Lecture 5: Gas Transport and Erythrocyte Physiology Flashcards
What is the function of erythrocyte?
- Carries oxygen to body
- Carries carbon dioxide to lungs
- Acid/base buffering
What matures into erythrocytes entering circulation?
Stem Cells –> Reticulocytes
What promotes production of red blood cells?
Erythropoietin (EPO)
Where is EPO produced?
Kidney
What promotes production of EPO?
Anemia low Hb Decreased RBF Central Hypoxia Low blood flow/volume
What regulates erythropoiesis?
Hypoxia Inducible Factor (HIF)
Where do red blood cells “die?”
Spleen via macrophages
What happens to heme?
Option 1: Heme –> Ferritin –> bone
Option 2: Heme –> Bilirubin –> Feces
What are the two ways oxygen is transported in blood?
- Dissolved (inadequate)
2. Bound to hemoglobin
How many oxygen molecules are bound to 1 hemoglobin
4 oxygen molecules
What are the 4 heme sites found on a hemoglobin?
2 alpha
2 beta
What does a “left shift” in an oxygen dissociation curve mean?
Increased affinity of hemoglobin for oxygen
-increased oxygen saturation
What diseases have a “left shift” in an oxygen dissociation curve?
Polycythemia: extra RBC and increased blood volume
Methemoglobinemia: increased met-hemoglobin
What does a “right shift” in an oxygen dissociation curve mean?
Decreased affinity of hemoglobin for oxygen
-unloading oxygen
What diseases have a “right shift” in an oxygen dissociation curve?
Anemia
-can also think of exercise
With a “right shift” in an oxygen dissociation curve, there is also an increase in?
Increased Hydrogen (decreased pH)
Increased temp
Increased CO2 content
Increased 2,3-DPG
Folate or B12 deficiency results in what?
Megaloblastic macrocytic anemia
Poor B12 absorption leads to what?
Pernicious anemia
What is microcytic anemia?
small RBC due to iron deficiency
What is hypochromic anemia?
pale RBC due to deficienct transport of transferrin
What is hemochromatosis?
Iron build up/overload
- liver cirrhosis
- skin pigmentation
- diabetes
What is the respiratory quotient?
RQ = [Vol of CO2 produced]/[Vol of O2 consumed]
What is the RQ of carbs?
1
What is the RQ of fats?
0.7
What is the RQ of protein?
0.9
How is carbon dioxide transported in blood?
- Dissolved carbon dioxide (inadequate)
- Carbamino compounds
- As bicarbonate
What are carbamino compounds?
Compound composed by the addition of carbon dioxide with a free amino group
How is bicarbonate formed?
- CO2 and Water —> H2CO3 via carbonic anhydrase
2. H2CO3 –> HCO3- + H+
What happens to hydrogen from H2CO3?
Buffered into red blood cells and carried in venous blood
What happens to HCO3 from H2CO3?
Exchanged for chloride across RBC and carried to lungs
