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Histology Exam 4 > Blood/hemopoiesis > Flashcards

Blood/hemopoiesis Flashcards

1
Q

What is blood?

A

Formed elements (cells) + plasma

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2
Q

What is plasma?

A

Water, proteins, and solutes.

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3
Q

What are the major proteins in plasma?

A

Fibrinogen, albumin, and globulins

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4
Q

How many erythrocytes are in the peripheral blood of an individual?

A

25 trillion

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5
Q

What percent of total blood volume do red cells comprise?

A

45%

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6
Q

Describe the shape, size, and staining of erythrocytes.

A

Biconcave cell with no nucleus or organelles
7-8 micrometers in diameter
Stain eosinophilic

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7
Q

What fraction of the RBC mass is hemoglobin?

A

1/3

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8
Q

What is the life span of an RBC?

A

120 days (approx.)

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9
Q

Where are red cells destroyed?

A

Spleen, liver, and bone marrow

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10
Q

What are reticulocytes?

A

New RBC’s from bone marrow - they complete hemoglobin synthesis and mature 1-2 days after entering circulation

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11
Q

What is and what causes sickle cell anemia?

A

Genetic alteration in the hemoglobin beta-chain. Single amino acid substitution - valine (nonpolar, hydrophobic) is substituted for glutamic acid (polar, charged, acidic). The altered hemoglobin (HbS) has different biochemical and physiological properties that produce sickling of RBC’s. Hb denatures and clusters band 3 protein, ankyrin, and spectrin.

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12
Q

What is the genetic defect in sickle cell anemia?

A

Single amino acid substitution in the hemoglobin beta-chain. Glutamic acid –> valine

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13
Q

Which proteins are denatured and clustered by Hb in sickle cell anemia?

A

band 3 protein, spectrin, and ankyrin

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14
Q

What systemic problems do sickled blood cells cause?

A
  • Deformed cells have difficulty in passing through the splenic sinuses, and are trapped and removed by macrophages
  • Sickle cells can adhere to capillary endothelial cells and occlude vessels
  • Spleen of patients with sickle cell anemia enlarged by the sequestering of the sickle cells in the cords and sinuses
  • Individuals with sickle cell disease have a shortened life span
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15
Q

What is hereditary spherocytosis?

A
  • Inherited disorder
  • Defects in RBC membrane (specifically membrane spectrin’s association with ankyrin and actin, which helps produce RBC biconcave shape and allows cells to change shape)
  • Results in spheroidal, less deformable cells.
  • These RBCs are susceptible to destruction by spleen macrophages.
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16
Q

What causes spherocytosis?

A
  • Spherocytosis patients have a spectrin deficiency (only have 60-90% of the spectrin of normal individuals)
  • Some spherocytosis patients have an ankyrin mutation
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17
Q

Why does it matter if RBCs are spheroidal?

A
  • They are less deformable
  • Their inability to alter shape results in sequestration in the splenic cords and failure to pass into splenic sinuses
  • This enables destruction by splenic macrophages
  • Patients then have anemia and splenomegaly (enlarged spleen)
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18
Q

What happens on the blood smears of spherocytosis patients?

A

Spherocytosis RBCs lack central pale zone in blood smears

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19
Q

Describe the relationship between actin, ankyrin, spectrin, and band 3 protein.

A

Band 3 is an integral membrane protein.
Ankyrin binds to the intracellular part of ankyrin and anchors spectrin dimers to band 3 protein.
Actin is also associated with spectrin.

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20
Q

What are platelets?

A

Cell fragments 2-5 micrometers in diameter, derived from megakaryocytes.

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21
Q

Describe megakaryocytes.

A
  • Large bone marrow cell
  • Megakaryocyte has platelet demarcation channels derived from the plasma membrane and continuous with the extracellular space.
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22
Q

What is the function of platelets?

A

Help with blood clotting, clot retraction, and clot dissolution. Also a source of vasoactive compounds (thromboxane A2) - derived via cyclooxygenase metabolism

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23
Q

What sorts of things do platelets contain?

A
  • Alpha granules: lysosomal in character
  • Dense core granules: contain serotonin, ADP, ATP, and calcium
  • Numerous cytoplasmic microtubules
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24
Q

What happens upon activation of platelets?

A

Platelets change from discoid shape to a more flattened appearance with extensive ruffling of cell membrane (associated with rearrangements of cytoskeleton), microtubule redistribution, and rapid polymerization of actin into microfilaments

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25
Q

What are neutrophils?

A

Granulocytes (9-12 micrometers in diameter), with a 3 lobed nucleus (up to 5 lobes as the cell matures). First phagocytic cell to appear during inflammation.

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26
Q

Do neutrophils undergo mitosis?

A

No - terminally differentiated

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27
Q

What types of granules do neutrophils contain?

A
  • Specific granules: small, with alkaline phosphatase and phagocytins (antibacterial proteins)
  • Azurophilic granules: larger, with myeloperoxidase and lysozomal enzymes
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28
Q

What percent of white cells in blood are comprised of neutrophils?

A

65-75%

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29
Q

Describe immature neutrophils (name, nucleus, lifespan).

A

Also called Stab/band cells. Have a horseshoe shaped nucleus. Live 6-10 hours in blood and 2-3 days in tissue.

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30
Q

What are basophils?

A

Granulocytes (10-12 micrometers in diameter) with a lobed nucleus (hard to see in blood smears).

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31
Q

Are basophils common in blood?

A

No, they occur in low numbers in blood.

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32
Q

What kind of granules do basophils contain?

A

Large basophilic granules that have hydrolytic enzymes, histamine, heparan sulfate proteoglycan, and slow reacting substance. Secrete eosinophil chemotactic factor.

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33
Q

What percent of white cells in blood are comprised of basophils?

A

0.5 - 2%

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34
Q

What is the lifespan of basophils?

A

1-10 hours in blood

35
Q

What do basophils bind? What is this similar to?

A

Cells bind IgE similar to mast cells

36
Q

What are eosinophils?

A

Granulocytes (12-15 micrometers in diameter) with bilobed nuclei.

37
Q

What kind of granules do eosinophils contain?

A

Large eosinophilic granules that contain arylsulfatase, histaminase, acid phosphatase, ribonuclease, and peroxidase.

38
Q

What does histaminase do?

A

Decreases severity of allergic reaction.

39
Q

What percent of white cells in blood do eosinophils comprise?

A

0-4% in adults

6% in children

40
Q

What happens to eosinophils during allergic reactions and parasitic infections?

A

They increase in number, leave bloodstream, and enter connective tissue

41
Q

What types of granulocytes are in blood? Name them in order from least to most prevalent.

A

Basophils: 0.5-2% of white cells in blood
Eosinophils: 0-4% of white cells in blood
Neutrophils: 65-75% of white cells in blood

42
Q

What are monocytes?

A

Agranular phagocytic leukocyte (20-25 micrometers in diameter) with an oval to kidney bean shaped (reniform) nucleus. Contains lysosomes.

43
Q

What percent of white cells in blood do monocytes comprise?

A

2-9%

44
Q

What is the lifespan of monocytes?

A

1-3 days in blood

45
Q

What happens when monocytes move from the blood into the tissue spaces?

A

They differentiate into other cells in the monocyte/macrophage lineage (macrophages, osteoclasts, and giant cells)

46
Q

Why are monocytes important?

A

They play a role in the regulation of immune response and inflammation.

47
Q

What are lymphocytes?

A

Small (6-9 micrometers), medium (10-12 micrometers), and large (13-18 micrometers) mononuclear cells

48
Q

What percent of white cells in blood do lymphocytes comprise?

A

20-35%

49
Q

What do lymphocyte nuclei look like?

A

Nucleus is round/oval in small/medium lymphocytes and may be more reniform in large lymphocytes.

50
Q

Do lymphocytes have a lot of cytoplasm?

A

No - very little cytoplasm evident.

51
Q

What are T-lymphocytes?

A

Derived from bone marrow and mature in thymus.

52
Q

What are B-lymphocytes?

A

Derived from bone marrow, lymphoid progenitor cells.

53
Q

What are Null cells?

A

Large granular lymphocytes

54
Q

What do natural killer (NK cells) and killer (K cells) originate from?

A

Null cells may differentiate into NK or K cells

55
Q

Do T cells or B cells have more surface projections?

A

In general T cells have fewer surface projections than B cells

56
Q

Describe fetal bone marrow.

A

In the fetus, bone marrow is an actively hematopoietic tissue.

57
Q

Describe adult bone marrow. How is it different from fetal bone marrow?

A

Adult bone marrow is less hematopoietic than fetal bone marrow because it regresses from hematopoietic red marrow to resting, fat-storing yellow marrow.

58
Q

Where is red marrow present in adults? Where is marrow typically taken from?

A

Vertebrae, sternum, ribs, skull, pelvis, and proximal femur. Bone marrow is typically taken from the iliac crest.

59
Q

When does hematopoiesis begin? In the yolk sac? In the liver?

A

Hematopoiesis begins early in embryonic development. It begins during the second week of gestation in the yolk sac. It begins during the sixth week of gestation in the liver.

60
Q

What are colony-stimulating factors (CSF)? What are some specific examples?

A

CSFs are cytokines which stimulate the differentiation of bone marrow progenitor cells

Interleukin-7 = lymphoid precursors - B/T cells
Granulocyte-monocyte CSF
Monocyte CSF
Granulocyte CSF

61
Q

What is erythropoietin? Where does it come from?

A

Erythropoietin from kidneys causes CFU-E (colony forming unit - erythrocyte) cells to differentiate into erythroblasts

62
Q

What is a basophilic erythroblast?

A

CFU-E –> basophilic erythroblast. Ribosomes accumulate in the cytoplasm, increasing erythroblast basophilia (first step of erythroblast development)(cytoplasm = blue, even though nucleus may be pink)

63
Q

How does a cell become a polychromatophilic erythroblast?

A

Basophilic erythroblast –> polychromatophilic erythroblast. Ribosomes bind hemoglobin mRNA, synthesizing hemoglobin which reduces the cell’s basophilia, turning it into a polychromatophilic erythroblast (cytoplasm = multicolored)

64
Q

What is an orthochromatic erythroblast?

A

Also called a normoblast, this happens when the hemoglobin concentration increases and the cytoplasm stains pink

65
Q

How does the cell finally become an erythroCYTE?

A
  • As hemoglobin accumulates, the nucleus condenses and undergoes a heterochromatic involution
  • Then, the cell sheds its nucleus, most mitochondria, and polyribosomes to form an erythrocyte
66
Q

What happens to the hemoglobin from destroyed RBCs?

A

It is degraded into

1) Bilirubins and other materials, excreted in bile
2) Iron, which is transported by the serum glycoprotein transferrin to bone marrow, where it is used to synthesize new hemoglobin

67
Q

What is the order of structures in erythropoiesis, from CFU-E to degradation?

A

CFU-E –> basophilic erythroblast –> polychromatophilic erythroblast –> orthochromatic erythroblast –> reticulocyte –> erythrocyte –> degradation

68
Q

What do granulocytes (neutrophils) develop from?

A

CFU-S cells, but the first recognizable granulocyte precursor is the myeloblast

69
Q

What is a myeloblast?

A

Large euchromatic nucleus with several nucleoli and no granules, in a basophilic cytoplasm

70
Q

What is a promyelocyte?

A

Developing granulocyte is called this when the cytoplasm accumulates a few azurophilic (nonspecific) granules, nucleus accumulates heterochromatin, and a slight indentation occurs in the nucleus

71
Q

What happens when the promyelocyte begins to differentiate?

A

It begins accumulating neutrophilic, eosinophilic, or basophilic specific granules in the cytoplasm, and the nucleus continues to condense and lobulate

72
Q

What is a metamyelocyte?

A

It has accumulated many specific granules but has yet to complete the process of nuclear condensation and lobulation

73
Q

What is the order of structures in granulopoiesis from CFU-S to granulocyte?

A

CFU-S –> myeloblast –> promyelocyte –> myelocyte –> metamyelocyte –> granulocyte

74
Q

Describe monopoiesis

A

Monocytes develop from the same CFU-S cells as granulocytes; however, there is a different developmental process that includes monoblast and promonocyte stages

75
Q

Describe lymphopoiesis

A

Lymphocytes develop from lymphoblasts, which are derived from CFU-Ly cells

76
Q

What are megakaryocytes?

A

Platelet precursors that develop from megakaryoblasts (differentiated CFU-S cells) in response to thrombopoietin (CFU-S –(thrombopoietin)–> megakaryo(cyto)blast –> megakaryocyte)

77
Q

Describe megakaryocytes

A

100 micrometers in diameter

Exist only in bone marrow and have a multilobulated nucleus

78
Q

Do megakaryocytes divide?

A

No - cell does not divide but becomes larger with nucleus becoming polyploid (as much as 64N) - process of endomitosis

79
Q

How/where are platelets released?

A

In the bone marrow vascular channels, megakaryocytes slowly release small cytoplasmic fragments (platelets) into the blood stream. Megakaryocytes fragment when the cell plasma membrane fuses with smooth ER membranes (of bone marrow vascular channels?)

80
Q

What is the lifespan of platelets?

A

Platelets remain in the bloodstream for 7-10 days and are replaced by new platelets from bone marrow

81
Q

What is acute lymphocytic leukemia?

A

Rapid growth of immature white blood cells (assuming lymphocytes - B cells, T cells, NK cells?). Common in children.

82
Q

What is acute myelogenous leukemia?

A

Unregulated growth of white blood cells from myeloid lineage (neutrophil, eosinophil, basophil, or monocyte). Common in adults.

83
Q

What is chronic lymphocytic leukemia?

A

B cell cancer mainly in adult males.

84
Q

What is chronic myelogenous leukemia? What causes it?

A

Unregulated growth of myeloid cells (neutrophils, eosinophils, basophils) in bone marrow. Caused by translocation between chromosome 9 and 22 (Philadelphia chromosome/translocation)

Histology Exam 4 (3 decks)

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