RBCs

Question 1

Define erythron

Answer 1

All erythroid cells in the body. Including immature and mature, as well as those in the bone marrow, spleen, and circulation.

Question 2

Define Hematopoiesis

Answer 2

Production of ALL blood cells

Question 3

Define erythropoiesis

Answer 3

Process of RBC production in bone marrow

Question 4

Define granulopoiesis

Answer 4

Process of WBC (eosinophils, neutrophils, basophils, leukocytes) production in bone marrow

Question 5

Define thrombopoiesis

Answer 5

Process of platelet/thrombocyte production in bone marrow

Question 6

Define hematopoietic cells

Answer 6

Precursors to blood cells found in blood or tissues

Question 7

Define anemia,

Answer 7

Decreased RBC number
Occurs when RBC production < RBC loss
Result: decreased Oxygen carrying capacity

Question 8

Define absolute erythrocytosis

Answer 8

Increased number of RBCs
Occurs when RBC production > RBC loss
Result: Sluggy blood

Question 9

Where does hematopoiesis occur?

Answer 9

Bone marrow (majority)- specifically axial and long bone central cavities of mammals
Other organs (extramedullary)- spleen and liver

Question 10

What are Howell-Jolly bodies?

Answer 10

Small fragments of non-functional nuclear material, which wasn’t extruded when the RBC left the bone marrow

Question 11

How long does it take to make a new erythrocyte?

Answer 11

5-7 days to go from rubriblast (1st precursor) to erythrocyte

Question 12

Which erythrocyte precursor is the last to have a nucleus?

Answer 12

metarubricyte (before reticulocyte)

Question 13

What hormone stimulates Erythropoiesis?

Answer 13

Erythropoietin (Epo)

Question 14

Where is Erythropoietin produced?

Answer 14

Kidney (~90%)

Liver (~10(

Question 15

What stimulates release of Erythropoietin?

Answer 15

Hypoxia in kidney/liver tissue (helps increase oxygen)

*other cytokines, hormones, and growth factors also regulate erythropoiesis

Question 16

What decreases erythropoiesis?

Answer 16

• Inflammatory cytokines (TNF-alpha, IL-6, IL-1(
• Abnormally high estrogen
• Low functional renal tissue (CKD), b/c low epo synthesis

Question 17

What benefit does the biconcave disc structure of RBCs provide?

Answer 17

Allows deformability, so RBCs can move through small vessels

Question 18

What species has ovoid and anucleated RBCs?

Answer 18

Camelids (llamas, alpacas, camels, etc)

Fun fact: This shape helps the RBCs to move through blood vessels, even when very dehydrated. It also allows the RBC to swell up to 240% when the animal drinks water (biconcave can only swell to 150%!).

Question 19

What species has ovoid and nucleated RBCs?

Answer 19

Reptiles, fish, avians/birds

Exceptions: Salamanders of genus Batrachoseps and Fish of genus Maurolicus

Question 20

What species have smaller RBC’s?

Answer 20

Ruminants and Horses
Sheep and Goats: 4.5 micrometers
Cattle and Horses: 5-6 micrometers

Question 21

What are the primary components of RBC structure?

Answer 21

Hemoglobin (Hgb)
Membrane & cytoskeleton
Enzymes for metabolism

Question 22

How many heme molecules are in 1 hemoglobin molecule?

Answer 22

4 heme molecules/1 hemoglobin

Question 23

How many available oxygen binding sites are available for oxygen on a heme molecule?

Answer 23

There is one oxygen binding site available per heme molecule

Question 24

What type of iron is found in a heme molecule?

Answer 24

ferrous iron

Question 25

What is Methemoglobin?

Answer 25

Has the feric form of iron, which is lacking the only binding site for oxygen to bind to

Question 26

How is methemoglobin turned into normal hemoglobin?

Answer 26

It is oxidized back to hemoblogin by cytochrome-b5-reductase

Question 27

Can hemoglobin be synthesized without mitochondria?

Answer 27

No, hemoglobin synthesis requires mitochondria. Therefore, all hemoglobin is made in RBC precursors.

Question 28

What are the 3 steps of hemoglobin synthesis?

Answer 28

1) Series of porphyrin reactions 2) Incorporation of ferrous iron into protoporhyrin IX to form heme 3) Binding of the 4 ferriheme & 4 globin molecules to form hemoglobin

Question 29

What are Porphyrins?

Answer 29

Heme precursors from porphobilinogen to protoporphyrin IX

Question 30

What is porphyria?

Answer 30

High concentration of porphyrins (heme precursors) in RBCs, plasma, and urine *can be congenital or aquired (lead toxicity)

Question 31

Clinical symptoms associated with porphyria

Answer 31

Photosensitivity due to porphyrins absorbing UV light and causing oxidative damage. May result in hemolytic anemia

Question 32

Clinical signs associated with disorders of RBC cytoskeleton

Answer 32

impacts RBC deformability, and result in abnormal shapes. Can also cause anemia

Question 33

How do RBCs generate energy?

Answer 33

With the Embden-Meyerhoff pathway (anaerobic glycolysis)

Question 34

What molecule helps oxygen leave the RBC and become available to tissues?

Answer 34

DPG | made by the Rapaport-Luebering pathway with glucose (Except pigs... inosine is used instead)

Question 35

How is DPG made?

Answer 35

Made by the Rapaport-Luebering pathway, at the expense of ATP that was generated with anaerobic glycolysis (Embden-Meyerhoff pathway)

Question 36

What does DPG do?

Answer 36

Decreases Hemoglobin's affinity for O2, so it is more readily available in the tissues

Question 37

An inherited defect in the Embden-Meyerhoff pathway can result in...

Answer 37

hemolytic anemias

Question 38

What pathway maintains hemoglobin?

Answer 38

Pentose phosphate pathway

Question 39

What pathway prevents methemoglobin?

Answer 39

Methemoglobin reductase pathway

Question 40

What happens to old erythrocytes?

Answer 40

Phagocytosed by macrophages in the spleen, liver, or bone marrow Exception: Cats: closed splenic circulation -> blood doesn't flow through red pulp, and therefore there is limited efficiency for removing RBCs