Rabu, 20 Maret 2013

Defence Mechanism of Human Body

Defence Mechanism of Human Body

Man suffers from various diseases by different pathogenic organisms such as viruses, bacteria, parasitic protozoans, helminthes etc.
Also many harmful organisms live in our body as symbionts, but sometimes they invade certain of our body tissues when the resistance of our body to the action of these organisms is very low.
Our body broadly has two lines of defense to fight against these infections.

1. Non-specific defence mechanism:
  The skin of our body acts as the physical barrier and it forms the first line of defence against the pathogens. The outer firm covering layer of the skin does not allow the bacteria and virus to enter into our body. The oil and sweat secreted by respective glands prevent the growth of microorganism on the surface of the skin
  Further, the lysozyme contained in the sweat helps in destroying the cell wall of the bacteria. Therefore the entry of the pathogens into the body does not become possible. So the pathogens may enter into the body through some injuries, if they occur on the surface of the body. Now the body’s second line of defence starts working. The capillaries of the blood vessels surrounding injured tissue become dilated and their wall becomes more permeable to the phagocytic WBCs. Therefore the WBCs come out and invade the foreign germs. 

Physical Barriers

The human body constantly faces attack from foreign invaders that can cause infection and disease. These invaders range from living microbes (MY-krobes), such as bacteria , fungi  , parasites  , and viruses  , to nonliving toxins, chemicals, and drugs. Fortunately, the body has a number of external and internal safeguards that prevent most dangerous invaders from entering and causing harm. The physical barriers that keep them at bay commonly are referred to as the body's first line of defense.
Skin, the largest body organ, provides both a physical and a chemical barrier against the outside world. The skin forms a protective layer that completely wraps around the body, shielding blood vessels, nerves, muscles, organs, and bones. When cuts or tears in the surface of the skin provide an entrance for infective agents, glands beneath the skin produce an enzyme that helps kill bacteria. 

Sumber : Bpk. Dr. Iskandar Zulkarnain

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