estimated average requirement; a nutrient intake value that is estimated to
meet the requirement of half of the healthy individuals in a particular
life stage and gender group.
diagnostic test that uses ultrasound to make images of the heart. It can be
used to assess the health of the valves and chambers of the heart, as well
as to measure cardiac output.
Ectoderm: The primary
germ layer that gives rise to the nervous system and the epidermis of skin
and its derivatives.
Effector: An organ of
the body, either a muscle or a gland, that responds to a motor neuron
hormones derived from a 20-carbon fatty acid (arachidonic acid); two
important types are prostaglandins and leukotrienes.
recording of the electrical activity of the brain, used to diagnose
neurological conditions such as seizure disorders (epilepsy).
compound that separates into ions when dissolved in water and is able to
conduct electricity; ionized (dissociated into positive and negative
ions) salts in the body fluids. Major electrolytes in the body include
sodium, potassium, magnesium, calcium, chloride, bicarbonate, phosphate.
atomic particle with a negative charge.
of electron carriers in mitochondria that transport electrons to and from
each other in a sequence, in order to generate ATP.
the 103 chemical substances that cannot be divided into simpler substances
by chemical means. For example, hydrogen, magnesium, lead, and uranium are
all chemical elements. Trace elements are chemical elements that are
required in very small (trace) amounts in the diet to maintain health. For
example, copper, selenium, and iodine are considered trace elements.
white, outermost layer of a tooth.
glands and parts of glands that secrete hormones that integrate and control
the body's metabolic activity. Endocrine glands include the pituitary,
thyroid, parathyroids, adrenals, pancreas, ovaries, and testes.
biological catalyst. That is, a substance that increases the speed of a
chemical reaction without being changed in the overall process. Enzymes are
vitally important to the regulation of the chemistry of cells and organisms.
examining disease occurrence in a human population.
known as seizure disorder. Individuals with epilepsy experience seizures,
which are the result of uncontrolled electrical activity in the brain. A
seizure may cause a physical convulsion, minor physical signs, thought
disturbances, or a combination of symptoms.
muscular tube that connects the throat to the stomach. When a person
swallows, the muscular walls of the esophagus contract to push food down
into the stomach.
causes or origin of a disease.
elimination of wastes from blood or tissues.
Extracellular fluid (ECF):
volume of body fluid excluding that in cells. ECF includes the fluid in
blood vessels (plasma) and fluid between cells (interstitial fluid).