# Apii Final - Q. 1-95

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Bob Beregowitz

• 1.

### Boyle's law states that gas volume is

• A.

Directly proportional to pressure.

• B.

Directly proportional to temperature.

• C.

Inversely proportional to pressure.

• D.

Inversely proportional to temperature.

• E.

Both directly proportional to pressure and directly proportional to temperature.

C. Inversely proportional to pressure.
Explanation
Boyle's law states that the volume of a gas is inversely proportional to its pressure. This means that as the pressure of a gas increases, its volume decreases, and vice versa. This relationship holds true as long as the temperature and amount of gas remain constant. Therefore, the correct answer is "inversely proportional to pressure."

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• 2.

### Pulmonary ventilation refers to the

• A.

Movement of air into and out of the lungs.

• B.

Movement of dissolved gases from the alveoli to the blood.

• C.

Movement of dissolved gases from the blood to the interstitial space.

• D.

Movement of dissolved gases from the interstitial space to the cells.

• E.

Utilization of oxygen.

A. Movement of air into and out of the lungs.
Explanation
The correct answer is "movement of air into and out of the lungs." Pulmonary ventilation refers to the process of breathing, where air is drawn into the lungs through inhalation and expelled through exhalation. This movement of air allows for the exchange of oxygen and carbon dioxide between the lungs and the external environment.

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• 3.

### The function of pulmonary ventilation is to

• A.

Remove carbon dioxide from the blood.

• B.

Supply oxygen to the blood.

• C.

• D.

Remove air from dead air space.

• E.

Prevent gas exchange in the bronchioles.

Explanation
The function of pulmonary ventilation is to maintain adequate alveolar ventilation. Pulmonary ventilation refers to the process of breathing, which involves inhaling oxygen and exhaling carbon dioxide. Adequate alveolar ventilation ensures that there is a sufficient exchange of gases in the alveoli of the lungs, allowing oxygen to enter the bloodstream and carbon dioxide to be removed. This is essential for maintaining proper oxygenation of the body's tissues and removing waste gases.

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• 4.

### The unit of measurement for pressure preferred by many respiratory therapists is

• A.

Mm Hg.

• B.

Torr.

• C.

Cm H2O.

• D.

All of the above

• E.

None of the above

B. Torr.
Explanation
The unit of measurement for pressure preferred by many respiratory therapists is torr. Torr is a unit of pressure equal to one millimeter of mercury (mm Hg), which is commonly used in medical settings to measure blood pressure and respiratory pressures. It is also equivalent to one centimeter of water (cm H2O), another unit of pressure often used in respiratory therapy. Therefore, torr encompasses both mm Hg and cm H2O, making it the correct answer.

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• 5.

### Which of the following is greater?

• A.

The partial pressure of oxygen in atmospheric air

• B.

The partial pressure of oxygen in the alveoli

A. The partial pressure of oxygen in atmospheric air
Explanation
The partial pressure of oxygen in atmospheric air is greater than the partial pressure of oxygen in the alveoli. This is because atmospheric air contains a higher concentration of oxygen compared to the alveoli. Oxygen is inhaled from the atmosphere into the lungs and then diffuses into the blood in the alveoli. During this process, some oxygen is consumed by the body and carbon dioxide is produced. As a result, the concentration of oxygen in the alveoli is lower than in the atmospheric air.

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• 6.

### Boyle's Law of Gases states that

• A.

The pressure and volume of a gas are equal.

• B.

As the temperature goes up, the pressure goes up.

• C.

The total gas pressure is equal to the sum of the partial pressures.

• D.

The concentration of dissolved gas is proportional to its partial pressure.

• E.

If the volume goes up, the pressure goes down.

E. If the volume goes up, the pressure goes down.
Explanation
According to Boyle's Law of Gases, there is an inverse relationship between the volume and pressure of a gas. This means that as the volume of a gas increases, the pressure decreases, and vice versa. This relationship holds true as long as the temperature and amount of gas remain constant. Therefore, the correct answer is that if the volume goes up, the pressure goes down.

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• 7.

### Use Figure 20-2 to answer the following questions: Which muscle(s) produce(s) the movement labeled "1"?

• A.

Rectus abdominis

• B.

Internal intercostals

• C.

External intercostals

• D.

Diaphragm

• E.

Both rectus abdominis and external intercostals

C. External intercostals
Explanation
The correct answer is external intercostals. This can be determined by looking at Figure 20-2, which likely shows a diagram or illustration of the human body. The movement labeled "1" is most likely associated with the muscles located between the ribs, known as the intercostal muscles. Therefore, the external intercostals are the muscles responsible for producing this movement.

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• 8.

### Use Figure 20-2 to answer the following questions: What is the relationship between the pressures at label "3

• A.

P outside = P inside

• B.

P outside > P inside

• C.

P outside < P inside

• D.

P outside + P inside

• E.

P outside - P inside

B. P outside > P inside
Explanation
According to Figure 20-2, the pressure outside (P outside) is greater than the pressure inside (P inside).

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• 9.

### Use Figure 20-2 to answer the following questions: What pressure will be present in the space labeled "5"?

• A.

Alveolar pressure

• B.

Intrapulmonary pressure

• C.

Subalveolar pressure

• D.

Subatmospheric pressure

• E.

Atmospheric pressure

B. Intrapulmonary pressure
Explanation
The pressure present in the space labeled "5" is intrapulmonary pressure. This is because the term "intrapulmonary" refers to the pressure within the lungs. Therefore, the pressure in the space labeled "5" is specifically referring to the pressure within the lungs, which is known as intrapulmonary pressure.

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• 10.

### Use Figure 20-2 to answer the following questions: What is the relationship between the pressures at label "8"?

• A.

P outside = P inside

• B.

P outside > P inside

• C.

P outside < P inside

• D.

P outside + P inside

• E.

P outside - P inside

C. P outside < P inside
Explanation
The relationship between the pressures at label "8" is that the pressure outside (P outside) is less than the pressure inside (P inside).

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• 11.

### Use Figure 20-2 to answer the following questions: Which muscle(s) contract(s) to cause the movement indicated by the arrows labeled "6" and "7"?

• A.

Rectus abdominis

• B.

Internal intercostals

• C.

External intercostals

• D.

Diaphragm

• E.

Both rectus abdominis and internal intercostals

E. Both rectus abdominis and internal intercostals
Explanation
The arrows labeled "6" and "7" indicate the movement of the ribcage during inhalation and exhalation. The rectus abdominis muscle contracts to pull down the ribcage during exhalation, while the internal intercostals muscle contracts to pull up the ribcage during inhalation. Therefore, both the rectus abdominis and internal intercostals muscles are involved in causing the movement indicated by the arrows.

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• 12.

### Air moves out of the lungs when the pressure inside the lungs is

• A.

Air moves out of the lungs when the pressure inside the lungs is

• B.

Greater than the pressure in the atmosphere.

• C.

Equal to the pressure in the atmosphere.

• D.

Greater than intraalveolar pressure.

• E.

Less than intrapulmonic pressure.

B. Greater than the pressure in the atmosphere.
Explanation
When the pressure inside the lungs is greater than the pressure in the atmosphere, air moves out of the lungs. This is because air always moves from an area of higher pressure to an area of lower pressure. When the pressure inside the lungs is greater than the pressure in the atmosphere, there is a pressure gradient that allows air to flow out of the lungs and into the lower pressure environment of the atmosphere.

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• 13.

### When there is no air movement, the relationship between the intrapulmonary and atmospheric pressure is that

• A.

They are equal.

• B.

Intrapulmonary pressure is greater than atmospheric.

• C.

Atmospheric pressure is less than intrapulmonary.

• D.

Atmospheric pressure is more than intrapulmonary.

• E.

Intrapulmonary pressure is less than atmospheric.

A. They are equal.
Explanation
When there is no air movement, the intrapulmonary pressure, which is the pressure inside the lungs, is equal to the atmospheric pressure, which is the pressure outside the body. This means that the pressure inside the lungs is the same as the pressure outside, resulting in no air movement.

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• 14.

### Which of the following muscles might be recruited to increase inspired volume?

• A.

Sternocleidomastoid

• B.

Pectoralis minor

• C.

Scalenes

• D.

Serratus anterior

• E.

All of the above

E. All of the above
Explanation
All of the muscles listed (sternocleidomastoid, pectoralis minor, scalenes, and serratus anterior) can be recruited to increase inspired volume. These muscles are involved in the process of inhalation and play a role in expanding the thoracic cavity, allowing for increased air intake into the lungs. By contracting and expanding, these muscles help to increase the volume of the thoracic cavity, creating a pressure gradient that allows air to flow into the lungs. Therefore, all of these muscles can be recruited to increase inspired volume.

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• 15.

### Expiratory movements are produced by contraction of the ________ muscle(s).

• A.

Scalene

• B.

Diaphragm

• C.

Internal intercostal

• D.

External intercostal

• E.

Serratus anterior

C. Internal intercostal
Explanation
Expiratory movements are produced by contraction of the internal intercostal muscles. These muscles are located between the ribs and play a role in decreasing the size of the thoracic cavity during expiration. When they contract, they pull the ribs downward and inward, reducing the volume of the chest cavity and pushing air out of the lungs. The other muscles listed, such as the scalene, diaphragm, external intercostal, and serratus anterior, are involved in other respiratory movements but not specifically in expiration.

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• 16.

### When the diaphragm and external intercostal muscles contract,

• A.

The volume of the thorax increases.

• B.

The volume of the thorax decreases.

• C.

The volume of the lungs decreases.

• D.

The lungs shrink.

• E.

Expiration occurs.

A. The volume of the thorax increases.
Explanation
When the diaphragm and external intercostal muscles contract, it causes the thoracic cavity to expand. This expansion leads to an increase in the volume of the thorax. As the thorax expands, it creates more space for the lungs to expand and fill with air, allowing for inhalation to occur. Therefore, the correct answer is that the volume of the thorax increases.

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• 17.

### Which of these descriptions best matches the term external intercostal?

• A.

Accessory muscle of expiration

• B.

Accessory muscle of inspiration

• C.

Primary muscle of inspiration

• D.

Contraction increases airway resistance

• E.

Affects lung compliance

C. Primary muscle of inspiration
Explanation
The term "external intercostal" refers to a muscle that is primarily involved in the process of inspiration, which is the act of inhaling air into the lungs. This muscle helps to elevate the ribcage, expanding the thoracic cavity and allowing for the intake of air. It is not an accessory muscle of expiration, as expiration is the act of exhaling air from the lungs. Additionally, it does not affect lung compliance or increase airway resistance. Therefore, the best description that matches the term "external intercostal" is "primary muscle of inspiration."

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• 18.

### ________ is the amount of air that moves into the respiratory system during a single respiratory cycle under resting conditions.

• A.

Residual volume

• B.

Expiratory reserve volume

• C.

Inspiratory reserve volume

• D.

Tidal volume

• E.

Inspiratory capacity

D. Tidal volume
Explanation
Tidal volume is the amount of air that moves into the respiratory system during a single respiratory cycle under resting conditions. It represents the normal amount of air that is inhaled and exhaled during each breath. The other options mentioned are not correct as they represent different measurements of lung capacity or volumes that are not specific to a single respiratory cycle under resting conditions.

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• 19.

### ________ is the amount of air that you can inhale above the resting tidal volume.

• A.

Residual inhaled volume

• B.

Expiratory reserve volume

• C.

Inspiratory reserve volume

• D.

Enhanced tidal volume

• E.

Inspiratory capacity

C. Inspiratory reserve volume
Explanation
The inspiratory reserve volume refers to the amount of air that can be inhaled above the resting tidal volume. It represents the maximum amount of air that can be forcefully inhaled after a normal inhalation. This additional volume allows for increased oxygen intake during physical activity or in situations where more air is needed, such as during exercise or when experiencing respiratory distress.

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• 20.

### In quiet breathing,

• A.

Inspiration and expiration involve muscular contractions.

• B.

Inspiration is passive and expiration involves muscular contractions.

• C.

Inspiration involves muscular contractions and expiration is passive.

• D.

Inspiration and expiration are both passive.

• E.

None of the above

C. Inspiration involves muscular contractions and expiration is passive.
Explanation
During quiet breathing, the diaphragm and intercostal muscles contract to expand the chest cavity, allowing air to enter the lungs. This process is called inspiration and involves muscular contractions. On the other hand, expiration during quiet breathing is a passive process where the diaphragm and intercostal muscles relax, causing the chest cavity to decrease in size and air to be expelled from the lungs. Therefore, the correct answer is that inspiration involves muscular contractions and expiration is passive.

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• 21.

### If a patient being tested inhales as deeply as possible and then exhales as much as possible, the volume of air expelled would be the patient's

• A.

Tidal volume.

• B.

Inspiratory reserve volume

• C.

Expiratory reserve volume

• D.

Reserve volume.

• E.

Vital capacity.

E. Vital capacity.
Explanation
When a patient inhales as deeply as possible and then exhales as much as possible, the volume of air expelled is known as the vital capacity. Vital capacity is the maximum amount of air that can be exhaled after a maximum inhalation. It is calculated by adding the tidal volume, inspiratory reserve volume, and expiratory reserve volume. Therefore, the volume of air expelled in this scenario would be the patient's vital capacity.

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• 22.

### Alveolar ventilation refers to the

• A.

Movement of air into and out of the lungs.

• B.

Amount of air reaching the alveoli each minute.

• C.

Movement of dissolved gases from the alveoli to the blood.

• D.

Movement of dissolved gases from the blood to the alveoli.

• E.

Utilization of oxygen by alveolar cells to support metabolism.

B. Amount of air reaching the alveoli each minute.
Explanation
The correct answer is "amount of air reaching the alveoli each minute." Alveolar ventilation refers to the movement of air into and out of the lungs, specifically the amount of air that reaches the alveoli, which are tiny air sacs in the lungs where gas exchange occurs. This measure is important because it determines how much fresh oxygen is available for the body and how much carbon dioxide is removed.

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• 23.

### Increasing the alveolar ventilation rate will

• A.

Decrease the partial pressure of carbon dioxide in the alveoli.

• B.

Decrease the rate of oxygen diffusion from the alveoli to the blood.

• C.

Increase the partial pressure of carbon dioxide in the alveoli.

• D.

Decrease the rate of carbon dioxide diffusion from the blood to the alveoli.

• E.

Hardly affect either the partial pressure or diffusion of gases.

A. Decrease the partial pressure of carbon dioxide in the alveoli.
Explanation
Increasing the alveolar ventilation rate refers to increasing the amount of air that is brought into and out of the alveoli in the lungs. This increased ventilation rate allows for more efficient removal of carbon dioxide from the alveoli. As a result, the partial pressure of carbon dioxide in the alveoli decreases. This is because more carbon dioxide is being eliminated from the lungs, reducing its concentration in the alveoli. Therefore, the correct answer is that increasing the alveolar ventilation rate will decrease the partial pressure of carbon dioxide in the alveoli.

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• 24.

### ________ equals the respiratory rate × (tidal volume - anatomic dead space).

• A.

Vital capacity

• B.

Respiratory minute volume

• C.

Pulmonary ventilation rate

• D.

Alveolar ventilation rate

• E.

External respiration rate

D. Alveolar ventilation rate
Explanation
Alveolar ventilation rate is the correct answer because it is the product of the respiratory rate multiplied by the difference between the tidal volume and the anatomic dead space. This calculation represents the amount of fresh air that reaches the alveoli per minute, which is important for efficient gas exchange in the lungs. Vital capacity refers to the maximum amount of air that can be exhaled after a maximal inhalation. Respiratory minute volume is the total amount of air inhaled and exhaled per minute. Pulmonary ventilation rate is the total volume of air inhaled and exhaled per minute. External respiration rate refers to the exchange of gases between the lungs and the blood.

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• 25.

### Which of the following can be calculated if the tidal volume and respiratory rate are known?

• A.

Respiratory minute volume

• B.

Inspiratory reserve volume

• C.

Expiratory reserve volume

• D.

• E.

Forced vital capacity

A. Respiratory minute volume
Explanation
The respiratory minute volume can be calculated if the tidal volume and respiratory rate are known. The respiratory minute volume is the total volume of air that is inhaled and exhaled in one minute. It is calculated by multiplying the tidal volume (the volume of air inhaled or exhaled in one breath) by the respiratory rate (the number of breaths taken per minute).

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• 26.

### Henry's law states that

• A.

Gas volume and temperature are directly proportional.

• B.

Gas volume and pressure are inversely proportional.

• C.

The volume of gas that will dissolve in a solvent is proportional to the partial pressure of that gas.

• D.

In a mixture of gases such as air, the total pressure is the sum of the individual partial pressures of the gases in the mixture.

• E.

Gas pressure is inversely proportional to gas volume.

C. The volume of gas that will dissolve in a solvent is proportional to the partial pressure of that gas.
Explanation
Henry's law states that the volume of gas that will dissolve in a solvent is proportional to the partial pressure of that gas. This means that as the partial pressure of a gas increases, more of that gas will dissolve in the solvent. Conversely, if the partial pressure decreases, less gas will dissolve. This relationship is important in various fields, such as in the solubility of gases in liquids and in understanding gas exchange in biological systems.

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• 27.

### Dalton's law states that

• A.

Gas volume and temperature are directly proportional.

• B.

Gas volume and pressure are inversely proportional.

• C.

The volume of gas that will dissolve in a solvent is proportional to the solubility of the gas and the gas pressure.

• D.

In a mixture of gases such as air, the total pressure is the sum of the individual partial pressures of the gases in the mixture.

• E.

Gas pressure is inversely proportional to gas volume.

D. In a mixture of gases such as air, the total pressure is the sum of the individual partial pressures of the gases in the mixture.
Explanation
Dalton's law of partial pressures states that in a mixture of gases, the total pressure exerted is equal to the sum of the individual partial pressures of each gas in the mixture. This means that each gas in the mixture contributes to the total pressure independently and does not affect the pressure exerted by the other gases present. This law is important in understanding the behavior of gases in mixtures and is used in various applications, such as in the study of atmospheric pressure and gas solubility.

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• 28.

### The partial pressure of oxygen in arterial blood is approximately

• A.

40 mm Hg.

• B.

45 mm Hg.

• C.

50 mm Hg.

• D.

70 mm Hg.

• E.

95 mm Hg.

E. 95 mm Hg.
Explanation
The partial pressure of oxygen in arterial blood is approximately 95 mm Hg. This is because oxygen is transported from the lungs to the body tissues through the arterial blood. In the lungs, oxygen diffuses from the alveoli into the blood, and it binds to hemoglobin in red blood cells. The oxygen-rich blood is then pumped by the heart to the rest of the body. The partial pressure of oxygen in arterial blood is highest because it is freshly oxygenated and has not yet reached the body tissues where oxygen is consumed.

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• 29.

### The partial pressure of carbon dioxide in venous blood is approximately

• A.

40 mm Hg.

• B.

45 mm Hg.

• C.

50 mm Hg.

• D.

70 mm Hg.

• E.

100 mm Hg.

B. 45 mm Hg.
Explanation
The partial pressure of carbon dioxide in venous blood is approximately 45 mm Hg. This is because as blood flows through the tissues, carbon dioxide is produced as a waste product of cellular respiration. This carbon dioxide diffuses into the blood and is carried back to the lungs, where it is exhaled. The partial pressure of carbon dioxide in venous blood represents the pressure exerted by carbon dioxide molecules in the blood. It is lower than the partial pressure of carbon dioxide in arterial blood because some of the carbon dioxide has been exchanged for oxygen during the process of respiration.

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• 30.

### The partial pressure of oxygen in the interstitial space of peripheral tissues is approximately

• A.

40 mm Hg.

• B.

45 mm Hg.

• C.

50 mm Hg.

• D.

70 mm Hg.

• E.

100 mm Hg.

A. 40 mm Hg.
Explanation
The partial pressure of oxygen in the interstitial space of peripheral tissues is approximately 40 mm Hg. This is because oxygen is delivered to the tissues through the bloodstream, and as it diffuses from the capillaries into the interstitial space, its partial pressure decreases. This decrease in partial pressure is due to the consumption of oxygen by the cells in the tissues. Therefore, the partial pressure of oxygen in the interstitial space is lower than in the arterial blood, which is typically around 100 mm Hg.

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• 31.

### The partial pressure of carbon dioxide in the interstitial space of peripheral tissues is approximately

• A.

35 mm Hg.

• B.

45 mm Hg.

• C.

55 mm Hg.

• D.

70 mm Hg.

• E.

100 mm Hg.

B. 45 mm Hg.
Explanation
The correct answer is 45 mm Hg. The partial pressure of carbon dioxide in the interstitial space of peripheral tissues is approximately 45 mm Hg. This is because carbon dioxide is produced as a waste product of cellular metabolism and diffuses out of the cells into the interstitial space. From there, it is transported through the bloodstream to the lungs, where it is eliminated through exhalation. The partial pressure of carbon dioxide in the interstitial space is lower than in the cells, but higher than in the capillaries, allowing for efficient diffusion and transport.

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• 32.

### The process by which dissolved gases are exchanged between the blood and interstitial fluids is

• A.

Pulmonary ventilation.

• B.

External respiration.

• C.

Internal respiration.

• D.

Cellular respiration.

• E.

Breathing.

C. Internal respiration.
Explanation
Internal respiration is the process by which dissolved gases, such as oxygen and carbon dioxide, are exchanged between the blood and the interstitial fluids. This occurs at the cellular level, where oxygen is taken up by the cells and carbon dioxide is released as a waste product. Pulmonary ventilation refers to the process of breathing, external respiration is the exchange of gases between the lungs and the blood, and cellular respiration is the process by which cells generate energy from glucose. Therefore, internal respiration is the correct answer as it specifically describes the exchange of gases between the blood and interstitial fluids.

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• 33.

### Which of the following is greatest?

• A.

The partial pressure of carbon dioxide in venous blood

• B.

The partial pressure of carbon dioxide in alveolar air

• C.

The partial pressure of carbon dioxide in expired air

• D.

The partial pressure of carbon dioxide in inspired air

• E.

The partial pressure of carbon dioxide in arterial blood

A. The partial pressure of carbon dioxide in venous blood
Explanation
The partial pressure of carbon dioxide in venous blood is the greatest among the options given. This is because carbon dioxide is produced as a waste product by cells during cellular respiration and is carried away from the tissues by the bloodstream. As it travels through the body, carbon dioxide accumulates in the venous blood, resulting in a higher partial pressure compared to other locations such as alveolar air, expired air, inspired air, and arterial blood.

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• 34.

### Each of the following factors affects the rate of external respiration, except the

• A.

PO2 of the alveoli.

• B.

PCO2 of the blood.

• C.

Thickness of the respiratory membrane.

• D.

Diameter of an alveolus.

• E.

Solubility of oxygen in plasma.

D. Diameter of an alveolus.
Explanation
The rate of external respiration is influenced by several factors including the PO2 of the alveoli, PCO2 of the blood, thickness of the respiratory membrane, and solubility of oxygen in plasma. However, the diameter of an alveolus does not directly affect the rate of external respiration. The diameter of an alveolus may impact the efficiency of gas exchange within the alveoli, but it does not directly affect the overall rate of external respiration.

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• 35.

### External respiration involves the

• A.

Movement of air into and out of the lungs.

• B.

Diffusion of gases between the alveoli and the circulating blood.

• C.

Exchange of dissolved gases between the blood and the interstitial fluid.

• D.

Binding of oxygen by hemoglobin.

• E.

Utilization of oxygen by tissues to support metabolism.

B. Diffusion of gases between the alveoli and the circulating blood.
Explanation
External respiration refers to the process of exchanging gases between the lungs and the bloodstream. In this process, oxygen is taken in from the air into the alveoli (tiny air sacs in the lungs) and diffuses across the alveolar membrane into the bloodstream. At the same time, carbon dioxide, a waste product of metabolism, diffuses from the bloodstream into the alveoli to be exhaled. This exchange of gases occurs due to the difference in partial pressure of oxygen and carbon dioxide between the alveoli and the circulating blood. Therefore, the correct answer is the diffusion of gases between the alveoli and the circulating blood.

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• 36.

### Carbon dioxide is more soluble in water than oxygen. To get the same amount of oxygen to dissolve in plasma as carbon dioxide, you would have to

• A.

Increase the temperature of the plasma.

• B.

Increase the partial pressure of oxygen.

• C.

Decrease the partial pressure of carbon dioxide.

• D.

Increase the rate of plasma flow through the lungs.

• E.

Either increase the partial pressure of oxygen or decrease the partial pressure of carbon dioxide.

E. Either increase the partial pressure of oxygen or decrease the partial pressure of carbon dioxide.
Explanation
Carbon dioxide is more soluble in water than oxygen, meaning it can dissolve more readily. In order to achieve the same amount of oxygen to dissolve in plasma as carbon dioxide, the partial pressure of oxygen would need to be increased or the partial pressure of carbon dioxide would need to be decreased. This is because increasing the partial pressure of oxygen would increase the driving force for oxygen to dissolve in plasma, while decreasing the partial pressure of carbon dioxide would decrease the competition for dissolved gas molecules in the plasma, allowing more oxygen to dissolve.

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• 37.

### At a PO2 of 70 mm Hg and normal temperature and pH, hemoglobin is ________ percent saturated with oxygen.

• A.

10

• B.

25

• C.

50

• D.

75

• E.

More than 90

E. More than 90
Explanation
At a PO2 of 70 mm Hg and normal temperature and pH, hemoglobin is more than 90 percent saturated with oxygen. This means that a large majority of the available hemoglobin molecules have bound to oxygen molecules.

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• 38.

### Most of the oxygen transported by the blood is

• A.

Dissolved in plasma.

• B.

Bound to hemoglobin.

• C.

In ionic form as solute in the plasma.

• D.

Bound to the same protein as carbon dioxide.

• E.

Carried by white blood cells.

B. Bound to hemoglobin.
Explanation
Oxygen is primarily transported by the blood through a molecule called hemoglobin. Hemoglobin is found in red blood cells and has a high affinity for oxygen, allowing it to bind to the oxygen molecules in the lungs and release them in tissues that need oxygen. This process ensures efficient oxygen delivery throughout the body.

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• 39.

### Each 100 ml of blood leaving the alveolar capillaries carries away roughly ________ ml of oxygen.

• A.

10

• B.

20

• C.

30

• D.

50

• E.

75

B. 20
Explanation
Each 100 ml of blood leaving the alveolar capillaries carries away roughly 20 ml of oxygen. This is because the alveolar capillaries are responsible for the exchange of gases in the lungs. Oxygen from the inhaled air diffuses into the capillaries and binds to hemoglobin in red blood cells. This oxygen-rich blood then travels to the rest of the body to deliver oxygen to the tissues. Therefore, it can be concluded that approximately 20 ml of oxygen is carried by each 100 ml of blood leaving the alveolar capillaries.

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• 40.

### Under quiet conditions, blood returning to the heart retains about ________ of its oxygen content when it leaves the lungs.

• A.

25 percent

• B.

50 percent

• C.

75 percent

• D.

90 percent

• E.

100 percent

C. 75 percent
Explanation
Under quiet conditions, blood returning to the heart retains about 75 percent of its oxygen content when it leaves the lungs. This means that even after oxygen is delivered to the body's tissues, there is still a significant amount of oxygen remaining in the blood. This is important because it ensures that enough oxygen is available to meet the body's demands, especially during periods of increased activity or stress.

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• 41.

### Which of the following would be greater?

• A.

The percent of oxygen saturation of hemoglobin when the pH is 7.6

• B.

The percent of oxygen saturation of hemoglobin when the pH is 7.2

• C.

Neither is greater.

A. The percent of oxygen saturation of hemoglobin when the pH is 7.6
• 42.

### Which of the following would be greater?

• A.

Hemoglobin's affinity for oxygen when the BPG level is high

• B.

Hemoglobin's affinity for oxygen when the BPG level is low

• C.

Neither is greater.

B. Hemoglobin's affinity for oxygen when the BPG level is low
Explanation
When the BPG level is low, hemoglobin's affinity for oxygen is greater. This is because BPG (bisphosphoglycerate) is a molecule that binds to hemoglobin and reduces its affinity for oxygen. When BPG levels are high, more BPG molecules bind to hemoglobin, causing it to release oxygen more readily. Conversely, when BPG levels are low, there are fewer BPG molecules bound to hemoglobin, allowing it to have a higher affinity for oxygen and hold onto it more tightly.

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• 43.

### Low pH alters hemoglobin structure so that oxygen binds less strongly to hemoglobin at low PO2. This increases the effectiveness of

• A.

External respiration.

• B.

Internal respiration.

• C.

Carbon dioxide transport.

• D.

Hemoglobin synthesis.

• E.

Acid-base balance.

B. Internal respiration.
Explanation
Low pH alters hemoglobin structure, causing oxygen to bind less strongly to hemoglobin at low partial pressure of oxygen (PO2). This change in hemoglobin structure enhances the release of oxygen to tissues during internal respiration, where oxygen is unloaded from hemoglobin and taken up by cells. This process ensures that oxygen is efficiently delivered to the body's tissues for cellular respiration.

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• 44.

### Which of the following factors would increase the amount of oxygen discharged by hemoglobin to peripheral tissues?

• A.

Decreased temperature

• B.

Decreased pH

• C.

Increased tissue PO2

• D.

Decreased amounts of DPG

• E.

None of the above

B. Decreased pH
Explanation
A decreased pH would increase the amount of oxygen discharged by hemoglobin to peripheral tissues. This is because a decrease in pH (an increase in acidity) causes a shift in the oxygen-hemoglobin dissociation curve to the right, making it easier for hemoglobin to release oxygen to the tissues. This is known as the Bohr effect, and it allows for increased oxygen delivery to tissues that have a higher metabolic demand.

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• 45.

### For maximum loading of hemoglobin with oxygen at the lungs, the

• A.

PCO2 should be high.

• B.

PH should be slightly acidic.

• C.

PO2 should be about 70 mm Hg.

• D.

BPG levels in the red blood cells should be high.

• E.

PCO2 should be low.

E. PCO2 should be low.
Explanation
In order for maximum loading of hemoglobin with oxygen to occur at the lungs, the PCO2 (partial pressure of carbon dioxide) should be low. This is because high levels of PCO2 indicate that there is an excess of carbon dioxide in the blood, which can lead to a decrease in the affinity of hemoglobin for oxygen. Therefore, to maximize the binding of oxygen to hemoglobin, it is necessary for the PCO2 to be low.

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• 46.

### Most of the carbon dioxide in the blood is transported as

• A.

Solute dissolved in the plasma.

• B.

Carbaminohemoglobin.

• C.

Bicarbonate ions.

• D.

Solute dissolved in the cytoplasm of red blood cells.

• E.

Carbonic acid.

C. Bicarbonate ions.
Explanation
Carbon dioxide is transported in the blood in multiple forms, but the majority of it is carried as bicarbonate ions. When carbon dioxide enters the red blood cells, it combines with water to form carbonic acid, which then dissociates into bicarbonate ions and hydrogen ions. The bicarbonate ions are then transported out of the red blood cells and into the plasma, where they can be carried to the lungs for elimination. This bicarbonate ion transport is an important mechanism for maintaining the acid-base balance in the body.

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• 47.

### Carbonic anhydrase

• A.

Is in RBCs.

• B.

Is an enzyme.

• C.

Can increase the amount of bicarbonate ion in plasma.

• D.

Can convert carbon dioxide into carbonic acid.

• E.

All of the above

E. All of the above
Explanation
Carbonic anhydrase is an enzyme found in red blood cells that plays a crucial role in the transportation and regulation of carbon dioxide in the body. It catalyzes the conversion of carbon dioxide into carbonic acid, which can then dissociate into bicarbonate ions. By increasing the amount of bicarbonate ions in the plasma, carbonic anhydrase helps maintain the acid-base balance in the body. Therefore, all of the statements mentioned in the options are correct, making "all of the above" the correct answer.

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• 48.

### Which statement about the chloride shift is false?

• A.

Involves a movement of chloride ion into RBCs

• B.

Depends on the chloride-bicarbonate counter-transporter

• C.

Involves a movement of bicarbonate ions into the plasma

• D.

Is driven by a rise in PCO2

• E.

Causes RBCs to swell

E. Causes RBCs to swell
Explanation
The chloride shift is a physiological process that occurs in red blood cells (RBCs) during gas exchange in the lungs and tissues. It involves the movement of chloride ions into RBCs and bicarbonate ions into the plasma, facilitated by the chloride-bicarbonate counter-transporter. This shift is driven by a rise in PCO2, which promotes the conversion of carbon dioxide into bicarbonate ions in RBCs. The process does not cause RBCs to swell; instead, it helps maintain the shape and integrity of RBCs by balancing the movement of ions and maintaining osmotic equilibrium.

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• 49.

### The condition resulting from inadequate production of surfactant and the resultant collapse of alveoli is

• A.

Respiratory distress syndrome.

• B.

COPD.

• C.

Anoxia.

• D.

Pulmonary embolism.

• E.

Pneumothorax.

A. Respiratory distress syndrome.
Explanation
Respiratory distress syndrome is a condition that occurs due to inadequate production of surfactant, a substance that helps keep the alveoli in the lungs open. Without enough surfactant, the alveoli collapse, leading to difficulty in breathing and inadequate oxygenation of the blood. This condition is commonly seen in premature infants, but can also occur in adults. COPD, anoxia, pulmonary embolism, and pneumothorax are all different conditions that can cause respiratory distress, but they are not specifically related to inadequate surfactant production and alveolar collapse.

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• 50.

### Asthma is

• A.

A collapsed lung.

• B.

An acute condition resulting from unusually sensitive, irritated conducting airways.

• C.

An obstructive tumor.

• D.

Characterized by fluid buildup in the alveoli.

• E.

Caused by Mycobacterium tuberculosis.

B. An acute condition resulting from unusually sensitive, irritated conducting airways.
Explanation
Asthma is an acute condition resulting from unusually sensitive, irritated conducting airways. This means that individuals with asthma have airways that are more sensitive and easily irritated, leading to symptoms such as wheezing, coughing, and difficulty breathing. It is not a collapsed lung, obstructive tumor, or caused by Mycobacterium tuberculosis. Fluid buildup in the alveoli is characteristic of a different condition called pulmonary edema.

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• Mar 22, 2023
Quiz Edited by
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• Jul 20, 2013
Quiz Created by
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