Podcast
Questions and Answers
What is the main function of beta2 receptors in the respiratory system?
What is the main function of beta2 receptors in the respiratory system?
- To increase alveolar ventilation
- To relax and dilate the airways (correct)
- To constrict the airways
- To activate muscarinic receptors
What is the difference between anatomic dead space and physiologic dead space?
What is the difference between anatomic dead space and physiologic dead space?
- Anatomic dead space includes the respiratory bronchioles and alveoli, while physiologic dead space does not.
- Anatomic dead space is the volume of the alveoli, while physiologic dead space is the volume of the conducting airways.
- Anatomic dead space is the volume of the conducting airways, while physiologic dead space includes the anatomic dead space plus a functional dead space in the alveoli. (correct)
- Anatomic dead space is the volume of the nose and mouth, while physiologic dead space is the total volume of the lungs.
What is the normal value for the FEV1/FVC ratio in a healthy person?
What is the normal value for the FEV1/FVC ratio in a healthy person?
- 0.6
- 0.7
- 0.5
- 0.8 (correct)
What is the main function of the muscarinic receptors in the respiratory system?
What is the main function of the muscarinic receptors in the respiratory system?
What is the main role of the respiratory muscles in the respiratory system?
What is the main role of the respiratory muscles in the respiratory system?
What is the purpose of the alveolar gas equation?
What is the purpose of the alveolar gas equation?
According to the gas laws, if the pressure of a gas increases, what will happen to its volume?
According to the gas laws, if the pressure of a gas increases, what will happen to its volume?
Which law describes the relationship between the partial pressures of gases in a mixture?
Which law describes the relationship between the partial pressures of gases in a mixture?
In the alveolar air, the partial pressure of oxygen (PAO2) is lower than the inspired air, while the partial pressure of carbon dioxide (PACO2) is higher. What is the reason for this?
In the alveolar air, the partial pressure of oxygen (PAO2) is lower than the inspired air, while the partial pressure of carbon dioxide (PACO2) is higher. What is the reason for this?
What is the partial pressure of oxygen (PO2) in mixed venous blood entering the pulmonary capillaries?
What is the partial pressure of oxygen (PO2) in mixed venous blood entering the pulmonary capillaries?
What is the term used to describe the situation where the total amount of gas transported across the alveolar-capillary barrier is limited by the diffusion process?
What is the term used to describe the situation where the total amount of gas transported across the alveolar-capillary barrier is limited by the diffusion process?
What happens when the diffusion distance for gases increases?
What happens when the diffusion distance for gases increases?
What is the primary cause of the negative intrapleural pressure?
What is the primary cause of the negative intrapleural pressure?
What happens if the negative intrapleural pressure is absent?
What happens if the negative intrapleural pressure is absent?
At volumes less than the functional residual capacity (FRC), what is the relationship between the collapsing force of the lungs and the expanding force of the chest wall?
At volumes less than the functional residual capacity (FRC), what is the relationship between the collapsing force of the lungs and the expanding force of the chest wall?
What happens to the compliance of the lungs and chest wall as expiration proceeds?
What happens to the compliance of the lungs and chest wall as expiration proceeds?
At volumes greater than the functional residual capacity (FRC), what is the relationship between the collapsing force of the lungs and the expanding force of the chest wall?
At volumes greater than the functional residual capacity (FRC), what is the relationship between the collapsing force of the lungs and the expanding force of the chest wall?
What is the primary factor that determines the compliance of the lungs during expiration?
What is the primary factor that determines the compliance of the lungs during expiration?
According to the passage, what happens when volume is less than the functional residual capacity (FRC)?
According to the passage, what happens when volume is less than the functional residual capacity (FRC)?
What is the primary cause of the negative intrapleural pressure described in the passage?
What is the primary cause of the negative intrapleural pressure described in the passage?
What happens to the compliance of the lungs and chest wall as expiration proceeds, according to the passage?
What happens to the compliance of the lungs and chest wall as expiration proceeds, according to the passage?
What is the relationship between the collapsing force of the lungs and the expanding force of the chest wall at volumes greater than the functional residual capacity (FRC)?
What is the relationship between the collapsing force of the lungs and the expanding force of the chest wall at volumes greater than the functional residual capacity (FRC)?
What is the primary factor that determines the compliance of the lungs during expiration, according to the passage?
What is the primary factor that determines the compliance of the lungs during expiration, according to the passage?
At high lung volumes, which of the following is true regarding the resistance of alveolar vessels?
At high lung volumes, which of the following is true regarding the resistance of alveolar vessels?
In which lung zone does the highest ventilation/perfusion (V/Q) ratio occur?
In which lung zone does the highest ventilation/perfusion (V/Q) ratio occur?
What is the primary cause of a left-to-right shunt?
What is the primary cause of a left-to-right shunt?
What is the normal value for the ventilation/perfusion (V/Q) ratio?
What is the normal value for the ventilation/perfusion (V/Q) ratio?
Which of the following is a consequence of low ventilation/perfusion (V/Q) ratio?
Which of the following is a consequence of low ventilation/perfusion (V/Q) ratio?
What is the primary function of the conducting zone of the respiratory system?
What is the primary function of the conducting zone of the respiratory system?
What is the result of a ventilation/perfusion (V/Q) mismatch in the lungs?
What is the result of a ventilation/perfusion (V/Q) mismatch in the lungs?
Which of the following scenarios represents a high V/Q ratio?
Which of the following scenarios represents a high V/Q ratio?
What is the primary cause of a low V/Q ratio?
What is the primary cause of a low V/Q ratio?
What is the effect of a high V/Q ratio on arterial blood gases?
What is the effect of a high V/Q ratio on arterial blood gases?
What is the primary function of erythropoietin (EPO) in the body?
What is the primary function of erythropoietin (EPO) in the body?
Which of the following best describes the Bohr effect?
Which of the following best describes the Bohr effect?
In which part of the oxygen-hemoglobin dissociation curve does a shift to the right occur?
In which part of the oxygen-hemoglobin dissociation curve does a shift to the right occur?
What is the primary cause of a ventilation/perfusion (V/Q) mismatch in the lungs?
What is the primary cause of a ventilation/perfusion (V/Q) mismatch in the lungs?
What is the primary consequence of a low ventilation/perfusion (V/Q) ratio in the lungs?
What is the primary consequence of a low ventilation/perfusion (V/Q) ratio in the lungs?
Which of the following best describes the relationship between the partial pressure of oxygen (PO2) and the partial pressure of carbon dioxide (PCO2) in the alveolar air?
Which of the following best describes the relationship between the partial pressure of oxygen (PO2) and the partial pressure of carbon dioxide (PCO2) in the alveolar air?
What is the term used to describe the situation where the total amount of gas transported across the alveolar-capillary barrier is limited by the diffusion process?
What is the term used to describe the situation where the total amount of gas transported across the alveolar-capillary barrier is limited by the diffusion process?
What is the primary factor that determines the compliance of the lungs during expiration?
What is the primary factor that determines the compliance of the lungs during expiration?
What is the partial pressure of oxygen (PO2) in the mixed venous blood entering the pulmonary capillaries?
What is the partial pressure of oxygen (PO2) in the mixed venous blood entering the pulmonary capillaries?
According to the gas laws, if the pressure of a gas increases, what will happen to its volume?
According to the gas laws, if the pressure of a gas increases, what will happen to its volume?
What is the primary role of deoxyhemoglobin in the transport of carbon dioxide?
What is the primary role of deoxyhemoglobin in the transport of carbon dioxide?
What is the primary mechanism by which bicarbonate ions (HCO3-) are transported from red blood cells to the plasma?
What is the primary mechanism by which bicarbonate ions (HCO3-) are transported from red blood cells to the plasma?
What would be the consequence if the hydrogen ions (H+) produced during the dissociation of carbonic acid were not buffered in red blood cells?
What would be the consequence if the hydrogen ions (H+) produced during the dissociation of carbonic acid were not buffered in red blood cells?
Which enzyme plays a critical role in the transport of carbon dioxide in red blood cells?
Which enzyme plays a critical role in the transport of carbon dioxide in red blood cells?
What is the primary driving force for the diffusion of carbon dioxide across cell membranes and into red blood cells?
What is the primary driving force for the diffusion of carbon dioxide across cell membranes and into red blood cells?
What characterizes dead space in the lungs?
What characterizes dead space in the lungs?
In regions of high V/Q, what is the typical characteristic?
In regions of high V/Q, what is the typical characteristic?
What is a characteristic of regions with low V/Q ratios?
What is a characteristic of regions with low V/Q ratios?
What condition is associated with a V/Q ratio of 0?
What condition is associated with a V/Q ratio of 0?
What is the main difference between dead space and high V/Q regions?
What is the main difference between dead space and high V/Q regions?
What happens when pulmonary capillary blood comes from regions with low V/Q ratios?
What happens when pulmonary capillary blood comes from regions with low V/Q ratios?
Which scenario best describes a high V/Q situation?
Which scenario best describes a high V/Q situation?
According to the passage, what is the primary cause of a ventilation/perfusion (V/Q) mismatch in the lungs?
According to the passage, what is the primary cause of a ventilation/perfusion (V/Q) mismatch in the lungs?
At high altitude, where the partial pressure of oxygen (PO2) in the inspired air is lower, what effect would this have on the oxygen-hemoglobin dissociation curve?
At high altitude, where the partial pressure of oxygen (PO2) in the inspired air is lower, what effect would this have on the oxygen-hemoglobin dissociation curve?
What is the primary effect of hyperventilation on the partial pressure of carbon dioxide (PCO2) in the blood?
What is the primary effect of hyperventilation on the partial pressure of carbon dioxide (PCO2) in the blood?
In regions of the lungs with a high ventilation/perfusion (V/Q) ratio, what is the typical characteristic?
In regions of the lungs with a high ventilation/perfusion (V/Q) ratio, what is the typical characteristic?
What is the primary mechanism by which carbon dioxide is transported in the blood?
What is the primary mechanism by which carbon dioxide is transported in the blood?
What effect does an increase in 2,3-diphosphoglycerate (2,3DPG) concentration have on O2 affinity to hemoglobin?
What effect does an increase in 2,3-diphosphoglycerate (2,3DPG) concentration have on O2 affinity to hemoglobin?
Under hypoxic conditions, what stimulates the production of 2,3-diphosphoglycerate (2,3DPG) in red blood cells?
Under hypoxic conditions, what stimulates the production of 2,3-diphosphoglycerate (2,3DPG) in red blood cells?
What is the impact of hyperventilation on arterial blood O2 levels?
What is the impact of hyperventilation on arterial blood O2 levels?
How does the kidney distinguish between a lack of red blood cells and a lack of oxygen based on the text?
How does the kidney distinguish between a lack of red blood cells and a lack of oxygen based on the text?
What happens in the tissues with CO2 produced from aerobic metabolism according to the passage?
What happens in the tissues with CO2 produced from aerobic metabolism according to the passage?
What happens to the partial pressure gradient for oxygen in the capillary at high altitudes?
What happens to the partial pressure gradient for oxygen in the capillary at high altitudes?
What is the primary effect of hyperventilation on blood pH and oxygen-hemoglobin dissociation?
What is the primary effect of hyperventilation on blood pH and oxygen-hemoglobin dissociation?
What occurs about one-third of the way along the pulmonary capillary in terms of oxygen equilibration?
What occurs about one-third of the way along the pulmonary capillary in terms of oxygen equilibration?
What is the primary consequence of a decrease in PCO2 in terms of hemoglobin's affinity for oxygen?
What is the primary consequence of a decrease in PCO2 in terms of hemoglobin's affinity for oxygen?
How do increases in PCO2 contribute to changes in blood pH and hemoglobin's oxygen-carrying capacity?
How do increases in PCO2 contribute to changes in blood pH and hemoglobin's oxygen-carrying capacity?
At high altitude, where the partial pressure of oxygen (PAO2) is reduced throughout the lungs, what is the primary effect on pulmonary blood flow?
At high altitude, where the partial pressure of oxygen (PAO2) is reduced throughout the lungs, what is the primary effect on pulmonary blood flow?
What is the primary mechanism by which the oxygen-hemoglobin dissociation curve shifts to the right in response to high altitude hypoxia?
What is the primary mechanism by which the oxygen-hemoglobin dissociation curve shifts to the right in response to high altitude hypoxia?
What is the primary effect of hyperventilation on the partial pressure of carbon dioxide (PCO2) in the alveolar air?
What is the primary effect of hyperventilation on the partial pressure of carbon dioxide (PCO2) in the alveolar air?
What is the primary mechanism by which carbon dioxide is transported in the blood from the tissues to the lungs?
What is the primary mechanism by which carbon dioxide is transported in the blood from the tissues to the lungs?
What is the primary effect of the Cl--HCO3- exchange (Cl- shift) mediated by the band 3 protein in red blood cells?
What is the primary effect of the Cl--HCO3- exchange (Cl- shift) mediated by the band 3 protein in red blood cells?
What is the primary driving force for the diffusion of carbon dioxide (CO2) from tissues into red blood cells?
What is the primary driving force for the diffusion of carbon dioxide (CO2) from tissues into red blood cells?
What is the primary function of deoxyhemoglobin in the transport of carbon dioxide?
What is the primary function of deoxyhemoglobin in the transport of carbon dioxide?
What would be the consequence if the hydrogen ions (H+) produced during the dissociation of carbonic acid were not buffered in red blood cells?
What would be the consequence if the hydrogen ions (H+) produced during the dissociation of carbonic acid were not buffered in red blood cells?
Which of the following best describes the Bohr effect?
Which of the following best describes the Bohr effect?
What is the primary mechanism by which bicarbonate ions (HCO3-) are transported from red blood cells to the plasma?
What is the primary mechanism by which bicarbonate ions (HCO3-) are transported from red blood cells to the plasma?
What is the primary mechanism by which increased temperature causes a rightward shift in the oxygen-hemoglobin dissociation curve?
What is the primary mechanism by which increased temperature causes a rightward shift in the oxygen-hemoglobin dissociation curve?
What is the primary effect of hyperventilation on the oxygen-hemoglobin dissociation curve?
What is the primary effect of hyperventilation on the oxygen-hemoglobin dissociation curve?
Which of the following is the primary effect of low ventilation-to-perfusion (V/Q) ratios on arterial blood gas values?
Which of the following is the primary effect of low ventilation-to-perfusion (V/Q) ratios on arterial blood gas values?
What is the primary mechanism by which erythropoietin (EPO) increases oxygen delivery to the tissues?
What is the primary mechanism by which erythropoietin (EPO) increases oxygen delivery to the tissues?
What is the primary effect of high altitude exposure on the oxygen-hemoglobin dissociation curve?
What is the primary effect of high altitude exposure on the oxygen-hemoglobin dissociation curve?
During exercise, why does the O2-hemoglobin dissociation curve shift to the right?
During exercise, why does the O2-hemoglobin dissociation curve shift to the right?
In high altitudes where alveolar PO2 is low, what stimulates peripheral chemoreceptors?
In high altitudes where alveolar PO2 is low, what stimulates peripheral chemoreceptors?
What effect does hyperventilation have on the O2-hemoglobin dissociation curve?
What effect does hyperventilation have on the O2-hemoglobin dissociation curve?
What stimulates the medullary inspiratory center to increase breathing rate?
What stimulates the medullary inspiratory center to increase breathing rate?
What happens to arterial blood PO2 at high altitudes with low alveolar PO2?
What happens to arterial blood PO2 at high altitudes with low alveolar PO2?
What is the primary reason for an increase in ventilation rate during exercise?
What is the primary reason for an increase in ventilation rate during exercise?
What causes the O2-hemoglobin dissociation curve to shift to the right during exercise?
What causes the O2-hemoglobin dissociation curve to shift to the right during exercise?
What response is triggered by severe hypoxemia due to low alveolar PO2 levels?
What response is triggered by severe hypoxemia due to low alveolar PO2 levels?
What changes in temperature and tissue pH contribute to the O2-hemoglobin dissociation curve shift during exercise?
What changes in temperature and tissue pH contribute to the O2-hemoglobin dissociation curve shift during exercise?
At high altitude, where the partial pressure of oxygen (PAO2) is reduced throughout the lungs, what is the primary effect on pulmonary blood flow?
At high altitude, where the partial pressure of oxygen (PAO2) is reduced throughout the lungs, what is the primary effect on pulmonary blood flow?
How do increases in PCO2 contribute to changes in blood pH and hemoglobin's oxygen-carrying capacity?
How do increases in PCO2 contribute to changes in blood pH and hemoglobin's oxygen-carrying capacity?
What is the primary effect of hyperventilation on blood pH and oxygen-hemoglobin dissociation?
What is the primary effect of hyperventilation on blood pH and oxygen-hemoglobin dissociation?
What is the primary mechanism by which increased temperature causes a rightward shift in the oxygen-hemoglobin dissociation curve?
What is the primary mechanism by which increased temperature causes a rightward shift in the oxygen-hemoglobin dissociation curve?
At high altitude, where the partial pressure of oxygen (PO2) in the inspired air is lower, what effect would this have on the oxygen-hemoglobin dissociation curve?
At high altitude, where the partial pressure of oxygen (PO2) in the inspired air is lower, what effect would this have on the oxygen-hemoglobin dissociation curve?
What is the primary mechanism by which increased 2,3-diphosphoglycerate (2,3DPG) concentration in red blood cells causes a rightward shift in the oxygen-hemoglobin dissociation curve?
What is the primary mechanism by which increased 2,3-diphosphoglycerate (2,3DPG) concentration in red blood cells causes a rightward shift in the oxygen-hemoglobin dissociation curve?
What is the primary effect of hyperventilation on the oxygen-hemoglobin dissociation curve?
What is the primary effect of hyperventilation on the oxygen-hemoglobin dissociation curve?
How does high altitude exposure affect the oxygen-hemoglobin dissociation curve?
How does high altitude exposure affect the oxygen-hemoglobin dissociation curve?
What is the primary effect of a low ventilation/perfusion (V/Q) ratio in the lungs?
What is the primary effect of a low ventilation/perfusion (V/Q) ratio in the lungs?
What is the primary mechanism by which carbon dioxide is transported in the blood from the tissues to the lungs?
What is the primary mechanism by which carbon dioxide is transported in the blood from the tissues to the lungs?
What is the primary mechanism by which the O2-hemoglobin dissociation curve shifts to the left in response to hyperventilation?
What is the primary mechanism by which the O2-hemoglobin dissociation curve shifts to the left in response to hyperventilation?
At high altitudes with low alveolar PO2, what is the primary effect on blood oxygen levels?
At high altitudes with low alveolar PO2, what is the primary effect on blood oxygen levels?
What is the primary effect of hyperventilation on the blood partial pressure of carbon dioxide (PCO2)?
What is the primary effect of hyperventilation on the blood partial pressure of carbon dioxide (PCO2)?
In regions with high ventilation-to-perfusion (V/Q) ratios, what is the primary characteristic of gas exchange?
In regions with high ventilation-to-perfusion (V/Q) ratios, what is the primary characteristic of gas exchange?
How does the shift in the O2-hemoglobin dissociation curve to the right affect pulmonary capillary blood in terms of CO2 transport?
How does the shift in the O2-hemoglobin dissociation curve to the right affect pulmonary capillary blood in terms of CO2 transport?
Which of the following is the primary mechanism by which the oxygen-hemoglobin dissociation curve shifts to the right in response to high altitude hypoxia?
Which of the following is the primary mechanism by which the oxygen-hemoglobin dissociation curve shifts to the right in response to high altitude hypoxia?
What is the primary reason for the right shift of the O2-hemoglobin dissociation curve due to increases in temperature?
What is the primary reason for the right shift of the O2-hemoglobin dissociation curve due to increases in temperature?
In exercising skeletal muscle, why is the O2-hemoglobin dissociation curve shift to the right considered logical?
In exercising skeletal muscle, why is the O2-hemoglobin dissociation curve shift to the right considered logical?
What is the primary effect of hyperventilation on blood pH and the oxygen-hemoglobin dissociation curve?
What is the primary effect of hyperventilation on blood pH and the oxygen-hemoglobin dissociation curve?
How does the kidney distinguish between a lack of red blood cells and a lack of oxygen, according to the passage?
How does the kidney distinguish between a lack of red blood cells and a lack of oxygen, according to the passage?
Which of the following effects is NOT typically associated with hyperventilation?
Which of the following effects is NOT typically associated with hyperventilation?
Which of the following is the primary mechanism by which carbon dioxide is transported in the blood?
Which of the following is the primary mechanism by which carbon dioxide is transported in the blood?
At high altitudes where alveolar PO2 is low, what effect would this have on the oxygen-hemoglobin dissociation curve?
At high altitudes where alveolar PO2 is low, what effect would this have on the oxygen-hemoglobin dissociation curve?
Which statement best describes how CO2 is primarily transported in the blood?
Which statement best describes how CO2 is primarily transported in the blood?
In regions of the lungs with a high ventilation/perfusion (V/Q) ratio, what is the typical characteristic?
In regions of the lungs with a high ventilation/perfusion (V/Q) ratio, what is the typical characteristic?
What is the primary mechanism by which the O2-hemoglobin dissociation curve shifts to the right during exercise?
What is the primary mechanism by which the O2-hemoglobin dissociation curve shifts to the right during exercise?
What is the primary effect of hyperventilation on the oxygen-hemoglobin dissociation curve?
What is the primary effect of hyperventilation on the oxygen-hemoglobin dissociation curve?
At high altitudes with low alveolar PO2, what is the primary effect on arterial blood PO2?
At high altitudes with low alveolar PO2, what is the primary effect on arterial blood PO2?
What is the primary effect of a ventilation/perfusion (V/Q) mismatch in the lungs?
What is the primary effect of a ventilation/perfusion (V/Q) mismatch in the lungs?
What is the primary mechanism by which carbon dioxide is transported in the blood from the tissues to the lungs?
What is the primary mechanism by which carbon dioxide is transported in the blood from the tissues to the lungs?
What is the primary cause of a low ventilation/perfusion (V/Q) ratio in the lungs?
What is the primary cause of a low ventilation/perfusion (V/Q) ratio in the lungs?
What is the primary effect of a high ventilation/perfusion (V/Q) ratio on arterial blood gases?
What is the primary effect of a high ventilation/perfusion (V/Q) ratio on arterial blood gases?
What is the primary mechanism by which erythropoietin (EPO) increases oxygen delivery to the tissues?
What is the primary mechanism by which erythropoietin (EPO) increases oxygen delivery to the tissues?
What is the primary effect of a decrease in PCO2 on hemoglobin's affinity for oxygen?
What is the primary effect of a decrease in PCO2 on hemoglobin's affinity for oxygen?
What is the primary consequence of a ventilation/perfusion (V/Q) mismatch in the lungs?
What is the primary consequence of a ventilation/perfusion (V/Q) mismatch in the lungs?
According to the passage, what is the primary mechanism by which hypoxic vasoconstriction in the lungs occurs?
According to the passage, what is the primary mechanism by which hypoxic vasoconstriction in the lungs occurs?
What is the primary mechanism by which the oxygen-hemoglobin dissociation curve shifts to the right in response to high altitude hypoxia?
What is the primary mechanism by which the oxygen-hemoglobin dissociation curve shifts to the right in response to high altitude hypoxia?
What is the primary effect of hyperventilation on the partial pressure of carbon dioxide (PCO2) in the alveolar air?
What is the primary effect of hyperventilation on the partial pressure of carbon dioxide (PCO2) in the alveolar air?
According to the passage, what is the primary factor regulating the distribution of pulmonary blood flow?
According to the passage, what is the primary factor regulating the distribution of pulmonary blood flow?
What is the primary mechanism by which carbon dioxide is transported in the blood from the tissues to the lungs?
What is the primary mechanism by which carbon dioxide is transported in the blood from the tissues to the lungs?
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Study Notes
Gas Laws
- General gas law: P1.V1 = P2.V2, where P is pressure and V is volume
- Boyle's law: if P increases, V decreases, and vice versa
- Dalton's law of partial pressures: the total pressure of a mixture of gases is equal to the sum of the partial pressures of each gas
- Henry's law: the concentration of a dissolved gas is directly proportional to the partial pressure of the gas
- Fick's law: the rate of diffusion of a gas is directly proportional to the partial pressure gradient
Gas Exchange
- In alveolar air, PAO2 is 100 mm Hg, and PACO2 is 40 mm Hg
- O2 leaves alveolar air and enters pulmonary capillary blood, while CO2 leaves pulmonary capillary blood and enters alveolar air
- Blood entering the pulmonary capillaries is mixed venous blood, with PO2 = 40 mm Hg and PCO2 = 46 mm Hg
- Diffusion limited gas exchange: the total amount of gas transported across the alveolar-capillary barrier is limited by the diffusion process
- Perfusion limited gas exchange: the total amount of gas transported across the alveolar-capillary barrier is limited by blood flow
Oxygen Transport
- O2 is bound to hemoglobin in red blood cells
- O2 binding capacity and O2 content: O2 is transported from the lungs to the tissues
- O2 hemoglobin dissociation curve: O2 is released from hemoglobin in response to decreasing pH and increasing temperature
- O2 delivery to tissues: O2 is released from hemoglobin in response to decreasing pH and increasing temperature
- Erythropoietin (EPO): a hormone that stimulates the production of red blood cells in response to hypoxia
Carbon Dioxide Transport
- CO2 is produced in the tissues from aerobic metabolism
- CO2 is transported in the blood in the form of HCO3- and carbaminohemoglobin
- CO2 transport in the blood: CO2 is transported from the tissues to the lungs
- HCO3- and Cl- exchange: an anion exchange protein called band three protein facilitates the exchange of HCO3- and Cl- across the red blood cell membrane
Pulmonary Blood Flow
- Pulmonary blood flow is directly proportional to the pressure gradient between the pulmonary artery and the left atrium
- Pulmonary blood flow is inversely proportional to the resistance of the pulmonary vasculature
- Hypoxic vasoconstriction: decreases in PAO2 produce pulmonary vasoconstriction, reducing blood flow to poorly ventilated areas of the lung
- At high altitude, PAO2 is reduced, producing global vasoconstriction of pulmonary arterioles and an increase in pulmonary vascular resistance
Regulation of Pulmonary Blood Flow
- The major factor regulating pulmonary blood flow is the partial pressure of O2 in alveolar gas, PAO2
- Decreases in PAO2 produce pulmonary vasoconstriction, reducing blood flow to poorly ventilated areas of the lung
- Hypoxic vasoconstriction mechanism: not well understood
- Fetal circulation: another example of global hypoxic vasoconstriction### Gas Laws
- Boyle's Law: P1.V1 = P2.V2, where an increase in pressure (P) results in a decrease in volume (V), and vice versa
- Gas laws include Dalton's law of partial pressures and Henry's law for concentrations of dissolved gases
- Diffusion of gases follows Fick's law
Gas Exchange
- In alveolar air, PO2 is 100 mm Hg, lower than in inspired air, while PCO2 is 40 mm Hg, higher than in inspired air
- O2 leaves alveolar air and enters pulmonary capillary blood, while CO2 leaves pulmonary capillary blood and enters alveolar air
- Blood entering pulmonary capillaries is mixed venous blood with a low PO2 (40 mm Hg) and high PCO2 (46 mm Hg)
Respiratory System
- Conducting zone includes the nose, mouth, trachea, bronchi, and bronchioles
- Respiratory zone includes respiratory bronchioles and alveoli
- Blood flow and ventilation rates affect gas exchange in the lungs
- Anatomic dead space is the volume of conducting airways that do not participate in gas exchange (approximately 150 ml in normal persons)
Oxygen Transport
- O2 binds to hemoglobin in blood, with a binding capacity and content that affects O2 delivery to tissues
- O2 hemoglobin dissociation curve shows the relationship between PO2 and O2 saturation
- Changes in the curve occur due to factors like pH, temperature, and 2,3-BPG levels
- Erythropoietin (EPO) is induced in response to hypoxia, leading to increased red blood cell production
Ventilation and Perfusion
- Ventilation (V̇) and perfusion (Q̇) ratios affect gas exchange in the lungs
- Ventilation/perfusion relationships can be affected by factors like pulmonary embolism and shunts
- Dead space is ventilation of lung regions that are not perfused
- High V̇/Q̇ regions have high ventilation relative to perfusion, while low V̇/Q̇ regions have low ventilation relative to perfusion
- Right-to-left shunts occur when perfusion of lung regions occurs without ventilation
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