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Haematology > Chapter 2: Erythropoiesis and Anaemia > Flashcards

Chapter 2: Erythropoiesis and Anaemia Flashcards

1
Q

What is the life span of an RBC?

A

120 days

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2
Q

What colour does haemoglobin stain?

A

pink

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3
Q

How does chromatin change as normoblasts develop?

A

condenses

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4
Q

How long does the reticulocyte circulate in the blood until it matures?

A

1-2days

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5
Q

How many mature red cells does on pronormoblast give rise to normally?

A

16

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6
Q

What cells of the kidney produce erythropoietin?

A

peritubular interstitial cells of the kidney

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7
Q

What is the stimulus for erythropoietin production?

A

oxygen tension in the tissues of the kidney

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8
Q

How does erythropoietin stimulate erythropoiesis?

A

increases number of progenitor cells committed to erythropoiesis by activating transcription factors eg GATA-2 involved in initiating erythroid differetiation in stem cells

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9
Q

What occurs with chronic increase in erythropoietin?

A

extension of eryhtropoiesis into fatty marrow and extramedullary sites

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10
Q

How many polypeptide chains does each molecule of haemoglobin have?

A

4

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11
Q

What are the three forms of Hb in adult blood?

A

HbA ; HbF and HbA2

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12
Q

What are the polypeptide chains in HbA?

A

2x alpha and 2x beta

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13
Q

What are the polypeptide chains in HbF?

A

2x alpha and 2xgamma

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14
Q

What are hte polypeptide chains found in HbA2?

A

2 x alpha and 2xdelta

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15
Q

Where does haem synthesis largely take place?

A

mitochondria

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16
Q

What are the main constituents of haem?

A

protoporphyrin and Fe2+

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17
Q

What happens to the haemoglobin moelcule when O2 is unloaded?

A

the beta chains are pulled apart, allowing 2,3 DPG to bind, resulting in a lower affinity for O2

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18
Q

What is methaemoglobinaemia?

A

circulating Hb has oxidised iron (3+) instead of Fe2+

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19
Q

What other name is the anaerobic glycolytic pathway known as?

A

Embden-Meyerhof pathway

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20
Q

What is the function of hte production of NADH in glycolysis?

A

needed by the enzyme methaemoglobin reductase to change ferric iron to ferrrous form

21
Q

What is the function of the hexose monophosphate shunt?

A

production of NADPH

22
Q

What is the function of NADPH?

A

links with glutathione which prevents oxidative stress to RBCs

23
Q

What enzyme is required for the hexose monophosphate shunt?

A

glucose-6-phosphate dehydrogenase deficiency

24
Q

What is the most abundant protein in the RBC cell membrane?

A

spectrin

25
Q

What is anaemia defined as?

A

reduction in haemoglobin concentration of the blood below normal for age and sex

26
Q

What would cause low reticulocyte count in anaemia?

A

marrow disease; deficiency of iron, B12 or folate; lack of erythropoietin (renal disease); reduced tissue O2 consumption; ineffective erythropoeisis; chronic inflammatory or malignant disease

27
Q

What is seen in the blood if there is ineffective eryhropoiesis?

A

unconjugated bilirubin and LDH

28
Q

What is macrocytic anaemia?

A

red cells are abnormally large

29
Q

How are marcocytic anaemias divided?

A

megaloblastic and non-megaloblastic

30
Q

What is seen in megaloblastic anaemias?

A

erythroblasts in the bone marrow show delayed maturation of the nucleus compared to the cytoplasm

31
Q

What causes the asynchronous maturation of the nucleus in megaloblastic anaemia?

A

defective DNA synthesis

32
Q

What is the usual cause of megaloblastic anaemia?

A

deficiency of vit B12 or folate

33
Q

What is the name of the IF-B12 receptor in the terminal ileum?

A

cubilin

34
Q

What is B12 mainly bound to in plasma?

A

haptocorrin

35
Q

Where is haptocorrin synthesised?

A

granulocytes and macrophages

36
Q

What protein delivers B12 to bone marrow and other tissues?

A

transcobalamin

37
Q

What is the function of methyl B12?

A

methionine synthesis: methylation of homocysteine to methionine

38
Q

What is the form of folate which circulates in plasma?

A

reduced monoglutamate form

39
Q

What is the function of folate?

A

conversion of uridine to thymidine

40
Q

Where is folate absorbed?

A

duodenum and jejunum

41
Q

What is the form of folate as a coenzyme?

A

methyl-THF

42
Q

What drugs inhibit folate reactions?

A

methotrexate; trimethoprim

43
Q

What is achlorhydria?

A

absence of HCl

44
Q

What antibodies are invovled in PA?

A

against gastric H/K ATPase and IF

45
Q

What are the features of vit B12 neuropathy?

A

progressive symmetrical neuropathy affecting peripheral sensory nerves- mainly DCML; lower limbs more than upper limbs

46
Q

What is the thought to be the cause of neuropathy with vit B12?

A

defective methylation of myelin

47
Q

What causes the non-megaloblastic macrocytic anaemia?

A

increased lipid deposition on the red cell membrane or alterations of erythroblast maturation time in marrow

48
Q

What is the most frequent cause of a riased MCV wtihout anaemia

A

alcohol

Haematology (29 decks)

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