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Hematology > Normal Physiology > Flashcards

Normal Physiology Flashcards

1
Q

Apoptoic cell characteristics

A

The entire cell may shrink, Chromatin condenses, Pieces of the nucleus appear spherical or abnormal

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2
Q

Embryological Hematopoiesis

A

18 days- Hematopoiesis starts
3 months- Hematopoiesis moves to liver, some in kidney and lymphoid tissues
6 months- Hematopoiesis moves to bone marrow

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3
Q

Hematopoietic micro environment

A

Cellular: stromal cells

Extra cellular: extra cellular matrix

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4
Q

Primary Lymphoid Tissues

A

Bone marrow, Thymus

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5
Q

Secondary Lymphoid Tissues

A

Spleen, Lymph nodes

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6
Q

Red Marrow contains

A

Stromal cells:
Macrophages: production of cytokines to stimulate cell development
Adipocytes: cells that produce fatty yellow bone marrow
Fibroblasts: produces a support network of collagen for developing cells (extracellular matrix)

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7
Q

Hematopoietically Active sites

A

After four years it is only in the medulla of the ends of the long bones and the pelvis; everywhere else is fatty yellow marrow

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8
Q

Hyperplasia

A

Higher than normal red cell production, red marrow moves into areas of yellow marrow; caused by infection, anemia, leukemia; can cause fractures of cortical bones in severe cases

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9
Q

Thymus activity

A

Active in young children when immunity is developing, atrophied in adults but can be reactivated if new T cells are necessary

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10
Q

Spleen functions

A

The removal of old or damaged RBCs from circulation (RBCs must squeeze through very small areas and endure hypoglycemia and hypoxia), Culled RBCs are phagocytized by macrophages
Remove abnormal inclusions from RBCs
Reservoir for PLTs and RBCs

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11
Q

Splenectomy

A

Helpful for patients with hemolytic anemia’s, letting abnormal RBCs live longer; liver can take over some of the culling function

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12
Q

Extramedullary Hematopoiesis

A

Occurs in Liver and Spleen (fetal organs)

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13
Q

Differentiation

A

The process of generating several “different” cell lines by allowing the expression of certain genes while restricting others

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14
Q

Hematopoietic Stem Cells

A

Pluripotent or multipotent; become myeloid/lymphoid stem cells or non-differentiating self replicating cells

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15
Q

Progenitor Cells

A

CFU: colony forming units
BFU: burst forming units
Highly mitotic and become more committed with each cell division

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16
Q

Normoblasts

A

Erythroblasts (nucleated RBCs) that go through maturation normally, all four stages of nRBC maturation, spend 5-7 days in bone marrow

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17
Q

Reticulocytes

A

Polychromatophilic RBCs
Not quite fully mature RBCs (spend 2-3 days maturing in BM), Do not have a nucleus, Not biconcave shaped, Stains somewhat more basophilic due to residual RNA

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18
Q

Erythrocyte Maturation

A

Rubriblast- Prorubricyte- Rubricyte- Metarubricyte- Reticulocyte- Erythrocyte
Gradual decrease in cell size, Gradual decrease in N:C ratio, Chromatin pattern condenses, Eventual expulsion of the nucleus, Cytoplasm becomes less basophilic, Increase in hemoglobin as the cell matures

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19
Q

Erythropoietin (EPO)

A

Hormone that is produced by specialized kidney cells, stimulated by hypoxia (Anemia, respiratory disease, etc)
Responsible for the development of the erythrocyte precursors

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20
Q

Difference between EPO and CSFs

A

CSFs are:
Responsible for the proliferation of precursor cells
Produced locally by stromal cells

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21
Q

Other hormones affecting Hematopoiesis

A

Adrenal cortical hormones: Androgens (Testosterone, Estrogen), Aldosterone, Cortisol
Miscellaneous: Thyroid hormone, Growth hormone

22
Q

Rubriblast (Pronormoblast)

A

Earliest recognizable RBC precursor
Cytoplasm: Stains deeply basophilic
Pale area next to nucleus (Golgi apparatus)
Only small amounts of hemoglobin are present
Nucleus takes up 80% of cell
Chromatin is fine, May contain few faint nucleoli

23
Q

Prorubricyte (Basophilic Normoblast)

A

Similar to the rubriblast
Cytoplasm- Deeply basophilic
Nucleus- Chromatin is more coarse than the rubriblast, Start to show parachromatin clearing, The “cracked” appearance of the nucleus, Nucleoli are usually not apparent

24
Q

Rubricyte (Polychromatic Normoblast)

A

last stage capable of undergoing mitosis
Cytoplasm: Less basophilic than earlier stages, Due to synthesis of large amounts of hemoglobin and lower RNA concentration
Described as blue-gray or light purple
Nucleus: lower N:C Ratio due to condensation of the nuclear chromatin, Chromatin is irregular and coarsely clumped, Increased parachromatin clearing

25
Q

Metarubricyte (Orthochromic Normoblast)

A

Cytoplasm: Mostly pink or salmon color, Due to concentration of hemoglobin, Looks very similar to the surrounding RBCs, Retains a slight basophilic hue
Nucleus: Last stage with a nucleus, Low N:C Ratio, Dark, heavily condensed chromatin, Often eccentric

26
Q

Reticulocyte

A

Before a developing RBC enters circulation the nucleus is extruded from the cytoplasm and digested by BM macrophages
After nuclear extrusion the cell is known as a reticulocyte
Flattened-disc shape, membrane is not biconcave, Central pallor is not apparent on smear, Last 20% of hemoglobin is made in this stage
Normally 0.5-2.5% of all circulating RBCs are retics

27
Q

Reticulocyte Identification

A

Supravital stain
Microscopic ID can only be made using a supravital stain
New Methylene Blue commonly used (makes residual RNA visible)
Wright stain
Cannot definitively visualize residual RNA
Retics have a slight bluish tinge- polychromatophilic erythrocytes

28
Q

Erythrocytes

A

Unable to synthesize new proteins (hgb) or lipids
Pink color
Biconcave disc shape (During the retic stage, the membrane is remodeled until it becomes biconcave), Size 7-8 µm in diameter, volume 80-100 fL, Central pallor

29
Q

Erythrocyte Membrane Functions

A

Oxygen transport, Durability/strength to survive for 120 days, Balances ion and water concentrations, Flexibility to fit through small vessels
Some integral proteins are called anion exchange proteins: function in the exchange of CO2 at the lungs, Peripheral proteins are mostly on the cytoplasmic face of the RBC

30
Q

Erythrocytes Membrane Structure

A

Phospholipid bilayer complex: Lipids – mostly cholesterol, Affects surface area and membrane permeability,
Integral proteins: Embedded in the bilayer, Function in the transport of molecules across membrane, Responsible for the zeta potential (negative charge), Blood group antigens
Peripheral proteins: Forms the cytoskeleton, Provides a flexible, fluid structure

31
Q

Erythrocyte Abnormality Effects

A

Increased cholesterol absorbs onto RBC
Causes expansion of the outer phospholipid leaflet
Abnormal membrane projections

32
Q

Erythrocyte Metabolism

A

Production of energy (ATP) through anaerobic glycolysis (Previously known as the Embden-Meyerhof pathway), No citric acid/TCA/Kreb’s cycle
ATP is necessary to maintain intracellular ion concentration
Important enzyme: Pyruvate kinase (PK)

33
Q

Causes of Hypoglycemic Erythrocytes

A

Normal in splenic circulation, Deficiency in pyruvate kinase
Results: May disrupt intracellular ion balance, Allows excessive water to enter, Cell loses biconcave shape, Assumes spherocytic shape, Becomes fragile, Culled by spleen or hemolyzed

34
Q

Hexose Monophosphate Shunt (HMP)

A

An offshoot of the glycolytic pathway, Protects hgb from being chemically oxidized (Oxidation prevents oxygen transport)
HMP maintains the function of glutathione, Glutathione becomes oxidized instead of hemoglobin, The main antioxidant is glutathione
Important enzyme: Glucose-6-phosphate dehydrogenase (G6PD)

35
Q

Methemoglobin Reductase Pathway

A

An offshoot of the glycolytic pathway, Helps return methemoglobin (Fe3+) to reduced state (Fe2+), Ensures that hgb can bind and transport O2
Important enzyme: Methemoglobin reductase, Deficiency results in a buildup of oxidized heme, Decreased O2 carrying capacity, Hypoxia results in cyanosis

36
Q

Structure of Hemoglobin

A

Porphyrin ring structure, Called “protoporphyrin IX”, Combines with one centrally located ferrous ion (Fe2+), Each iron ion can bind one molecule of O2
There are 4 heme subunits per hgb molecule, Each heme subunit is bound to a globin chain, 4 subunits and 4 globin chains

37
Q

Deoxyhemoglobin

A

Iron ions in the ferrous state

38
Q

Oxyhemoglobin

A

Iron ions in the ferric state

39
Q

HGB Synthesis

A

Occurs in the mitochondria and cytoplasm of erythrocyte precursors

40
Q

Rapoport-Leubering shunt

A

Produces 2,3 bisphosphoglycerate
Competes with O2 for a binding site; the concentration of O2 at the lungs is much higher than 2,3 BPG so O2 “wins” the competition at high concentrations bound and ready for transport
In hypoxic tissues 2,3 BPG facilitates the release of oxygen; 2,3 BPG pushes O2 off of the RBC where it diffuses into the tissue, increasing the amount of oxygen being released to tissues

41
Q

Hemoglobin A

A

The predominant form in healthy adults

α2β2

42
Q

Hemoglobin F

A 
The predominant form in a developing fetus and newborns: α2γ2
A gamma (γ) globin chain is simply a beta chain with serine in place of histidine at the 143rd position, Serine interferes with the function of 2,3 BPG Allows a Hgb F to have a higher affinity for O2 than Hgb A; Hgb F essentially “takes” O2 from maternal circulation
43
Q

Normal Adult Hemoglobin Composition

A 
Hgb A: α2β2
>95%
Hgb A2: α2δ2
1-4% 
Hgb F: α2γ2
<2%
44
Q

Other hemoglobin types

A

Hgb S: Sickle cell anemia

Hgb C: Hgb C disease

45
Q

Nonfunctional Hemoglobin

A

Methemoglobin: Hgb with iron in the ferric state, Cannot bind O2
Sulfhemoglobin: Sulfur bound to heme, Severely decreased O2 affinity
Carboxyhemoglobin: Hgb has much higher affinity for carbon monoxide (CO) than O2, Produces cherry red appearance to blood and skin, O2 cannot bind, CO poisoning can be lethal

46
Q

Erythrocyte Destruction

A 
Usually simply the result of aging
Erythrocyte disorders
Shorten the lifespan of the RBC, Or result in immediate destruction
Two methods
Extravascular/Intravascular destruction
47
Q

Extravascular Destruction

A

Conserves and recycles important RBC components
RBCs are culled by the spleen (BM and liver can also participate)
RBCs are required to pass through small openings and endure hypoglycemia (Healthy cells survive unharmed) while aged, rigid, damaged or poikilocytic cells become spherocytic and are culled

48
Q

Extravascular Recycling

A

Iron from heme, Amino acids from globin chains
Heme is further broken down to unconjugated bilirubin, Carried to the liver and converted to conjugated bilirubin and excreted in the feces
Excessive extravascular hemolysis: Caused by several types of anemia, May result in spleen overload/failure, Jaundice

49
Q

Intravascular Destruction

A

Most RBCs are extravascularly destroyed but some lyse in circulation, Released hemoglobin circulates freely (Free hgb may be toxic in high levels-Can induce apoptosis in surrounding cells)
Hgb is bound by haptoglobin and rendered non-toxic then carried to the liver to be recycled
Excessive intravascular hemolysis: Caused by several hemolytic anemia’s, Causes a depletion of haptoglobin

50
Q

What percent of whole blood is made up of leukocytes and platelets?

A

1%

51
Q

What does a “shift to the left” in an oxygen dissociation curve mean?

A

That the hemoglobin is holding on to oxygen more tightly, reducing oxygen delivery

52
Q

Serum Ferritin is an indicator of?

A

storage iron

Hematology (17 decks)

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