1

Microanatomy, October 2002

Hematocrit / Measure of the volume of packed RBC per unit volume of blood
Normal: 40% in women; 45% in men 52% in newborns; 35% in children <10
Polycthemia / Indicated by increased hematocrit, Merck 896
Anemia / Indicated by decreased hematocrit or blood loss

Leukocytes

/ White blood cells; host defense; called “buffy coat” in centrifuged sample; 1% of total volume; on top of RBC in centrifuged tube; 6000-10,000/microliter

Granulocytes

/ Leukocytes with granules which include neutrophils, eosinophils, basophils

Neutrophils

/ 9-12 micrometer granulocyte; pink cytoplasm; highly lobed nucleus matures from dense mass of clumped chromatin; in circulation 6-7 hrs; lifespan of a few days; nucleus sometimes has Barr body; cytoplasm has azurophilic and specific granules; first line of defense; attracted to site of inflammation by chemotaxis; diapedesis; actively phagocytic; ingest bacteria and form secondary lysosomes (see process in notes p. 190)
Azurophilic granules / In neutrophiles; primary lysosomes with myeloperoxidase, acid phospatase, and other hydrolytic enzymes
Specific graules / Secondary granules; most abundant; contain alk phos, colagenase, lactoferrin, and lysozyme
Diapedesis / Manner of neutrophil entering tissue through endothelial wall (dia: through, pedesis: to leap)
Opsonins / Plasma components such as IgG and C3b which can coat bacteria and enhance neutrophil’s attack
How to Kill a Bacteria
By M. Neutrophil / (1) Specific granulues discharge contents into phagosome; (2) pH lowered via proton pumps; (3) azurophilic granules discharge into phagosome
Ex. Superoxide anions from ox burst, lysosomal destruction of cell wall; lactoferrin binding iron
Energy anaerobic; from glycolysis

Eosinophils

/ Slightly larger than neutrophil; 3-4 hrs in blood stream; life span 8-12 days; bilobed nuleus; ~200 specific granules/cell; elongate granules larger than neutrophil granules and contain large amounts of major basic protein; contains peroxide, eosinophilic peroxide, acid phos, ribonuclease; highly concentrated in mucosa linings open to exterior
Fx: unclear; large increases in parasitic infection and allergic states; selectively ingest antibody complexes; likely to counteract inflammatory responses initiated by histamine and other mediators from basophils and mast cells
Major basic protein / Contained in center of eosinophil granule; accounts for eosin affinity

Basophils

/ Slightly smaller than neutrophils; segmented nucleus with irregular # of lobes; has largest granules; water soluable granules contain peroxidase, histamine and heparin (=metachromasia); little phagoxytosis; no lysosomal enzymes; similar to mast cells but derived from diff’t bone marrow precursors
Fx: Contain IgE receptors w/ IgE bound; bind allergen and degranulate; histamine released upon degranulation partially responsible for itching and swelling
IgE / Increased up to 20 fold in Pt with hay fever, asthma or allergic dermatitis; introduced allergen combines with IgE on basophil and causes massive degranulation
Agranulocytes
/ Leukocytes w/out granules which include lymphocytes and monocytes

Lymphocytes

/ Small cells with dense compact round nucleus surrounded by thin rim of cytoplasm; nuc about size of RBC; occasional azurophil granule; continually migrate among lymphoid tissue via blood pathway; relative abundance decreases from 60% at two weeks of age to 20-30% by age 15; arise in yolk sac or bone marrow, but mature in other lymphoid organs

B-cells

/ Competent to produce antibodies; primary immune response results in low levels of circulating antibody; subsequent exposure leads to high levels of antibody thru secondary response

Plasma cells

/ B-cells in tissue that actually produce antibody

Humoral Immune Response

/ Primary immune response with low level production of circulating antibody, followed by high levels of antibody formed with subsequent exposure and secondary response; mediated by B-cells

T-cells

/ Lymphocytes which stimulate or dampen response of other T-cells and B-cells; from embryonic yolk sac cells in thymus

Helper cells

/ T-cells that simulate other T-cells and B-cell in response to antigen

Suppressor cells

/ T-cells that dampen response of other T-cells and B-cells

Cytotoxic or Killer Cells

/ T-cells involved in cell-mediated immunity

Cell-mediated immunity

/ Cytotoxic or Killer T-cells that recognize and kill cells displaying foreign antigen (ex. Tumor cells, virus-infected cells, foreign grafts)

Natural Killer and Stem Cells

/ Look like lymphocytes, but don’t have B or T receptors

Monocytes

/ Largest WBC normally seen in peripheral blood smear; nucleus round or horse-shoe shaped; less condensed chromatin; cytoplasm stained gray-blue often with auzurophil granules; spend ~36 hrs in circulation before going to tissues to work where they they differentiate into macrophages and may survive in tissues for months; role in phagocytosis; antigen presenting cell form lymphocyte

Macrophages

/ Cells in tissues from differentiated monocytes; may survive there for months
Differential count / Method of determining relative abundance of leukocytes
Leukemia / Indicated by increased WBC
Platelets
/ Non-nucleated cell fragments which mature from megakaryoblasts; 2-3 micrometers; 200,000-400,000/microliter; survive 10 days in circulation; functions in blood clotting; has thick glycoprotien coat (fx in platlet adhesion);
Marginal band of MT / Maintains platelet normal ovid shape
Canalicular system / Facilitates release of granular components
Hyalomere / Peripheral light blue staining part of platelet; has greater concentration of actin and myosin than any other cell type except muscle (filopodial projections made of dense microfilament mats arise here upon activation)
Granulomere / Platelets central azurophilic granule-containing zone
Alpha granules / Most abundant platlet granule; contain fibrinogen, von Willedbrand factor, platlet-derived growth factor
Delta granules / Platelet granules which secrete Ca, ATP, ADP; also take up and store serotonin
Lambda granules / lysosomes
Plasma / Defn: Liquid portion of blood that remains if blood is anticoagulant-treated.
90% water; 7-9% proteins (albumin, alpha and beta globulins, gamma globulins, fibrinogen); remainder consist of inorganic constituents like Na, bicarbonate, and Ca and organic constituents like hormones, aa, and glucose
Albumin / Maintains COP (colloid osmotic pressure) within capillaries
Alpha globulin / Glycoprotiens, HDLs, ceruloplasmin, and prothrombin
Beta globulin / Transferrin, LDLs
Gamma globulin / Antibodies
Fibrinogen / Major clotting protiens
Serum / Liquid portion of blood that remains after blood is allowed to clot.

Erythrocytes

/ RBC, ~7.5 micrometers; concentration of 5 x 10^6 M/microliter; bicocave disk-shaped bag of Hb (good S:V for gas exchange); no nucleus; should appear normocyitic and normochromatic; life span of 120 days after which the spleen removes them from circulation
Eosinophilic / “acid-loving”; bases that stain oarnge to pink
Basophilic / “base-loving” stain blue
Azurophilic / Affinity for converted methylene blue; stain purple
Microcytic / Small (as in RBC)
Macrocytic / Large
Anisocytosis / Abnormal variations in size
Hypochromatic / Less Hb
Hyperchomatic / More Hb
Poikilocytosis / Diversity in cell shape
HbS / Sickled cells; difficult passage thru spleen; hemolysis; anemia
Thalassemia or HbF persistance / See target cells, hypochromia, microcytosis; anemia results
Spherocytosis / Result of mutations in spectrin genes; see spherocytes (loss of biconcave disc); Sx hemolytic anemia
Hereditary Elliptocytosis / Result of mutations in spectrin, Band 4.1, and Band III (all three of which contribute to cell structure under plasma membrane) mutations; see elliptocytes (cigar-shaped cells); Sx: mild hemolytic anemia
Hemolytic
Reticulocytes / New RBC that retain some ribosomal RNA and stain differently (notes p. 188); account for 8% of RBC population; mature w/in 24 hours
Polychromatophilic Erythrocytes
Hemopoiesis / Process in bone marrow by which all cells in peripheral blood mature
Fetal Hemopoiesis / Between 2-6 weeks of development, formation of primitive erythrocytes occurs in “blood islands” of body stalk and yolk sac; at 6 weeks liver and spleen generate definitive erythrocytes
Primitive Erythrocytes / Develop between 2-6 weeks of development in body stalk and yolk sac; are nucleated
Definitive Erythrocytes / Developed by liver and spleen from six weeks gestation until bone marrow is formed at 5 months of gestation; anucleate
Postnatal Hemopoiesis / Occurs in red bone marrow
Red Bone marrow / Site of postnatal hemopoisis; found in all bones at birth, but by age 4-5 adipose tissue replaces red marrow in long bones (= “yellow marrow”); red marrow in adult found in vertebrae, ribs, skull, sternum, bones of pelvis, and in proximal ends of some long bones
Yellow Marrow / Adipose cells in bone marrow; only hemopoies in some pathologic conditions