

Question 10

The normal pH range of arterial blood is:

Accepted Answer

7.35-7.45

Answer

7.20-7.30

Answer

7.10-7.20

Answer

7.00-7.10

Question 11

The primary means of carbon dioxide transport in the bloodstream is:

Accepted Answer

Bound to bicarbonate ions

Answer

Dissolved in plasma

Answer

Bound to hemoglobin

Answer

Bound to chloride ions

Question 12

Which of the following describes the alveolar ventilation rate?

Accepted Answer

The volume of air exchanged per minute

Answer

The rate of gas diffusion across the respiratory membrane

Answer

The difference between inspiratory and expiratory volumes

Answer

The partial pressure of oxygen in the alveoli

Question 13

The primary cause of chronic obstructive pulmonary disease (COPD) is:

Accepted Answer

Repeated exposure to inhaled toxins

Answer

Altered immune response

Answer

Genetic predisposition

Answer

Viral infection

Question 14

Gas exchange occurs through the process of:

Accepted Answer

Diffusion: movement of gases from high to low concentration

Answer

Osmosis: movement of solvent across a semi-permeable membrane

Answer

Active transport: movement of molecules against a concentration gradient requiring energy

Answer

Facilitated diffusion: movement of molecules assisted by carrier proteins

Question 15

Commonly measured respiratory parameters in clinical settings do NOT include:

Accepted Answer

Cardiac output: volume of blood pumped by the heart per minute

Answer

Tidal volume: volume of air inhaled or exhaled with each breath

Answer

Respiratory rate: number of breaths per minute

Answer

Arterial oxygen saturation (SaO2): percentage of oxygen-saturated hemoglobin in arterial blood

Question 16

A major risk factor for developing chronic obstructive pulmonary disease (COPD) is:

Accepted Answer

Smoking

Answer

Air pollution

Answer

Obesity

Answer

Alcohol consumption

Question 17

Surfactant in the lungs primarily functions to:

Accepted Answer

Lower surface tension at the air-liquid interface

Answer

Enhance diffusion of gases

Answer

Lubricate the airways

Answer

Filter inhaled particles

Question 18

The hormone that stimulates erythropoietin production by the kidneys is:

Accepted Answer

Hypoxia

Answer

Erythropoietin

Answer

Hypercapnia

Answer

Acidosis

Question 19

Which of the following is NOT a characteristic of the respiratory system?

Accepted Answer

Regulates body temperature

Answer

Provides a large surface area for gas exchange

Answer

Assists in maintaining acid-base balance

Answer

Filters inhaled particles

Question 20

How does an increase in the partial pressure of oxygen in the alveoli influence the rate of oxygen uptake?

Accepted Answer

Increases the rate of oxygen uptake

Answer

Decreases the rate of oxygen uptake

Answer

Does not affect the rate of oxygen uptake

Question 21

Which of the following is an essential characteristic of a valid multiple choice question stem?

Accepted Answer

Clear, concise, and includes only essential information.

Answer

Provides answer options that are equally plausible.

Answer

Includes images to enhance visual appeal.

Question 22

What is the primary function of a distractor in a multiple choice question?

Accepted Answer

To provide a plausible but incorrect answer choice to test students' understanding.

Answer

To make the question more challenging with irrelevant information.

Question 23

What is the physiological significance of the Bohr effect?

Accepted Answer

Facilitates oxygen unloading in tissues

Answer

Increases hemoglobin affinity for oxygen

Answer

Decreases hemoglobin affinity for oxygen

Answer

Facilitates carbon dioxide loading in tissues

Question 24

What is the primary purpose of the respiratory system?

Accepted Answer

To facilitate the exchange of gases between the blood and the environment

Answer

To synthesize hormones

Answer

To regulate body temperature

Question 25

Which of the following blood gas values represents a case of respiratory acidosis?

Accepted Answer

PaCO2 = 70 mmHg, HCO3- = 35 mEq/L

Answer

PaCO2 = 40 mmHg, HCO3- = 20 mEq/L

Answer

PaCO2 = 50 mmHg, HCO3- = 30 mEq/L

Answer

PaCO2 = 35 mmHg, HCO3- = 25 mEq/L

Question 26

Which of the following is a hallmark of obstructive lung disease?

Accepted Answer

Increased airway resistance

Answer

Increased lung volumes

Answer

Normal blood pH

Answer

Decreased lung compliance

Question 27

What is the most common underlying cause of acute respiratory distress syndrome (ARDS)?

Accepted Answer

Sepsis

Answer

Pneumonia

Answer

Asthma

Answer

Congestive heart failure

Question 28

Which factor does NOT influence the rate of gas diffusion across the respiratory membrane?

Accepted Answer

Temperature of the environment

Answer

Surface area of the membrane

Answer

Thickness of the membrane

Answer

Concentration gradient of the gases

Question 29

Which of the following factors does NOT influence the rate of diffusion of gases across the respiratory membrane?

Accepted Answer

pH

Answer

Thickness

Answer

Concentration gradient

Answer

Surface area

Question 30

The partial pressure of a gas refers to:

Accepted Answer

The pressure exerted by that gas when occupying a specific volume in a mixture of gases

Answer

The total pressure exerted by multiple gases

Answer

The pressure difference between two gases

Question 31

Which of the following lung structures is responsible for producing surfactant?

Accepted Answer

Type II pneumocytes

Answer

Alveolar macrophages

Answer

Bronchial epithelial cells

Answer

Type I pneumocytes

Question 32

The main site of gas exchange in the lungs is the:

Accepted Answer

Alveoli

Answer

Trachea

Answer

Bronchi

Question 33

Which brainstem structure serves as a primary respiratory control center, regulating breathing rhythm?

Accepted Answer

Medulla oblongata

Answer

Cerebellum

Answer

Pons

Answer

Hypothalamus

Question 34

Which hormone, produced primarily by the kidneys, stimulates red blood cell production (erythropoiesis)?

Accepted Answer

Erythropoietin

Answer

Insulin

Answer

Testosterone

Answer

Growth hormone

Question 35

Characterized by inflammation and scarring of the alveoli, which respiratory disease can lead to impaired gas exchange?

Accepted Answer

Interstitial lung disease

Answer

Asthma

Answer

Emphysema

Answer

Chronic bronchitis

Question 36

A decreased partial pressure of oxygen in arterial blood (PaO2) can be caused by several factors. Which of the following is MOST likely to directly contribute to a lower PaO2?

Accepted Answer

Reduced alveolar ventilation

Answer

Decreased metabolic rate

Answer

Increased oxygen diffusion capacity

Answer

Elevated hemoglobin concentration

Question 37

What is the primary driving force behind gas exchange in the lungs, enabling oxygen uptake and carbon dioxide removal?

Accepted Answer

Partial pressure gradients of gases between alveoli and capillaries

Answer

Active transport mechanisms

Answer

Osmotic pressure differences

Question 38

Emphysema is characterized by alveolar destruction, leading to impaired gas exchange. What is the primary reason for this difficulty?

Accepted Answer

Decreased surface area for gas exchange due to alveolar destruction

Answer

Enhanced diffusion capacity

Answer

Increased blood flow to the lungs

Question 39

Anemia often results in reduced oxygen-carrying capacity. What is the PRIMARY reason for this decrease?

Accepted Answer

Reduced number of red blood cells or hemoglobin content

Answer

Decreased oxygen diffusion across the alveolar membrane

Answer

Increased oxygen consumption by tissues

Question 40

How does the level of carbon dioxide (CO2) in the blood affect pH?

Accepted Answer

Increased carbon dioxide levels lead to a decrease in pH (acidity)

Answer

Carbon dioxide and pH are not directly related

Answer

Increased carbon dioxide levels lead to an increase in pH (alkalinity)

Question 41

During exercise, the oxygen-hemoglobin dissociation curve shifts to the right. What is the primary physiological consequence of this shift?

Accepted Answer

Enhanced oxygen delivery to working muscles

Answer

Increased oxygen affinity to hemoglobin

Answer

Decreased oxygen delivery to working muscles

Question 42

Which of the following factors has the LEAST direct influence on the rate of gas diffusion across the alveolar-capillary membrane?

Accepted Answer

Blood pressure in the pulmonary artery

Answer

Partial pressure gradient of the gas

Answer

Surface area of the membrane

Question 43

A patient presenting with pulmonary edema would likely experience impaired gas exchange. What is the underlying mechanism for this impairment?

Accepted Answer

Increased diffusion distance due to fluid accumulation in the alveoli

Answer

Enhanced gas exchange due to increased blood flow

Answer

No significant effect on gas exchange

Question 44

Ventilation-perfusion matching refers to the optimal relationship between which two physiological processes?

Accepted Answer

Air flow (ventilation) and blood flow (perfusion) in the lungs

Answer

Total volume of air inhaled and exhaled in one minute

Answer

Ratio of oxygen uptake to carbon dioxide production

Question 45

A mountain climber experiences a decrease in atmospheric pressure as they ascend. How does this change affect the partial pressure of oxygen in the alveoli?

Accepted Answer

The partial pressure of oxygen in the alveoli decreases.

Answer

The partial pressure of oxygen in the alveoli increases.

Answer

The partial pressure of oxygen in the alveoli remains unchanged.

Question 46

A patient diagnosed with chronic obstructive pulmonary disease (COPD) has difficulty exhaling. Which change in gas exchange is most likely to occur due to this condition?

Accepted Answer

Increased alveolar partial pressure of carbon dioxide (PaCO2)

Answer

Increased alveolar partial pressure of oxygen (PaO2)

Answer

Decreased alveolar partial pressure of carbon dioxide (PaCO2)

Question 47

The oxygen-hemoglobin dissociation curve shifts to the right under conditions of increased acidity (lower pH). What is the physiological significance of this shift?

Accepted Answer

Enhanced oxygen delivery to tissues with higher metabolic demand.

Answer

Reduced oxygen delivery to tissues with higher metabolic demand.

Answer

Increased oxygen affinity to hemoglobin.

Question 48

Which of the following factors directly influences the rate of diffusion of gases across the alveolar-capillary membrane?

Accepted Answer

Partial pressure gradient

Answer

Cardiac output

Answer

Oxygen-hemoglobin affinity

Answer

Blood flow rate

Question 49

A patient with severe asthma experiences bronchospasm, leading to airway narrowing. What is the most likely effect on ventilation-perfusion matching?

Accepted Answer

Ventilation-perfusion mismatch characterized by decreased ventilation relative to perfusion.

Answer

No significant change in ventilation-perfusion matching.

Answer

Improved ventilation-perfusion matching.

Question 50

Which of the following conditions is most likely to cause a leftward shift in the oxygen-hemoglobin dissociation curve?

Accepted Answer

Alkalosis (increased pH)

Answer

Increased body temperature

Answer

Acidosis (decreased pH)

Question 51

A patient with pulmonary fibrosis has thickened alveolar walls, impairing gas exchange. Which of the following mechanisms is primarily affected in this scenario?

Accepted Answer

Diffusion of gases across the alveolar-capillary membrane

Answer

Ventilation-perfusion matching

Answer

Oxygen-hemoglobin binding affinity

Question 52

A patient with chronic lung disease experiences hypoxemia (low blood oxygen). Which of the following physiological responses is most likely to occur as a compensatory mechanism?

Accepted Answer

Increased respiratory rate and depth

Answer

Increased carbon dioxide retention

Answer

Decreased cardiac output

Answer

Decreased respiratory rate