Angle that is smaller than a right angle (less than 90Â°). Angle formed by two lines or two perpendicular planes that measures 90Â°. Symbol denoting that a straight line meets another at a right angle. Symbol denoting that two straight lines do not remain at a constant distance from one other. Symbol denoting that two straight lines remain at a constant distance from one another.
Constriction vs. Dilation. Constriction and dilation are opposite, but related, processes in the body. Whereas dilation is an opening or widening of a structure or passageway to increase material flow, constriction leads to a decrease in material flow by closing the passage.
Constriction is a narrowing or closing of a passageway. Constriction is a key regulation step for many different processes in the body, and is usually coupled with dilation, which is an opening or widening of a structure or passageway to facilitate the needs of the body under given conditions.