RBC physiology Flashcards
Explain how hypoxia causes RBC formation
renal tissue hypoxia –> increaed hypoxia-inducible factor-1 –> binds to hypoxia response elements –> induces transcription of erythropoietin
erythropoietin affects to early stages of RBC development –> production of proerythroblats from hematopoietic stem cells
What interleukin induces growth and reproduction of all stem cell types
Interleukin-3
What stage of RBCs leaves the bone marrow?
reticulocytes - lose their remaining basophilic material within 1-2 days –> mature RBC
How fast does hypoxia induce RBC production?
erythyropoietin production picks up within minutes to hours
new RBCs don’t appear until 5 days later
What two vitamins are required for maturation of RBCs?
Folic acid (B9)
Cobalamin (B12)
What are the consequences of cobalamine and folate deficiency for RBCs?
large RBCs (macrocytes) with flimsy cell membranes
can carry O2 normally but short half-life (half to 1/3)
What substance is vital for vitamin B12 absorption and what cells and organ secrete it?
parietal cells of the stomach secreting intrinsic factor
Explain the metabolism of iron
iron absorption SI –> binds with apotransferrin (produced in liver and excreted via bile)
–> forms transferrin –> circulation –> storage in cytoplasm of cells (especially liver) by binding to apoferritin –> forms ferritin
What forms when there’s too high cc of iron in the blood?
forms hemosiderin
What type of anemia develops in iron deficiency?
hypochromic anemia (RBCs have less hemoglobin)
What is the life span of a RBC?
107 days dog
73 days cat
What type of anemia occurs with chronic blood loss?
microcytic hypochromic anemia
What suppresses iron absorption?
Hepcidin
* produced by the liver
* internalized ferroportin - needed for GI absorption
