Blood and Its Components

 

Blood and Its Components

Introduction

Blood is a vital fluid that circulates throughout the body, delivering oxygen and nutrients to tissues while removing waste products. It plays a crucial role in maintaining homeostasis, immunity, and temperature regulation.

Composition of Blood

Blood consists of four main components:

1. Plasma (55%)
2. Red Blood Cells (RBCs) – Erythrocytes (45%)
3. White Blood Cells (WBCs) – Leukocytes (<1%)
4. Platelets – Thrombocytes (<1%)

1. Plasma

• A yellowish fluid making up about 55% of blood volume.
• Composed of 90% water, proteins (albumin, globulins, fibrinogen), electrolytes (sodium, potassium, calcium), hormones, enzymes, and waste products.
• Functions: Transports nutrients, hormones, and waste; helps in blood clotting and immunity.

2. Red Blood Cells (Erythrocytes)

• Make up about 45% of blood volume.
• Biconcave, disk-shaped, and lack a nucleus.
• Contain hemoglobin, which binds and transports oxygen and carbon dioxide.
• Lifespan: 120 days.
• Functions: Oxygen transport from lungs to tissues, carbon dioxide removal to lungs.

3. White Blood Cells (Leukocytes)

• Less than 1% of blood but essential for immunity.
• Types:
  • Neutrophils (phagocytosis of bacteria and fungi)
  • Lymphocytes (T-cells and B-cells for immunity)
  • Monocytes (differentiate into macrophages for debris clearance)
  • Eosinophils (fight parasites, involved in allergic reactions)
  • Basophils (release histamine for inflammation response)
• Functions: Defense against pathogens, immune system regulation.

4. Platelets (Thrombocytes)

• Small, cell fragments that aid in blood clotting.
• Lifespan: 7-10 days.
• Functions: Prevent excessive bleeding by forming clots, initiating tissue repair.

Functions of Blood

• Transport: Oxygen, nutrients, waste, hormones.
• Regulation: Body temperature, pH balance, fluid balance.
• Protection: Immunity via WBCs, clotting via platelets.

Understanding blood and its components is crucial for diagnosing and treating medical conditions such as anemia, infections, and clotting disorders.