wk 11, lec 2 Flashcards
what are red blood cells aka
erythrocytes
what do RBCs contain
- Carry O2
- Contain hemoglobin bind O2 in lungs and release in tissues (for gas transport and exchange)
- Remove CO2 (bring back to lungs for exhalation)
where are RBCs made
- Made in bone marrow
o Erythron= proliferating marrow erythroid precursors + circulating RBCs
RBC lifecycle
120 days
where are RBC recycled
where are made in fetus
- Recycled in liver and spleen
o Made in spleen and liver in fetus
shape of RBC
- Biconcave shape; maximize SA for gas exchange and to move through vessels
when will hemoglobin bind and dissociate at low and high [ ]
o Hemoglobin binds oxygen at high [ ]
o Oxygen dissociates from Hb at low [ ]
o Healthy O2 saturation in Hb is 95-99%
when will Hb bind Co2
o HB binds CO2 with low affinity
what do RBCs have to convert CO2 in bicarbonate HCO3-
carbonic anhydrase
what do RBC lack
nuclei
o Cant synthesize protein and limit lifespan
what are RBC derived from
from myeloid progenitor (pronormoblast)
steps to form RBC
- RBCs derived from myeloid progenitor (pronormoblast)
o Stimulated to divide by GM-CSF and erythropotein (EPO)
o Before nucleus extruded; RBC accumulate Hb and proteins
o The late normoblast because anucleate
o Reticulocyte has remnants of golgi, ER, ribosomes which get extruded to become mature RBC
what 2 things stimulate myeloid progensit to divide and get closer to being RBC
GM-CSF and erythropoietin (EPO)
how many times does pronormoblast divide to make RBC and via stimulation of what
- Pronormoblast divides to make 16-32 mature RBCs via EPO stimulation
where is EPO erythropoietin made
kidneys by epithelial cells
- EPO made in kidney by epithelial cells ; what happens in high vs low oxygen conditions
o High oxygen conditions= hypoxia inducible factor (HIF) is ubiquinated and degraded by proteasomes
o Low oxygen conditions= HIF binds proteins, is translocated to the nucleus and stimulates EPO production (make more RBCs)
high or low oxygen to make EPO
low oxygen
generation of RBC depends on
EPO, bone marrow, adequate iron and amino acids for HB production
which energy pathway for RBC to get ATP
- RBC need glycolysis for ATP (no oxidative metabolism bc no mitochondria)
what antioxidant to RBC have
- RBC have glutathione stores when in high oxygen and cant make new proteins need to be able to combat free radical production
cytoskeleton in RBC - if absent what disorder does it cause
- Cytoskeletal proteins help RBC maintain shape –> disorder = loss of red cell mass (anemia)
subunits in hemoglobin
2 alpha and 2 other chains
what does each subunit in hemoglobin contain
o Each subunit has heme moiety containing iron to bind oxygen
what is the majority type of hemoglobin and what is less
- 97% is HbA (2 alpha, 2 beta chains)
o 2% is HbA2 (2 alpha, 2 delta chains)