Erythrocytes Flashcards

1
Q

What is bone marrow transit time?

A

5 days

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2
Q

Reticulocytes normally remain in bone marrow how long?

A

2-3 days

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3
Q

Normal HCT range

A

37-55%

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4
Q

CRF HCT range

A

22-25%, can be as low as 0%

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5
Q

The original rubriblast produces how many RBCs?

A

4 divisions - 16 RBCs

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6
Q

How is erithropoietin release regulated?

A

The kidney responds to hypoxia by activating the hormone erythropoietin.

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7
Q

What does erythropoietin do?

A

Erythropoietin stimulates stem cell differentation to rubriblasts and early reticulocyte release.

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8
Q

How do androgens effect erythropoiesis?

A

They stimulate erythropoietion or potentiate its action.

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9
Q

How do estrogens effect erythropoiesis?

A

Estrogens have an inhibitory effect on erythropoiesis.

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10
Q

RBC life span in dogs

A

120 days

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11
Q

RBC life span in cats

A

70 days

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12
Q

RBC life span in cows

A

160 days

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13
Q

RBC life span in horses

A

145 days

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14
Q

How do old RBCs leave circulation under normal circumstances?

A

The major route of blood cell loss is phagocytosis by RE cells. A minor route is intravascular lysis and release of hemoglobin. The routes of RBC destruction are similar in hemolytic anemia.

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15
Q

What is the primary function of hemoglobin (Hb)?

A

HB carries oxygen and carbon dioxide.

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16
Q

What does hematocrit or packed cell volume measure?

A

Hematocrit (Hct) or packed cell volume (PCV) is the percentage of blood composed of red blood cells.

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17
Q

What components are evident in a centerfuged capillary tube?

A

There are three portions of centerfuged whole blood - a red cell layer, a white cell layer (the “Buffy coat”) and plasma.

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18
Q

What can plasma be used to evaluate?

A

Plasma can be used for plasma protein concentration using a refractometer. Plasma fibrinogen can be measured by using a heat precipatior and refractometer.

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19
Q

What is the normal appearance of plasma in the dog and cat?

A

clear and colorless

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20
Q

What is the normal appearance of plasma in the horse and cow?

A

light yellow

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21
Q

What is the appearance of icteric plasma?

A

yellow and clear

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22
Q

What is the appearance of hemoglobinemic plasma?

A

Pink to red and clear

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23
Q

What is the appearance of lipemic plasma?

A

whitish and turpid

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24
Q

Where can microfilaria be found in centerfuged whole blood taken from heartworm positive animals?

A

Microfilaria can be found in the layer of plasma just above the Buffy coat.

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25
Q

What is hemoglobin concentration?

A

Hemoglobin concentration is the most direct measure of oxygen transport capacity of the blood. It should be abut 1/3 of the total PCV.

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26
Q

How is hemoglobin concentration determined?

A

Hemoglobin concentration is most frequently determined via automated methods. Its accuracy is +/- 5% and the presence of lipemia or an abnormal number of Heinz bodies can result in an abnormally high reading.

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27
Q

How is the red blood cell count determined?

A

There are two methods to determine the red blood cell count. Automatic counters are more accurate. Direct counts using a hemocytometer have a large margin of error +/-20%.

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28
Q

How does anemia effect the Hct, Hb, and RBC counts?

A

low values

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29
Q

How does absolute polycythemia effect Hct, Hb and RBC counts?

A

high values

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30
Q

How does splenic contraction effect Hct, Hb and RBC counts?

A

high values

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31
Q

What species is splenic contraction common in?

A

excited horses

32
Q

What does hemoglobin consist of?

A

Hemoglobin consists of 4 globin chains (made of amino acid sequences) each binding to a heme group.

33
Q

What nutrient does the diet need to contain an adequate supply of in order to produce globin?

A

protein

34
Q

What is body iron content regulated by?

A

Body iron content is regulated by the rate of iron absorption (rather then excretion).

35
Q

What is the body’s iron absorption rate regulated by?

A

The body’s iron absorption rate is regulated by the amount of storage iron (most of which is in hemoglobin) and the rate of erythropoiesis.

36
Q

What is necessary for the absorption of iron?

A

a copper containing protein

37
Q

Where is most of the body’s iron stored?

A

hemoglobin

38
Q

What is required for erythropoiesis in only some species?

A

B vitamins

39
Q

What are characteristics of a hematopoetic stem cell?

A

The hematopoetic stem cell is a multipotential stem cell which differentiates into a unipotential cell. It is self-replicating and responsive to erythropoietin.

There are three different types - erythrocytic, granulo-monocytic, and megakaryotic.

40
Q

Where does erythropoiesis occur?

A

Erythropoiesis occurs exrtavascularly in bone marrow, and with prolonged stimulus it occurs in places other then bone marrow (ex. spleen).

41
Q

What is a multipotential stem cell?

A

Multipotency describes progenitor cells which have the gene activation potential to differentiate into multiple, but limited cell types.

42
Q

What is an erythroid precursor?

A

An erythroid precursor cell is a unipotent blood stem cell that has differentiated from a multipotential stem cell.

43
Q

What is a rubriblast?

A

A rubriblast is the earliest stage of development of an erythrocyte.

44
Q

What is a prorubricyte?

A

Basophilic normoblast

45
Q

What is a rubricyte?

A

an immature red blood cell that has a nucleus, is about half the size of developing red blood cells in preceding stages, and has cytoplasm that stains erratically blue, purplish, and gray due to the presence of hemoglobin : polychromatic normoblast

46
Q

What is a metarubricyte?

A

a normoblast, the last nucleated stage in the development of an erythrocyte

47
Q

What is a reticulocyte?

A

an immature red blood cell without a nucleus, having a granular or reticulated appearance when suitably stained.

48
Q

What is an erythrocyte?

A

.a red blood cell that (in humans) is typically a biconcave disc without a nucleus. Erythrocytes contain the pigment hemoglobin, which imparts the red color to blood, and transport oxygen and carbon dioxide to and from the tissues

49
Q

How do changes in hydration affect Hct, Hb, and RBC count values?

A

Dehydration results in increased values, and overhydration results in decreased values.

50
Q

What is splenic contraction?

A

The spleen has the ability to change how big it is. If a flight animal undergoes stress the spleen contracts, pushing out the blood contained within. Blood in the spleen has a high concentration of RBCs - approximately 80%.

51
Q

What does mean corpuscular volume indicate?

A

Mean corpuscular volume (MCV) indicates the average size of the RBCs.

52
Q

How is mean corpuscular volume determined?

A

Hct * 10/RBC count (10^6) = MCV (femtoliters)

Automated machines do the calculations today.

53
Q

How do macrocytic anemias - ex. B12 and folic acid deficiencies - affect MCV values?

A

increased value

54
Q

How does reticulocytosis affect MCV values?

A

transitory increase

55
Q

How does iron deficiency affect MCV values?

A

decreased values

56
Q

Define normocytic.

A

normally-sized cell

57
Q

Define microcytic.

A

abnormally small cell

58
Q

Define macrocytic.

A

abnormally large cell

59
Q

How is mean corpuscular hemoglobin concentration determined?

A

Hb * 100/Hct = MCHC (g/dL)

60
Q

Define normochromic.

A

normally colored

61
Q

Define hypochromic.

A

abnormally colored

62
Q

How does iron deficiency affect MCHC?

A

decreased value

63
Q

How does hemolysis affect MCHC?

A

increased value

64
Q

How is erythrocyte sedimentation performed?

A
  1. Fill winthrobe hematocrit tube
  2. allow to stand 1 hour
  3. record level of top of RBC column
65
Q

What is erythrocyte sedimentation used to evaluate?

A

Certain autoimmune diseases. Of limited diagnostic value.

66
Q

What is increased ESR associated with?

A

Increased ESR is associated with tissue damage, inflammation, and increased fibrinogen.

67
Q

Where is fibrinogen produced?

A

Fibrinogen is a plasma protein produced by the liver.

68
Q

What are the functions of fibrinogen?

A

Fibrinogen functions in the clotting mechanism of the blood, and moves into the extravascular spaces to assist in localization of disease processes.

69
Q

How is the plasma protein:fibrinogen ratio calculated?

A

TPP-F/F = PP:F

70
Q

What are normal fibrinogen values?

A

Greater then 15:1 is normal, less then or equal to 10:1 represents an absolute increase in fibrinogen.

71
Q

What morphological changes are seen during erythropoiesis?

A

Cells become smaller. Nuclei also become smaller. Division stops in the late rubricyte stage, and the nucleus is extruded during the metarubricyte stage.

72
Q

How do reticulocytes and erythrocytes migrate into peripheral blood?

A

Reticulocyes and erythrocytes migrate into the venous sinuses of bone marrow and then to the peripheral blood.

73
Q

Only mature RBCs enter the bloodstream in which species?

A

horses

74
Q

Define pyknotic.

A

refers to a dying nucleus that has become dense and small

75
Q

Where is red bone marrow found?

A

Red bone marrow is found at the ends of the long bones and in the flat bones (ex. scapula, ribs, sternum, etc.)