Hematopoiesis

Question 1

What is hematopoiesis

Answer 1

The formation of blood cells

Question 2

Where does hematopoiesis occur?

Answer 2

in the red bone marrow

Question 3

What is the name of the hematopoietic stem cell

Answer 3

the hemocytoblast

Question 4

What are all formed elements of blood made from

Answer 4

hemocytoblast

Question 5

What is leukopoiesis

Answer 5

The formation of leukocytes

Question 6

How is leukopoiesis regulated

Answer 6

by cytokines called colony stimulating factors

Question 7

What is a cytokine

Answer 7

a cell signaling molecule

Question 8

What is the first step of leukopoeisis

Answer 8

The hemocytoblast (stem cell)

Question 9

what is the second step in leukopoeisis

Answer 9

It becomes either a myeloid stem cell or a lymphoid stem cell

Question 10

What is the 3rd step in leukopoeisis

Answer 10

This step is about committed cells “Blast cells”
The myeloid stem cell branches off into 2 different blast cells where as the lymphoid stem cell becomes only one type of blast cell

Question 11

What is the 4th step in leukopoeisis

Answer 11

The lymphoid stem cell route will progress to a lymphocyte (T or B cell).
The myeloid stem cell route will either become a monocyte, or it will differentiate further into 3 different myelocytes

Question 12

What is the 5th step of leukopoeisis

Answer 12

The myelocytes become band cells which are almost full grown leukocytes

Question 13

What is the 6th step of leukopeoisis

Answer 13

The basophil, eosinophil and neutrophil will finally be matured and made

Question 14

What is thrombocytopoiesis

Answer 14

formation of thrombocytes (platelets)

Question 15

How is thrombocytopoiesis regulated

Answer 15

By thrombopoietin (TPO)

Question 16

What organ is thrombopoietin made by

Answer 16

the kidneys

Question 17

What is the general idea of how platelets are formed

Answer 17

By fragmentation of large blast cells called magakaryocytes

Question 18

Explain what is the first step of thrombocytopoiesis

Answer 18

The hemocytoblast (the stem cell)

Question 19

What happens after the hemocytoblast in thrombocytopoiesis

Answer 19

The myeloid stem cell

Question 20

What happens after the myeloid stem cell in thrombocytopoiesis

Answer 20

The megakaryocyte is formed (can make over 4000) platelets, Frgamentation occurs and platelets are made

Question 21

What is erythropoiesis

Answer 21

The formation of erythrocytes

Question 22

how long does erythropoiesis take

Answer 22

approx. 3-5 days

Question 23

How many RBCS are made per minute

Answer 23

2 million (15ml a day)

Question 24

how is production of RBCS enhanced?

Answer 24

By the steroid hormone testosterone

Question 25

What is one main requirement of erythropoiesis

Answer 25

Needs Iron to make the O2 carrying pigment hemoglobin

Question 26

What does each heme have

Answer 26

A porphyrin ring with an iron in the middle the O2 binds to

Question 27

What is the difference between fetal and maternal hemoglobin

Answer 27

Fetal has 2 alpha globing and 2 GAMMA globing which has a higher affinity for oxygen so it can pull oxygenn off of maternal hemoglobin

Question 28

What is the 1st step off erythropoiesis

Answer 28

The hemocytoblast (undifferentiated stem cell)

Question 29

What is after the hemocytoblast in erythropoiesis

Answer 29

myeloid stem cell

Question 30

What is after the myeloid stem cell in erythropoiesis

Answer 30

the proerythroblast (committed cell)

Question 31

What is after the proerythroblast in erythropoiesis

Answer 31

The erythroblast

• Phase 1: Ribosome synthesis
• Phase 2: hemoglobin synthesis

Question 32

What is after the erythroblast in erythropoiesis

Answer 32

The normoblast

-Phase 3: Nucleus is ejected

Question 33

What is after the normoblast

Answer 33

The reticulocyte (enters circulation) 
it is a young erythrocyte with many ribosomes

Question 34

What happens after the reticulocyte

Answer 34

The erythrocyte (mature cell) *The end

Question 35

What control erythropoiesis

Answer 35

The glycoprotein hormone (EPO) erythropoietin

Question 36

what secrets erythropoietin

Answer 36

The kidneys in response to Hypoxia (O2 deficiency)

Question 37

How do we filter old RBCs out of circulation

Answer 37

the liver and spleen trap them & macrophages in the spleen and liver phagocytize them

Question 38

What is the first step of the hemoglobin being recycled

Answer 38

The hemoglobin is metabolized by spleen and liver macrophages

Question 39

what does hemoglobin split into

Answer 39

heme and globin

Question 40

What does the globin break down into

Answer 40

Amino acids and then they enter circulation

Question 41

What does the heme break down into

Answer 41

1) biliverdin (Green pigment) (from the ring part)

2) Iron

Question 42

What does the biliverdin become

Answer 42

1) Bilirubin (yellow pigment) which is conjugated to protein albumin for transport
2) bilirubin is a component of bile which is excreted by the liver in the form of bile into the small intestine
3) bile is metabolized by bacteria in the large intestine
4) It becomes either urobilins (yellow) or stercobilins (brown)
5) urobilins are excreted in urine and feces
6) stercobilins are excreted just in feces

Question 43

What does the iron become

Answer 43

1) first it is bound to the transport protein in blood (Transferrin)
2) then it either goes to the liver and spleen or the bone marrow
3) In the bone marrow its reused in erythropoiesis
4) in the liver and spleen it is stored and iron/protein complexes called ferritin and hemosiderin