Cambridge (CIE) IGCSE Biology

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(Blood)

Blood Clotting & White Blood Cells

The Body’s Defenders: White Blood Cells & Clotting 

 

Lymphocytes & Phagocytes: Extended

White blood cells (WBCs) are like your body’s tiny defenders. They help protect you from germs and diseases. There are two main “guard types” you should know about:

Phagocytes

  • These cells are like hungry “Pac-Men,” gobbling up germs (called pathogens).
  • They engulf (surround) and digest these invaders, keeping you safe.

 

 

Lymphocytes

  • These are like “smart defenders” that produce antibodies—special “locks” that fit germs like keys, making it easier to stop them.

Together: Phagocytes and lymphocytes work as a team to catch, break down, and help remove germs.

 

What Is Blood Clotting?

  • Blood clotting is like your body’s emergency patch kit when you get a cut,
  • Platelets, tiny cell fragments help form a “plug” and start a chain reaction that turns fibrinogen into fibrin—like turning liquid glue into a net.
  • This net traps cells and forms a scab, stopping bleeding and blocking germs from getting in.

 

In simple terms: Cut +Platelets Fibrin net Scab No more bleeding \text{Cut } + \text{Platelets } \to \text{Fibrin net } \to \text{Scab } \to \text{No more bleeding }

 

 

 

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Think of phagocytes as “germ-eaters” and lymphocytes as “germ-taggers.”

Platelets are your body’s “emergency repair team,” stopping leaks.

Clotting not only stops bleeding but also helps keep germs out.

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