Blood Components: Platelets and White Blood Cells

Blood Components

Platelets

• Also known as thrombocytes
• Small, irregularly-shaped blood cells
• Produced in the bone marrow
• Functions:
  • Blood clotting and hemostasis
  • Release chemicals that attract white blood cells to sites of injury
• Normal count: 150,000 - 450,000 per microliter of blood

White Blood Cells (Leukocytes)

• Produced in the bone marrow
• Part of the immune system
• Functions:
  • Defend against infection and disease
  • Engulf and digest foreign particles and bacteria
• Types:
  • Neutrophils: most abundant, primarily combat bacterial infections
  • Lymphocytes: produce antibodies and provide long-term immunity
  • Monocytes: mature into macrophages, which engulf foreign particles
  • Eosinophils: combat parasitic infections and play role in allergic reactions
  • Basophils: involved in inflammation and allergic responses
• Normal count: 4,500 - 11,000 per microliter of blood

Red Blood Cells (Erythrocytes)

• Produced in the bone marrow
• Functions:
  • Carry oxygen from lungs to body tissues
  • Carry carbon dioxide from body tissues to lungs
• Characteristics:
  • Flexible, disk-shaped cells
  • Contain hemoglobin, a protein that binds to oxygen
• Normal count: 4.5 - 5.5 million per microliter of blood
• Lifespan: approximately 120 days

Plasma

• Liquid portion of blood
• Makes up approximately 55% of total blood volume
• Composition:
  • 92% water
  • 7% proteins (albumin, globulins, fibrinogen)
  • 1% nutrients, hormones, gases, and waste products
• Functions:
  • Transports proteins, nutrients, hormones, and waste products
  • Regulates blood pH and temperature
  • Maintains blood pressure

Blood Components

Platelets

• Also known as thrombocytes, produced in the bone marrow
• Small, irregularly-shaped blood cells with a normal count of 150,000 - 450,000 per microliter of blood
• Functions include blood clotting and hemostasis, and releasing chemicals that attract white blood cells to sites of injury

White Blood Cells (Leukocytes)

• Produced in the bone marrow, part of the immune system
• Functions include defending against infection and disease, engulfing and digesting foreign particles and bacteria
• Normal count: 4,500 - 11,000 per microliter of blood
• Five types: neutrophils, lymphocytes, monocytes, eosinophils, and basophils

Red Blood Cells (Erythrocytes)

• Produced in the bone marrow, flexible, disk-shaped cells
• Functions include carrying oxygen from lungs to body tissues and carbon dioxide from body tissues to lungs
• Contain hemoglobin, a protein that binds to oxygen
• Normal count: 4.5 - 5.5 million per microliter of blood, with a lifespan of approximately 120 days

Plasma

• Liquid portion of blood, making up approximately 55% of total blood volume
• Composition: 92% water, 7% proteins, and 1% nutrients, hormones, gases, and waste products
• Functions include transporting proteins, nutrients, hormones, and waste products, regulating blood pH and temperature, and maintaining blood pressure

Blood Composition

• Blood consists of approximately 55% plasma and 45% formed elements (RBCs, WBCs, platelets)

Plasma

• Comprises 92% water, 7% proteins, and 1% nutrients, hormones, gases, and waste products
• Functions include transport of nutrients, hormones, and proteins, regulation of pH and blood pressure, and maintenance of oncotic pressure

Red Blood Cells (RBCs or Erythrocytes)

• Characteristics: biconcave disk shape, no nucleus, contains hemoglobin (Hb) for oxygen binding
• Functions: oxygen transport from lungs to tissues, carbon dioxide transport from tissues to lungs

White Blood Cells (WBCs or Leukocytes)

• Types:
  • Neutrophils (50-70%): fight bacterial infections
  • Lymphocytes (20-40%): fight viral infections and produce antibodies
  • Monocytes (2-8%): mature into macrophages to fight infections
  • Eosinophils (1-3%): fight parasitic infections
  • Basophils (0.5-1%): involved in allergic responses
• Function: defense against infection and disease

Platelets (Thrombocytes)

• Characteristics: small, anucleate cells, release chemical signals to attract WBCs and initiate blood clotting
• Function: blood clotting and hemostasis

Blood Types

• Classified based on ABO blood group system (A, B, AB, O) and Rh blood type system (Rh+, Rh-)
• Combinations of ABO and Rh blood type result in 8 possible blood types: A+, A-, B+, B-, AB+, AB-, O+, O-