Respiratory 3 Flashcards
How is majority of O2 transported? The rest?
Majority is transported on hemoglobin, a very small amount is dissolved and transported in the blood
T/F: affinity for O2 decreases as O2 molecules attach to hemoglobin
False!
as they attach, conformation changes occur allowing the subsequent O2 molecules to bind more readily
What is O2 saturation?
The % of available heme units bound to O2 at any given time
What relationship does the O2-Hb dissociation curve describe?
The relationship of partial pressure to the binding of O2 to heme and its subsequent dissociation from heme
How does temperature effect the O2-Hb sat curve?
Higher temps promote hemoglobin and O2 to dissociate faster, lower temps inhibit dissociation
What happens to the O2-Hb sat curve with exercise (locally)
During exercise, muscle release large amounts of heat which increases the ability for O2 to dissociate which helps provide active tissues with more O2
T/F: elevated DPG inhibits the dissociation of O2 from hemoglobin
false! it promotes it
What are some hormones that stimulate the production of 2,3-diphosphoglycerate?
- androgens
- epinephrin
- thyroid/growth hormones
What is the Bohr effect?
Arises from the relationship between pH and O2’s affinity for hemoglobin
- lower pH (acidic) promotes dissociation
- higher pH (basic) inhibits O2 dissociation
How is CO2 transported?
1. bicarbonate (HCO3-) which dissolves in the plasma
2. some CO2 dissolved directly in plasma
3. Bound to hemoglobin
Where/when is bicarb produced?
In erythrocytes after CO2 diffuses into the capillaries and subsequently into the erythrocytes
What happens when the bicarb builds up in the erythrocytes?
Some will leave the erythrocytes and move down [] gradient, into the plasma in exchange for chloride ions
Why does the chloride shift occur?
Because by exchanging negative ions the charge of the erythrocyte nor the blood changes
T/F: at the pulmonary capillaries the chemical reaction that produced bicar is reversed and CO2 and H2O are produced
True
What part of hemoglobin does CO2 bind to?
the amino acids on the globin portions to form carbaminohemoglobin
Why does the blood leaving the lungs have a lower partial pressure of CO2 than in the tissues?
Because CO2 is expelled in the lungs
What is the haldane effect?
Arises from the relationship between the partial pressure of O2 and the affinity of hemoglobin for CO2
- hemoglobin saturated with O2 does not readily bind CO2
-CO2 will only bind when O2 is not bound AND the partial pressure of O2 is low
