260b Erythropoiesis

Question 1

Erythron

Answer 1

progenitor + mature RBC; continuously renew from BM

Question 2

Erythropoiesis

Answer 2

kidneys release EPO based on oxygen tension (low O2 tension increased HIF-1 transcription factor –> activates EPO gene expression)

goes to BM to make new RBCs

Question 3

reticulocyte

Answer 3

early RBC from BM in blood

Question 4

hematocrit - what is it? what does dehydration do? hemorrhage?

Answer 4

packed RBC volume compared to total blood volume (aka RBC concentration)

dehydration increases hemtocrit due to less plasma

hemorrhage - no change in RBC concentration in the first few hours (both plasma and RBC lost), after a few hours the plasma volume increases which decreased Hct for ~ 30 days (until RBC are made again)

Question 5

anemia

Answer 5

decreased hemoglobin/Hct

Question 6

polycythemia

Answer 6

increased RBC count

Question 7

reticulocytosis

Answer 7

increased young RBCs

Question 8

mean corpuscular volume (MCV)

Answer 8

size of RBC

micro/normo/macro

Question 9

mean corpuscular hemoglobin concentration (MCHC)

Answer 9

amount of Hb in RBC

normo/hypo

Question 10

erythroid precursors in BM - how long does this take?

Answer 10

process takes 2 weeks –> reticulocytes 0-3 days in BM –> ~ 1 day in circulation (unless due to anemia then 2-4 days)

Question 11

mature RBC life cycle

Answer 11

120 days in circulation

Question 12

reticulocytes

Answer 12

immature RBCs

no nucleus, but still have mitochondria, ribosomes, golgi, etc

stain with methylene blue OR have solid red color unlike normal RBC with white center

Question 13

RBC - shape, content, membrane features, E?

Answer 13

biconcave w/out nucleus or mito

Hb makes up 33%

membrane allow pliability

E via glycolysis

Question 14

hemoglobin

Answer 14

tetramer with 4 heme groups - each can bind O2 molecule

synthesizes in BM

heme = Fe bound to protoporphyrin in mito

protein globin from cytoplasmic ribosome binds heme to form Hb in cytoplasm

globin determines type of Hb

Question 15

RBC - shape, content, membrane features, E?

Answer 15

biconcave w/out nucleus or mito

Hb makes up 33%

membrane allow pliability

E via glycolysis

Question 16

hemoglobin

Answer 16

tetramer with 4 heme groups - each can bind O2 molecule

heme = Fe bound to protoporphyrin
protein globin binds heme

globin determines type of Hb

Question 17

chromosomes of globins

Answer 17

non-a (B) = 11

a = 16

Question 18

RBC degradation

Answer 18

Mo in BV, BM, spleen, liver eat old RBCs via phagocytosis

Globin –> reusable aa’s
Fe
heme –> bilirubin –> binds albumin –> liver –> conjugated with glucuronic acid –> bile

Question 19

excess porphyrin is stored how?

Answer 19

complexed to zinc

Question 20

RBC degradation

Answer 20

Mo in BV, BM, spleen, liver eat old RBCs via phagocytosis

Globin –> reusable aa’s
Fe
heme –> bilirubin –> binds albumin –> liver –> conjugated with glucuronic acid –> bile

Question 21

what increases O2 dissociation from Hb?

Answer 21

shifts O2 sat curve to the right (sat on y axis, PO2 on x axis)

increased:
Temp
H+ concentration (lower pH) - Bohr effect
CO2
2,3 - BPG (stimulated by deoxyhemoglobin)

Question 22

normal Hb saturation

Answer 22

arterial - 95 mmHg, >97%

venous - 40 mmHg, 75%

Question 23

what increases O2 dissociation from Hb?

Answer 23

shifts O2 sat curve to the right (sat on y axis, PO2 on x axis)

increased:
Temp
H+ concentration (lower pH) - Bohr effect
CO2
2,3 - BPG (stimulated by deoxyhemoglobin)

Question 24

fetal Hb vs maternal Hb dissociation curve?

Answer 24

fetal is shifted left – much highter affinity for O2

at same PO2, fetal Hb binds more O2 to get a higher percent saturation

Question 24

fetal Hb vs maternal Hb dissociation curve?

Answer 24

fetal is shifted left – much highter affinity for O2

at same PO2, fetal Hb binds more O2 to get a higher percent saturation