Components of Blood

Blood is a vital fluid that supports life by transporting essential substances throughout the body. Understanding its components—plasma, red and white blood cells, platelets, and proteins—helps us grasp how our body functions and maintains health.

1. Plasma

   • Comprises about 55% of total blood volume and is primarily made up of water (90%).
   • Contains proteins (such as albumin, globulins, and fibrinogen), electrolytes, nutrients, hormones, and waste products.
   • Functions as a medium for transporting cells, nutrients, and waste throughout the body.

2. Red blood cells (Erythrocytes)

   • The most abundant cells in blood, responsible for transporting oxygen from the lungs to tissues and carbon dioxide from tissues back to the lungs.
   • Lack a nucleus and organelles, allowing more space for hemoglobin, the protein that binds oxygen.
   • Have a lifespan of about 120 days, after which they are removed by the spleen and liver.

3. White blood cells (Leukocytes)

   • Part of the immune system, responsible for defending the body against infections and foreign invaders.
   • There are several types, including neutrophils, lymphocytes, monocytes, eosinophils, and basophils, each with specific functions.
   • Can move out of blood vessels to reach sites of infection or inflammation.

4. Platelets (Thrombocytes)

   • Small cell fragments that play a crucial role in blood clotting and wound healing.
   • Form a temporary plug at the site of a blood vessel injury to prevent excessive bleeding.
   • Release chemicals that promote the clotting process and attract more platelets to the site.

5. Hematocrit

   • The percentage of blood volume that is made up of red blood cells.
   • A higher hematocrit indicates a greater concentration of red blood cells, which can affect oxygen transport efficiency.
   • Normal ranges vary by age and sex, with lower values often indicating anemia.

6. Hemoglobin

   • A protein found in red blood cells that binds to oxygen and carbon dioxide, facilitating gas exchange.
   • Each hemoglobin molecule can carry four oxygen molecules, significantly increasing the blood's oxygen-carrying capacity.
   • Abnormal levels can indicate various health conditions, including anemia or polycythemia.

7. Blood types (ABO system)

   • Blood is classified into four main types: A, B, AB, and O, based on the presence or absence of antigens on the surface of red blood cells.
   • Type O is considered the universal donor, while AB is the universal recipient.
   • Blood type compatibility is crucial for safe blood transfusions and organ transplants.

8. Rh factor

   • A protein that can be present on the surface of red blood cells, leading to Rh-positive or Rh-negative blood types.
   • Important in pregnancy, as an Rh-negative mother carrying an Rh-positive baby can develop antibodies that may harm the fetus.
   • Rh compatibility is also critical for blood transfusions.

9. Serum

   • The liquid portion of blood that remains after coagulation, lacking clotting factors.
   • Contains antibodies, electrolytes, hormones, and nutrients, making it useful for diagnostic tests.
   • Plays a role in immune responses and can be used for therapeutic purposes.

10. Fibrinogen

    • A soluble plasma protein that is converted into fibrin during the clotting process, forming a mesh that stabilizes blood clots.
    • Essential for wound healing and preventing excessive bleeding.
    • Levels can be measured to assess clotting disorders or inflammation.