Gas exchange and gas transport Flashcards
(31 cards)

Concentration and pressure are __________ related
Directly
External ventilation stage two: pulmonary gas exchange (diffusional exchange of gases between _________ and _________. 
Alveolus and pulmonary capillaries
Dalton’s law
Partial pressure: in a mixture of gases,
P(total) = P1 + P2 +P3 +…
Henry’s law
Cg= Kg (Pg)
Cg= [g] in water Pg= partial pressure of the gas in the air Kg= henry’s constant (solubility of the gas in water)
More simply, P= C if we know something about the solubility of the gas and water
This law compares partial pressures in the air and solubility in water
Henry’s law
 *because Alveolus is lined with water
- CO2 is about 20 times more soluble in water than oxygen
Three determinants of alveolar gas
1) metabolic rate
2) atmosphere P(gas)
3) ventilation rate
(CO2 or oxygen) highest in cells and lowest in atmosphere
CO2
Opposite for oxygen
What is the order of diffusion from the alveolar air space through the respiratory membrane to the capillary?
- Type 1 cell (epithelial cell in alveolar wall)
- areolar basement membrane
- capillary basement membrane
- endothelial cell in capillary wall
- opposite diffusional gas exchange occurs between systemic capillaries and tissues 
External ventilation stage three….
Gas transport (transport of O2) 
 ____% of O2 dissolved in plasma (this is the PO2)
____% carried on hemoglobin
1
99
How many subunits does hemoglobin have?
For subunits. 02 can stick and carry four 02 molecules
What causes the curve line instead of a straight line for the hemoglobin-oxygen disassociation curve.
Corporative binding 
Key physiologic factors affecting Hb-O2 affinity
- pH (Bohr effect)
- Temperature
- CO2 (carbamino effect)
How does pH (Bhor effect) effect Hb-O2 affinity?
- H + bind to allosteric region of hemoglobin and decrease the affinity for O2
- Acid helps hemoglobin release O2 for use
How does temperature affect Hb-O2 affinity?
An increase in temperature helps get more oxygen??
How does CO2 (carbamino effect) influence Hb-O2 affinity? 
CO2 combined to a different allosteric site than H+
P(CO2) decreases and % of Hb increases
Of total CO2 carried in the blood:
____% dissolved in plasma (PCO2)
____% carried on hemoglobin
____% dissolved in blood as bicarbonate ion (HCO3-) 
5
7
88
At tissues, CO2 diffuses into blood and is converted into ________. At Long, bicarb is converted back to CO2 and diffuses into Alveolus 
Bicarbonate 
When CO2 increases the results in the formation of each plus which….
Lowers pH (Bhor effect) 
If H+ introduced form some other source, bicarb can act as a
Buffer
There’s a close relationship between _____, _______, and pH
CO2, bicarb
Henderson – Hasselbalch equation
pH= 6.1 + Log. [HCO3-]/ [CO2]
What are The two things that affect acid/base disturbances?
-  respiratory (always due to changes in PCO2) 
2. Metabolic (changes in bicarbonate) 
