The immune system has the task of protecting the body from all foreign antigens. Development of the immune system occurs in stages. It begins during growth in a mother's womb and continues until death. Three types of immune responses develop: natural immunity during fetal development, adaptive immune response after birth from exposure to antigens, and passive immune response from other sources.
Before humans are born, many parts of the body must develop in order to survive outside the womb. The vascular, respiratory, and digestive systems develop to prepare babies for life in the world. Development of the immune system starts during the growth of an unborn child. The fetus is exposed to antibodies from the mother, and the immune system develops a resistance before birth. This is classified as natural immunity that protects infants from illness and disease as their delicate immune systems progress in development outside the womb.
Adaptive immune response occurs after birth. Development of the immune system for this type of response occurs through exposure to antigens. An adaptive immune response is developed over time. The body becomes immune to specific antigens after exposure. Vaccinations are a way to create immunity.
In contrast to a natural immunity that is present from before birth, passive immune response occurs from other sources, such as passing antibodies from mother to child in breast milk. There are some instances when inoculations are used. An inoculation involves inducing antibody production artificially. This triggers an immune response to a specific antigen much sooner than if the immune system were allowed to respond on its own.
Although the development of the immune system continuously occurs throughout a human's lifetime, there are some cases that lead to a disruption of immune system development. Such instances include genetic immune disorders, autoimmune disorders, and acquired immune disorders.
Genetic immune disorders are commonly present before or immediately following birth. Also called primary immune deficiency diseases, these immune disorders are evident if repeated instances of the same illness occurs. The illnesses are often common, such as ear infections, and can be treated when identified quickly.
Autoimmune disorders are another complication for the development of the immune system. An autoimmune disorder causes the body to think its own tissues are foreign antigens. Rheumatic fever and arthritis are common forms of these disorders.
Acquired immune disorders are not hereditary but can be passed from mother to child during birth or through breast milk. These disorders, such as human immunodeficiency virus, cause a delay in overall development of children. The development of the immune system is halted, and the body does not have the ability to defend against illnesses without the aid of medications.