Lecture 17: Gas Exchange and Transport

partial pressure

the pressure exerted by a single gas

13.7% or 104mmHg

what is the partial pressure of O2?

5.2% or 40mmHg

what is the partial pressure of CO2?

partial pressure gradients

What is the driving force behind gas movement during pulmonary and tissue gas exchange?

high to low pressure

how do gases move down pressure gradients?

104

what is the partial pressure of O2 in the alveoli?

40

what is the partial pressure of CO2 in the alveoli?

104

what is the partial pressure of O2 in the pulmonary vein?

40

what is the partial pressure of CO2 in the pulmonary vein?

40

what is the partial pressure of O2 in the pulmonary artery?

45

what is the partial pressure of CO2 in the pulmonary artery?

104

what is the partial pressure of O2 in the systemic artery?

40

what is the partial pressure of CO2 in the systemic artery?

40

what is the partial pressure of O2 in the systemic veins?

45

what is the partial pressure of CO2 in the systemic veins?

40

what is the partial pressure of O2 in the tissues?

45

what is the partial pressure of CO2 in the tissues?

surface area for exchange, distance gases must travel, and perfusion to the tissue

what are the factors that influence external and internal respiration?

directly related; increase or decrease with surface area

how would surface area for exchange influence gas exchange?

decrease as distances got further

how does distance impact efficiency of gas exchange?

increase if there is more blood

how does perfusion influence gas exchange?

ventilation-perfusion matching

degree of match between the amount of air that reaches the alveoli (ventilation) and the amount of blood flow (perfusion)

directly related, as one changes so does the other

how are ventilation and perfusion related?

bound to hemoglobin, dissolved in plasma, or converted to bicarbonate

what are the three ways O2 and CO2 can be transported?

bound to hemoglobin

how is the majority of O2 transported in the blood?

yes, but it does not compete for a hemoglobin binding site

can CO2 bind to hemoglobin? how does this impact O2 binding?

HHb + O2 <—> HbO2 + H+

what is the equation for O2 transport in hemoglobin?

pulmonary capillaries

where does the forward reaction for oxygen transport through hemoglobin occur?

systemic capillaries

where does the reverse reaction of oxygen transport through hemoglobin occur?

RBC

generally, where does the reaction for O2 transport in hemoglobin occur?

the affinity for oxygen binding to hemoglobin

what does the oxygen-hemoglobin dissociation curve show?

high altitude

what conditions promote a PO2 of 40 and O2 hemoglobin saturation of 75%?

temperature, H+, PCO2, and BPG

what factors will cause a shift in the oxygen-hemoglobin dissociation curve?

increase in temperature, H+, PCO2, and BPG

what will cause a right shift in the oxygen-hemoglobin curve?

decrease in temperature, H+, PCO2, and BPG

what will cause a left shift in the oxygen-hemoglobin curve?

decreases the affinity, so O2 will favor unloading from hemoglobin

how does a right shit in the oxygen-hemoglobin curve change % saturation of hemoglobin and O2 unloading from hemoglobin?

increases the affinity, so O2 will not favor unloading from hemoglobin

how does a left shit in the oxygen-hemoglobin curve change % saturation of hemoglobin and O2 unloading from hemoglobin?

conversion to bicarbonate

what is the predominant form of transport of CO2 in the blood?

carbonic anhydrase

what enzyme facilitated CO2 conversion to bicarbonate?

RBC

generally, where does the reaction for CO2 to bicarbonate ions occur?

systemic capillaries

where does the forward reaction of CO2 to bicarbonate occur?

pulmonary capillaries

where does the reverse reaction for CO2 to bicarbonate ions occur?

chloride and bicarbonate ions move in opposite directions to balance out charges

how does the carbonic acid buffer system maintain blood pH for CO2 conversion?

the forward of O2 and reverse of CO2 occur in pulmonary capillaries; the reverse of O2 and forward of CO2 occur at systemic capillaries

how are the CO2 and O2 reactions complimentary to each other during pulmonary and tissue gas exchange?