The human immune system.

Human Immune System comprised of the Body Defense Mechanisms, Antigen and Antibody and Immune Response.

A. The body defense mechanism.

The body has two layers of immunity, that immunity nonspecific and specific immunity. Bacteria, viruses, and foreign substances must be through nonspecific immune system in advance. If nonspecific immunity are not able to destroy it, substances that infect the next will face the specific immune system.

1. Immunity Nonspecific (Default).

The innate immune system of a person from birth. Innate immunity is nonspecific, meaning that the immune system is always prepared to face any infection that enters the body. Immune mechanism is effective against microorganisms without the experience of previous contact with the organism.

Nonspecific immunity there is some external, some are internal. External immunity is also known as surface protection, because it protects the outer body. Internal immunity is more cellular and chemical protection.

a. External immunity.

External immunity consists of epithelial tissue that protects our body (skin and mucous tissue) and the resulting secretion. Aside from being a barrier entry of the disease, the epithelial produce protective substances. For example, the results of the acidic skin secretions so toxic to the bakery. Saliva (saliva) and tear can also kill the bacteria. Mucus (phlegm) trap microorganisms and so can not get into the digestive and respiratory tract.

b. Internal immunity.

The internal immunity against bacteria, viruses, or foreign substances are capable of passing external immunity. Internal immunity in the form of chemical stimulation and involves phagocytic cells, natural killer cells, anti-microbial proteins that fight foreign substances that have entered the body, and inflammation (swelling) and fever.

Phagocytic cells that play a role in the internal immunity among others neutrophils, macrophages, and eosinophils. Neutrophils will be phagocytic (eat) if it meets the material maker in the network infection. Macrophages will attaches to polysaccharides on the surface of the body of microbes and then ingest the microbes. Eosinophils tasked to attack parasites that are large, such as worms.

Natural killer cells attack the parasite cells by removing the destructive compounds called perforin. Natural killer cells can lyse and kill cancer cells and virus before the adaptive immune system is activated. The antimicrobial protein increases the body's defenses by attacking the microorganisms directly or by inhibiting reproduction mikroorgnisme. One important antimicrobial proteins to protect cells from viral attack is interferon.

Other internal immune inflammatory response (inflammation) and fever. Inflammation is triggered by physical trauma, excessive heat, bacterial infections, and others. Inflammation is local or just turn up on the infected areas while the fever spread throughout the body.

2. Specific Immunity (Adaptive).

If bacteria, viruses, and foreign substances successfully passed the innate immune system (nonspecific), then foreign substances will be faced by the adaptive immune system. Adaptive immunity is specific, meaning that defense mechanism relies on the formation of a specific immune response against microorganisms that provide stimulation.

Adaptive immunity can be natural or artificial. Natural adaptive passive immunity obtained by the infant from his mother's womb, while the active adaptive immunity obtained for example through infection (illness beforehand). Artificial adaptive immunity in the form of passive transfer of antibodies from others, whereas active artificial adaptive immunity gained through immunization.

Based on the cells involved in the mechanism, adaptive immunity is divided into two, namely the humoral immunity and cell-mediated immunity (cell-mediated immunity).

a. Humoral immunity.

Most elements play a role in humoral immunity are antibodies produced by B cells lymphocytes. Antibodies found in humor (fluid) of the body, such as blood and lymph fluids and functioned binding bacteria and bacterial toxins, as well as marking the virus for further destroyed by white blood cells.

b. Mediated immune Sel.

The most important factor in immunity are living cells, ie cells T lymphocytes. These cells are active against bacteria and viruses in the body in the infected cells. These cells can also fight protozoa, fungi and parasitic worms.

B. Antigen and Antibody.

1. Antigen

An antigen is a chemical substance that can stimulate the immune system (immune) to generate a specific response. Examples of antigen is the outer capsule or bacterial cell wall. Antigen also called immunogen.

Antigen has two important characteristics, as follows :

Immunogenicity.

Namely the ability to trigger multiplication of specific antibodies and lymphocytes

Reactivity.

Namely the ability to react with the activated lymphocytes and antibodii released by immune reaction.

In addition there are also antigen molecule called hapten. Hapten is a simple chemical substance or a portion of the antigen that does not cause immune response, but if the hapten binding to proteins of the body, the immune system will recognize it as a dangerous substance.

2. Antibody.

Antibodies are proteins that formed as a response to a specific antigen and held a reaction to these antigens. Antigen can not directly destroy the antigen. The main function is to disable antigens and marking antigen for further destruction. Generally, if an antibody meets the antigen will form antigen-antibody complexes.

Immunoglobulin G (IgG).

Immunoglobulin G is the only immunoglobulin capable through the placenta. IgG is given passive immunity from mother to child. IgG is the main defense against infection for babies in the first weeks of life are reinforced by IgG from colostrum.

Immunoglobulin A (IgA).

Immunoglobulin A is one of the immunoglobulin found in external secretions, for example in the airway mucosa, intestinal, urinary, genital, saliva, tears, and breast milk. Immunoglobulin A can neutralize the virus and block the attachment of the epithelial cells.

Immunoglobulin M (IgM).

Immunoglobulin M is an antibody that was first synthesized in antigen stimulus. IgM synthesis is done by the time of fetal intrauterine. Therefore, can not pass through the placenta, the IgM newborns are signs of intrauterine infection.

Immunoglobulin D (IgD).

D immunoglobulin was first discovered as a myeloma protein. IgD is always attached to the outer surface of B lymphocytes IgD cells function as antigen receptors of B lymphocytes cells and is important for the activation of B cells.

Immunoglobulin E (IgE).

IgE is secreted by plasma cells in the skin, mucosa and tonsils. If the tip of IgE triggered by antigen, will cause the cells to release histamn inflammation that causes inflammation and allergic reactions.

C. Immune Response.

If the body is exposed to an antigen, the immune response will occur. The first introduction to an antigen will generate a primary immune response. If after some time, a person exposed to the same antigen, it will display a secondary immune response.

1. Primary Immune Response.

After the antigen into the body, the antibodies do not immediately formed in the blood serum. The period between the administration of antigen and antibody formation is called the latent period or period of induction. Long latency period of about 6-7 days. In the latent period, antigen delivered on immunocompetent cells, the B cells that produce antibodies. This period witnessed proliferase and differentiation of cells B. After a latency period, then entered the period biosynthesis. The initial phase of the period boisintesis is phase logarithmically characterized by a growing number of antibodies logarithmically in the body, followed by phases of a steady, ie where the speed of protein synthesis is equal to the speed of catabolism her, and ending phase of decline, ie where katabolismen antibody faster than its synthesis ,

2. Secondary Immune Response.

The second encounter with the same antigen ever given previously will restore secondary immune response. When the antigen is exposed on the body, the antibodies are still present in serum will shrink, this phase is called the negative phase. Antigen and antibody in the serum would then form the antigen-antibody complexes. If the dose of antigen bit, a robust immune response will not occur. This is probably because the antigen serum has been used to form the antigen-antibody complexes. Conversely, if enough doses of antigen, B cells are left to form antibodies that appear secondary response.

3. Differences in Response Primary and Secondary Response.

In the event the primary response to stimulation, precursor cells divide and hold differentiation into antibody-forming cells that produce IgM and IgG. During this process form the memory cells, which are still limited. Following the secondary response, cells that senditif against antuigen number had grown rapidly so that the synthesis of antibodies increases.

Secondary immune response that appears to be faster, more durable and more effective than previous response. That is because the immune system has been better prepared against antigens as memory cells prepared against antigens. These memory cells will eventually cause immunological memory.
Thank you for reading this article. Written and posted by Bambang Sunarno. sunarnobambang86@gmail.com
author:
https://plus.google.com/105319704331231770941.
name: Bambang Sunarno.
http://primadonablog.blogspot.com/2015/09/the-human-immune-system.html
DatePublished: 12 September 2015 at 17:51

Tag : Human Immune System.

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