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:
VINDICATE ME, where:
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)