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 of blood vessels means that there is less heat radiated to the environment. This is why prolonged cold can lead to frostbite- the fingers and toes don't get enough blood sent to them and the tissues begin to die. Blood vessels dilate to radiate heat to the environment. Due to Homeostasis (maintanance of the internal environment) when your too cold, your blood vessels constrict to preserve heat which makes blood flow slower. when your warm, your blood flows better and mroe heat is released.