Erythrocyte physiology Flashcards
Describe the function of erythrocytes
- delivery O2 and nutrients
- removal of waste products
- homeostasis
- immune
Blood composition
- plasma
- cellular (formed elements)(RBC, WBC, platelets)
hematocrit
% of blood that is cells (vast majority are RBCs)
what stimulates erythropoiesis
- tissue hypoxia
- low O2 delivery to kidney
what does tissue hypoxia lead to
accumulation of hypoxia inducible factor (HIF) (normal oxygenation is ubiquinated)
what does deficiency of heme cause?
microcytic anemia
what does deficiency of vit B12 cause
- macrocytic anemia
- def in B12 due to pernicious anemia
was does def in folate cause?
macrocytic anemia
oxygen capacity
how much O2 can be carried by heme
1.34 x measures (Hb)
oxygen content
How much oxygen IS being carried by heme
= o2 capacity x o2 saturation
oxygen saturation
% available spots on heme with O2 bound
-measure with pulse ox
what is ATP used for in RBC
- keeping iron in Fe2+ state
- maintaining membrane flexibility
- ion ATPases
- preventing oxidation of hemoglobin
consequences of RBC not having enough ATP
- membrane becomes stiff
- RBC snags spleen=ruptures
- iron can move into Fe3+ -alters O2 transport for worse
what happens to old RBC
filtered in spleen
what happens to old hemoglobin molecules
peptide chains: broken into AA
heme: broken down by liver kidneys gut through bilirubin
iron: recycle to new heme
Polycythemia
Too many RBCS
- more O2 carrying capacity but,
- blood becomes thicker
- heart works harder to pump blood
Hemochromatosis
Genetic mutation/ decrease in hepcidin
iron overload
primary Polycythemia
- bone marrow making RBC when no need to
- related to mutation in receptor for thrombopoietin?
methemoglobinemia
Ferrous iron converted to Ferric form (Fe 3+)
- in this state can’t bind O2 (anemia)
- decreases O2 carrying capacity of blood
how is ferrous iron affected in methemoglobinemia
- increase affinity for O2
- unable to release O2 to tissue
- tissue is hypoxic
- confusion and cyanosis
