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RBCs
What are the most numerous cells in blood?
anucleated
In mammals, RBCs are nucleated/anucleated
nucleated
In non-mammals, RBCs are nucleated/anucleated
gas exchange
What is the primary function of erythrocytes?
increased surface area for gas exchange
What is the benefit of the biconcave disc shape of RBCs?
bone marrow
What is the primary site of hematopoiesis?
bone marrow
Where does RBC proliferation and maturation occur?
oxygen to body and co2 from lungs
What is the circulating pool of blood?
splenic RBCs
What is the reserve pool of blood?
spleen
Where does destruction of old RBCs occur?
cats
There is less of a splenic reserve pool in what species?
spleen and liver
Where can blood be made, other than bone marrow, when there is increased demand?
maturation
Erythrocytes proliferate (reduce in size) in response to what?
erythropoietin
RBC production is stimulated by what?
kidneys
Where is erythropoietin produced?
increased mRNA for hemoglobin and cytoskeletal protein production
What accounts for blue cytoplasm of RBCs?
hemoglobin
What accounts for the red/orange staining of RBCs?
inhibits mitosis and cells mature without further divisions
What is the response of high hemoglobin content in RBCs?
shape, diameter, immature RBCs
Microscopic differences in RBCs across species are mostly related to what?
immature RBCs
What are polychromatophils?
horses
In what species are polychromatophils not found?
erythropoiesis
Polychromatophils are increased with accelerated ______________.
dogs, cats, horses/cattle, sheep/goats
What is the species order, from largest to smallest, of RBC diameter?
diameter
Central pallor correlates with what other aspect of RBCs?
echinocytosis, polychromatophils, anisocytosis, howell-jolly bodies, rouleaux, nRBC
What RBC changes may be seen in health? (6)
spiked shape, glass contact/pathologic
What is echinocytosis and when is it usually induced?
anemia
Polychromatophils can be increased in response to what?
variation in RBC size
What is anisocytosis?
splenic microanatomy
Why are Howell-Jolly bodies seen more in cats?
late stage immature RBC progenitors
What are reticulocytes?
no, all counted reticulocytes are polychromatophils but not all polychromatophils are reticulocytes
Are reticulocytes the same thing as a polychromatophil?
amount of RNA they contain
What characterizes the different types of reticulocytes?
aggregate, punctate
What are the different types of reticulocytes?
cats
In what species are only aggregate reticulocytes counted?
new methylene blue staining (stains mRNA)
How are reticulocytes identified?
accelerated erythropoiesis
An increased number of reticulocytes can be seen in circulation due to what?
horses
In what species are reticulocytes not seen?
variation in RBC size
What is anisocytosis?
variation in RBC shape
What is Poikilocytosis?
polychromasia, heinz bodies, howell jolly bodies, basophilic stippling
What RBC morphologies can be seen with Wright-Giemsa stain?
reticulocytes, heinz bodies
What RBC morphologies can be seen with New-methylene blue staining?
linear chains of RBCs
What is rouleaux?
horses, cats
In what species are rouleaux most prominent?
abnormal positively charged blood proteins that interferes with negative RBC charge
Rouleaux increases with what?
cytoskeletal proteins
What maintains erythrocyte shape with flexibility?
hemoglobin
95% of the dry weight of RBCs is what?
erythroid, macrophages
Synthesis of erythrocytes occurs in ___________ precursors and is aided by _______________.
surface antigens (different by species)
What are blood groups determined by?
8
How many DEA (dog erythrocyte antigen) groups are there?
DEA1, induces antibodies with exposure
What is the most important dog blood group and why?
A, B, and AB
What are the cat blood groups?
A
What is the most common cat blood group?
AB
What blood type is the least common in cats?
isoerythrolysis, foal RBCs attacked by colostral antibodies to paternally-derived RBC antigens
Aa and Qa blood types in foals commonly cause what?
many groups and factors vary by breed differences
What is unique about blood groups of horses and cattle?
cattle
What species has very complex blood groups?
glycolysis, hexose monophosphate shunt, anaerobic glycolysis, NADH reduces metHgb, diphosphoglycerate shunt
What are the 5 major biochemical pathways in RBCs?
Great hikers always need directions
Mnemonic for 5 major biochemical pathways in RBCs?
glucose
What is the primary energy source for RBCs?
pigs
In what species is glucose not the primary energy source?
generates NADH, a reducing agent to combat oxidative injury
What is the role of the hexose monophosphate shunt in RBCs?
yields 2 ATP and 2 NADH, PFK
What is the role of anaerobic glycolysis in RBCs?
anemia
PFK deficiency leads to...
more active PFK and more DPG shunt
In anaerobic glycolysis, what does low pH mean?
provides 23DPG at expense of ATP which increases hemoglobin affinity for oxygen
What is the role of Diphosphoglycerate (DPG) shunt in RBCs?
pH
Shunting is affected by _______.
deoxygenated Hgb
Most H+ is buffered by what?
HCO3- in RBCSs and plasma, dissolved, carbaminohemoglobin
How is CO2 carried in blood?
phosphofructokinase in glycolysis, less 2-3DPG entering lungs
What does acidic venous blood inhibit?
CO2 and H2O
HCO3- enters RBCs and combines with H+ to form what?
23DPG
RBCs leaving lungs have low _________ and thus high Hgb affinity for oxygen.
production
In health RBC destruction matches what?
species size
The life span of RBCs correlates with what?
mediate RBC phagocytosis by macrophages
What is the role of senescence antigens?
decreased enzyme activities, increased oxidative damage/membrane loss, increased rigidity, leads to trapping in splenic red pulp
What happens to RBCs as they age?
1%
____ of RBCs a day are made and destroyed.
billions
__________ of senescent RBCs are destroyed daily.
recycled
What is the fate of iron in phagocytized Hgb?
broken down into amino acids
What is the fate of globins in phagocytized Hgb?
converted to unconjugated bilirubin (bu) that is taken up by the liver for excretion
What is the fate of heme in phagocytized Hgb?
Bu enters plasma and binds albumin, enters hepatocytes without albumin, conjugated with glucuronide to become water soluble (Bc), transported into canaliculi, Bc degraded to urobilinogen (Ub) in the gut, some excreted in urine or returned to liver for biliary excretion
What are the steps of the bilirubin pathway for heme excretion?
brown
In the last step of the bilirubin pathway, Ub is converted to stercobilinogen (Sb) which is _________.
diet and intestinal absorption
What is the source of iron?
small
Daily uptake of iron is ________ % of total body Fe.
need
Absorption of iron increases with _______.
RBC Hgb, storage, other molecules like myoglobin, cytochromes, certain enzymes
Iron is distributed in 3 major sites in health, what are they?
50-70
About ____________% of iron is in RBC Hgb.
25-40%
About _______% of iron is in storage (as hemosiderin or ferritin).
<10%
How much iron is found in other molecules not in RBCs or storage?
young
________ animals have little to no Fe storage.
fast-growing pigs
Which species is susceptible to clinical Fe deficiency?
Hgb synthesis and RBC production
Fe deficiency impairs what?
peptide hormone produced by hepatocytes
What is hepcidin?
regulates iron in body by decreasing absorption in intestines
What is the role of hepcidin?
inflammation
Hepcidin increases with what?
low body iron or hypoxia (anemia)
Hepcidin decreases with what?
transports iron out of cells
What is ferroportin?
enterocyte and macrophage membranes
Hepcidin binds ferroportin where?
blocks or internalizes it's actions leading to decreased iron absorption and increased hemosiderin stores
What happens when hepcidin binds ferroportin?
storage protein for iron
What is hemosiderin?
