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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ahmad baihaqi
NIM 1112503964
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