increasing the volume of the chest cavity and thus lowering the pressure which allows for air to be pulled into the lungs
portions of the air passages that do not have a respiratory surface
how is breathing controlled?
pH detectors in the medullary respiratory center cause the breathing rate to increase in response to exercise
explain how oxygen moves from the alveolus to the blood
diffuses across the wall
does this because the blood has a smaller PO2 than what the PO2 is in the alveolus
a nonprotein group that is binder to the four polypeptide chains found in hemoglobin
contains an iron ion that can bind to an oxygen molecule
why is the the oxygen-hemoglobin equilibrium curve S-shaped?
because the binding of each successive oxygen molecule to a subunit of the hemoglobin molecule causes a conformational change in the protein that makes the remaining subunits much more likely to bind to oxygen (*called cooperating binding*)
why is cooperative binding important?
it makes hemoglobin sensitive to changes in the PO2 of tissues
shape changes in hemoglobin resulting from a decrease in PH and an increase in temperature cause hemoglobin to be more likely to release O2 at any given value of tissue PO2
catalyzes the formation of carbonic acid from carbon dioxide in water
how is most CO2 transported in blood?
in the form of HCO3- (the bicarbonate ion)
why is the carbonic anhydrase activity in red blood cells so important?
the protons produced by the reaction induce the Bohr shift which makes hemoglobin more likely to release oxygen
the partial pressure of CO2 in blood drops when it is converted to soluble bicarbonate ions which maintains the PP gradient
how does hemoglobin act as a buffer?
when it is not carrying oxygen molecules, it has a high affinity for protons which are present because of the dissociation of carbonic acid
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