phsiology 3

Question 1

What tends to decrease airway resistance?

Asthma
Stimulation by sympathetic fibers
Treatment with acetylcholine
Exhalation to residual volume

Answer 1

Stimulation by sympathetic fibers

Question 2

Which of the following would be expected to increase the measured airway resistance?

Stimulation of parasympathetic nerves to the lungs
Low lung volumes
Release of histamine by mast cells
Forced expirations
All of the above

Answer 2

All of the above

Question 3

Several students are trying to see who can generate the highest expiratory flow. Which muscle is most effective at producing a maximal effort?

Diaphragm
Internal intercostals
External intercostals
Rectus abdominis
Sternocleidomastoid

Answer 3

Rectus abdominis

Question 4

With a slow decrease in left heart function, which of the following will minimize the formation of pulmonary edema?

An increase in plasma protein concentration due to fluid loss
Increase in the negative interstitial hydrostatic pressure
Increased pumping of lymphatics
Increase in the concentration of interstitial proteins

Answer 4

Increased pumping of lymphatics

Question 5

A 22-year-old woman has a pulmonary compliance of 0.2 L/cm H2O and a pleural pressure of −4 cm H2O. What is the pleural pressure (in cm H2O) when the woman inhales 1.0 liter of air?
−6
−7
−8
−9
−10

Answer 5

−9

Question 6

A patient has a dead space of 150 milliliters, FRC of 3 liters, tidal volume (VT) of 650 milliliters, expiratory reserve volume (ERV) of 1.5 liters, total lung capacity (TLC) of 8 liters, and respiratory rate of 15 breaths/min. What is the residual volume (RV)?
A) 500 milliliters
B) 1000 milliliters
C) 1500 milliliters
D) 2500 milliliters
E) 6500 milliliter

Answer 6

C) 1500 milliliters

Question 7

A patient has a dead space of 150 milliliters, FRC of 3 liters, VT of 650 milliliters, ERV of 1.5 liters, TLC of 8 liters, and respiratory rate of 15 breaths/min. What is the alveolar ventilation (Va)?
A) 5 L/min
B) 7.5 L/min
C) 6.0 L/min
D) 9.0 L/min

Answer 7

B) 7.5 L/min

Question 8

What happens during exercise?
A) Blood flow is uniform throughout the lung
B) Lung-diffusing capacity increases because blood flow is continuous in all pulmonary capillaries
C) Pulmonary blood volume decreases
D) The transit time of blood in the pulmonary capillaries does not change from rest

Answer 8

B) Lung-diffusing capacity increases because blood

flow is continuous in all pulmonary capillaries

Question 9

. A person with normal lungs has an oxygen (O2) consumption of 750 ml O2/min. The hemoglobin (Hb) 
concentration is 15 g/dl. The mixed venous saturation 
is 25%. What is the cardiac output?
A) 2500 ml/min
B) 5000 ml/min
C) 7500 ml/min
D) 10,000 ml/min
E) 20,000 ml/min

Answer 9

B) 5000 ml/min

Question 10

A cardiac catheterization is performed in a healthy adult. The blood sample withdrawn from the catheter shows 60% O2 saturation, and the pressure recording shows oscillations from a maximum of 27 mm Hg to a minimum of 12 mm Hg. Where was the catheter tip located?
A) Ductus arteriosus
B) Foramen ovale
C) Left atrium
D) Pulmonary artery
E) Right atrium

Answer 10

D) Pulmonary artery

Question 11

If alveolar surface area is decreased 50% and pulmonary edema leads to a doubling of diffusion distance, how does diffusion of O2 compare with normal?
A) 25% increase
B) 50% increase
C) 25% decrease
D) 50% decrease
E) 75% decrease

Answer 11

E) 75% decrease

Question 12

Which diagram in the above figure best illustrates the pulmonary vasculature when the cardiac output has increased to a maximum extent?
A) A
B) B
C) C
D) D
E) E

Answer 12

A) A

Question 13

A human experiment is being performed in which forearm blood flow is being measured under a variety of conditions. The forearm is infused with a vasodilator, resulting in an increase in blood flow. Which of the following occurs?

A) Tissue interstitial partial pressure of oxygen (Po2) will increase
B) Tissue interstitial partial pressure of carbon dioxide (Pco2) will increase
C) Tissue pH will decrease

Answer 13

A) Tissue interstitial partial pressure of oxygen (Po2) will increase

Question 14

Blood gas measurements are obtained in a resting patient who is breathing room air. The patient has an arterial content of 19 ml O2/min with a Po2 of 95. The mixed venous O2 content is 4 ml O2/100 ml blood. Which condition does the patient have?
A) An increase in physiological dead space
B) Pulmonary edema
C) A low Hb concentration
D) A low cardiac output

Answer 14

D) A low cardiac output

Question 15

. A normal male subject has the following initial conditions (in the steady state):
Arterial Po2 = 92 mm Hg
Arterial O2 saturation = 97%
Venous O2 saturation = 20%
Venous Po2 = 30 mm Hg
Cardiac output = 5600 ml/min
O2 consumption = 256 ml/min
Hb concentration = 12 gm/dl
If you ignore the contribution of dissolved O2 to the O2
content, what is the venous O2 content?
A) 2.2 ml O2/100 ml blood
B) 3.2 ml O2/100 ml blood
C) 4 ml O2/100 ml blood
D) 4.6 ml O2/100 ml blood
E) 6.2 ml O2/100 ml blood
F) 10.8 ml O2/100 ml blood
G) 16 ml O2/100 ml blood

Answer 15

B) 3.2 ml O2/100 ml blood

Question 16

A man fell asleep in his running car. He was unconscious when he was brought into the emergency
department. With carbon monoxide (CO) poisoning, you would expect his alveolar O2 partial pressure
(Pao2) would be _______, while his arterial O2 content
(Cao2) would be ______.
A) Normal, decreased
B) Decreased, decreased
C) Increased, normal
D) Increased, normal

Answer 16

A) Normal, decreased

Question 17

A person with normal lungs at sea level (760 mm Hg) 
is breathing 50% O2. What is the approximate alveolar 
Po2?
A) 100
B) 159
C) 306
D) 330
E) 380

Answer 17

C) 306

Question 18

A person’s normal VT is 400 milliliters with a dead space of 100 milliliters. The respiratory rate is 12 breaths/min. The person undergoes ventilation during surgery, and the VT is 700 with a rate of 12. What is the approximate alveolar Pco2 for this person?
A) 10
B) 20
C) 30
D) 40
E) 45

Answer 18

B) 20

Question 19

which conditions is alveolar Po2 increased and alveolar Pco2 decreased?
A) Increased Va and unchanged metabolism
B) Decreased Va and unchanged metabolism
C) Increased metabolism and unchanged Va
D) Proportional increase in metabolism and Va

Answer 19

A) Increased Va and unchanged metabolism

Question 20

The diffusing capacity of a gas is the volume of gas that will diffuse through a membrane each minute for a pressure difference of 1 mm Hg. Which gas is often used to estimate the O2-diffusing capacity of the lungs?
A) CO2
B) CO
C) Cyanide gas
D) Nitrogen
E) O2

Answer 20

B) CO

Question 21

A 67-year-old man has a solid tumor that pushes
against an airway, partially obstructing air flow to the distal alveoli. Which point on the V/Q line of the O2-CO2 diagram above corresponds to the alveolar gas of these distal alveoli?
A) A
B) B
C) C
D) D
E) E

Answer 21

B) B

Question 22

42) A 55-year-old man has a pulmonary embolism that completely blocks the blood flow to his right lung. Which point on the V/Q line of the O2-CO2 diagram above corresponds to the alveolar gas of his right lung?
A) A
B) B
C) C
D) D
E) E

Answer 22

E) E

Question 23

The figure above shows a lung with a large shunt in which mixed venous blood bypasses the O2 exchange areas of the lung. Breathing room air produces the O2partial pressures shown on the diagram. What is the O2 tension of the arterial blood (in mm Hg) when the person breathes 100% O2 and the inspired O2 tension 
is greater than 600 mm Hg?
A) 40
B) 55
C) 60
D) 175
E) 200
F) 400
G) 600

Answer 23

C) 60

Question 24

Which of the following describes diffusing capacity of O2 in the lung?

A) Does not change during exercise
B) Is greater than diffusing capacity for CO2
C) Is greater in residents at sea level than in residents at 3000 meters altitude
D) Is directly related to alveolar capillary surface area

Answer 24

D) Is directly related to alveolar capillary surface area

Question 25

``` 45) A 32-year-old medical student has a fourfold increase in cardiac output during strenuous exercise. Which curve on the above figure most likely represents the changes in O2 tension that occur as blood flows from the arterial end to the venous end of the pulmonary capillaries in this student? A) A B) B C) C D) D E) E ```

Answer 25

E) E

Question 26

``` 46) The above figure shows changes in the partial pressures of O2 and CO2 as blood flows from the arterial (Art) end to the venous (Ven) end of the pulmonary capillaries. Which diagram best depicts the normal relationship between Po2 (red line) and Pco2 (green line) during resting conditions? A) A B) B C) C D) D E) E ```

Answer 26

A) A

Question 27

Which of the following would be true if the blood lacked red blood cells and just had plasma and the lungs were functioning normally? A) The arterial Po2 would be normal B) The O2 content of arterial blood would be normal C) Both A and B D) Neither A nor B

Answer 27

A) The arterial Po2 would be normal

Question 28

``` A person with anemia has an Hb concentration of 12 g/dl. He starts exercising and uses 12 ml O2/dl. What is the mixed venous Po2? A) 0 mm Hg B) 10 mm Hg C) 20 mm Hg D) 40 mm Hg E) 100 mm Hg ```

Answer 28

C) 20 mm Hg

Question 29

A stroke that destroys the respiratory area of the medulla would be expected to lead to which of the following? A) Immediate cessation of breathing B) Apneustic breathing C) Ataxic breathing D) Rapid breathing (hyperpnea) E) None of the above (breathing would remain normal)

Answer 29

A) Immediate cessation of breathing

Question 30

What is the most important pathway for the respiratory response to systemic arterial CO2 (Pco2)? A) CO2 activation of the carotid bodies B) Hydrogen ion (H+) activation of the carotid bodies C) CO2 activation of the chemosensitive area of the medulla D) H+ activation of the chemosensitive area of the medulla E) CO2 activation of receptors in the lungs

Answer 30

D) H+ activation of the chemosensitive area of the | medulla

Question 31

``` The afferent (sensory) endings for the Hering-Breuer reflex are mechanoreceptors located in the A) Carotid arteries B) Alveoli C) External intercostals D) Bronchi and bronchioles E) Diaphragm ```

Answer 31

D) Bronchi and bronchioles

Question 32

An anesthetized man is breathing with no assistance. He then undergoes artificial ventilation for 10 minutes at his normal VT but at twice his normal frequency. He undergoes ventilation with a gas mixture of 60% O2 and 40% nitrogen. The artificial ventilation is stopped and he fails to breathe for several minutes. This apneic episode is due to which of the following? A) High arterial Po2 suppressing the activity of the peripheral chemoreceptors B) Decrease in arterial pH suppressing the activity of the peripheral chemoreceptors C) Low arterial Pco2 suppressing the activity of the medullary chemoreceptors D) High arterial Pco2 suppressing the activity of the medullary chemoreceptors E) Low arterial Pco2 suppressing the activity of the peripheral chemoreceptors

Answer 32

C) Low arterial Pco2 suppressing the activity of the | medullary chemoreceptors

Question 33

At a fraternity party a 17-year-old male places a paper bag over his mouth and breathes in and out of the bag. As he continues to breathe into this bag, his rate of breathing continues to increase. Which of the following is responsible for the increased ventilation? A) Increased alveolar Po2 B) Increased alveolar Pco2 C) Decreased arterial Pco2 D) Increased pH

Answer 33

B) Increased alveolar Pco2

Question 34

A 54-year-old woman with advanced emphysema due to long-term cigarette smoking is admitted to the hospital for shortness of breath. She is diagnosed with pulmonary hypertension. Her arterial blood gases are Po2 = 75 mm Hg Pco2 = 45 mm Hg pH = 7.35 What is the cause of the pulmonary hypertension in this woman? A) Increased alveolar Pco2 B) Increased sympathetic tone C) Decreased alveolar Po2 D) Decreased pulmonary capillary number

Answer 34

D) Decreased pulmonary capillary number

Question 35

Which of the following occurs during atelectasis of one lung? A) Increase in arterial Pco2 B) A 40% decrease in Po2 C) Normal blood flow in the lung with atelectasis D) Slight decrease in arterial content

Answer 35

D) Slight decrease in arterial content

Question 36

While breathing room air, a patient with chronic obstructive pulmonary disease, has a systemic arterial Pco2 of 65 mm Hg and a Po2 of 40 mm Hg. Supplemental oxygen is administered at a 40% fractional concentration of oxygen in inspired gas (Fio2), which resulted in an increase of Po2 to 55 mm Hg and Pco2 to 70 mm Hg. Which of the following describes the supplemental O2? A) Restored arterial dissolved O2 to normal B) Did not change breathing C) Reduced the hypoxic stimulation of breathing D) Increased the pulmonary excretion of CO2

Answer 36

C) Reduced the hypoxic stimulation of breathing