RBC Physiology

Question 1

Are are the 2 main components of blood?

Answer 1

Cells + liquid

Question 2

What is the liquid component of blood called?

Answer 2

Plasma

Question 3

What are the 3 main blood cell types? Which is commonest

Answer 3

Red cells (commonest)
White cells
Platelets

Question 4

What is the term for blood cell production?

Answer 4

Haematopoiesis

Question 5

What sort of stem cell produces blood cells?

Answer 5

Pluripotent - capable of any cell type

Question 6

At birth where does haematopoiesis occur?

Answer 6

Liver, spleen, bone marrow

Question 7

Where does haematopoesis occur in a child?

Answer 7

Bone marrow - decreasing number of active sites

Question 8

Where does haematopoiesis occur in an adult?

Answer 8

Bone marrow of skull, sternum, pelvis, proximal femur

Question 9

What are the 2 main progenitors in the haematopoietic tree?

Answer 9

Lymphoid and myeloid

Question 10

What cell type do both lymphoid and myeloid progenitors produce?

Answer 10

Dendritic cells

Question 11

What cell types do lymphoid progenitors give rise to?

Answer 11

T cells
B cells
NK cells

Question 12

What cell types do myeloid progenitors give rise to?

Answer 12

Erythrocytes
Platelets
Mast cells
Granulocytes
Macrophages

Question 13

Put these stages of erythropoiesis in order:

• Reticulocyte
• Pronormoblast
• Basophilic normoblast
• Orthochromatic normoblast
• Erythrocyte
• Polychromatophilic normoblast

Answer 13

Erythropoiesis:

• Pronormoblast
• Basophilic/ early normoblast
• Polychromatic/ intermediate normoblast
• Orthrochromatic/ late normoblast
• Reticulocyte
• Erythrocyte

Question 14

Which statements are true about reticulocytes:

• Smaller that mature erythrocyte
• Have a nucleus
• Contain RNA remnants
• Hypochromatic
• Exist for a few days
• Have just left the bone marrow

Answer 14

Which statements are true about reticulocytes:

• Smaller that mature erythrocyte FALSE LARGER
• Have a nucleus FALSE
• Contain RNA remnants TRUE
• Hypochromatic FALSE POLYCHROMATIC
• Exist for a few days TRUE
• Have just left the bone marrow TRUE

Question 15

Name 3 causes of a raised reticulocyte count

Answer 15

Haemolysis
>12 hours after acute blood loss
Following Fe supplement in Fe deficiency

Question 16

In a patient with a raised reticulocyte count, what tests are useful for determining the cause?

Answer 16

Look for Hb breakdown products

Seen in haemolysis

Question 17

When do normoblasts loose their nucleus?

Answer 17

When optimal Hb content

Question 18

Where are normoblasts found?

Answer 18

In the bone marrow

Question 19

What is the consequences of a RBC having no nucleus?

Answer 19

Can’t divide
Can’t replace damaged protein
Limits lifespan
Fits more Hb in

Question 20

What term describes the shape of a RBC? What is the importance of this shape?

Answer 20

Biconcave
Can withstand high arterial pressure
Contains Hb
>SA for gas exchange

Question 21

What are 3 functions of RBCs?

Answer 21

Delivers O2
Hb H+ buffer
Transport CO2

Question 22

What is the name of the enzyme that generates bicarbonate?

Answer 22

Carbonic anhydrase

Question 23

Where is Epo produced? And in what circumstances?

Answer 23

By kidneys

If they sense hypoxia

Question 24

What effects does Epo have?

Answer 24

Stimulates erythroid hyperplasia to increase marrow activity

Question 25

Why is energy production in the RBC limited?

Answer 25

No mitochondria

Question 26

How do RBCs produce energy?

Answer 26

Glycolysis AKA Embden-Meyerhof pathway

Question 27

What are the net products of glycolysis?

Answer 27

ATP + NADH

Question 28

What is the function of NADH in RBCs?

Answer 28

Prevents Fe2+ oxidation to Fe3+ metHb, can’t carry O2

Question 29

What is the Rapapoport-Lubering shunt?

Answer 29

Alternate route for glucose to pyruvate via 2,3-DBG when does it happen? maybe in oxidative environment?

Question 30

What is the allosteric effect?

Answer 30

When 1 oxygen binds to a Hb subunit the shape changes to increase the affinity for O2

Question 31

Where are old / abnormal RBCs removed? What cell type is responsible for this?

Answer 31

Spleen | Macrophages

Question 32

Macrophages recycle old red cells. What are the globin chains recycled to?

Answer 32

Amino acids

Question 33

Macrophages recycle old red cells. What are the heme chains recycled to?

Answer 33

Brown to iron + bilirubin Iron transferred back to barrow erythroblasts Heme converted to bilirubin

Question 34

What are the intermediate steps of heme conversion to bilirubin?

Answer 34

Heme to porphyrin to bilverdin to bilirubin

Question 35

What happens to bilirubin after it leaves the spleen?

Answer 35

Conjugated in liver, then excreted in bile

Question 36

Reactive oxygen species are made in a ______ environment

Answer 36

Oxygen rich

Question 37

Reactive oxygen species free radicals oxidise things they shouldn't such as ...

Answer 37

DNA

Question 38

Name 2 free radicals

Answer 38

Hydrogen peroxide | Superoxide

Question 39

What thing removes the free radical hydrogen peroxide?

Answer 39

Glutathione and G6PD enzyme

Question 40

What thing remove the superoxide free radical?

Answer 40

Superoxide dismutase enzyme

Question 41

CO2 transport: 30% as _____ 60% as _____ 10% as _____

Answer 41

30% carbamino-Hb 60% bicarbonate 10% dissolved

Question 42

What cycle is B12 responsible for?

Answer 42

Methionine cycle

Question 43

What cycle overlaps with the methionine cycle?

Answer 43

Folate cycle

Question 44

B12 and folate both aid in what in the RBC?

Answer 44

DNA synthesis

Question 45

What are the main components of Hb?

Answer 45

Haem + globin chain

Question 46

What is a haem group made of?

Answer 46

Iron + porphyrin ring

Question 47

What is the function of iron in Hb?

Answer 47

Binds oxygen

Question 48

What are the globin chains in adult haemoglobin HbA?

Answer 48

2 alpha chains | 2 delta chains

Question 49

What are the globin chains in fetal haemoglobin HbF?

Answer 49

2 alpha | 2 gamma

Question 50

How does fetal haemoglobin differ in function from adult haemoglobin?

Answer 50

Increased saturation at same partial pressure of oxygen

Question 51

What effect does chronic anaemia have on the oxygen Hb dissociation curve? What molecule in the RBC is attributed to this?

Answer 51

Shifts curve right (double check this) | Increased 2,3-DPG

Question 52

How many molecules of oxygen can 1 molecule of Hb carry?

Answer 52

4

Question 53

Free haemoglobin binds to Fe3+ producing what?

Answer 53

MetHb which can't carry O2

Question 54

What are the types of granulocyte? Which is commonest?

Answer 54

Neutrophil commonest Eosinophil Basophil

Question 55

What are the 2 states of iron in the most?

Answer 55

Fe2+ (ferric) | Fe3+ (ferrous)

Question 56

What are the location of iron within the body?

Answer 56

``` Most in Hb Parenchyma Myoglobin Enzymes Macrophages Marrow ```

Question 57

Where is iron absorbed?

Answer 57

Duodenum

Question 58

What food interferes with Fe absorption?

Answer 58

Tannins in tea | others

Question 59

Iron in the liver is bound to what protein?

Answer 59

Ferritin

Question 60

Iron in macrophages is bound to what protein?

Answer 60

Ferritin

Question 61

What protein is responsible for transporting iron throughout the circulation?

Answer 61

Transferrin

Question 62

What protein is responsible for Fe transport out of cells to transferrin?

Answer 62

Ferroportin

Question 63

Where does transferrin transport iron from? Where to?

Answer 63

From macrophages / intestine / hepatocyte To tissues expressing transferrin receptors (erythroid marrow)

Question 64

Serum ferritin is raised in malignancy and sepsis since it is an ______

Answer 64

acute phase protein

Question 65

What protein is a negative regulator of Fe uptake? What is its function?

Answer 65

Hepcidin Degrades ferroportin

Question 66

What effect does iron deficiency have on hepcidin?

Answer 66

Decreases

Question 67

Where is hepcidin produced?

Answer 67

Liver