| IBS | See Irritable Bowel Syndrome. |
| Ichthyosis | |
| Icterus | Jaundice. |
| Idiopathic | Arising spontaneously or from an obscure or unknown cause. |
| IgA | See Immunoglobulin A. |
| IgE | |
| IGF-1 | Insulin-like growth factor. |
| IL-2 | Interleukin-2. |
| Ileocecal | |
| Ileostomies | See Ileostomy. |
| Ileostomy | |
| Ileum | |
| Ileus | |
| Immune Response | See Immune System. |
| Immune System | A complex that protects the body from disease organisms and other foreign bodies. The system includes the humoral immune response and the cell-mediated response. The immune system also protects the body from invasion by making local barriers and inflammation. The process may involve acquired immunity (the ability to learn and remember a specific infectious agent), or innate immunity (the genetically programmed system of responses that attack, digest, remove, and initiate inflammation and tissue healing). |
| Immunity | See Immune System. |
| Immunoglobulin A | |
| Immunoglobulin E | See IgE. |
| Immunostimulant | An agent that stimulates either innate or acquired immunity. In the U.S., immunotherapy is relegated to experimental drugs, but a number of plant substances are used in Europe as immunostimulants. |
| Immunosuppressant | An agent that acts to suppress the body's natural immune response. |
| Immunotherapy | |
| In Vitro | In an artificial environment, such as the test tube. |
| In Vivo | Occurring within a living animal. |
| Incontinence | |
| Incontinent | See Incontinence. |
| Indolent | A sluggish and unresolving condition, often with ulcerations and necrosis. |
| Infraorbital | |
| Inguinal | |
| Inguinal Nodes | See Lymph Nodes. |
| Inositol | |
| Inotropic | |
| Insidious | A symptom or condition of gradual onset or development. |
| Insoluble Fiber | See Dietary Fiber. |
| Insoluble Fibers | See Dietary Fiber. |
| Insulin | |
| Interferon | |
| Intergluteal | Between the buttocks. |
| Interstitial Cystitis | |
| Interstitial Fluid | The hydrogel that surrounds cells in soft tissues. It is a mucopolysaccharide starch gel, and the serum that leaves the blood capillaries flows through this gel, some to return to the exiting venous blood, some to enter the lymph system. "The blood feeds the lymph, and the lymph feeds the cells." Interstitial fluid that flows through the starch colloid is this lymph. |
| Intertrigo | |
| Intestinal Flora | |
| Intestinal Roundworm | See Ascaris lumbricoides. |
| Intraperitoneal | |
| Intravenous Infusion | |
| Intravenous Pyelogram | |
| Intrinsic Factor | One of two proteins secreted from the lining of the stomach whose sole purpose is (it seems) to cradle B12 and carry it through the digestive system until it reaches the absorption sites in the last foot of small intestine. There it slips from one protein to the other, and into the cell membranes where its handed over to the specialized blood protein that can carry it safely to the final target tissues (3 times out of 4, the bone marrow). Apparently cyanocobalamin (B12) has "parts that fall off", radicals that twirl around in five directions on three charge potentials, and is generally not very durable. |
| Involuntary Muscle | See Smooth Muscle. |
| Involutional | Reducing an enlarged organ to normal size. |
| Iodine | |
| IP6 | Inositol Hexaphosphate. |
| Iritis | |
| Iron | |
| Irrigation Therapy | Washing out a cavity or wound with a fluid; irrigation of the kidney parenchyma and the urinary tract by addition of increased amounts of liquid, usually a mild herbal teas with aquaretic or diuretic properties. |
| Irritable Bowel Syndrome | |
| Ischemia | |
| Ischemic | See Ischemia. |
| Ischialgia | Hip pain. |
| Ischuria | Retention or suppression of urine. |
| ISH | Isolated Systolic Hypertension. |
| Isoleucine | |
| IU | International Unit: An arbitrarily defined but agreed upon unit that depends on what is being measured.
mIU: 0.001 or one thousandth of an IU.
uIU: 0.000001 or one millionth of an IU. |
| IV | See Intravenous Infusion. |
