p.14
Gas Exchange Mechanisms
What happens to arterial blood when it reaches the tissue?
Dissolved O2 diffuses out of systemic capillaries into cells.
p.4
Diffusion Principles in Respiratory Physiology
What factors are constant in our respiratory tissue affecting diffusion?
Surface area for gas exchange, membrane permeability, and membrane thickness.
p.9
Physiological Responses to Low Oxygen Levels
What happens if the alveolar P O2 can't reach 100 mm Hg?
It leads to low arterial P O2 and reduces oxygen delivery to cells, causing symptoms like headache, dizziness, and nausea.
p.16
Oxygen-Hemoglobin Dissociation Curve
What role does the respiratory system play in relation to the oxygen-hemoglobin dissociation curve?
Gas exchange and transport.
p.5
Gas Exchange Mechanisms
Is equilibrium equivalent to equal concentrations of air molecules in air and water?
No, equilibrium does not mean equal concentrations.
p.3
Gas Exchange Mechanisms
What are the two main components of gas exchange in the respiratory system?
Exchange of gases between compartments (diffusion across cell membranes) and transport of gases in the blood.
p.13
Gas Exchange Mechanisms
What is the sequence of oxygen diffusion from the alveoli to hemoglobin?
O2 from alveoli to plasma to RBC to Hb.
p.18
Factors Affecting Gas Exchange
How does temperature affect oxygen-hemoglobin binding?
Increased temperature decreases the affinity of hemoglobin for oxygen, leading to more oxygen being unloaded to the tissues.
p.12
Hemoglobin Structure and Function
What are the components of hemoglobin?
Four subunits, each containing a globin and an iron-containing heme group.
p.18
Factors Affecting Gas Exchange
How does P CO2 affect hemoglobin's structure?
P CO2 alters the structure of hemoglobin, decreasing its affinity for oxygen.
p.17
Oxygen-Hemoglobin Dissociation Curve
What is the Bohr effect?
The shift in the hemoglobin-oxygen curve resulting from a change in pH, leading to more oxygen being released from hemoglobin to the tissues.
p.15
Oxygen-Hemoglobin Dissociation Curve
What happens to hemoglobin saturation when alveolar P O2 falls to ≥ 60 mm Hg?
Hemoglobin still reaches > 90% saturation.
p.11
Transport of Gases in Blood
How does hemoglobin increase oxygen transport in blood?
By binding to oxygen molecules, allowing for a greater total oxygen carrying capacity.
p.20
Carbon Dioxide Transport Mechanisms
What is the reaction catalyzed by carbonic anhydrase?
CO2 + H2O ↔ H2CO3 ↔ H+ + HCO3-.
p.15
Oxygen-Hemoglobin Dissociation Curve
What is reflected by the steep slope in the oxygen-hemoglobin dissociation curve?
A significant reduction in % saturation of hemoglobin as P O2 decreases.
p.5
Oxygen and Carbon Dioxide Solubility
What does low O2 solubility imply about concentrations at equilibrium?
Concentrations are not equal despite equal PO2 in air and water.
p.3
Transport of Gases in Blood
What do pulmonary veins do in the respiratory system?
They carry oxygenated blood from the lungs to the left atrium of the heart.
p.19
Hemoglobin Structure and Function
What is the difference between maternal hemoglobin (HbA) and fetal hemoglobin (FHb)?
Fetal hemoglobin has two gamma chains, enhancing its ability to bind oxygen in low-oxygen environments.
p.14
Oxygen-Hemoglobin Dissociation Curve
How does the equilibrium of oxygen-Hb binding reaction get disturbed?
Due to the decrease in plasma P O2.
p.18
Factors Affecting Gas Exchange
What happens to hemoglobin's affinity for oxygen when tissue metabolism increases?
The affinity of hemoglobin for oxygen decreases.
p.13
Hemoglobin Structure and Function
What does the binding and release of oxygen in hemoglobin depend on?
The P O2 of plasma surrounding the RBC.
p.15
Oxygen-Hemoglobin Dissociation Curve
What is the relationship between P O2 and hemoglobin saturation?
The % saturation of hemoglobin increases as P O2 increases.
p.5
Gas Exchange Mechanisms
What does equilibrium in gas movement refer to?
The movement of air molecules from air to water is equal to the movement from water back to air.
p.13
Gas Exchange Mechanisms
What causes more oxygen to diffuse from alveoli to red blood cells?
The removal of dissolved O2 in plasma decreases plasma P O2.
p.15
Oxygen-Hemoglobin Dissociation Curve
What occurs when P O2 falls below 60 mm Hg?
There is a significant reduction in % saturation of hemoglobin.
p.12
Hemoglobin Structure and Function
What is the composition of a small portion of adult hemoglobin (HbA2)?
Two α chains and two δ chains.
p.12
Hemoglobin Structure and Function
What is the composition of fetal hemoglobin (HbF)?
Two α chains and two γ chains.
p.21
Carbon Dioxide Transport Mechanisms
What reaction occurs when carbon dioxide combines with water?
CO2 + H2O → H2CO3 (carbonic acid).
p.3
Diffusion Principles in Respiratory Physiology
What is the significance of diffusion in gas exchange?
It allows gases to move across cell membranes between compartments.
p.1
Gas Exchange Mechanisms
What is the primary function of the respiratory system?
Gas exchange and transport.
p.14
Gas Exchange Mechanisms
What occurs to plasma P O2 as oxygen diffuses into cells?
Plasma P O2 decreases accordingly.
p.19
Hemoglobin Structure and Function
How does fetal hemoglobin (FHb) adapt to the low-oxygen environment of the placenta?
It binds oxygen more effectively due to its unique structure.
p.19
Transport of Gases in Blood
What happens to oxygen released by maternal hemoglobin at the placenta?
It is picked up by fetal hemoglobin.
p.14
Transport of Gases in Blood
What is the sequence of oxygen release from hemoglobin to the cells?
O2 from Hb to plasma, then from plasma to cells.
p.19
Hemoglobin Structure and Function
What role does the change in hemoglobin structure play in oxygen binding?
It affects the affinity of hemoglobin for oxygen, particularly in different environments.
p.18
Factors Affecting Gas Exchange
What is the carbamino effect?
It is the reaction of CO2 with hemoglobin to form Hb·CO2, which alters the structure of hemoglobin and decreases its affinity for oxygen.
p.17
Oxygen-Hemoglobin Dissociation Curve
How does a decrease in plasma pH affect hemoglobin's ability to bind oxygen?
A decrease in pH from 7.4 to 7.2 decreases the % saturation of hemoglobin from 75% to ~60% at P O2 of 40 mm Hg.
p.5
Gas Exchange Mechanisms
In what forms can gas molecules exist?
In gaseous form or dissolved in liquid.
p.16
Oxygen-Hemoglobin Dissociation Curve
How much oxygen do cells typically use at rest from the oxygen transport system?
¼ of the available oxygen.
p.4
Diffusion Principles in Respiratory Physiology
What is Fick's law of diffusion?
It states that the diffusion rate is proportional to the surface area, concentration gradient, and membrane permeability, and inversely proportional to membrane thickness.
p.5
Diffusion Principles in Respiratory Physiology
What happens when a gas is placed in contact with water?
A pressure gradient is created, causing gas molecules to move until equilibrium is reached.
p.16
Oxygen-Hemoglobin Dissociation Curve
What physiological significance does the oxygen-hemoglobin dissociation curve have?
It provides a large reservoir of oxygen that cells can draw on when metabolism increases.
p.17
Factors Affecting Gas Exchange
What happens to hemoglobin's oxygen release during exercise?
During exercise, anaerobic metabolism releases H+ into the cytoplasm and extracellular fluid, increasing H+ concentration and decreasing pH, which shifts the HbO2 curve to the right.
p.13
Gas Exchange Mechanisms
What happens in the pulmonary capillaries regarding oxygen?
O2 dissolved in plasma diffuses into red blood cells where it binds to hemoglobin.
p.17
Oxygen-Hemoglobin Dissociation Curve
What is the effect of pH on hemoglobin's oxygen saturation at a P O2 of 40 mm Hg?
At pH 7.2, hemoglobin releases 13% more oxygen compared to pH 7.4.
p.10
Transport of Gases in Blood
How is oxygen primarily transported in the blood?
Bound to hemoglobin (> 98%) and dissolved in plasma (< 2%).
p.21
Carbon Dioxide Transport Mechanisms
What is the form of carbon dioxide that binds with hemoglobin?
Hb • CO2 (carbaminohemoglobin).
p.3
Transport of Gases in Blood
What is the role of systemic veins?
They carry deoxygenated blood from the body tissues back to the right atrium of the heart.
p.6
Gas Exchange Mechanisms
How does temperature affect gas solubility in the body?
It can be ignored as body temperature is relatively constant.
p.8
Gas Exchange Mechanisms
How does carbon dioxide (CO2) move from tissues to capillaries?
Down its partial pressure gradient.
p.6
Oxygen and Carbon Dioxide Solubility
What characterizes a less soluble gas?
Very few gas molecules dissolve in the liquid even at high partial pressure.
p.2
Hemoglobin Structure and Function
What is the structure of hemoglobin?
Hemoglobin is a protein composed of four subunits, each containing an iron atom.
p.12
Hemoglobin Structure and Function
What is the composition of most adult hemoglobin (HbA)?
Two α chains and two β chains.
p.3
Transport of Gases in Blood
What is the role of pulmonary arteries in the respiratory system?
They carry deoxygenated blood from the right ventricle to the lungs for gas exchange.
p.3
Transport of Gases in Blood
What is the function of systemic arteries?
They carry oxygenated blood from the left ventricle to the body tissues.
p.21
Carbon Dioxide Transport Mechanisms
What is the role of chloride in carbon dioxide transport?
Chloride antiport allows HCO3- to leave the RBC in exchange for Cl- to maintain electrical neutrality.
p.10
Diffusion Principles in Respiratory Physiology
What is the significance of the fused basement membranes in gas exchange?
They allow for efficient diffusion of gases between alveoli and capillaries.
p.7
Gas Exchange Mechanisms
What is the role of the circulatory system in gas exchange?
It transports oxygen from the lungs to peripheral tissues.
p.22
Gas Exchange Mechanisms
What are the partial pressures of oxygen and carbon dioxide in the alveoli?
P O2 = 100 mm Hg, P CO2 = 40 mm Hg.
p.6
Oxygen and Carbon Dioxide Solubility
What does solubility of a gas refer to?
How easily a gas dissolves in a liquid.
p.8
Gas Exchange Mechanisms
What happens to CO2 at the pulmonary capillaries?
It diffuses from venous capillaries to the alveoli.
p.2
Physiological Responses to Low Oxygen Levels
What is the consequence of low arterial oxygen content?
It can lead to hypoxia and impaired cellular function.
p.2
Transport of Gases in Blood
What role does hemoglobin play in gas transport?
Hemoglobin transports oxygen from the lungs to the tissues and carbon dioxide from the tissues back to the lungs.
p.2
Oxygen-Hemoglobin Dissociation Curve
What is the physiological significance of the shape of the hemoglobin dissociation curve?
It allows for efficient oxygen loading in the lungs and unloading in the tissues.
p.9
Impact of Altitude on Gas Exchange
How does P O2 in air change with altitude?
P O2 decreases along with atmospheric pressure (P atm).
p.4
Diffusion Principles in Respiratory Physiology
What does the diffusion rate depend on according to Fick's law?
Surface area, concentration gradient, membrane permeability, and membrane thickness.
p.7
Gas Exchange Mechanisms
How does oxygen move from the alveoli into the capillaries?
Oxygen moves down its partial pressure gradient.
p.4
Diffusion Principles in Respiratory Physiology
What is the relationship between diffusion distance and gas exchange?
Shorter diffusion distance enhances gas exchange efficiency.
p.7
Gas Exchange Mechanisms
What happens to the partial pressure of oxygen (P O2) in the pulmonary vein leaving the lung?
It equals the P O2 in the alveoli, which is 100 mm Hg.
p.11
Hemoglobin Structure and Function
What percentage of oxygen is carried by red blood cells with hemoglobin at normal P O2?
98% of their maximum load.
p.10
Transport of Gases in Blood
What is the role of red blood cells (RBC) in oxygen transport?
They carry oxygen bound to hemoglobin to cells for cellular respiration.
p.21
Carbon Dioxide Transport Mechanisms
How does hemoglobin help in maintaining body pH?
Hemoglobin buffers and binds to hydrogen ions (H+) to prevent sharp changes in body pH.
p.10
Gas Exchange Mechanisms
What is the role of surfactant in the alveolar air space?
It reduces surface tension, helping to keep alveoli open for gas exchange.
p.10
Physiological Responses to Low Oxygen Levels
What happens to oxygen after it is transported to cells?
It is used in cellular respiration.
p.21
Carbon Dioxide Transport Mechanisms
What happens to HCO3- in red blood cells during carbon dioxide transport?
HCO3- leaves the RBC in exchange for Cl-.
p.2
Gas Exchange Mechanisms
What is the primary function of the respiratory system?
Gas exchange and transport.
p.6
Oxygen and Carbon Dioxide Solubility
Which gas is more soluble in water, CO2 or O2?
CO2 is more soluble than oxygen in water.
p.5
Gas Exchange Mechanisms
What is the significance of the Respiratory System in relation to gas exchange?
It is responsible for gas exchange and transport.
p.10
Gas Exchange Mechanisms
What structures facilitate gas exchange in the lungs?
Alveolar membrane and capillary endothelium.
p.21
Carbon Dioxide Transport Mechanisms
What is the significance of carbonic anhydrase (CA) in red blood cells?
CA catalyzes the conversion of CO2 and H2O to H2CO3, facilitating carbon dioxide transport.
p.6
Oxygen and Carbon Dioxide Solubility
What characterizes a soluble gas?
A large amount of gas molecules goes into solution even at low gas pressure.
p.8
Gas Exchange Mechanisms
What is the significance of the P O2 and P CO2 gradients in gas exchange?
They facilitate the diffusion of oxygen and carbon dioxide between alveoli and tissues.
p.2
Oxygen-Hemoglobin Dissociation Curve
What does the hemoglobin dissociation curve represent?
It shows the relationship between the partial pressure of oxygen and the saturation of hemoglobin with oxygen.
p.2
Factors Affecting Gas Exchange
What factors affect the oxygen-hemoglobin dissociation curve?
Factors include pH, temperature, and levels of carbon dioxide.
p.7
Gas Exchange Mechanisms
How does oxygen diffuse from the plasma into cells?
Oxygen diffuses down its partial pressure gradient until venous blood has the same P O2 as the cells.
p.6
Gas Exchange Mechanisms
What are the three factors that affect the movement of gas from air to liquid?
Pressure gradient, temperature, and solubility of the gas.
p.2
Oxygen and Carbon Dioxide Solubility
How do the solubilities of oxygen and carbon dioxide compare?
Carbon dioxide is more soluble than oxygen.
