UNIT VIII: THE HEMATOLOGIC SYSTEM

COMPONENTS OF THE HEMATOLOGIC SYSTEM

  • Blood composition: 92% water, 8% solutes (6 quarts or 5.5 L).
  • Plasma: 50-55% of blood volume; contains proteins for transport (albumins, lipoproteins), defense (immunoglobulins, globulins), clotting factors (fibrinogen).

FORMATION AND DIFFERENTIATION OF BLOOD CELLS

  • Stem cells in bone marrow; differentiate into blood components: erythrocytes (RBCs), leukocytes (WBCs), platelets.
  • Erythrocytes: most abundant (48% in males, 42% in females), contain hemoglobin, live for 120 days.
  • Leukocytes: defense against infection, normal count 5000-10,000 cells/mm3, include granulocytes (neutrophils, eosinophils, basophils) and agranulocytes (lymphocytes, monocytes).

PLATELETS AND COAGULATION

  • Platelets: cytoplasmic fragments involved in coagulation, normal count 140,000-340,000/mm3, live for 8-11 days; initiate coagulation cascade in response to injury.

HEMATOPOIESIS

  • Continuous process of blood cell production; takes place in bone marrow.
  • Regulated by erythropoietin and other factors influencing stem cell function and differentiation.

ANEMIA

  • Defined as reduction in RBC count or hemoglobin; classified by etiology, size, and hemoglobin content.
  • Types include normocytic-normochromic, microcytic hypochromic (iron deficiency), and macrocytic (vitamin B12 or folate deficiency).

LEUKEMIA

  • Malignant disorders characterized by excessive production of leukocytes; types include acute (ALL, AML) and chronic (CML, CLL).
  • Clinical manifestations: pallor, fatigue, bleeding, infections, bone pain; diagnostics involve blood tests and bone marrow aspiration.

MALIGNANT LYMPHOMAS

  • Neoplasms from lymphocyte proliferation; Hodgkin and non-Hodgkin lymphomas.
  • Clinical manifestations: lymphadenopathy, fever, weight loss. Treatment often involves chemotherapy and/or radiation.