Dilatatie

Dilatatie, or dilatation, is the act or result of widening or expanding a hollow or enclosed structure, or of increasing a quantity. The term is used in several fields to denote enlargement that preserves form, from mathematics to medicine. In everyday use it often refers to widening openings such as pupils or vessels, while in technical contexts it can describe a transformation that scales objects.

In geometry, a dilation is a similarity transformation about a fixed center that enlarges or shrinks figures by a scale factor k. Each point P maps to P' along the line PC with P' = C + k(P - C). Distances are multiplied by |k|, and angles between figures are preserved. When k > 1 the figure grows, when 0 < k < 1 it shrinks, and k < 0 reverses orientation.

In physiology and medicine, dilation refers to the widening of hollow structures. Vasodilation is the widening of blood vessels; mydriasis is the dilation of the pupil. Dilation results from relaxation of smooth muscle and can be triggered by neural signals, hormones, or pharmacological agents. Pathological dilation can occur in the heart (for example, dilated cardiomyopathy) or in other organs, potentially affecting function and circulation.

Dilatation is often contrasted with constriction or compression, the processes that reduce size. In many disciplines, precise definitions depend on the context and the specific structure being described, but the core idea is a change in size that preserves overall form or function.