Hematology Flashcards
Erythrocyte life span?
120 days
Define erythrocytosis.
Polycythemia (increased hematocrit)
Define anisocytosis.
Varying erythrocyte sizes.
Define poikilocytosis.
Varying erythrocyte shapes
What is a reticulocyte?
Immature RBC; reflects erythroid proliferation
Thrombocyte life span?
8-10 days
What is contained in thrombocytes?
Dense granules (ADP and calcium) Alpha granules (vWF, fibrinogen, fibronectin)
What causes petechiae?
Thrombocytopenia or decreased platelet functino
What does vWF bind to?
Gp1b
What does the fibrinogen receptor bind to?
Gp2b3a
What are the two broad categories of leukocytes?
Granulocytes (neutrophils, eosinophils, basophils, mast cells) and mononuclear cells (monocytes, lymphocytes)
What is the normal WBC differential?
Neutrophils ~60% Lymphocytes ~30% Monocytes ~6% Eosinophils ~3% Basophils ~1%
What is contained within azurophilic granules (lysosomes) of neutrophils?
Proteinases, acid phosphatase, myeloperoxidase, beta-glucuronidase
When are hypersegmented neutrophils (6+ lobes) seen?
Vitamin B12/folate deficiency
What are band cells?
Immature neutrophils; when increased, they reflect states of increased myeloid proliferation (bacterial infections, CML)
List the 5 major neutrophil chemotactic agents.
C5a, IL-8, LTB4, kallikrein, platelet-activating factor
How do monocytes appear on blood smear?
Large, kidney-shaped nucleus
Extensive “frosted glass” cytoplasm
What activates macrophages?
IFN-gamma
What role do macrophages play in initiating septic shock?
Lipid A from bacterial LPS binds CD14 on macrophages to initiate septic shock
What is the role of eosinophils?
Defend against helminthic infection
Produces histaminase, major basic protein (MBP, a helminthotoxin), eosinophil peroxidase, eosinophil cationic protein, and eosinophil-derived neurotoxin
How do eosinophils appear on blood smear?
Bilobate nucleus
Packed with large eosinophilic granules of uniform size
What is the role of basophils?
Mediate allergic reaction
Granules contain heparin (anticoagulant) and histamine (vasodilator); leukotrienes synthesized and released on demand
How do basophils appear on blood smear?
Densely basophilic granules
What is the role of mast cells?
Mediate allergic reactions in local tissues
Bind the Fc portion of IgE to membrane; IgE cross-links upon Ag binding -> degranulation -> release of histamine, heparin, trypstase, and eosinophil chemotactic factors
What is the major link between innate and adaptive immune systems?
Dendritic cells (highly phagocytic APCs)
How do lymphocytes appear on blood smear?
Round, densely staining nuclei with a small amount of pale cytoplasm
B cells are part of the ___ immune response. They originate from stem cells and mature in the ___. They migrate to peripheral lymphoid tissue, including what three places? When antigen is encountered, B cells differentiate into ___ and ___. They can also function as an ___.
Humoral; bone marrow; follicles of lymph nodes, white pulp of spleen, unencapsulated lymphoid tissue; plasma cells (Ab producers); memory cells; APC via MHC II
What are the CD markers of B cells?
CD 19, 20, 21
T cells mediate the ___ immune response. They originate from stem cells in the ___ and mature in the ___.
Cellular; bone marrow; thymus
The majority of circulating lymphocytes are ___ (80%).
T cells
How do plasma cells appear on blood smear?
“Clock-face” chromatin distribution and eccentric nucleus, abundant RER, well-developed Golgi apparatus; found in bone marrow and normally do not circulate in peripheral blood
Where and when does fetal erythropoiesis occur?
Yolk sac (3-8 weeks) Liver (6 weeks-birth) Spleen (10-28 weeks) Bone marrow (18 weeks to adult) "Young Liver Synthesizes Blood"
What are the embryonic globins?
Zeta and epsilon
When does the major shift from fetal HbF to adult HbA1 occur?
Around 6 months postnatal
What will cause a hemolytic reaction in a person with type A blood?
Receiving B or AB blood
What will cause a hemolytic reaction in a person with type B blood?
Receiving A or AB blood
What will cause a hemolytic reaction in a person with type AB blood?
None - they are the universal recipient of RBCs and universal donor of plasma because they have no Ab
What will cause a hemolytic reaction in a person with type O blood?
Receiving any non-O blood; they are the universal donor of RBCs and the universal recipient of plasma because they have no RBC Ag, but both anti-A and anti-B antibodies
Describe what happens to the different types of Hgb on electrophoresis gel.
Hgb migrates from the negatively charged cathode to the positively charged anode.
HbA (adult, normal beta chain) migrates the farthest, followed by HbF (fetal, normal gamma chain), HbS (sickle cell beta chain), and HbC (hemoglobin C beta chain).
“A Fat Santa Clause”
The missense mutations in HbS and HbC replace glutamic acid (negative) with valine (neutral) and lysine (positive)
What are the steps of primary hemostasis (platelet plug formation)?
- Injury (endothelial damage -> transient vasoconstriction)
- Exposure (vWF binds exposed collagen)
- Adhesion
- Activation (ADP binding to P2Y12 receptor induces GP2b3a expression at platelet surface)
- Aggregation (Fibrinogen binds Gp2b3a receptors and links platelets)
What happens after vWF binds to exposed collagen?
Platelets bind vWF via GP1b receptor at the site of injury only. Platelets undergo a conformational change. They release ADP and calcium (necessary for coagulation cascade), TXA2. ADP helps platelets adhere to the endothelium.
What are the pro-aggregation factors?
- TXA2 (released by platelets)
- Decreased blood flow
- Increased platelet aggregation
What are the anti-aggregation factors?
- PGI2 and NO (released by endothelial cells)
- Increased blood flow
- Decreased platelet aggregation
What are spur cells and how do they appear on blood smear?
Acanthocytes; spiny
What is basophilic stippling?
Aggregation of residual ribosomes in red blood cells
What are teardrop cells and how do they appear on blood smear?
Dacrocytes; tear drop shape
What are bite cells and how do they appear on blood smear?
Degmacyte; bite taken out
What are burr cells and how do they appear on blood smear?
Echinocyte - projections, more uniform and smaller than acanthocytes
What are schistocytes and how do they appear on blood smear?
Fragmented RBCs; examples include helmet cells