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Heme > Structure and Function of Blood Cells (Strom) > Flashcards

Structure and Function of Blood Cells (Strom) Flashcards

1
Q

Describe the process of looking at blood cells with a microscope.

A
  1. Get blood
  2. Put in a tube with EDTA to keep it from clotting
  3. Put a drop of it on a slide
  4. Use another slide to spread the clot out
  5. let it dry
  6. Stain (with “wright-giemsa” stain)
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2
Q

Describe the properties and components of the wright-giemsa stain.

A
  1. Eosin is the main component and is aromatic/acidic/negatively charged.
  2. It is soluble in ethanol NOT H2O.
  3. Stains hydrophobic and basic macromolecules (i.e. Hgb)
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3
Q

What is a variants of eosin-Y that is capable of binding to amine groups for use with flow cytometry?

A

FITC (fluorescein isothiocyanate)

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4
Q

What cells are rare in peripheral blood (<5% of leukocytes) and are elevated in the context of allergic reactions and infections with parasites?

A

eosinophil

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5
Q

In what context do the numbers of eosinophils increase in number?

A

allergic reactions and infection with parasites

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6
Q

What cell type is identified with methylene blue staining?

A

basophil

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7
Q

Describe the properties of methylene blue stain.

A
  1. aromatic and basic
  2. soluble in water or methanol
  3. stains hydrophobic acidic macromolecules (i.e. nucleic acids)
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8
Q

What cells are rare in peripheral blood (<1% of leukocytes) and degranulates in allergic reactions?

A

Basophil

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9
Q

What other cell are basophils related to?

A

tissue mast cells

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10
Q

What cell types binds little of eosin or methylene blue?

A

neutrophils

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11
Q

What color do the cytoplasmic granules of neutrophils stain?

A

light pink

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12
Q

What is the life span of a neutrophil?

A

<1 day

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13
Q

Normally, neutrophils make up __-__% of leukocytes but can increase ___ fold during infections.

A

40-70%; 10 fold

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14
Q

What are NETs?

A

neutrophil extracellular traps: the chromatin of dead neutrophils kill pathogens and can assist in controlling sepsis *also may contribute to sepsis-assc conditions like pre-eclampsia

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15
Q

Knowing the __(cell type)__ count is essential in evaluating any infectious disease.

A

Neutrophil

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16
Q

What are the mechanisms that neutrophils use as weapons/tactics?

A

Phagocytosis, degranulation, NETs

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17
Q

What mediator do neutrophils secrete which can lyse bacteria?

A

lysozyme

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18
Q

How can a monocyte be distinguished from a lymphocyte on a smear?

A

monocytes often have bent or ameboid nuclei while the nuclei of lymphocytes is more round

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19
Q

Monocytes are ___-___% of blood leukocytes.

A

3 to 8%

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20
Q

T or F: All macrophages in tissues are derived from monocytes.

A

F: most but not all

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21
Q

What is the role of monocytes?

A

phagocytose and present Ag on MHC class II to lymphoctes (which is usually done in the lymphatic system)

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22
Q

Lymphocytes are ___-___% of lood leukocytes.

A

20 to 30%

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23
Q

What is the life span of a lymphocyte?

A

days to years

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24
Q

What are the types of lymphocytes and which one is more predominant

A

T cells > #s B cells and NK

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25
Q

How are reactive lymphocytes distinguished from resting lymphocytes? From monocytes?

A

reactive more cytoplasm and more prominent nucleoli

get a pathologist or hematologist

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26
Q

What is the life span of a platelet?

A

9-10 days

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27
Q

What are the 4 functions of platelets listed in lecture?

A
  1. form primary hemostatic plug (aggregation)
  2. stimulate coag cascade to form fibrin clot
  3. wound healing by simulating fibroblast growth and migration
  4. Ag presentation
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28
Q

What are the neutrophil variants seen in bacterial infections?

A
  1. left shift (inc in immature forms)

2. inc cytoplasmic granules

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29
Q

What are the lymphocyte variations seen with infection?

A

Reactive forms (larger nuclei and more cytoplasm) **which is seen in many viral syndromes

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30
Q

What are the 7 RBC design requirements?

A
  1. flexible shape
  2. durable membrane
  3. max Hgb/O2 carrying capacity
  4. offset osmotic pressure
  5. Anti-oxidant system
  6. energy supply
  7. tune down complement
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31
Q

Describe the shape of RBCs.

A

flexible biconcave disc with 360 degree fold capacity

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32
Q

What is the lifespan of a RBC?

A

100 days

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33
Q

Why is the RBC membrane so durable?

A

They have intracellular cytoskeleton made of spectrin (alpha and beta chains dimers) which interacts with ankyrin, a protein found on the inner leaflet of membrane. This interaction increases the durability of RBC membrane

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34
Q

Mutations in the RBC spectrin reinforced membrane can result in ____ or _____ shapes

A

spherical or ellipsoid

**also leads to anemia bc RBCs are destroyed from lack of membrane integrity

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35
Q

How do RBCs maximize O2 carrying capacity?

A

eliminate dead weight organelles like nuclei and pack as high of a conc as Hgb as possible that does not cause Hgb to ppt

36
Q

What can cause Hgb to ppt?

A
  1. too high of a Hgb conc
  2. minor changes to amino acid sequence
  3. oxidative damage

**when Hgb ppts it causes lysis

37
Q

What are consequences of the fact that Hgb is a terrific bacterial growth medium?

A

bac can enter RBC or the bac can lyse RBCs

38
Q

How do RBCs offset osmotic pressure?

A

pump out Na+ out of cell via Na/K pump

*uses ATP

39
Q

What is the net plasma conc of Na and K?

A

144 mM (140 mM from Na and 4mM from K)

40
Q

What is the net intracell conc of Na and K?

A

111 mM (11mM from Na and 100mM from K)

41
Q

Describe the anti-oxidant sys in RBCs.

A

GSH removes H2O2 by allowing H2O2 to oxidize it rather than the Hgb.

GSH –> G-SS-G

The disulfide bond can be removed with reductase and NADPH

42
Q

T or F: The Anti-oxidant system in RBCs requires energy in the form of ATP.

A

F: energy in the form of NADPH

G-SS-G + NADPH –> GSH + NADP

43
Q

Why do RBCs use anaerobic respiration?

A

bc if they used O2 to make its energy it would consume the O2 that it is supposed to be transporting

44
Q

Do RBCs have mitochondria?

A

No

45
Q

RBCs use __(pathway)__ to make NADPH

A

pentose shunt

46
Q

What is the first enzyme in the pentose shunt (used to make NADPH)?

A

glc 6 phosphatase DH

47
Q

Describe how RBCs are able to tune down complement fixation.

A

have DAF on surface to block alternative pathway (both C3 convertase and MAC formation)

48
Q

What are examples of RBC morphological variants?

A
  1. not enough Hgb = hypochromatic and/or microcytic
  2. residual mRNA
  3. precipitated Hgb
  4. Schistocytes
49
Q

What is anisocytosis?

A

abnormal RBC sizes (from not enough Hgb)

50
Q

What is poikilocytosis?

A

abnormal RBC shapes (from not enough Hgb)

51
Q

What is hypochroma?

A

lack of color/lack of Hgb detected by eosin

52
Q

What is polychromasia?

A

RBCs with excess residual mRNA and therefore shows up bigger and having a bluish tinge with methylene blue stain.

53
Q

What does polychromasia indicate?

A

pt is making a lot of RBCs (probably bc they are losing a lot of them somehow)

54
Q

What can cause precipitated Hgb?

A

-genetic defect in Hgb structure-oxidized Hgb

55
Q

How are bite cells formed?

A

tissue based phagocytes try to repair oxidized/precipitated Hgb which results in chunks of the cell being removed

56
Q

What are bite cells suggestive of? (what deficiency)

A

G6PD deficiency (bc a defect in G6PD is a defect in the anti-oxidant system –> disulfide bonds formed –> ppt of Hgb –> macrophages remove ppt Hgb)

57
Q

How are schistocytes formed?

A
  1. due to mechanical lysis
  2. microangiopathic processes
  3. fibrin laces vessels and RBCs get cut into fragments ***these 3 might all be considered the same thing…
58
Q

T or F: Bite cells and schistocytes are different terms describing the same phenomenon.

A

F: they look similar but are not the same thing

59
Q

What is the supernatent of unclotted blood called?

A

plasma

60
Q

What is the supernatant of clotted blood called?

A

serum

61
Q

Lab testing of clotting methods is performed on (plasma or serum)

A

plasma

62
Q

What does hematocrit measure?

A

the % of blood volume occupied by RBCs

63
Q

How is hematocrit measured?

A

RBC volume / total blood volume

64
Q

What does the hemocytometer measure?

A

manual measure of white cells and platelets

65
Q

What does the simple spin hematocrit measure?

A

manual measure of red cells and Hgb

66
Q

How are Hgb levels measured currently?

A

With a hematology analyzer’s spectrophotometer. Cyanide generates a blue color when mixed with Hgb which the spectrophotometer measures

67
Q

What are reticulocytes?

A

immature RBCs (inc reticulocytes, think polychromasia)

68
Q

How are reticulocytes measured?

A

spectrophotometry with methylene blue added which reacts with mRNA**this measures how well pt is able to compensate

69
Q

Describe a Coulter chamber

A

A small container of fluid placed in a larger container of the same fluid. The small container has a tiny opening thru which fluid is pumped at a very precise rate into the larger container –> hole –> small container –> waste container

70
Q

When a direct current is added to the Coulter chamber, what is measured?

A

peak number = cell count

peak height = cell volume

71
Q

When an alternating current is added to the Coulter chamber, what is measured?

A

peak height = cell complexity (lobular nuclei)

72
Q

What are all the values that a hematology analyzer measures?

A 
Hemoglobin red cell count (RBC)
Mean red cell volume (MCV) 
Red cell distribution width (RDW)
Platelet count
Mean platelet volume (MPV)
73
Q

What is the mean red cell volume indicate?

A

size of RBC = if the cells have too much or no enough Hgb

74
Q

Why is the hematocrit value less precise measure of Hgb?

A

the value can be altered by lab artifacts, drugs, or various disease states

75
Q

Hemoglobin X 3 =

A

hematocrit

76
Q

If the CBC does not match the reported hematocrit, you should use the _____ to decide how anemic the pt is. In this instance, what is abnormal and why?

A

hemoglobin

MCV (mean red cell volume) is abnormal due to artifacts such as red cells clumping or due to a disease

77
Q

How are white cells measured exclusively? What is a limitation of this test?

A
  1. mix blood sample with soln that lyses red cells (isotonic ammonium chloride)
  2. run thru coulter chamber
  3. diff leukocyte population show up on diff locations in graph produced

limitation = eosinophils and basophils are not well separated from other populations

78
Q

How are baso and eosinophils seperated out from the rest of the population of white cells for measurement?

A

use the flow cytometer before the coulter chamber to seperate them from neutrophil population *adds measurement of complexity to do this

79
Q

How does a flow cytometer work?

A

laser in flow cytometer measures forward scatter to measure cell size/shape*used to differentiate baso and eosinophils from neutrophils

80
Q

How are immature platelets measured (immature platelet fraction , IPF)?

A

using flow cytometry to detect excess mRNA

81
Q

What does an increase in IPF indicate?

A

pt is compensating for decreased platelet number

82
Q

Per ul, how many platelets are consumed each day?

A

7000 per ul (11%)

83
Q

The IPF will go (up or down) in pts whose thrombocytopenia is due to impaired function.

A

up (3x normal)

84
Q

Are linear or exponential platelet turnover rates normal?

A

linear is normal and exponential and abnormal (thrombocytopenic)

85
Q

What can the hematology analyzer NOT count reliably?

A
  • bands
  • blasts (may be counted as lymphocytes or monocytes)
  • red cell fragments (counted as platelets)-platelet clumps (can get artificial thrombocytopenia)
86
Q

What is found in peripheral blood smear that can indicate acute leukemia?

A

blasts

Heme (38 decks)

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