Human Physiology - Gas Exchange and Transport
What is the state of having 4 molecules of O2 per one hemoglobin molecule?
100% saturation of hemoglobin
What is the percentage of oxygen that is dissolved in the plasma?
2%
What lowers the affinity of Hb for O2?
2,3-DPG
What percentage of CO2 is bound to hemoglobin?
23%
What is the limit of O2 per hemoglobin molecule?
4 molecules of O2 per hemoglobin molecule
What percentage of CO2 is dissolved in plasma?
7%
What percentage of bicarbonate is in plasma?
70%
What is the percentage of oxygen in the arterial blood?
98%
Erythrocytes
Biconcave discs that maximize flexibility and deformability with a high surface area to volume ratio
What dramatically raises blood O2 carrying capacity?
Hemoglobin
High amount of RBC =
High O2
Left shifted curve
Higher affinity of Hb for O2; "lets go of O2 harder"
Why is blood red?
Iron is bound to the heme group in the protein hemoglobin
When is O2 affinity highest at?
Low temperatures, low PCO2, and high pH
Right shifted curve
Lower affinity of Hb for O2; "lets go of O2 easier"
What happens when partial pressures are equal in both phases?
Net movement stops
What is the equation of oxygen binding to hemoglobin?
O2 + Hb -> HbO2; reversible
What keeps plasma (and blood) viscosity low?
Packing hemoglobin in red blood cells
What are the three parts of a centrifuged blood sample?
Plasma, buffy coat, and hematocrit
What is in the buffy coat?
Platelets and white blood cells
Hemoglobin binds to O2 when PO2 is high, what does hemoglobin to when PO2 is low?
Releases O2 when PO2 is low
What curve is due to low pH and high PCO2 in active tissues, facilitating unloading of O2 from hemoglobin?
Right-shifted dissociation curve
Factors that affect the solubility of gases
Temperature, other dissolved solutes, pH
When are individual hemoglobin molecules the most stable?
When completely unsaturated and fully saturated states
Hematocrit
a standard index of RBC and Hb content
Arterial oxygen content
controlled by both ventilation-perfusion in lungs and by hemoglobin in RBCs
Hemoglobin
delivers oxygen to lungs then tissues/body
Chronic hypoxia
leads to an increase in DPG levels/ high altitude = right shifted curve
Anemia
low levels of hemoglobin
Oxygen affinity is HIGHEST at
low temperature, low pCO2, and high pH
2,3-DPG
lowers the affinity of Hb for CO2
HbA1c
measure of diet/glucose over large period of time
Glycosylation (glycation)
non-allosteric binding occurs with glucose
Hemocyanin
respiratory pigment found in invertebrates (molluscs, arthropods) containing two copper atoms that reversibly bind oxygen
Function 'goal' of hemoglobin
to saturate with oxygen in lungs THEN release oxygen in the tissues
