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Haematology I > Haematopoiesis > Flashcards

Haematopoiesis Flashcards

1
Q

___________ is the development of all blood cells.

A

Haematopoiesis

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2
Q

Mature blood cells have a limited lifespan, and only ____________ are capable of renewing themselves.

A

Lymphocytes

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3
Q

Replacement of peripheral haematopoietic cells is a function of the ___________ __________ cells (HSCs) found in the bone marrow.

A

Haematopoietic stem

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4
Q

Haematopoietic stem cells are capable of _____-__________, and differentiation into all blood cell lines.

A

Self-renewal

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5
Q

Committed _________ stem cells are destined to develop into distinct cell lines.

A

Progenitor

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6
Q

Committed lymphoid stem cells will be involved in _________, producing lymphocytes.

A

Lymphopoiesis

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7
Q

Differentiation is determined by various growth factors, or ___________, such as erythropoietin’s ability to stimulate the production of red blood cells.

A

Cytokines

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8
Q

True or false: differentiation and maturation of the stem cells into the functional cellular elements is the initial step of blood cell formation.

A

True

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9
Q

Proliferation, differentiation, and maturation of haematopoietic cells occurs in the ________ __________ and the widespread lymphatic system.

A

Bone marrow

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10
Q

Only erythrocytes are made in the ____ ____ of the embryo.

A

Yolk sac

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11
Q

Aorta-gonads-mesonephros (AGM) is located along the developing _________.

A

Aorta

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12
Q

When the bone marrow becomes the chief site of haematopoiesis, leucocyte and _____________ production become more prevalent.

A

Thrombocyte

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13
Q

Haematopoiesis in the bone marrow is called ___________ haematopoiesis.

A

Medullary

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14
Q

Haematopoiesis in areas other then the _______ __________is called extramedullary haematopoiesis.

A

Bone marrow

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15
Q

______________ __________ can lead to hepatomegaly and/or splenomegaly (increase in size of the liver or spleen).

A

Extramedullary haematopoiesis

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16
Q

Haematopoietically active tissue is found in the _______ marrow.

A

Red

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17
Q

Inactive, fatty marrow is the ______ marrow.

A

Yellow

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18
Q

In certain pathologic states, the bone marrow can increase its activity to 5-___ times its normal rate.

A

10

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19
Q

When activity is increased, bone marrow is said to be hyperplastic/__________, because it replaces the yellow marrow with red marrow.

A

Hypercellular

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20
Q

List two pathological states with which increase bone marrow activity is associated.

A

Excess bleeding, and malignant disease

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21
Q

Haematopoietic tissue may also become inactive or _________ (hypocellular), due to chemicals, genetics, etc..

A

Hypoplastic

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22
Q

Myeloproliferative disease (MPD), that replaces haematopoietic tissue with __________ tissue.

A

Fibrous

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23
Q

List three functions of the spleen.

A

Extramedullary haematopoiesis, pitting of RBC, and immune response

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24
Q

The ___________ ___________ ________ (also called the reticular endothelial system or RES) is involved in cellular destruction.

A

Mononuclear phagocytic system

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25
Q

______________ is the development of WBC, or leucocytes.

A

Leucopoiesis

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26
Q

List the stages of granulocytopoiesis.

A

HSC
Progenitor cell
Myeloblast (18-20µm)
Promyelocyte (22-25µm)
Myelocyte (18-20µm)
Metamyelocyte (14-20µm)
Band neutrophil
Neutrophil (segmented neutrophil; polymorphonuclear (PMN) cell) (12-15µm)

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27
Q

List the stages of thrombopoiesis.

A

HSC
Progenitor cells
Megakaryocyte
Platelets are released by fragmentation of the cytoplasm Thrombopoietin (TPO) stimulates the production of platelets

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28
Q

Megakaryocytes have a highly _________ DNA content.

A

Polyploid

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29
Q

The reference range for ____________ for a male is 4.5-5.9x1012/L, and for a female is 3.8-5.2x1012/L.

A

Erythrocytes

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30
Q

What are the two components of an erythrocyte?

A

Cytoplasm and plasma membrane

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31
Q

______________ are dedicated to respiratory gas transport.

A

Erythrocytes

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32
Q

Erythroblastic islands, and central macrophages, surrounded by developing erythroblasts, are found scattered throughout the bone marrow, close to marrow ________.

A

Sinuses

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33
Q

Outline the steps of erythropoiesis.

A

Haematopoietic stem cells (HSC)
Committed erythroid progenitor cell (CMP)
Differentiates to burst-forming unit-erythroid (BFU-E)
Differentiates to colony-forming unit-erythroid (CFU-E)
Proerythroblast (EPO stimulation transforms CFU-E to proerythroblast)
Basophilic erythroblast
Polychromatic erythroblast
Orthochromatic erythroblast
Erythroblasts mature to reticulocyte stage in marrow (5-7 days)
Reticulocytes are released into peripheral blood where they circulate for one to two days before becoming mature red blood cells

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34
Q

What are the three phases of the erythrocyte development pathway?

A

Ribosome synthesis in early erythroblasts
[Hb] accumulation in late erythroblasts
Ejection of the nucleus from erythroblasts and formation of reticulocytes

35
Q

True or false: reticulocytes have a nucleus.

A

False

36
Q

Polychromatic erythrocytes may also be called ____________.

A

Reticulocytes

37
Q

Too few RBC leads to tissue ________.

A

Hypoxia

38
Q

Too many RBC causes undesirable blood ___________.

A

Viscosity

39
Q

Erythropoiesis is hormonally controlled, and depends on adequate supplies of _______, amino acids, and B vitamins.

A

Iron

40
Q

Erythropoietin (EPO) secretion by the _________ is triggered by hypoxia due to decreased RBC or haemoglobin content.

A

Kidneys

41
Q

Intracellular iron is stored in protein-iron complexes such as ferritin and ______________.

A

Haemosiderin

42
Q

Circulating iron is loosely bound to the transport protein ___________.

A

Transferrin

43
Q

Vitamin B12 or __________ deficiency will cause problems with nuclear maturation.

A

Folate

44
Q

No mitochondria means no citric acid cycle can be undertaken, and there is only __________ ATP production in erythrocytes.

A

Anaerobic

45
Q

The life span of an erythrocyte is ______ - ______ days.

A

100-120

46
Q

Dying RBC are engulfed by macrophages of the mononuclear phagocytic system in ___________ haemolysis.

A

Extravascular

47
Q

Haem and globin are separated and the ______ is salvaged for reuse in intravascular haemolysis.

A

Iron

48
Q

_______________ consists of four haem groups, and four polypeptide chains (globins; two alpha, two beta).

A

Haemoglobin

49
Q

Haem is a ring of carbon, hydrogen, and nitrogen atoms (______________ ring), with an attached iron atom, positioned in a poly peptide chain, close to the surface of the [Hb] molecule. Each haem combines reversibly with oxygen molecules.

A

Protoporphyrin

50
Q

Globins are two pairs of polypeptide chains, typically consisting of 141-____ amino acids each.

A

146

51
Q

List the globin chain types.

A

α, β, y, and Δ chains, as well as paediatric Ɛ (epsilon) and ζ (zeta).

52
Q

How many oxygen molecules can a haemaglobin molecule carry?

A

Four

53
Q

Outline the synthesis of haemoglobin.

A

Synthesis begins in the proerythroblast. 65% is produced during erythroblast stage; 35% is at reticulocyte stage. Haem is produced in the mitochondria. Porphyrins are tetrapyrroles (four pyrrole rings). The main site contains ALAS. Globin is produced in polyribosomes. In the nucleus, transcription of DNA to mRNA occurs. tRNA is translated to globin polypeptide chains on the ribosomes, then proceeds to be released from the ribosomes to the cytoplasm of the cell. The genes encoding globin chains are α, ζ, y, β, and Ɛ. There is one copy of each globin gene per chromatid, meaning that per person, two of each globin gene are found (excepting a and gamma). Eight functional globin chains exist, arranged in two clusters. b-cluster (β, Δ, e, and y genes) on the short arm of Chromosome 11. a-cluster, located on the short arm of chromosome 16, contains α and ζ genes). Globin synthesis starts at the third week of gestation. Embryonic [Hb] includes Gower I and II, and Portland. Foetal [Hb]F outstrips [Hb]A. Haemoglobin F, made of α2y2, is found in the foetus.
In adults, [Hb]A, [Hb]A2, and [Hb]F are present; [Hb]A makes up the moiety

54
Q

In adults, an alpha and a non-alpha chain of haemoglobin combine to form a ____________.

A

Heterodimer

55
Q

Two heterodimers spontaneously combine to form ____________.

A

Tetramers

56
Q

For females, reference range for haemoglobin is 120-___g/L.

A

160

57
Q

For males, the haemoglobin reference range is ____-174g/L.

A

140

58
Q

98.5% of oxygen is _________ (oxyhaemoglobin), and 1.5% is in plasma.

A

HgbO2

59
Q

What is the primary function of haemoglobin?

A

Carriage of oxygen from the lungs to the tissues

60
Q

Less importantly, the carriage of CO2 from the tissues to the lungs is another role of [___], but only 13% of CO2 is bound to it.

A

Hb

61
Q

Reaction of [Hb] and oxygen is ________________.

A

Oxygenation

62
Q

When oxygenated, 2,3-BPG (bisphosphoglycerate) (also known as 2,3-DPG (diphosphoglycerate)) is __________.

A

Expelled

63
Q

________ chains are pulled apart when oxygen is unloaded, permitting entry of 2,3-BPG, resulting in lower affinity of O2.

A

Beta

64
Q

___________ is [Hb] bound to oxygen.

A

Oxyhaemoglobin

65
Q

____________ is [Hb], after oxygen diffuses into tissues (reduced [Hb]).

A

Deoxyhaemoglobin

66
Q

Carbaminohaemoglobin occurs when [Hb] is bound to carbon dioxide; it binds to globin’s ___________ _______.

A

Amino acids

67
Q

Carbon dioxide loading takes place in the ___________.

A

Tissues

68
Q

What is haemoglobin’s P50?

A

26.6 mmHg

69
Q

Left shifts indicate ___________ oxygen affinity.

A

Increased

70
Q

________ shifts show decreased oxygen affinity.

A

Right

71
Q

List the factors that affect the normal shape of the curve.

A

Concentration of 2,3-DPG (2,3-BPG)
H+ ion concentration (pH)
CO2 in red blood cells
Structure of [Hb]

72
Q

What is required for a right shift of the curve?

A

High 2,3-DPG
High H+
High CO2
[Hb]S

73
Q

Low 2,3-DPG and [Hb]F are associated with ________ shifts.

A

Left

74
Q

True or false: haemoglobin can be altered by drugs and chemicals.

A

True

75
Q

______________ is iron in the ferric (Fe+++) state (incapable of binding with oxygen) .

A

Methaemoglobin

76
Q

Sulfhaemoglobin arises from irreversible oxidation of haemoglobin, and when a __________ atom combines with haem group.

A

Sulfur

77
Q

________________ cannot transport O2, as the haemoglobin has greater affinity for carbon dioxide.

A

Carboxyhaemoglobin

78
Q

List two fates of haemoglobin.

A

Extravascular haemolysis, involving macrophages in the spleen (or the liver and bone marrow, to a lesser extent), and intravascular haemolysis, which involves the disassociation of haemoglobin into αβ dimers

79
Q

Porphyrin is degraded to a green pigment, ___________.

A

Biliverdin

80
Q

Biliverdin is converted to a ___________ pigment called bilirubin.

A

Yellow

81
Q

The _____________ metabolise bilirubin into urobilinogen and stercobilinogen.

A

Intestines

82
Q

____________ are metabolised into amino acids, and released into the circulation.

A

Globins

83
Q

Outline the process of intravascular haemolysis.

A

Dimers are bound to haptoglobin, then carried to liver (too large to be excreted by kidneys, and processed. Haptoglobin levels may decrease in acute haemolytic states. When haptoglobin is depleted, free αβ dimers may be filtered by kidneys. Dimers that are reabsorbed are catabolised to bilirubin and iron enter plasma pool. Some iron remains in tubular cells, and it complexes with ferritin and haemosiderin. Tubular cells loaded with iron are sloughed off and excreted in urine, and may be detected as haemosiderinuria

Haematology I (4 decks)

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