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The immune system is one of the thirteen physiological systems in the human body. It is concerned with the role of protecting the body against infections from pathogens which brings about diseases; hence the body’s safeguard or defence mechanism against diseases. The immune system is peculiar in function as it possesses the ability to recognize strange and foreign substances that enter the body; with an ability to differentiate between the non-self(which is the strange substance) and cells belonging to the body, which do not pose any threat.
The coordination of the system works according to two general forms. These are the innate immunity forms and the acquired immunity forms. The innate immunity otherwise known as the “first line of defence in the body” is natural and non-specific. This immunity is inbuilt and can be said to be that which is passed down from a mother to her child. By been non-specific, it means that it attacks or stops every foreign object from entering the body, without necessarily identifying the intruder type. The skin and the mucus lining fall under this. Acquired immunity form, on the other hand, is specific and acquired, hence the name. It comes to play as a result of an initial particular stimulus.
This immunity type targets a specific pathogen for which the body had been previously sensitive to. Compared to the innate immunity, the function of the acquired immunity is more of a process. An individual is usually given this immunity through immunization (the use of vaccines) and from anamnesia of the pathogen. Anamnesia is the ability of the system to remember a previous attack from a pathogen, which consequently makes the immune response more rapid in instances of subsequent attack.
The Transmission of The Immune System
The Blood is the medium through which cells involved in body protection (immune system) circulate. These cells develop from common precursors called stem cells and they are found in the bone marrow. Phagocytotic cells carry out immune aid by ingesting the foreign particle and digesting it. In a different instance, once the message is received of the presence of a stranger (or an injury to body tissues), blood cells and proteins are released and directed towards the site of impact. The cells surround the area creating a fence around the pathogen and fighting it. The resultant is a yellowish fluid (pulse) which can be seen on the injury surface which consists of dead white blood cells together with dead cells of the intruding pathogen.
Fever: A Form of Defense Mechanism in Humans
Also, it is interesting to note that fever is a defence mechanism in humans and it is a strong indicator of disease infection. When fever as an immune response occurs, the body sought to increase its temperature, such that the invading pathogens are not able to survive (since they would normally survive at normal human temperature). We should note that not every pyrexia (fever) should be considered a major threat but rather an investigation should be made towards the cause of the rise in temperature. Furthermore, fever can also function as an alarm for activating other required immune responses.
The mechanism by which fever serves as an immune response is controlled by the hypothalamus part of the brain. The hypothalamus regulates the body temperature at 37°c and switches up in response to chemical toxins and wastes from pathogenic invaders. Physical effects would include cold chills, while internally there is an increase in metabolic rates and there is constriction of the blood vessels. ( Read an interesting article on how a child’s blood group is formed from the parent’s blood here)
Various Levels of Immunity Strengths and Responses
Varying levels of immunity strength and response among individuals are known to exist. This present in forms of susceptibility and vulnerability to disease infections and the ability of the various individuals’ body to successfully overcome such infections. Innate immunity is absolutely not sufficient to combat all of the infectious diseases that are peculiar to man, thus the use of vaccines through acquired immunity. But basically, it is possible that some individuals possess comparatively lower levels of immunity as a result of some defects in their immune mechanism. This condition is termed immuno-suppression, which may be caused by factors such as autoimmunity. This is an abnormal immunity condition in which the body cells undergo variations and are in turn considered as non-self, it may be caused by a history of a severe infection or it may be induced by certain drugs such as those used in regulating graft rejection.
Immunity differences in people may also be attributed to factors present in their genetic constitution, some of which seem like a positive modification. For example, it is a confirmed report that sickle cell anaemia persons (read more about sickle cell and its crisis here) is very much less susceptible to Plasmodium falciparum, the malaria-causing agent, as compared to other individuals of different genotype(read more on genotype and malaria here) if exposed to infection.
The body works with the antigen stimulus to produce antibodies which are produced only specifically.
Immune Systems and Child Growth
Note that the immune systems are at different levels of capacity at the various stages of development and growth. Hence, the body may not be able to combat an infection adequately at childhood as in adulthood. Newborn babies and growing children have weaker immune systems and it is at this point that the overall system just begins to form. Thus, it should be a period when they are protected and less exposed to infections. This is also a reason why they are immunized almost immediately after birth. As growth continues, the child gets more exposed, may experience some little infections which enable it to obtain some forms of acquired immunity. The growing child requires a lot of nutrients that would help build the whole body systems. Vitamins and mineral components of food(read an interesting article on the importance of food and water to the body here) are notable immune builders.
As maturity becomes more pronounced, it is expected that the individual’s ability to withstand disease(read more about the common disease in Nigeria and their causes here) is at optimum. This tends to diminish as old age sets in, thus the immune system functionality tends to appear as a curve over time.
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