Erythrocyte Physiology Flashcards
Oxygen Sensing Pathway
If high O2, HIF-alpha ubiquinated and destroyed; if low O2, HIF-alpha accumulates and acts as TF binding to HIF-beta receptor in nucleus; increases transcription of erythropoietin in kidneys which gets released to blood and goes to bone marrow to act; also increases Fe enzymes
Protein hormone that travels through the blood; receptor connected to JAK2/STAT5 pathway; stem cell/erythroid lineage
Erythropoietin
Requirements for adequate erythropoiesis
Adequate nutrition
Iron availability (microcytic and pale)
B12 & Folate (macrocytic anemia bc cannot make DNA)
How much O2 can Hb carry
1.34 mL O2/g Hb
flexibility of membrane; ion transport (ATPase); to maintain Fe2+ not Fe3+; and to prevent oxidation of Hb
ATP use by RBCs
Results of anemia
decrease O2 capacity and content; decrease O2 delivery to tissue; and increased workload on the heart
Why does hemochromatosis not cause more RBCs to be made?
kidney is getting enough oxygen so no more erythropoietin is being made and sent to bone marrow
Too many RBCs; more O2 carrying capacity but thicker blood and heart has to work harder
Polycythemia
too many RBCs but normal bone marrow; Usually too much erythropoietin in response to low oxygen or from a tumor
Secondary Polycythemia
Bone marrow is making RBCs when there is no need; could be mutation in receptor for thrombopoietin
Primary Polycythemia
Too many RBCs due to altitude and lack of oxygen
Physiologic Polycythemia
Oxygen Capacity
total amount of O2 that can be carried in our blood assuming every heme is bound
Oxygen Content
amount of O2 actually carried in our blood
Formula for O2 calculations
Oxygen content = oxygen capacity x saturation
