blood cells 1: red cells Flashcards
explain the origin and function of red cells, recall the intravascular life span of red cells, and list the physiological factors that influence the rate of red cell production
where do blood cells originate?
multipotent haemopoietic stem cells in bone marrow
what do multipotent stem cells differentiate into?
lymphoid stem cells (-> T, B & NK cells)
& myeloid stem cells (-> granulocytes, erythroids & megakaryocytes)
what are the key features of stem cells?
ability to self-renew & produce mature progeny
how are stem cells able to carry out their function?
they have the ability to divide into 2 cells with different characteristics - one can differentiate to mature cell & other is stem cell
what is the cell lineage for red cells?
multipotent haemopoietic stem cell -> myeloid stem cell -> proerythroblast -> erythroblast -> erythrocyte
what is erythropoiesis and what does it require?
production of red cells - requires erythropoietin produced (in resopnse to hypoxia)
what is the erythropoietin negative feedback cycle?
hypoxia / anaemia -> erythropoietin produced -> increased red cell production by bone marrow -> increased oxygen delivery
where is erythropoietin produced?
90% in kidneys (juxtatubular interstitial cells), 10% in liver hepatocytes / interstitial cells
how long do erythrocytes survive in the blood?
120 days
what is the main function of erythrocytes?
oxygen transport, also responsible for transporting some CO2
how are erythrocytes removed?
by phagocytic cells in spleen
how can you tell how many immature erythrocytes are in the circulation?
reticulocyte stain (& count number of reticulocytes) or normal blood film (and look for uptake of dye by immature erythrocytes)
