{I band}{}{Area between the ends of two adjacent myosin myofilaments within a myofibril; Z disk divides the I band into two equal parts.}

{ileum}{}{Third or posterior-most portion of the small intestine.}

{implantation}{}{Embedding an embryo in the lining of the uterus.}

{indeterminate}{}{Divisions or cleavages of embryonic cells that can be separated and still form a complete organism.}

{inferior}{}{Situated below something else; pertaining to the lower surface of a part.}

{inhibitory neuron}{}{Neuron that produces IPSPs and has an inhibitory influence.}

{inhibitory postsynaptic potential [IPSP]}{}{Hyperpolarization in the postsynaptic membrane that causes the membrane potential to move away from threshold.}

{insertion}{}{More movable attachment point of a muscle; usually the lateral or distal end of a muscle associated with the limbs.}

{inspiration}{}{Breathing in; inhalation.}

{integumentary system}{}{Body system composed of the skin and its accessory organs.}

{intercalated disk}{}{Cell-to-cell attachment with gap junctions between cardiac muscle cells.}

{intermediate filament}{}{Thin protein strands in the cytoskeleton that provide support and structure to cells.}

{interneuron}{}{Neuron between a sensory neuron and a motor neuron; internuncial or association neuron.}

{interphase}{}{Period between active cell divisions when DNA replication occurs.}

{intramembranous bone}{}{Bone that forms from membranelike layers of primitive connective tissue.}

{intramembranous ossification}{}{Formation of bone from ossification of layers of connective tissue.}

{intramural plexus [plexi]}{}{The submucosal and myenteric plexuses.}

{intron}{}{Section of DNA in a gene that does not contain information for the protein encoded by that gene.}

{inversion}{}{Inward turning movement of sole of foot.}

{ion}{}{Atom or group of atoms carrying a charge of electricity by virtue of having gained or lost one or more electrons.}

{ionic bond}{}{Chemical bond that is formed when one atom loses an electron and another accepts that electron.}

{ipsilateral}{}{Structures on opposite sides of the body.}

{irregular bone}{}{A bone with a shape that is not flat, long, or short.}

{isotonic}{}{Solution that causes cells to neither shrink nor swell.}

{isthmus of thyroid}{}{Constriction connecting the two larger parts of the thyroid.  Other organs with an isthmus include the constriction between the body and the cervix of the uterus and the portion of the uterine tube between the ampulla and the uterus.}