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OS1 - Heme > Blood Cell Structure & Function > Flashcards

Blood Cell Structure & Function Flashcards

1
Q

What do you stain a blood smear with for viewing under a microscope?

A

Wright-Giemsa stain

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2
Q

Hb is going to pick up what stain under the microscope?

A

eosin. Due to its hydrophobic, basic nature

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3
Q

Numbers of this WBC type are found increased in the context of allergic reactions and infection with parasites:

A

Eosinophils

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4
Q

Mature cells of this WBC type are bi-lobed and have basic granules that pick up eosinophilic stain.

A

Eosinophils

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5
Q

Basophils pick up what stain with their acidic granules?

A

Methylene Blue

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6
Q

Eosin is an acidic or basic stain?

A

acidic. it stains basic molecules (eosinophilic granules)

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7
Q

Methylene blue is an acidic or basic stain?

A

basic. it stains acidic molecules (basophilic granules)

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8
Q

Eosinophils usually make up what percent of WBCs in a count?

A

< 5%

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9
Q

Basophils usually make up what percent of WBCs in a count?

A

< 1%

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10
Q

What would trigger basophils to degranulate?

A

presence of allergen

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11
Q

Describe the presence of cytoplasmic granules in monocytes and lymphocytes.

A

No granules

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12
Q

Monocytes make up between ____ - _____% of WBCs found in the blood.

A

3-8%

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13
Q

Monocytes give rise to this WBC found in tissue during infection or trauma.

A

Macrophages

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14
Q

Is monocytosis (lots of monocytes) specific for any particular pathology?

A

No

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15
Q

Lymphocytes make up ___-___% of blood WBCs.

A

20-30%

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16
Q

List the lymphocytes in order of predominance in the blood.

A

T cells, B cells, NK cells

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17
Q

Describe the life span of lymphocytes.

A

Days to years

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18
Q

Describe the morphology of a reactive lymphocyte.

A

“reactive” forms (which increase in number in viral syndromes) have more cytoplasm, sometimes prominent nucleoli

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19
Q

List the two “large, granular” lymphocytes.

A

Cytotoxic T cells and NK cells

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20
Q

Describe the morphology of large, granular lymphocytes.

A

NK and Cytotoxic T-cells sometimes show small numbers of basophilic cytoplasmic granules (“large granular lymphocytes”)

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21
Q

What cell is being described?
“Neutral” cells (Neutrophils)
with cytoplasmic granules that stain light pink, binding little of either eosin or methylene blue. “segmented” nuclei.

A

Neutrophils

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22
Q

Describe the lifespan of neutrophils.

A

Short. < 1 day

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23
Q

Describe the “weapons” of neutrophils in response to infection.

A

Phagocytosis
Degranulation
Formation of extracellular traps (NETS)

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24
Q

Describe the action of neutrophils in response to an infection.

A

Migrate in response to chemokines
Recognize and swarm the enemy
Degrade and immobilize the enemy
Minimize collateral damage

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25
Q

What are the cytokines that attract neutrophils?

A

IL-8. binds IL-8 receptor (CXCR-2) on neutrophils

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26
Q

What molecules on the neutrophil cell surface are responsible for “grabbing” and “holding” the infecting organism for destruction?

A

Integrins: CD11a/CD18 complex

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27
Q

What recognition receptors are present on the neutrophil cell surface for grabbing and holding infecting organisms?

A

Toll-like receptors
Complement receptors
Fc receptors

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28
Q

Neutrophils secrete these chemokines:

A

CXCL2
IL-8
TNF

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29
Q

Describe the neutrophil process for immobilizing and degrading invading organisms.

A 
Phagocytose it (via the same receptors that recognized it)
Chew up its polysaccharide cell wall with lysozyme
Chew up its proteins with various proteases
Kill it with bleach (hypochlorite)
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30
Q

Describe the neutrophil process that minimizes collateral damage.

A

Apoptosis

Release of chromatin-derived NETs

31
Q

An immature neutrophil with a horseshoe shaped nuclei is called a ______ form, and is found normally in this percentage in smears.

A

band; < 5%

32
Q

A form of neutrophil a step less mature than a band cell is termed a _________ , and has bean shaped nuclei.

A

metamyelocyte

33
Q

A form of neutrophil a step less mature than a metamyelocyte is termed a __________ , and has a rounded nuclei.

A

myelocyte

34
Q

The term, “left shift” refers to what, in the context of a neutrophil differential.

A

abnormal presence of immature neutrophils

35
Q

Describe the granulation of a neutrophil present at a site of infection.

A

increased cytoplasmic granules (“toxic granulation”)

36
Q

Describe the nuclei of platelets.

A

No nuclei

37
Q

What happens to the platelet count in iron deficient pts?

A

It increases

38
Q

Describe the life span of platelets.

A

9-10 days

39
Q

Describe the function of platelets.

A

1) Primary hemostatic plug (adherence/activation/aggregation)
2) Stimulate coagulation cascade (fibrin formation/clot retraction)
3) Stimulate wound healing (fibroblast growth/migration)
4) Immune function (including antigen presentation and pathogen inactivation)

40
Q

List the requirements of platelets that allow them to do their jobs well.

A 
Must be present in large numbers
Need to recognize damaged blood vessels 
Need to swarm onto the damage, fast
Patch the damage 
Rebuild the vessel wall
41
Q

Describe the quantity requirements of platelets to prevent spontaneous bleeds and stop small (non-spontaneous) bleeds.

A

You need about 10,000 per ul to not bleed spontaneously
You need about 50,000 per ul to stop most small bleeds
You store more in the spleen – they’re released when you get scared

42
Q

Describe how platelets recognize damaged blood vessel walls and bind to factors, starting the repair process.

A

Bind subendothelial collagen via a surface protein called Gp1b
Functional augmentation scheme:
cable-like adaptor (vWF) sticks to the exposed collagen, changes shape slightly, flaps in the breeze
Platelets bind the adaptor (vWF)

43
Q

Describe how deficiencies or defects in vWF can adversely affect bleeding and clotting.

A

If the adaptor (vWF) is in short supply, patients bleed a lot
If the adaptor is too short, patients bleed a lot
If the adaptor is too long, they clot excessively

44
Q

Describe the process by which platelets swarm onto the damage of a blood vessel and begin repair by cross-linking.

A

Binding collagen or vWF causes platelet activation
Activated platelets bind vWF and fibrinogen more avidly
Fibrinogen is the precursor to fibrin. You have lots of it in your plasma.
That results in aggregation (mostly via crosslinking of platelets)
Activation/aggregation is autocatalytic; activated platelets secrete mediators that augment activation/aggregation

45
Q

Describe how platelets patch and stabilize repair of damaged blood vessels.

A

Activation/aggregation also promotes activation of the coagulation cascade
A series of plasma proteases that, when activated, deposits a fibrous mesh, made up mostly of fibrin
AND
If the coagulation cascade gets activated first, it causes platelet activation
The final product is a strong, stable, fibrin-based clot

46
Q

Describe the contribution of platelets to rebuilding the blood vessel wall.

A

Activated platelets secrete growth factors that stimulate fibroblasts and smooth muscle cells

47
Q

What is the name of the cable that maintains the shape of a RBC and what are the proteins that make up the anchor points in the RBC plasma membrane?

A

Spectrin (alpha chain & beta chain); ankyrin, palladin, glycophorin

48
Q

What happens to RBC flexibility if the Hb within RBCs precipitates?

A

Lose flexibility, jam up capillaries. Cells rupture.

49
Q

How do RBCs maintain their osmotic gradient?

A

Pump Na out of the cell via Na/K ATPase pumps

50
Q

Why must RBCs be anti-oxidant in nature?

A

O2 is a powerful oxidant (via generation of H2O2)
Oxidized–SH groups on hemoglobin become crosslinks (R1-SS-R2)
Result: Hgb denaturation and/or precipitation
Oxidized iron (Fe+++) can’t carry O2
Result: Hemoglobin containing Fe+++ (Methemoglobin)
Result: patient is hypoxic even though the top two causes of same (anemia, lung disease) might not be present

51
Q

Describe the process by which Glutathione neutralizes the toxic effects of H2O2

A

Glutathione (GSH) eliminates peroxide before it can damage the machinery
Requires NADPH

Cytochrome b5 reductase reduces Methemoglobin back to normal hemoglobin
Requires NADH

52
Q

Describe the design features that allow RBCs to make energy for themselves if they do not have mitochondria.

A

Design features:

Chuck the mitochondria 
Use glycolysis to make ATP and NADH
Use the pentose shunt to make NADPH
First potential failure point in the pathway:  
    Glucose 6 phosphate dehydrogenase
53
Q

Describe the process by which Glutathione neutralizes the toxic effects of H2O2

A

Glutathione (GSH) eliminates peroxide before it can damage the machinery
Requires NADPH

Cytochrome b5 reductase reduces Methemoglobin back to normal hemoglobin
Requires NADH

54
Q

Describe the design features that allow RBCs to make energy for themselves if they do not have mitochondria.

A

Design features:

Chuck the mitochondria 
Use glycolysis to make ATP and NADH
Use the pentose shunt to make NADPH
First potential failure point in the pathway:  
    Glucose 6 phosphate dehydrogenase
55
Q

Describe a RBCs ability to tune down complement fixation.

A

Why it’s needed:
The alternative complement fixation pathway is active at a low rate all the time.
Normal blood cells have to slow it down to survive

How it works:
A normal cell surface protein slows down complement fixation
It’s called Decay accelerating factor (DAF, CD55)
First potential failure point in the system

56
Q

What is poikilocytosis?

A

Poikilocytes are abnormally shaped red blood cells

57
Q

How does residual mRNA present microscopically in RBCs?

A

Polychromasia (seen as elevated reticulocyte #, usually with accelerated production of RBCs)
-is a disorder where there is an abnormally high number of red blood cells found in the bloodstream as a result of being prematurely released from the bone marrow during blood formation.

58
Q

What is poikilocytosis?

A

Poikilocytes are abnormally shaped red blood cells

59
Q

How does residual mRNA present microscopically in RBCs?

A

Polychromasia (usually seen with accelerated production)

60
Q

Why would Hb precipitate in RBCs?

A

Can be due to a genetic defect in Hb structure (hemoglobinopathy)
Can be due to oxidized Hb (forms small clumps, “Heinz bodies”)

61
Q

What happens when Hb precipitates in a RBC?

A

Can alter the shape of the red cell (sickle shape, for example)

62
Q

How can tissue-based phagocytes perform damage repair to oxidized Hb in RBCs?

A

remove chunks of the cell, resulting in “bite” cells (RBCs that look like a cookie with a bite taken out of it)

63
Q

What are schistocytes?

A

RBC fragments. Can be due to mechanical lysis or “microangiopathic” processes. Resulting cells look as though they’ve been sliced in half.

64
Q

What are the methods for quantifying blood cells?

A

manual count
Spectrophotometry
Conductivity (Coulter method)
Flow cytometry

65
Q

How do we quantify Hb?

A

Spectrophotometry.
Lyse cells, add cyanide.
Color changes to varying degrees of blue. Quantify color change (% absorption). This gives you Hb concentration.

66
Q

How do we quantify RBCs?

A

spin down the whole blood sample. RBC % of whole blood volume (RBCs, WBCs, plasma) is called hematocrit.

67
Q

Under what pathological circumstances may you find giant platelets in a peripheral blood smear?

A

bone marrow pathology. Basically, stuff is getting kicked out of the bone marrow and into the circulation.

68
Q

What are reticulocytes?

A

Circulating immature RBCs. They usually only circulate for a day before maturing and compose ~1% of the RBCs in the circulation.

69
Q

How do you find hematocrit from Hb value?

A

multiply Hb by 3.
eg: Hb 15 = Hct 45
Finding Hb from Hct works in reverse. Divide by 3.

70
Q

What is a faster and more accurate way to quantify RBCs than manually?

A

Conductivity (Coulter chamber)

  • peak # = cell #
  • peak height = cell volume
71
Q

Describe the automated leukocyte differential.

A 
Uses conduction (Coulter chamber).
Alternating current as opposed to direct current with RBC quantifying. 
Peak height = cell complexity = lobulated nuclei & granules
72
Q

If the RBC is producing an insufficient amount of ATP via glycolysis, what will happen to the RBC and why?

A

Cell will burst (lyse) from swelling with water because can’t work Na/K ATPase pumps to move Na out of the cell and reduce intracellular osmotic pressure

73
Q

List a few quantitative limitations of automated cell analyzers.

A

Bands and other immature granulocytes are counted as neutrophils by most analyzers.
Blasts may be counted as lymphocytes or monocytes.
Red cell fragments may not be detected, will usually be counted as platelets.
Platelet clumps are not always detected by the analyzer and can result in an artifactual thrombocytopenia.

OS1 - Heme (31 decks)

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