Human body is invaded by disease-causing organisms ( pathogens) and the body fights against the same day to day. The mucous membrane lining of the mouth nose and digestive system and Skin prevents physically the entry of Pathogens When there is a cut on the skin blood clot formation takes place and seals the entry. These are known as natural defence mechanism.
The digestive system is covered by normal body flora which prevents pathogens to become established. The presence of flora creates a shortage of nutrient for the pathogen.
The respiratory system – the nose and passageways leading to the lungs – is lined with cells that produce a sticky fluid called mucus that traps invading microbes and dust. Tiny hairs called cilia move in a wave-like motion and waft the microbes and dust particles up to the throat, where they are either coughed or sneezed out or swallowed and then passed out of the body in stools.
The pathogens are destroyed by the enzymes of saliva and tears. Hydrochloric acid in the stomach destroys many pathogens that enter the body in food and drink. urinary system flushes out pathogens through urine.
Second line defence.
The pathogens manage to enter the body then the second line of defence is activated which is non-specific and stops any type of pathogen. Phagocytes are a type of white blood cell that move by action similar to amoeba. They send out pseudopodia which allow them to surround invading pathogens and engulf them and the enzymes released by phagocytes breaks down the trapped microbes before they can do any harm. This process is called phagocytosis.
The third line defence
The immune response. The invading pathogens are attached with antigens and are unique to each pathogen. The antigen is recognised by the
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immune system and produces an antibody against it that are specific to that antigen. Each antibody has a unique binding site shape that locks on to the specific shape of the antigen. The antibodies destroy the antigen (pathogen) which is then engulfed and digested by macrophages.
White blood cells can also produce chemicals called antitoxins which destroy the toxins (poisons) some bacteria produce when they have invaded the body.
The immune system memorises the antibody production against a specific pathogen (Antigen) and acts fast and immediate if the same pathogen invades again. IMMUNE BOOSTERS ARE VERY MUCH REQUIRED