Introduction to Hematology

Introduction to Hematology

• Hematology derives from Greek, combining "haima" (blood) and "logos" (study).
• Blood is a red liquid circulating through the heart, veins, arteries, and capillaries.

Types of Blood Vessels

• Arteries:

  • Distributing blood vessels exiting the heart with thickest walls.
  • Diameter: approximately 4 mm.

• Veins:

  • Collecting blood vessels returning to the heart, largest vessels with an irregular lumen.
  • Diameter: approximately 5 mm.

• Capillaries:

  • Smallest blood vessels facilitating exchange between arterial and venous systems.
  • Diameter: approximately 8 micrometers (um).

Functions of Blood

• Respiratory: Transports oxygen and carbon dioxide.
• Nutritional: Provides nutrients to cells.
• Excretory: Eliminates waste products.
• Buffers body pH and maintains temperature.
• Carries hormones and contributes to defense mechanisms.

Blood Composition

• Liquid Portion:
  • Plasma: Unclotted blood component.
  • Serum: Liquid portion after clotting.
• Solid Portion:
  • Red Blood Cells (RBCs): Erythrocytes; also known as erythroplastids or akaryocyte (nucleus-free cells).
  • White Blood Cells (WBCs): Leukocytes; categorized as granular (Basophils, Eosinophils, Neutrophils) and agranular (Lymphocytes, Monocytes).
  • Platelets: Thrombocytes involved in clotting.
• Gaseous Portion: Includes oxygen and carbon dioxide.

Blood Collection

• Patient Identification:

  • Confirm patient’s full name, age, gender, and birthdate; should be done by the patient.
  • Critical step; mislabeling is a significant error.

• Phlebotomist Hygiene:

  • Essential for maintaining health and hygiene: clean clothes, hair, and short fingernails.
  • Adhere to standard precautions, especially with gloves and handwashing.

Characteristics of Blood

• Fluid state (in vivo).
• Slightly alkaline pH.
• Average specific gravity: 1.055.