Respiratory Physio Flashcards
What is the P50 of Hgb?
Partial pressure of O2 at which hemoglobin is 50% saturated.
What state is hemoglobin in when the P50 is high?
Taut
What state is hemoglobin in when the P50 is low?
Relaxed
When Hgb is in the relaxed state, what kind of affinity for oxygen does it have and how does the curve shift?
What about when it is in the taut state and how does the curve shift?
High affinity
Left shift
Low affinity
Right shift
At what location does hemoglobin have a high affinity for oxygen? Low affinity for oxygen?
Lungs
Tissues
What are some conditions when you would see a right shift of the P50 hgb curve? Are you on or offloading oxygen at that time?
Left shift?
Decreased CO2, [H+], 2B/DPG, low temps. Onloading O2.
Increased CO2, [H+], 2-B/DPG, high temperature. Offloading O2.
What is the Bohr effect?
Increased CO2 in blood causes O2 to be displaced from hemoglobin. Occurs in tissues and describes release of oxygen.
What is the Haldane effect?
Binding of O2 with hemoglobin causes CO2 to be displaced from hemoglobin. Occurs in Lungs and describes the release of CO2.
Where is most oxygen found in the body?
98% bound to hemoglobin (1-2%) dissolved in plasma.
What are the 3 major forms of carbon dioxide in the body?
- Dissolved in plasma (7%)
- In RBCs (70%)
- Bound to hemoglobin (23%)
How does carbon dioxide and water cause a chloride shift in the red blood cell?
CO2 + H2O makes carbonic acid under the influence of carbonic anhydrase. Carbonic acid dissociates into H+ and HCO3- (bicarb).
The H+ combines with carbamino compounds and the leftover bicarb diffuses out of the cell while Cl- diffuses in causing a chloride shift.
Where is carbonic anhydrase catalyzing important reactions in the body?
- In the RBC to combine CO2 and water
- In parietal cells leading to acid secretions
- In pancreatic cells to allow for bicarb secretion
- In the renal tubules where the intercalated cells of the collecting duct are involved in acid/base balance.
Where is CO2 the more important regulator of regulation of respiration, centrally or peripherally?
Centrally because CO2 can cross BBB where H+ cannot.
What is the name of the cell that is found in the chemoreceptors that is sensitive to O2 changes? How does that cell result in respiratory stimulation of CN ____?
Glomus cell
Decreased O2 leads to potassium eflux and Ca influx leading to cell depolarization and dopamine release which results in respiratory stimulation of CN 9 (glossopharyngeal).
Where is the respiratory center located?
Pons and medulla