Question 1

Axons of respiratory motor neurons in the _______ medulla leave the CNS and form the phrenic nerve that innervates the _______; these neurons fire during normal inhalation.Respiratory motor neurons in the _______ medulla communicate via thoracic spinal nerves to the _______; these neurons fire during strenuous exercise.

Accepted Answer

The dorsal medulla contains respiratory motor neurons that form the phrenic nerve to innervate the diaphragm for normal inhalation. The ventral medulla communicates with intercostal muscles during strenuous exercise.

Question 2

Which feature characterizes CO₂?

Accepted Answer

The feature that characterizes CO₂ is that it is a metabolic waste product.

Question 3

In red blood cells, _______ reversibly converts carbonic acid to bicarbonate ions and hydrogen ions.

Accepted Answer

Carbonic anhydrase is the enzyme responsible for catalyzing the reversible conversion of carbonic acid (H2CO3) to bicarbonate ions (HCO3-) and hydrogen ions (H+). This occurs in red blood cells to help regulate blood pH as well as transport CO2 in the blood.

Question 4

The major site of PCO₂ sensitivity is located on the _______ and is directly stimulated by _______.

Accepted Answer

The major site of PCO2 sensitivity is the ventral surface of the medulla, which is directly stimulated by H+ ions. Changes in PCO2 affect the concentration of H+ in the cerebrospinal fluid, which in turn stimulates the central chemoreceptors located on the ventral surface of the medulla.

Question 5

Which statement is true?

Accepted Answer

The conversion of carbon dioxide (CO₂) and bicarbonate ions (H₂O) into carbonic acid is catalyzed by carbonic anhydrase, which is present in high levels in red blood cells. Therefore, this conversion proceeds very rapidly in red blood cells.

Question 6

Which statement about human fetal hemoglobin is true?

Accepted Answer

Fetal hemoglobin has a higher affinity for oxygen than adult hemoglobin, allowing it to extract oxygen from maternal blood in the placenta.

Question 7

Air is about 78% nitrogen, and atmospheric pressure is about 760 mm Hg at sea level.The partial pressure of nitrogen at sea level is about _______ mm Hg.

Accepted Answer

The answer of Air is about 78% nitrogen, and atmospheric...

Question 8

Which feature characterizes carotid and aortic bodies?

Accepted Answer

Carotid and aortic bodies are chemoreceptors that detect decreases in oxygen (hypoxia) and increases in carbon dioxide (hypercapnia) and acidosis in the blood, which can occur at high altitudes. This leads to increased ventilation to compensate for the decrease in oxygen availability. Therefore, the correct characteristic feature of carotid and aortic bodies is that they stimulate increased breathing rate at high altitude.

Question 9

During tidal breathing, respiratory _______ neurons in the medulla _______ just before the start of an _______.

Accepted Answer

During tidal breathing, the respiratory motor neurons in the medulla increase their firing rate just before the start of an inhalation. This results in the contraction of the diaphragm and intercostal muscles, which expands the thoracic cage, and air is drawn into the lungs. Choice A is incorrect because the respiratory motor neurons increase their firing rate just before the start of inhalation and not exhalation. Choice B is incorrect because during tidal breathing, the respiratory motor neurons increase their firing rate just before the start of inhalation and not decrease their firing rate. Choice D and E are incorrect because during tidal breathing, it is the respiratory motor neurons that are involved in the control of breathing, and not the sensory neurons.

Question 10

Which feature characterizes 2,3-bisphosphoglyceric acid (BPG)?

Accepted Answer

2,3-bisphosphoglyceric acid (BPG) binds to deoxygenated hemoglobin, reducing its affinity for oxygen, which causes hemoglobin to release more oxygen to the tissues.

Question 11

The Bohr effect is the phenomenon whereby decreases in _______ cause hemoglobin to _______ O₂.

Accepted Answer

The Bohr effect describes how changes in pH affect the ability of hemoglobin to bind or release oxygen. As pH decreases (becomes more acidic), hemoglobin will release oxygen more readily. Therefore, the correct choice is B, where decreases in pH cause hemoglobin to release oxygen.

Question 12

When a patient has pulmonary fibrosis, excess connective tissue is deposited in the lungs making the lungs less elastic.This has the effect of _______ the vital capacity of the patient.

Accepted Answer

The answer of When a patient has pulmonary fibrosis, excess...

Question 13

A human's basic breathing rhythm is generated in the _______ and modified by neurons in or above the _______.

Accepted Answer

The basic breathing rhythm is generated in the medulla, which is located in the brainstem. This rhythm can be modified by neurons in or above the pons, which is also part of the brainstem. Therefore, the correct answer is B - medulla; pons.

Question 14

Choose the order that accurately reflects how increasing amounts of CO₂ are transported.

Accepted Answer

The answer of Choose the order that accurately reflects how...

Question 15

Refer to the figure showing a region in the human lung.  Surfactant can be found along the surface labeled _______, which is in an alveolus of the lung and serves to decrease the work necessary to inflate the lungs.

Accepted Answer

The answer of Refer to the figure showing a region...

Question 16

Which characterizes a right shift in the O₂-binding/dissociation curve of hemoglobin?

Accepted Answer

A right shift indicates that a higher partial pressure of oxygen (PO2) is needed to achieve the same level of oxygen saturation, meaning hemoglobin has a decreased affinity for oxygen.

Question 17

Which statement about how breathing is regulated is true?

Accepted Answer

Fishes are very sensitive to decreasing levels of O2 in their arterial blood, which is crucial for their survival in aquatic environments where oxygen levels can vary.

Question 18

By converting CO₂ to H₂CO₃, carbonic anhydrase _______the PCO₂ in endothelial cells, red blood cells, and plasma, thereby _______ diffusion of CO₂ from tissue cells to these locations.

Accepted Answer

The addition of CO₃ to the peptide sequence indicates that carbonic anhydrase has catalyzed the conversion of CO2 and water to HCO3- and H+. HCO3- is represented as CO₂ in the peptide sequence. The conversion of CO2 to HCO3- by carbonic anhydrase in endothelial cells, red blood cells, and plasma helps to maintain the pH balance in the blood. By converting CO₂ to HCO3-, carbonic anhydrase reduces the concentration of CO2 and increases the concentration of HCO3-. This facilitates the diffusion of CO2 from the tissue cells to these locations. Therefore, choice A, "reduces; facilitating" is the best choice.

Question 19

An increase in 2,3-bisphosphoglyceric acid (BPG) would be associated with

Accepted Answer

BPG is a molecule that binds to hemoglobin and promotes the release of oxygen to tissues. At high altitudes, where there is less oxygen available in the air, the body increases its production of BPG to compensate for the decreased oxygen levels.

Question 20

The largest proportion of CO₂ carried by the blood is in the form of

Accepted Answer

The largest proportion of CO2 carried by the blood is in the form of bicarbonate ions (HCO3-) carried in the plasma. This process involves the conversion of CO2 into bicarbonate ions within red blood cells, which then diffuse into the plasma.

Quiz 48: Gas Exchange

Which feature characterizes CO₂?

In red blood cells, _______ reversibly converts carbonic acid to bicarbonate ions and hydrogen ions.

The major site of PCO₂ sensitivity is located on the _ and is directly stimulated by _.

Which statement is true?

Which statement about human fetal hemoglobin is true?

Air is about 78% nitrogen, and atmospheric pressure is about 760 mm Hg at sea level.The partial pressure of nitrogen at sea level is about _______ mm Hg.

Which feature characterizes carotid and aortic bodies?

During tidal breathing, respiratory ___ neurons in the medulla _ just before the start of an _____.

Which feature characterizes 2,3-bisphosphoglyceric acid (BPG) ?

The Bohr effect is the phenomenon whereby decreases in _ cause hemoglobin to _ O₂.

When a patient has pulmonary fibrosis, excess connective tissue is deposited in the lungs making the lungs less elastic.This has the effect of _______ the vital capacity of the patient.

A human's basic breathing rhythm is generated in the _ and modified by neurons in or above the _.

Choose the order that accurately reflects how increasing amounts of CO₂ are transported.

Refer to the figure showing a region in the human lung. Surfactant can be found along the surface labeled _______, which is in an alveolus of the lung and serves to decrease the work necessary to inflate the lungs.

Which characterizes a right shift in the O₂-binding/dissociation curve of hemoglobin?

Which statement about how breathing is regulated is true?

By converting CO₂ to H₂CO₃, carbonic anhydrase _the PCO₂ in endothelial cells, red blood cells, and plasma, thereby _ diffusion of CO₂ from tissue cells to these locations.

An increase in 2,3-bisphosphoglyceric acid (BPG) would be associated with

The largest proportion of CO₂ carried by the blood is in the form of

Quiz 48: Gas Exchange

Which feature characterizes CO2?

In red blood cells, _______ reversibly converts carbonic acid to bicarbonate ions and hydrogen ions.

The major site of PCO2 sensitivity is located on the _______ and is directly stimulated by _______.

Which statement is true?

Which statement about human fetal hemoglobin is true?

Air is about 78% nitrogen, and atmospheric pressure is about 760 mm Hg at sea level.The partial pressure of nitrogen at sea level is about _______ mm Hg.

Which feature characterizes carotid and aortic bodies?

During tidal breathing, respiratory _______ neurons in the medulla _______ just before the start of an _______.

Which feature characterizes 2,3-bisphosphoglyceric acid (BPG) ?

The Bohr effect is the phenomenon whereby decreases in _______ cause hemoglobin to _______ O2.

When a patient has pulmonary fibrosis, excess connective tissue is deposited in the lungs making the lungs less elastic.This has the effect of _______ the vital capacity of the patient.

A human's basic breathing rhythm is generated in the _______ and modified by neurons in or above the _______.

Choose the order that accurately reflects how increasing amounts of CO2 are transported.

Refer to the figure showing a region in the human lung. Surfactant can be found along the surface labeled _______, which is in an alveolus of the lung and serves to decrease the work necessary to inflate the lungs.

Which characterizes a right shift in the O2-binding/dissociation curve of hemoglobin?

Which statement about how breathing is regulated is true?

By converting CO2 to H2CO3, carbonic anhydrase _______the PCO2 in endothelial cells, red blood cells, and plasma, thereby _______ diffusion of CO2 from tissue cells to these locations.

An increase in 2,3-bisphosphoglyceric acid (BPG) would be associated with

The largest proportion of CO2 carried by the blood is in the form of

Which feature characterizes CO₂?

The major site of PCO₂ sensitivity is located on the _ and is directly stimulated by _.

During tidal breathing, respiratory ___ neurons in the medulla _ just before the start of an _____.

The Bohr effect is the phenomenon whereby decreases in _ cause hemoglobin to _ O₂.

A human's basic breathing rhythm is generated in the _ and modified by neurons in or above the _.

Choose the order that accurately reflects how increasing amounts of CO₂ are transported.

Which characterizes a right shift in the O₂-binding/dissociation curve of hemoglobin?

By converting CO₂ to H₂CO₃, carbonic anhydrase _the PCO₂ in endothelial cells, red blood cells, and plasma, thereby _ diffusion of CO₂ from tissue cells to these locations.

The largest proportion of CO₂ carried by the blood is in the form of