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The immune system must maintain its responsiveness to pathogenic antigens to prevent infections. The immune system has developed mechanisms in which orally ingested antigens can suppress following immune responses on a local and systemic level. [26] Oral tolerance may have evolved to prevent hypersensitivity reactions to food proteins. [27]
Immunology is a branch of biology and medicine [1] that covers the study of immune systems [2] in all organisms.. Immunology charts, measures, and contextualizes the physiological functioning of the immune system in states of both health and diseases; malfunctions of the immune system in immunological disorders (such as autoimmune diseases, hypersensitivities, [3] immune deficiency, [4] and ...
Innate immune systems are found in all animals. [2] If pathogens successfully evade the innate response, vertebrates possess a second layer of protection, the adaptive immune system, which is activated by the innate response. [3] Here, the immune system adapts its response during an infection to improve its recognition of the pathogen.
[2] [9] The beta cells can still secrete insulin but the body has developed a resistance and its response to insulin has declined. [4] It is believed to be due to the decline of specific receptors on the surface of the liver , adipose , and muscle cells which lose their ability to respond to insulin that circulates in the blood.
A representation of the cholera epidemic of the 19th century. For thousands of years mankind has been intrigued with the causes of disease and the concept of immunity. The prehistoric view was that disease was caused by supernatural forces, and that illness was a form of theurgic punishment for "bad deeds" or "evil thoughts" visited upon the soul by the gods or by one's enemies. [8]
Schematic of the HPA axis (CRH, corticotropin-releasing hormone; ACTH, adrenocorticotropic hormone) Hypothalamus, pituitary gland, and adrenal cortex The hypothalamic–pituitary–adrenal axis (HPA axis or HTPA axis) is a complex set of direct influences and feedback interactions among three components: the hypothalamus (a part of the brain located below the thalamus), the pituitary gland (a ...
Scheme of the complement system. The complement system, also known as complement cascade, is a part of the humoral, innate immune system and enhances (complements) the ability of antibodies and phagocytic cells to clear microbes and damaged cells from an organism, promote inflammation, and attack the pathogen's cell membrane. [1]
A scanning electron microscope image of a single human lymphocyte. The adaptive immune system, AIS, also known as the acquired immune system, or specific immune system is a subsystem of the immune system that is composed of specialized cells, organs, and processes that eliminate pathogens specifically.