Haemopoiesis, Erythropoiesis And Iron

Question 1

Where are blood cells produced

Answer 1

In the bone marrow

Question 2

Describe the difference in distribution between infanthood and adulthood of bone marrow

Answer 2

Infant: Extensive throughout skeleton
Adult: Predominantly in pelvis, sternum, skull, ribs, vertebrae

Question 3

Describe the process of haematopoeisis

Answer 3

Multipotential hematopoetic stem cells
Go to Common lymphoid progenitor cells–>Lymphocytes

Also go to Common Myeloid Progenitor–>Megakaryocyte+Granulocyte+Erthyocyte

Question 4

What system controls and removes blood cells

Answer 4

Reticuloendothelial system

Question 5

What organ is responsible for the disposal of blood cells

Answer 5

The spleen

Question 6

What is the membrane of rbcs specialised to do? If damaged, what does it make the rbc

Answer 6

Make rbc flexible

Makes rbc fragile and likely to lyse–>anaemia

Question 7

What are the three properities that globin chains add to haemoglobin

Answer 7

protect haem group from oxidation, Increase solubility, Permits variation in oxygen affinity

Question 8

Describe how erythropoiesis is controlled

Answer 8

Reduced pO2–>Increase erthyropoetic hormone (from kidney)–>Increased synthesis of rbcs in the bone marrow–>Increased pO2–>Reduction in production of Erythropoetin

Question 9

Name the two main metabolic pathways in rbcs

Answer 9

Glycolysis

Pentose Phosphate Pathway

Question 10

How is iron in the body controlled

Answer 10

By controlling the absorption of iron and the iron released from macrophages. No mechanism for excretion

Question 11

In which two carriers is iron stored

Answer 11

Ferritin- eg in hepatocytes

Haemosiderin-Macrophage iron

Question 12

Where is the majority of iron stored.. what about the other 5% of iron?

Answer 12

Majorityin hepatocytes as ferritin

Hemosiderin constitutes the remaining 5% in kupffer cells (macrophages in the liver)

Question 13

Does haem iron exist as ferrous iron (Fe2+) or ferric iron (Fe3+)?

Answer 13

Ferrous. Non haem exists as ferric iron

Question 14

Describe th eprocess of how ferric iron is transported into the bloodstream from the gi system

Answer 14

In the stomach Fe3+–>Fe2+
Fe2+ binds to transferrin
Enters epithelial cellls lining the intestine
Either stored in the enterocyte as ferritin or transported into the bloodstream via ferroportin
Then either stored in the liver or used in Hb

Question 15

How is iron taken into cells

Answer 15

By binding of iron-transferrin complex to transferrin receptor

Question 16

What two substances aid in the absorbtion of iron?

Answer 16

Ascorbic acid and vit C

Question 17

What is the name of the central regulator of iron metabolism and how does it work?

Answer 17

Hepcidin
Released by the liver
Synthesis is increased in iron overload
binds to ferroportin and prevents it working
so iron can enter epithelial cells, but remains stored there aas cannot enter the bloodstream

Question 18

List 6 symptoms if anaemia

Answer 18

tiredness
Pallor
decreased exercise tolerance
cardiac symptoms (eg angina)
Tachycardia
increased resp rate

Question 19

Name two tests used to test for iron deficiency

Answer 19

Ferritin( if otherwise well. Acute phase protein so can increase with inflammation

CHR

Question 20

Suggest treatments for iron deficiency

Answer 20

Dietary advice
Oral iron supplements
Intramuscular iron injections
Intravenous iron
Transfusion (only if severely anaemic)

Question 21

Describe the process of hereditary haemochromatosis (why iron incresses)

Answer 21

Mutations in the HFE gene
HFE normally competes with transferrin for binding to transferrin receptor
Mutated HFE cant bind so transferrin has no competition, so too much iron enters cells from GI system

Question 22

What chemical stimulayes
a- Lymphocyte production
b- Megakaryocyte production
c- Erythrocyte production
d- Granulocyte production

Answer 22

a- ILs and TNFs
b- thrombopoietin
c- Erythropoetin
d- Granulocyte colony stimulating factor

Question 23

What does the RES consist of?

Answer 23

Phagocytic cells

Question 24

Give 4 functions of red blood cells

Answer 24

carry Hb
Maintain Hb in a reduced state
generate energy
maintain osmotic equilibrium

Question 25

How is Haemoglobin catabolised?

Answer 25

Hb–>Haem–>bilirubin
Bilirubin goes to the liver, used for bile
bile absorbed in the colon and excreted in the kidneys

Question 26

what can increased destruction of red blood cells lead to an why?q

Answer 26

Jaundice

Product of Hb catabolism is bilirubin

Question 27

Name four sites where available iron is kept

Answer 27

Hb
Myoglobin
tissue iron
transported iron in serum

Question 28

Two features of the blood film in iron deficiency anaemia?

Answer 28

Hypochromic red blood cells (Decreased Hb in cells)

Microcytic red blood cells

Question 29

Three causes of iron deficiency?

Answer 29

Decreased uptake
Increased loss (Eg Gi problems)
Excessive use (pregnancy)

Question 30

What is haemochromatosis? Complication?

Answer 30

Iron deposition in organs–>organ damage

Liver cirrhosis, diabetes, skin pigmentation, hypogonadism, cardiomyopathy

Question 31

Two causes of haemochromatosis?

Answer 31

Hereditary or transfusion associated