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What is the main role of the blood platelets (thrombocytes) in the blood?

  • A

    Oxygen transport.

  • B

    Immune defense.

  • C

    Blood sugar regulation.

  • D

    Blood coagulation.

COMPONENTS OF BLOOD

Blood consists of blood plasma (55% of blood) and blood cells (45% of blood).

1) PLASMA

Plasma consists mainly of water (about 90%), along with various proteins, electrolytes (such as sodium and potassium), hormones, vitamins, glucose, and other nutrients and waste products. The main role of plasma is to transfer its components around the body (i.e. proteins and hormones) and help carry the waste products away.

2) BLOOD CELLS

i) Red blood cells (RBCs): The RBCs transport oxygen from the lungs to tissues and carry carbon dioxide back to the lungs. They contain a protein called hemoglobin which binds oxygen in the lungs and release it in tissues, facilitating cellular respiration.

ii) White blood cells: White blood cells are integral to the immune system and play an essential role in defending the body against infections and foreign invaders.

iii) Platelets: Platelets are critical for preventing excessive bleeding and facilitating wound healing. Their role in hemostasis ensures that blood clots form appropriately in response to injury.


Red blood cells (erythrocytes) → carry oxygen in combination with hemoglobin
White blood cells (leucocytes) → ward off infections
Platelets (thrombocytes) → help blood to clot (blood coagulation)

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