Respiratory Physiology IV Flashcards
Forms of gas in circulation
Dissolved gas
Bound gas
Chemically modified gas
O2 is carried in blood in which two forms?
Dissolved form and bound form
Oxyhemoglobin
O2 bound
Deoxyhemoglobin
O2 not bound
Methemoglobin
Fe3+ heme, will not bind/transport O2
Hemoglobin S
- Variant of Hb that causes sickle cell disease
- Amino acid substitution (glutamate to valine)
Definition of oxygen binding capacity
Maximum amount of O2 bound to Hb
Definition of oxygen content
02-binding capacity x % saturation
Definition of oxygen delivery
Cardiac output x O2 content of blood
O2 saturation curve
- % saturation of Hb is a function of the PO2 in the blood
- Cooperativity in binding of O2
Right shift of O2 saturation curve results in what?
More unloading of O2 to tissues
Left shift of O2 saturation curve results in what?
Hb has higher affinity for O2, so less unloading to tissues
What causes O2 saturation curve shift to right?
Decreased pH and increased CO2
Increased body temperature
Increased 2,3-DPG
What causes O2 saturation curve shift to left?
Increased pH and decreased CO2 Decreased body temperature Decreased 2,3-DPG Carbon monoxide poisoning Hb F
Forms of CO2 in circulation
Dissolved gas
Bound gas (to Hb)
Chemically modified gas (carried as HCO3-)
Long term regulation of blood pH
Kidneys can alter secretion rate of hydrogen ions and re-absorption rate of bicarbonate to control blood pH
Short term regulation of blood pH
Variations in alveolar ventilation can be used to correct pH
Metabolic acidosis
Decrease in HCO3- leads to decrease in pH (diarrhea)
Metabolic alkalosis
Increase in HCO3- leads to increase in pH (vomiting)
Respiratory acidosis
Hypoventilation resulting in CO2 retention and decreased pH
Respiratory alkalosis
Hyperventilation resulting in CO2 loss and increased pH
