Second lines of Defense

If microbes get past your first line of defence, it is up to the second line of defence, your immune system, to keep you from getting sick. It is made up of lots of different cells that are always patrolling your body and fighting any bad microbes they find :

• Phagocytes - cells which "eat" foreign material to destroy them :
• Nutrinophils - phagocytize bacteria
• Eosinophyls - secrete enzymes to kill parasitic worms
• Basophils - secrete histamine to enhance inflammation
• Macrophages - "big eaters" phagocytize just about anything

These highly specialized white blood cells surround, engulf and destroy antigens that could compromise your body’s health.

Your body is exposed to many different types of microbes everyday, so your immune system is always hard at work, keeping you healthy!

image's source : The Immune System : (http://www.uic.edu/classes/bios/bios100/summer2002/lect18.htm)

First Lines of Defense

In this section, we are going to talk about the first lines of defense, which are part of the Non-specific immunity: it includes the skin and respiratory, digestive, and circulatory system.

The skin: it prevents pathogens from entering the body, (except for the case of injury). Secretions from the skin are acidic, which prevent the growth of pathogens in this environment.

Respiratory system: it traps the pathogens through cilia and mucus (hairlike structures). The mucus contain enzymes that weaken the pathogen and expel it from the body through coughing or sneezing

Digestive system: it defenses the body through the saliva of the mouth ,enzymes of the stomach , pancreas and liver ,hydrochloric cid in the stomach and mucus on the digestive tract

Circulatory system: contain white blood cell that patrol the body, and digest bacteria invaded. Fever is developed when white blood cells don’t destroy the bacteria quickly, because some pathogens are sensitive to temperature that slows their growth and activity and speed up body defense.

What will happen if the pathogens get past these first-line defenses???

Souce of image: Human Diseases and Conditions (http://www.humanillnesses.com/General-Information-and-Infectious-Diseases-A-Co/Body-Defenses.html)