Saturday, April 16, 2011

What is our Immune System and how does it work?

Immune System in our bodies serves the defense mechanism and can be divided into first, second and third line of defense. It is a complicated body system and shares an analogy to a nation (country), the Border Patrol, the Immigration system, the Army, the Navy, the Air Force, the Marines, the Special Forces, the Secret Service, the CIA, the NSA, the FBI, the Police, the detectives and other security personnel along with all their training academies. The prime purpose of our Immune System is to deter, defend and thwart any attack on any of the body systems including itself. It utilizes both non-specific and specific defense mechanisms and uses very sophisticated organic hardware (Skin - as a barrier along with its shedding mechanism, water resistance, Langerhans cells, many anti-microbial secretions including peroxide; Mucosal barrier - with saliva containing anti-microbial lysozyme, and secretory antibody IgA; Cell-mediated Immune system including all the different types of White Blood Cells; Humoral Immune system including Immunoglobulins  and the Complement system and the Lymphatic System with its organs - lymph nodes, lymph vessels, spleen, thymus, tonsils) along with the  adaptive software (genetic material - DNA).

This brief overview and analogy can easily make us understand how our Immune System works and learns about our body's internal and external environment and keeps it from changing and getting damaged until it works normally.

The battle-grounds inside the body are the sites of injury and the way our immune system responds to it and are referred to as sites of inflammation that result in swelling, redness, heat, pain, sometimes total or partial loss of function. Depending on the nature of injury and the type of forces deployed by the body to fight these battles with foreign agents (antigens and haptens combined with body proteins) the inflammation might be acute (over a short period of time and usually severe), sub-acute (less severe and more insidious than acute), chronic (long standing and not severe) or acute on chronic(severe and on top of a long standing injury).

Injury in our bodies can take various forms and helps us understand the nature and cause of various disease processes and syndromes.

An easy way to remember most of these causes is to remember the mnemonic:


V - Vascular (Heart, Blood vessels, Bone Marrow and the Blood itself)
I - Infections (Bacterial, Viral, Fungal, Protozoans, Parasitic)
N - Neoplasia [new growths: Benign (non-cancerous) and Malignant (cancerous) and Nervous System (Brain disease, Psychiatric and Psycho-social, Spinal cord and Nerves)]
D - Dietary, Drugs (medications and substance abuse) and Developmental
I - Iatrogenic (Illness caused by medical examination or treatment) and Idiopathic (unknown cause) and Immune system
C - Congenital (condition present at birth)
A - Autoimmune (Immune system fails to differentiate between self and non-self and starts attacking our own body)
T - Trauma
E - Endocrine (Hormonal) and Environmental

M - Metabolic (Genetic Inborn errors of metabolism and problems with chemical reactions in the body)
E - Eating Habits and Exercise (lack of) and Education (lack of)

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