Here's how it works:
* Recognizing Threats: The immune system has specialized cells that can identify foreign invaders like bacteria, viruses, fungi, and parasites. It also recognizes abnormal cells, such as those found in cancer.
* Attacking and Destroying: Once a foreign substance is identified, the immune system launches a coordinated attack. This involves:
* White blood cells: These cells engulf and destroy invaders or release chemicals that kill them.
* Antibodies: These proteins bind to and neutralize invaders.
* Cytokines: These signaling molecules help coordinate the immune response.
* Remembering: The immune system remembers past encounters with invaders. This allows for a faster and more effective response if the same invader is encountered again.
Here are some other body systems that play a role in protection, though their primary function is different:
* Skin: The skin acts as a physical barrier, preventing entry of many foreign substances.
* Respiratory system: The respiratory system contains mucous membranes and cilia that trap and remove inhaled pathogens.
* Digestive system: The digestive system uses stomach acid and enzymes to break down and kill many pathogens that are ingested.
While these other systems contribute to overall protection, the immune system is the primary defense mechanism against foreign substances.
