physio ch 17

The respiratory quotient is calculated as the

ratio of the volume of carbon dioxide produced per volume of oxygen consumed.

At sea level, if oxygen is consumed by the body cells at a rate of 300 mL per minute, then how much oxygen diffuses from the alveoli into the blood in the pulmonary capillaries?

300 mL per minute

Oxygenated blood is found in which of the following?

pulmonary vein only

Movement of oxygen and carbon dioxide between alveoli and blood occurs by what process?

simple diffusion

Which of the following does NOT contribute to the rapid movement of gases into and out of the blood within the lungs?

rapid blood flow

At sea level the air pressure which equals 1 atmosphere is

760 mm Hg.

In a mixture of gases, the driving force for the movement of an individual gas within that mixture is ultimately the

partial pressure of that gas.

What is the most abundant gas in the air that we breathe?

nitrogen

What percentage of air is oxygen?

21%

What percentage of air is carbon dioxide?

< 1%

What is the partial pressure of oxygen in a gas mixture that is 40% oxygen, 40% argon, and 20% helium, when the total pressure of the gas is 1000 mm Hg?

400 mm Hg

What is the partial pressure of oxygen in air at sea level?

160 mm Hg

As humidity increases, the partial pressure of oxygen in air

decreases as the total pressure of air remains the same.

As the air is saturated with water vapor (humidified) upon entry into the conducting pathway, there will be

a decrease in the partial pressure of the remaining gases.

At equilibrium, the gas molecules that dissolve in solution and those that remain in the gaseous phase are, by definition, at the same

partial pressure.

The relationship between the concentration of a gas in solution and the partial pressure of that gas can be described by

Henry's law.

Which of the following can increase the concentration of a particular gas in a solution?

Increase the partial pressure of that gas exposed to the solution.

At equilibrium, which of the following statements is TRUE when helium and nitrogen are present in a gas at equal partial pressures over water?

The partial pressures of helium and nitrogen in the water are equal.

Which statement best describes why O2 and CO2 can both be exchanged simultaneously at the alveoli and pulmonary capillaries?

Each gas acts independently and diffuses down its own partial pressure gradient.

Which statement best describes the cause of decompression sickness?

Nitrogen gas bubbles form in the blood, joints, and nervous system as pressure decreases from too fast an ascent.

Gangrene is often caused by anaerobic bacteria deep in tissues that lack adequate blood flow and adequate oxygen supply. Many times, gangrene can be treated by putting the patient into a hyperbaric chamber. Which statement best describes why this type of therapy is effective?

The increased pressure drives more oxygen into the bloodstream and, therefore, anaerobic bacteria cannot survive in the presence of oxygen.

The mixing of atmospheric air within the dead space of the conducting zone of the lung upon inspiration results in a partial pressure of

oxygen in the alveoli that is lower than atmospheric.

Which of the following causes a decrease in the P of air as it enters the conducting zone of the lungs?

humidifying the air

Pulmonary edema describes a condition where the uptake of oxygen and unloading of carbon dioxide is reduced as a consequence of a(n)

thickening of the diffusion barrier by fluid accumulation in the alveoli.

Your patient is in the hospital due to left heart failure. In your observation, you notice that she has a very low pulse oximeter reading, her skin is turning blue, and she appears to be in respiratory distress (rapid shallow breathing). You immediately call the doctor because you recognize that these symptoms indicate \________,a life-threatening situation.

pulmonary edema

What is the most common cause of pulmonary edema?

left heart failure

During intense exercise, the metabolic activity of muscle causes \________ in the partial pressure of oxygen in the tissue, \________ the movement of oxygen into the tissue.

a decrease : facilitating

Mixed venous blood samples can be taken from which of the following blood vessels?

pulmonary artery

The venous blood in the right ventricle is referred to as "mixed" because the blood that enters the heart

comes from tissue with differing metabolic activities.

What is an increase in alveolar ventilation to match the demands of increased metabolic activity in the cells called?

hyperpnea

Hyperventilation would lead to a(n) \________ within the systemic arteries.

increase in PO2 and decrease in PCO2

Hypoventilation would lead to a(n) \________ within the systemic arteries.

decrease in PO2 and increase in PCO2

What is a decrease in carbon dioxide within the blood called?

hypocapnia

What percentage of oxygen is transported in the plasma?

1.5%

What percentage of oxygen is transported by hemoglobin?

98.5%

The majority of oxygen present within the blood is

bound to hemoglobin in red blood cells.

Each \________ on the hemoglobin subunit is capable of binding an oxygen molecule, thereby allowing \________ oxygen to bind with one hemoglobin molecule.

heme : four

What is the primary driving force for the binding of oxygen to hemoglobin?

PO2

Which statement best describes why the law of mass action explains the loading and unloading of oxygen in hemoglobin?

As oxygen levels in the pulmonary capillaries increase, more oxyhemoglobin is formed. Conversely, as oxygen levels in the systemic capillaries decrease, the reaction reverses and releases oxygen from hemoglobin.

If hemoglobin is saturated (1.3 mL of oxygen per gram) and there are 150 grams of hemoglobin per liter of blood, how much oxygen can be delivered to the tissue if cardiac output is 15 liters per minute?

2925 mL O2/min

What is the definition of anemia?

a decrease in the oxygen carrying capacity of the blood

What is labored or difficult breathing called?

dyspnea

What is a deficiency of oxygen in the tissues called?

hypoxia

What is rapid shallow breathing called?

tachypnea

What is a decrease in oxygen in the blood called?

hypoxemia

As oxygen binds to hemoglobin, the \________ of the hemoglobin molecule will change through a process of \________ such that the binding of oxygen is enhanced.

affinity : positive cooperativity

Which of the following statements is FALSE regarding a leftward shift in the hemoglobin-oxygen dissociation curve?

It can be caused by an increase in PCO2.

Which of the following statements is FALSE regarding a rightward shift in the hemoglobin-oxygen dissociation curve?

It can be caused by a decrease in 2,3-BPG.

Which of the following will cause a shift in the hemoglobin-oxygen dissociation curve to the right?

both an increase in temperature and an increase in 2,3-BPG

As it leaves the lung in the pulmonary vein, blood is \________ saturated with oxygen.

98%

Which of the following increases oxygen unloading from hemoglobin?

increased carbon dioxide in the tissue

Which of the following will increase the unloading of oxygen within the tissue?

increased hydrogen ion concentration, increased body temperature, and increased PCO2

Which of the following will increase the loading of oxygen onto the hemoglobin molecule within the lungs?

decreased hydrogen ion concentration

In the systemic arteries, the partial pressure of oxygen is approximately \________, and hemoglobin is approximately \________ saturated with oxygen.

100 mm Hg : 98%

In the pulmonary arteries, the partial pressure of oxygen is approximately \________, and hemoglobin is approximately \________ saturated with oxygen.

40 mm Hg : 75%

Which statement best describes why oxygen is unloaded in tissue that is highly active?

As temperature increases due to increased metabolism, the affinity of hemoglobin for oxygen is decreased.

Which statement best describes the Bohr effect?

The Bohr effect refers to a decrease in pH which decreases the affinity of hemoglobin for oxygen.

The carbamino effect describes a change in the conformation of hemoglobin that is induced by a(n)

increase in CO2.

Which of the following statements about 2,3-BPG is FALSE?

2,3-BPG increases the affinity of hemoglobin for oxygen.

Where in blood does the conversion of CO2 to bicarbonate occur?

erythrocytes

What is the primary mechanism of carbon dioxide transport in blood?

as bicarbonate dissolved in the plasma

Which statement best describes how people die of carbon monoxide poisoning?

Carbon monoxide is toxic because it binds more readily to hemoglobin than oxygen, thereby decreasing the oxygen carrying capacity of blood.

The presence of bicarbonate ions in the blood has an important direct effect, aside from the transport of CO2, that involves

maintaining acid-base balance.

Within an erythrocyte, the conversion of CO2 to bicarbonate is prevented from reaching equilibrium by the

efflux of bicarbonate from the erythrocyte via the chloride shift.

The hydrogen ions released by the dissociation of carbonic acid are buffered by their

binding to hemoglobin.

The Haldane effect describes the increase in the affinity of hemoglobin for CO2 in the presence of a lowered

PO2

During quiet breathing, a person's breathing cycle consists of

contraction and relaxation of inspiratory muscles.

Which of the following nerves has activity during quiet inspiration?

both the phrenic nerve and external intercostal nerves

During active breathing, bursts of action potentials are observed to occur

asynchronously in the inspiratory and expiratory motor neurons.

The \________ is the respiratory center that appears to facilitate the transition between inspiration and expiration.

pontine respiratory group

In the model for quiet breathing, expiration is induced by

abrupt termination of inspiration.

Coughing is initiated by \________ located in the \________.

irritant receptors : trachea

Peripheral chemoreceptors are specialized cells in contact with arterial blood that respond directly to changes in blood

PO2, pH, and PCO2.

Central chemoreceptors are neurons in the medulla that respond directly to changes in

cerebrospinal fluid pH.

Chemoreceptors respond primarily to changes in P indirectly by its effect on

hydrogen ion concentration.

Hyperventilation will cause changes in P that are detected by the chemoreceptors which causes a(n)

decrease in breathing rate and depth of breathing.

Which of the following best describes a chemoreceptor response to PO2?

Central chemoreceptors do not respond to changes in PO2.

A decrease in P within the lung will result in a \________ in the pulmonary vasculature and a \________ in the bronchioles.

weak vasodilation : bronchoconstriction

A local bronchodilation within the alveolus will result in a(n) \________ in the ventilation-perfusion ratio in that region. A vasoconstriction of pulmonary arteriole diameter will result in a(n) \________ in the ventilation-perfusion ratio in that region.

increase : increase

The primary effect of increased PO2 in the lungs is to cause \________ which \________ the ventilation-perfusion ratio back to a normal level.

vasodilation : decreases

The primary effect of increased PCO2 in the lungs is to cause \________ which \________ the ventilation-perfusion ratio back to a normal level.

bronchodilation : increases

What is the normal pH range for blood?

7.38-7.42

Which statement best describes the effect on the body due to pH changes either above or below the normal range?

Changes in pH can denature proteins that serve as enzymes and receptors throughout the body, resulting in widespread effects on the body.

When the blood becomes \________, it can lead to a depression in the activity of the central nervous system.

acidic

The buffering capacity of hemoglobin is directly related to its ability to bind with

hydrogen ions.

Bicarbonate is an important buffer in blood and its concentration is regulated by the

kidneys.

A change in the ratio of bicarbonate to carbon dioxide concentration in the blood will

change blood pH.

Respiratory acidosis will result from a(n)

increase in blood CO2 concentration.

Assuming resting conditions at sea level, what is the partial pressure of oxygen in air?

160 mm Hg

Assuming resting conditions at sea level, what is the partial pressure of oxygen in alveoli?

100 mm Hg

Assuming resting conditions at sea level, what is the partial pressure of carbon dioxide in alveoli?

40 mm Hg

Assuming resting conditions at sea level, what is the partial pressure of oxygen in pulmonary veins?

100 mm Hg

Assuming resting conditions at sea level, what is the partial pressure of carbon dioxide in pulmonary veins?

40 mm Hg

Assuming resting conditions at sea level, what is the partial pressure of oxygen in systemic arteries?

100 mm Hg

Assuming resting conditions at sea level, what is the partial pressure of carbon dioxide in systemic arteries?

40 mm Hg

Assuming resting conditions at sea level, what is the partial pressure of oxygen in systemic veins?

40 mm Hg

Assuming resting conditions at sea level, what is the partial pressure of carbon dioxide in systemic veins?

46 mm Hg

Assuming resting conditions at sea level, what is the partial pressure of oxygen in pulmonary arteries?

40 mm Hg

A decrease in the affinity of hemoglobin for oxygen caused by the binding of carbon dioxide to hemoglobin is described by the

carbamino effect.

A decrease in the affinity of hemoglobin for oxygen caused by the binding of a hydrogen ion to hemoglobin is described by the

Bohr effect.