Anatomy

Question 1

Erythrocytes

Answer 1

Carries O2 to tissue and CO2 to lung (chloride-HCO3- on surface to sequester HCO3-)
Large surface area to volume ratio; anucleave and biconcave

Lifespan: 120 days
Source of energy: glucose (90% glycolysis, 10% HMP shunt)

Question 2

Erythrocytosis
Anisocytosis
Poikilocytosis

Answer 2

Erythrocytosis: polycythemia (increased hematocrit)

Anisocytosis: varying sizes

Poikilocytosis: varying shapes

Question 3

Reticulocytes

Answer 3

Immature erythrocytes; marker of erythroid proliferation

Question 4

Platelets

Answer 4

Primary hemostasis - aggregates with other platelets and interacts with fibrin to form plug

Small cytoplasmic fragments from megakaryocytes

Dense granules (ADP, calcium)
Alpha granules (vWF, fibrinogen)

1/3 store in spleen
Thrombocytopenia or platelet dysfunction results in petechiae

Question 5

Leukocytes

Answer 5

Defense against infections

2 groups:
Granulocytes (basophils, eosinophil, neutrophils)
Mononuclear (lymphocytes, monocytes)

Normally 4000 - 10 000 cells

Question 6

WBC Differential

Answer 6

Neutrophils (54-62%)
Leukocytes (25-33%)
Monocytes (3-7%)
Eosinophils (1-3%)
Basophils (0-0.75%)

Question 7

Neutrophils

Answer 7

Acute inflammation (bacterial); phagocytic

Multilobed nucleus

Small, numerous granules: alkaline phosphatase, collagenases, lysozyme, lactoferrin

Large azurophilic granules (lysozymes): acid phosphatase, peroxidase, beta-glucuronidase

Hypersegmented polyps (>5 lobes) - Vitamin 12 or folate deficiency

Increased bands reflect myeloid proliferation (bacterial infections, CML)

Question 8

Monocyte

Answer 8

Differentiate into macrophages

Large, kidney-shaped nucleus
“Frosted glass” cytoplasm

Question 9

Macrophages

Answer 9

Phagocytose bacteria, cell debris, old RBC; scavenges damaged cells and tissues

Long half life; activated by gamma-interferon

Can function as APC cell (MHC-II)
CD14 as cell surface

Question 10

Eosinophil

Answer 10

Helminthic infection (major basic protein)

Bilobe nucleus
Large eosinophilic granules of uniform size

Highly phagocytic for antigen-anttibody complexes

Produces histaminase/arylsulfatase (helps limit reaction after mast cell degranulations

Question 11

Causes of Eosinophilia

Answer 11

[NAACP]

Neoplastic
Allergy
Asthma
Collagen vascular disease
Parasite (invasive)

Question 12

Basophil

Answer 12

Mediates allergic reaction

Densely basophilic granules with heparin (anticoagulant), histamine (vasodilator) and leukotrienes (LTD4)

Question 13

Mast cells

Answer 13

Mediates allergic reaction (resemble basophils but not the same cell); metachromasia of cytoplasm

Bind Fc portion of IgE -> cross-links upon antigen binding -> degranulation of histamine, heparin, eosinophil chemotactic factor

Type I hypersensitivity reaction

Cromolyn sodium prevents mast cell degranulation (asthma prophylaxis)

Question 14

Dendritic cells

Answer 14

Antigen-presenting cells (express MHC II and Fc receptors)

Skin = Langerhan cells

Question 15

Lymphocyte

Answer 15

Adaptive immunity
B and T cells

Round, densely staining nucleus with small amount of pale cytoplasm

Question 16

B lymphocytes

Answer 16

Humoral immune response
From bone marrow stem cells; mature in marrow

Migrates to peripheral lymphoid tissue (lymph node, white pulp of spleen, unencapsulated lymphoid tissue)

Differentiate into plasma cells when encountered antigens -> produce antibodies and memory cells

Can function as APC (MHC II)

Question 17

Plasma cells

Answer 17

Produce large amounts of antibody specific to an antigen

Off-center nucleus, clock face chromatin distribution, abundant RER and well developed Golgi

Multiple myeloma - plasma cell cancer

Question 18

T lymphocytes

Answer 18

Cellular immune response
From bone marrow stem cells -> mature in thymus

Differentiate into cytotoxic (CD8+, MHCI) and helper (CD4+, MHCII), and regulatory T cells
CD28 (costim signal) for T-cell activation

Majority circulating lymphocytes are T cells

Question 19

Blood group: antigens and antibodies

Answer 19

Group A: A antigen on RBC, anti-B in plasma

Group B: B antigen on RBC, anti-A on plasma

Group AB: A and B antigen on RBC, no antibodies in plasma - “universal recipient” of RBC; “universal donor” of plasma

Group O: no antigen on RBC, anti-A and anti-B antibodies in plasma - “universal donor” or blood, “universal recipient” of plasma

Incompatible blood transfusions can cause immunologic response, hemolysis, renal failure, shock and death

Anti-A and B antibodies - IgM (do not cross placenta)

Question 20

Rh antigens

Answer 20

Rh antigen on RBC surface

Rh- mothers exposed to fetal Rh+ make IgG anti-Rh factors

Subsequent pregnancies -> cross placenta and cause hemolytic disease of newborn (erythroblastosis fetalis)

Tx: Rho(D) immune globulin for mother at first delivery to prevent initial sensitization of Rh- mother to Rh antigen