Respiratory Physiology II Ch 11 Flashcards
The respiratory Zone
diffusion of 02 into the blood and co2 out of the blood occurs here (alveoli where epithelia cells contact external mediums)
The Respiratory membrane
extremally thin barrier in the Respiratory zone which separates alveolar air from blood in the capillaries
What is the driving force for the diffusion of gases
Partial pressures( gas diffusion occurs down the gas partial pressure gradient )
The Partial pressure of gases in the fluid phase
The partial pressure of as which is dissolved in a liquid is equal to the partial pressure of that gas in the air phase with which the fluid is a eq w
( the capacity of water to hold 02 is much lower then that of air )
gases diffuse according to what
Their partial pressures not their concentrations
Most efficient Gas exchanger
Least is found in mammals most is found in fish
and blood PO2> expired PO2 in efficient system
The increase respiratory surface provides the most efficient system
PP of O2 does what during each step of the O2 transport pathway
Decreases
Oxygen transport Pathway
Ventilation–> diffusion across r pathway surface–> Circulation–> cellular utilization
Alveolar air and blood leaving lungs PP
very similar PP
PP in blood leaving lungs and entering systemic capillary beds
they are the same
PP in cells vs blood
They are very different
PP in venous blood leaving the systemic capillaries and entering the pulmonary capillary beds
They are the same
Haemoglobin
Each composed of 4 subunits each of which consists of a heme ring which binds 1 O2 molecules and and polypeptide which binds CO2 and other accessory’s.
transport of O2 via haemoglobin
as blood passes through the tissues 02 diffuses into the tissues and reduces the Blood P02 which promotes the release of 02 thus formation of deoxyhemoglobin thus making Hb desaturated in the tissues
Positive Allosteric modulator for haemoglobins affinity for 02
O2
negative allosteric modulator in hemoglobin for H and CO2
O2
How does O2 binding promote further O2 binding
when O2 binds it removes salt bridges and favors protein conformation in the R sate
Flat region of the Hb-oxygen eq curve
Provides safety margin for 02 loading if arterial P02 falls ( this region is highly saturated with hemoglobin)
The Knee and steep part of the Hb-oxygen curve
Located to enhance O2 unloading during exercise, this area is associated with small decrease in the venous Po2(mild hemoglobin saturation)
The bohr shift on the Hb-oxygen eq curve
Improves O2 unloading during exercise
increase in PvCO2 shifts curve right and decrease in VpH also shifts curve right
Increase in temperature and Hb-equilibrium curve
Increase in blood temp shifts the curve right enhancing the unloading of O2
Increase in RBC phospahte does what to the Hb-oxygen eq curve
Shifts it right
Transport of CO2 in the blood
10% is physically dissolved
30% binds to Hb to form carbamino-CO2
60% is transported as HCO3 ion and dissolved in the plasma
role of Carbonic Anhydrase
to catalyze reactions
