Erythropoiesis

Question 1

What is the mesoblastic stage?

Answer 1

3rd week of foetal development

Erythrocytes develop in the yolk sac and mesothelial placental layers

Question 2

What is the hepatic stage?

Answer 2

6th week of foetal development

Erythrocytes develop in the liver and spleen

Question 3

What is the myeloid stage?

Answer 3

3 months onwards during foetal development

Erythrocytes develop in bone marrow

Question 4

Where are erythrocytes developed in children up to 5?

Answer 4

Bone marrow of all bones

Question 5

Where are erythrocytes developed in people aged between 5 and 20/25?

Answer 5

Bone marrow of long bones

Question 6

Where are erythrocytes developed in people aged above 25?

Answer 6

Bone marrow of membranous bones

Question 7

What is myeloid tissue

Answer 7

Bone marrow

Question 8

Unit of measurment for blood count?

Answer 8

Cubic l

Question 9

What is the normal erythrocyte count for men?

Answer 9

5.2+/-0.3*10^6

Question 10

What is the normal erythrocyte count of women?

Answer 10

4.7+/-0.3*10^6

Question 11

Where is erythropoietin produced and why

Answer 11

Fibroblast interstitial cells around proximal convuluted tubule of kidney
Oxygen levels here only determined by carrying ability of blood. EPO cells sensitive to hypoxia, so if hypoxia occurs must be to do with oxygen carriage

Question 12

Effects of EPO (2)

Answer 12

• Rapid maturation of committed bone marrow cells

- In 1-2 days increases number of circulating reticulocytes

Question 13

Effect of testosterone on EPO

Answer 13

Enhanced EPO production (hence why boys have higher RBC count)

Question 14

What is a rouleaux

Answer 14

Stack/ clump of RBCs

Question 15

What causes increased number of rouleaux

Answer 15

Inflammatory reactions or abnormal protein levels reduces negative charge on erythrocytes so they clump together

Question 16

What is effect of rouleaux in blood test

Answer 16

Settle more quickly due to increased density. Non specific marker of infection

Question 17

What do red blood cells require ATP for?

Answer 17

Protein pumps and GLUT1 transporters

Question 18

How do red blood cells gain ATP?

Answer 18

Anaerobic glycolysis

Question 19

How do red blood cells gain NAPDH?

Answer 19

Pentose phosphate pathway

Question 20

What is glutathione

Answer 20

Reducing agent in blood that scavenges reactive oxygen and is oxidised in process

Question 21

What do reactive oxygen species do?

Answer 21

Form in cells and convert ferrous iron in haemoglobin to ferric iron, giving methaemoglobin.

Question 22

Action of glutathione reductase?

Answer 22

Regenerates glutathione by using NADPH as electron donor.

Question 23

What is the only non-mitochondrial source of NADPH?

Answer 23

Hexose monophosphate shunt

Question 24

How do they splenic macrophages detect old erythrocytes?

Answer 24

• Changes in cell surface antigens

- Changes in deformability

Question 25

What initially happens to trapped RBCs

Answer 25

Engulfed by splenic macrophages and broken open by osmotic lysis

Question 26

Product of osmotic lysis of RBCs?

Answer 26

Globin proteins and haem group

Question 27

What happens to globin proteins after osmotic lysis?

Answer 27

Broken to amino acids

Question 28

Action of haemoxygenase enzyme on haem group?

Answer 28

Breaks into biliveroin

Question 29

Action of biliverdin reductase in biliveroin

Answer 29

Breaks into bilirubin which then binds to albumin and is transported out spleen into blood

Question 30

What form is bilirubin when in splenic blood

Answer 30

Unconjugated

Question 31

Where and how does bilirubin become conjugated

Answer 31

Liver | Bound to gluronic acid by hepatocytes

Question 32

Effect of conjugating bilirubin

Answer 32

Becomes more water soluble

Question 33

Where does conjugated bilirubin get transported to

Answer 33

Small intestine

Question 34

What happens to 90% of conjugated bilirubin

Answer 34

Converted to urobilogen and excreted as faeces

Question 35

What happens to 10% of conjugated bilirubin

Answer 35

COnverted to urobilogen and goes to liver via portal vein. Then goes to kidney and excreted as urine

Question 36

What is urobilogen further oxidised to

Answer 36

Stercobilin

Question 37

What 2 cells does the haematopoetic stem cells differentiate into

Answer 37

Common lymphoid progenitors | Common myeloid progenitor/ proerythroblast

Question 38

Describe changes undergone by proerythroblast to form erythrocyte

Answer 38

- Differentiates into erythroblast - Nucleus shrinks - Cytoplasm fills with haemoglobin - Now reticulocyte - Reticulocyte expels nucleus

Question 39

Name 3 cells (not including erythrocyte) that proerythroblast can differentiate into

Answer 39

- Megakaryocyte - Mast cell - Myeloblast

Question 40

What do myeloblasts differentiate into

Answer 40

Granulated white cells

Question 41

What do common lymphoid progeniors differentiate into

Answer 41

Lymphocytes

Question 42

What is the diameter of an erythrocyte

Answer 42

7.8

Question 43

What do erythrocytes stain with

Answer 43

Eosin

Question 44

What is the volume of erythrocyte

Answer 44

90 cu mm

Question 45

Why do reticulocytes show dark marks when stained

Answer 45

Ribosomal RNA stains darker

Question 46

What % of blood cells are reticulocytes

Answer 46

Approx 1%

Question 47

Name the granulocytes

Answer 47

``` Basophil Neutrophil Monocyte Eosinophil Macrophage ```

Question 48

What is a macrophage produced from

Answer 48

Monocyte

Question 49

A rise in what is thought to signal for RBC to be removed from circulation

Answer 49

Increase in methamoglobin

Question 50

What is the normal level of conjugated bilirubin in the blood

Answer 50

0.1-0,3mg/dl

Question 51

What gives urine its yellow colour

Answer 51

Urobilirubin