48 Questions
Which gas exchange occurs between alveoli and blood?
PO2 alveolar air $>$ PO2 blood and PCO2 blood $>$ PCO2 alveolar air
What is the normal range for PO2 in arterial blood?
85–100 mm Hg
What is the normal range for PCO2 in venous blood?
35–45 mm Hg
What happens to gas exchange between blood and tissues?
PO2 blood $>$ PO2 tissue and PCO2 tissue $>$ PCO2 blood
Which cells initiate an increase in ventilation in response to a decrease in PO2, an increase in pH, and an increase in PCO2?
Peripheral chemoreceptors
Where are the central chemoreceptors located?
In the CNS
What happens if the O2 falls below 60 mm Hg?
It triggers a reflex in carotid body cells
Which receptors respond to physical injury or irritation in the airway mucosa?
Irritant receptors
What is responsible for affecting the patterns of ventilation?
Cerebrum and hypothalamus
What can affect breath rate and depth by bypassing the brain stem?
Limbic system
What is converted to bicarbonate and H+ in the brain ECF?
CO2
What responds to changes in PCO2 in the arterial blood?
Central chemoreceptors
What factors affect oxygen-hemoglobin binding?
Changes in plasma pH, temperature, and PCO2
How is carbon dioxide primarily transported in the blood?
As bicarbonate ions
What enhances fetal hemoglobin's ability to bind oxygen?
Its structure
Which enzyme converts CO2 to bicarbonate ions in red blood cells?
Carbonic anhydrase
What controls breathing in the body?
Neurons in the medulla
What influences oxygen-hemoglobin binding along with the Bohr effect?
2,3-bisphosphoglycerate (2,3-BPG) production
What does gas movement in alveoli depend on?
Pressure gradient, gas solubility in liquid, and temperature
How does hemoglobin pick up oxygen in the blood?
Picking up maximum oxygen possible under normal conditions
What removes CO2 from the lungs?
Diffusion down the PCO2 gradient from blood to alveoli
What maintains electrical neutrality during CO2 transportation?
Chloride shift
What controls inspiratory and expiratory muscles?
Neural networks in the brainstem
How is continuous ventilation modulation achieved?
Through chemoreceptor- and mechanoreceptor-linked reflexes and higher brain centers
What is the normal range for PO2 in arterial blood?
85-100 mm Hg
What is the normal range for PCO2 in venous blood?
35-45 mm Hg
Where are the central chemoreceptors located?
In the brain stem
What happens to gas exchange between alveoli and blood?
PO2 alveolar air > PO2 blood and PCO2 blood > PCO2 alveolar air
Which receptors are located in the carotid bodies and sense changes in PO2, pH, and PCO2?
Specialized glomus cells
Where are the central chemoreceptors located and what do they respond to?
Located in the CNS and respond to changes in PCO2
Which reflex is responsible for terminating inspiration if tidal volume exceeds a certain volume?
Hering-Breuer inflation reflex
Which brain centers can change the control of the brain stem on breath rate and depth?
Cerebrum and hypothalamus
What is the primary function of peripheral chemoreceptors located in the carotid bodies?
To sense changes in PO2, pH, and PCO2
What does the dorsal respiratory group (DRG) control?
Inspiratory muscles
What is the role of the limbic system in affecting breath rate and depth?
It can bypass the brain stem to affect breath rate and depth
What is the function of the irritant receptors in the airway mucosa?
To respond to physical injury or irritation
What factors affect oxygen-hemoglobin binding?
Changes in plasma pH, temperature, and PCO2
What enhances fetal hemoglobin's ability to bind oxygen?
Its structure
How is carbon dioxide primarily transported in the blood?
As bicarbonate ions
What controls breathing in the body?
Neurons in the medulla
What removes CO2 from the lungs?
Diffusion down the PCO2 gradient from blood to alveoli
What is the role of 2,3-bisphosphoglycerate (2,3-BPG) in oxygen-hemoglobin binding?
Influences oxygen-hemoglobin binding
How is gas movement in alveoli dependent?
On pressure gradient, gas solubility in liquid, and temperature
What is the function of carbonic anhydrase in RBCs?
Converts CO2 to bicarbonate ions
What affects oxygen-hemoglobin binding along with the Bohr effect?
H+ and CO2
What initiates an increase in ventilation in response to a decrease in PO2, an increase in pH, and an increase in PCO2?
Chemoreceptor-linked reflexes
What maintains electrical neutrality during CO2 transportation?
Chloride shift
What responds to changes in PCO2 in the arterial blood?
Central chemoreceptors
Study Notes
Factors Affecting Gas Exchange and Hypoxia
- Gas movement in alveoli is proportional to pressure gradient, gas solubility in liquid, and temperature.
- Gas entering capillaries first dissolves in plasma; hemoglobin picks up maximum oxygen possible under normal conditions.
- Several factors affect oxygen-hemoglobin binding, including changes in plasma pH, temperature, and PCO2.
- The Bohr effect and 2,3-bisphosphoglycerate (2,3-BPG) production influence oxygen-hemoglobin binding.
- Fetal hemoglobin's structure enhances its ability to bind oxygen in low-oxygen environments.
- Carbon dioxide is transported in plasma, diffused into RBCs, bound to hemoglobin, or converted to bicarbonate ions.
- Carbonic anhydrase in RBCs converts CO2 to bicarbonate ions; chloride shift maintains electrical neutrality.
- Hemoglobin's interaction with H+ and CO2 affects its binding affinity for oxygen.
- CO2 is removed from the lungs by diffusion down the PCO2 gradient from blood to alveoli.
- Neural networks in the brainstem act as a central pattern generator, controlling inspiratory and expiratory muscles.
- Continuous modulation of ventilation occurs through chemoreceptor- and mechanoreceptor-linked reflexes and higher brain centers.
- Neurons in the medulla control breathing, with the dorsal and ventral respiratory groups playing different roles.
Factors Affecting Gas Exchange and Hypoxia
- Gas movement in alveoli is proportional to pressure gradient, gas solubility in liquid, and temperature.
- Gas entering capillaries first dissolves in plasma; hemoglobin picks up maximum oxygen possible under normal conditions.
- Several factors affect oxygen-hemoglobin binding, including changes in plasma pH, temperature, and PCO2.
- The Bohr effect and 2,3-bisphosphoglycerate (2,3-BPG) production influence oxygen-hemoglobin binding.
- Fetal hemoglobin's structure enhances its ability to bind oxygen in low-oxygen environments.
- Carbon dioxide is transported in plasma, diffused into RBCs, bound to hemoglobin, or converted to bicarbonate ions.
- Carbonic anhydrase in RBCs converts CO2 to bicarbonate ions; chloride shift maintains electrical neutrality.
- Hemoglobin's interaction with H+ and CO2 affects its binding affinity for oxygen.
- CO2 is removed from the lungs by diffusion down the PCO2 gradient from blood to alveoli.
- Neural networks in the brainstem act as a central pattern generator, controlling inspiratory and expiratory muscles.
- Continuous modulation of ventilation occurs through chemoreceptor- and mechanoreceptor-linked reflexes and higher brain centers.
- Neurons in the medulla control breathing, with the dorsal and ventral respiratory groups playing different roles.
Test your knowledge of the factors influencing gas exchange and hypoxia with this quiz. Explore concepts such as gas movement in alveoli, oxygen-hemoglobin binding, carbon dioxide transport, and the neural control of breathing. Gain insight into the physiological mechanisms that underlie respiratory function and regulation.
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