Gas Exchange & Respiration Flashcards
Respiration
The transport of oxygen to cells, involves three diff processes
Ventilation
exchange of air between the lungs and environment (the physical act of breathing)
Gas Exchange
exchange of O2 and CO2 in alveoli and bloodstream (occurs passively in diffusion)
Cell Respiration
the act of the cells using O2 to make ATP
Diaphragm
muscle at the bottom of the ribs that is responsible for the act of breathing; drops down when contracting to increase volume and decrease pressure
Which muscles contract in inhalation?
Diaphragm and external intercostal muscles
Features of Alveoli
TRIM
T- thin wall, made of single-layer squamous cells
R-rich capillary network, allows for better gas exchange
I- Increased SA: Volume ratio, allows for optimization of O2 transfer
M- moist, prevents alveoli from collapsing and allows gases to dissolve
Type 1 Pneumocyte
Type of alveoli cell responsible for gas exchange, made of squamous cells and is 95% of alveoli surface
Intercostal Muscles
Muscles that are found on the inside and outside of the rib cage, responsible for inhalation
Dalton’s Law of Partial Pressure
Law that states that the total pressure in a system is proportional to the amount of pressure being enacted by each individual component (ie. air pressure is composed of pressure from O2, nitrogen, and more)
Type 2 Pneumocyte
Type of alveoli cell that secretes surfactants to keep a moist environment and prevent alveolus from sticking to each other
Why is it hard to breathe at high altitudes?
The total environmental pressure is lower, so while the concentration of O2 is the same, the partial pressure of O2 is lower, and therefore there’s less force pushing the oxygen into the lungs, leading to a lack of oxygen
Structure of hemoglobin
4 globular units, 2 alpha and 2 beta structures, and each polypeptide has an iron containing heme group that O2 binds to
Oxygen affinity
Refers to how well hemoglobin picks up and keeps the oxygen
Cooperative Binding
Process by which the hemoglobin undergoes a conformational change when an oxygen is bound to it, which means that when you gain an oxygen, it becomes easier and easier to pick up oxygen the more oxygen molecules are already bound to the hemoglobin
Factors that Effect the Oxygen Dissociation Curve
Higher temperature and a lower pH move the oxygen dissociation curve to the right, because the hemoglobin protein is destabilized and releases the O2 more readily
Why is the oxygen dissociation curve an S curve?
Because of cooperative binding, oxygen does not bind to hemoglobin at a linear rate
How is fetal hemoglobin different?
It contains a gamma instead of a beta subunit, and has a higher affinity for oxygen so it can take oxygen from mother’s hemoglobin through passive diffusion
Myoglobin
Contains 1 heme group, and can only contain one oxygen. Type of oxygen transport molecule found in the muscles as backup during exercise. Has a high affinity for oxygen, so will only release it when conditions are dire
Why is Dalton’s Law important?
Because gases with a larger gradient between partial pressures will diffuse faster than those with a smaller gradient. At high altitudes, the partial pressure of the air outside and the air in the capilliaries is closer than at sea level, so it diffuses slower and we get less oxygen
Bohr Effect
The drop in pH in the blood due to CO2 and increased presence of acids, which then shifts the oxygen dissociation curve to the right.
The presence of CO2 also reduces hemoglobin’s affinity for oxygen, and the acidity caused by the HCO3- also destabilizes the protein
Process of bohr effect + CO2
- CO2 moves from cells into the blood stream, and 70% is diffused into an RBC
- CO2 combines with H20 to form carbonic acid (H2CO3)
- Carbonic acid (H2CO3) immediately dissociates and loses an H+ ion, forming bicarbonate ions (HCO3-)
- Production of H+ ions increases acidity of blood
- HCO3- moves out of RBC and Cl- moves in (chloride shift) to keep the erythrocyte a neutral charge
- HCO3- binds with loose Na+ to form NaHCO3 (sodium bicarbonate) which prevents HCO3- from liberating another H+ ion
Haldane Effect
Says that oxygen displaces CO2 carried by hemoglobin to allow for oxygenation and gas exchange in the lungs
Anhydrase
Reverts carbonic acid back into CO2 and H2O
