Dictionary

Body systems

Anatomy and the conditions of each body system, from the heart and lungs to the skin.

intellectual disabilityA condition that starts in childhood with limits in thinking and learning and in everyday living skills.

intercostalBetween the ribs.

intermittent auscultationChecking the baby's heart rate during labor at set times with a hand-held Doppler or fetoscope, instead of continuous monitoring.

internal jugular veinA large vein deep on each side of the neck that carries blood from the brain, face and neck back toward the heart.

interstitialRelating to the small spaces between cells or between the parts of a tissue or organ.

interstitial fluidThe fluid in the spaces between the body's cells, outside the blood vessels.

intervalThe time or space between two events, such as between two contractions in labor or between two waves on an ECG.

intestinalHaving to do with the intestines, the long tube that runs from the stomach to the anus.

intestineThe long tube of the digestive tract between the stomach and the anus, made up of the small and large intestine.

intimate partner violencePhysical, sexual or emotional harm, stalking or control by a current or former partner or spouse.

intoxicationA state in which alcohol, a drug or a poison changes how a person thinks, acts or how the body works.

intracellular fluidThe fluid inside the body's cells.

intracranialInside the skull.

intracranial pressureThe pressure inside the skull, made by the brain, the blood and the fluid around the brain.

intrauterineInside the uterus.

intrauterine deviceA small T-shaped device that a health care provider places inside the uterus to prevent pregnancy.

intrauterine growth restrictionSlower than expected growth of a fetus in the uterus, with an estimated weight below the 10th percentile for its age.

intrinsic factorA protein made by the stomach lining that the body needs in order to absorb vitamin B12 from food.

intussusceptionA condition in which one part of the intestine slides into the part next to it, like a telescope.

inversionA turning inward or upside down; for the foot, turning the sole in toward the other foot.

involuntary muscleMuscle that works without a person's conscious control, such as smooth muscle and heart muscle.

involutionThe process by which the uterus shrinks back to its size and position from before pregnancy, after the birth.

iodineA mineral the thyroid gland uses to make thyroid hormone; it is also used to kill germs on the skin and in some contrast dyes.

IPFIdiopathic pulmonary fibrosis: a long-term lung disease of unknown cause in which lung tissue becomes thick and scarred.

irisThe colored ring of muscle in the eye that controls the size of the pupil.

iron-deficiency anemiaAnemia caused by too little iron in the body, so the bone marrow cannot make enough hemoglobin.

irritable bowel syndromeA long-term bowel condition with belly pain and changes in bowel habits, such as diarrhea, constipation or both.

ischemiaToo little blood flow to a part of the body, so the tissue does not get enough oxygen.

ischemic strokeA stroke caused by a blocked artery that cuts off blood flow to part of the brain.

isotonicHaving the same concentration of dissolved particles as blood, so water does not move into or out of cells.