Glossary Terms


action potential - transient all-or-nothing reversal of a membrane potential


bradycardia - a reduction in heart rate from the normal level


baroreceptor - a sensory nerve ending that is stimulated by changes in pressure, as those in the walls of blood vessels.


chemoreceptor - a sensory receptor specifically sensitive to certain molecules


conduit - a pipe or channel for conveying fluids


depolarization - The reduction or reversal of the potential difference that exists across the cell membrane at rest


dorsal - towards the back


endothelium - single cell layer forming the internal lining of blood vessels


hemocoel - the space between the endoderm and the ectoderm in some invertebrates


inferior vena cava - vein that brings blood from the lower portions of the body to the right atrium


interstitial fluid - fluid existing between tissues or cells


isometric - an absence of volume change of blood in the contraction of the ventricle in the heart


pacemaker - an excitable cell or tissue that fires spontaneously and rhythmically


posterior - the back of the body


proximal - nearer to the attachment of an extremity or nearer to the point of origin


pulmonary - pertaining to or affecting the lungs


refractory stage - the period during the repolarization of the cell membrane during which the cell cannot generate another action potential.


repolarize - the return of resting polarity of a cell membrane that has been depolarized


sinuses - spaces surrounding an organ


superior vena cava - vein that brings blood from the upper portions of the body to the right atrium


systemic - pertaining to or affecting the body


threshold - the membrane potential at which votage sensitive sodium gates open, permitting a rapid influx of sodium ions, which results in the depolarization phase of an action potential.


ultrafiltration - the process of filtration of colloidal particles by using pressure or suction and a semipermeable membrane


vasoconstriction - contraction of circular muscle of arterioles, decreasing their volume and increasing the vascular resistance


vasodilation - a widening of the lumen or interior space of the blood vessels, increasing the blood flow.


ventral - towards the belly