Difference Between Dilation and Dilatation

Main Difference – Dilation vs Dilatation

Dilation and dilatation are two terms used interchangeably to describe different types of enlargements in medicine and biology. The main difference between dilation and dilatation is that dilation describes the passive enlargements whereas dilatation describes active enlargements. The pupil of the eye dilates passively under natural conditions. The enlargement of the obstructed vessel with a balloon catheter is an example of dilatation. Dilation is the act of dilating or stretching out. Dilatation refers to a region of dilation, surgical enlargement of a region or an area of abnormal enlargement.

Key Areas Covered

1. What is Dilation
      – Definition, Characteristics, Examples
2. What is Dilatation
      – Definition, Characteristics, Examples
3. What are the Similarities Between Dilation and Dilatation
      – Outline of Common Features
4. What is the Difference Between Dilation and Dilatation
      – Comparison of Key Differences

Key Terms: Autonomic Nervous System, Curettage, Dilatation, Dilation, Pupillary Dilation, Smooth Muscles, Vasodilation

What is Dilation

Dilation refers to the act of becoming wider, larger, or more open. It is controlled by the autonomic nervous system. Therefore, dilation cannot be consciously controlled. The term, dilation is used to describe bodily natural processes. Hence, dilation is used to describe passive, enlarging processes in the body. Smooth muscles are the muscles involved in dilation. Smooth muscles are one of the three types of skeletal muscles in the body, which are found in blood vessels, muscle sphincters, internal organs such as bronchi, stomach, and bladder. The relaxation of smooth muscles leads to the dilation of different bodily structures. Dilation regulates the passage of fluids, materials as well as solids inside the body. The opposite action of dilation is constriction. Dilated and constricted blood vessels are shown in figure 1.

Main Difference - Dilation vs Dilatation

Figure 1: Vasodilation and Vasoconstriction

Pupillary dilation, vasodilation, coronary dilation, and dilation of the cervix are the examples of dilation. Pupillary dilation is a physiological response of the pupil of the eye. It changes the size of the pupil in response to the amount of light coming to the eye. Vasodilation is the enlargement of the blood vessels. Coronary dilation is the enlargement of the coronary arteries in response to chemical or neurological stimulations. Dilation of the cervix can occur during the childbirth.

What is Dilatation

Dilatation refers to the action of being dilated. The term, dilatation is used describe more pathological, enlargement processes, which are governed by external sources rather than bodily natural physiological processes. Therefore, dilatation is considered as an active process. During dilatation, the anatomical structures of the body are typically more dilated beyond the normal conditions. Dilatation can occur either due to pathological conditions inside the body or surgical procedures. Dilatation and curettage are shown in figure 2.

Difference Between Dilation and Dilatation

Figure 2: Dilatation and Curettage

The enlargement of the ureter due to calculus is an example of dilatation. The enlargement of the obstructed vessel with a balloon catheter is another example of dilatation. The dilatation of the cervix occurs during curettage in which the contents of the uterus are removed surgically. During this process, a surgical curette is passed into the uterus to remove the endometrium. The curettage in the uterus is mostly used to correct dysfunctional uterine bleeding.

Similarities Between Dilation and Dilatation

Both dilation and dilatation are two terms used to describe enlargements of the bodily structures.
Definitions of both dilation and dilatation are used interchangeably.

Definition

Dilation: Dilation refers to the act of becoming wider, larger, or more open.

Dilatation: Dilatation refers to the action of being dilated beyond normal dimensions.

Significance

Dilation: Dilation is the act of dilating.

Dilatation: Dilatation is the noun that describes the verb dilate.

Active/Passive Process

Dilation: Dilation is a passive process.

Dilatation: Dilatation is an active process.

Cause

Dilation: Dilation is regulated by the autonomic nervous system.

Dilatation: Dilatation occurs by external, clinical or surgical influences.

Physiological/Pathological

Dilation: Dilation is physiological.

Dilatation: Dilatation is pathological.

Extent of the Enlargement

Dilation: Anatomical structures enlarge within their normal dimensions during the dilation.

Dilatation: During dilatation, anatomical structures enlarge beyond their normal dimensions.

Examples

Dilation: Vasodilation, pupillary dilation, coronary dilation, and dilation of the cervix are examples of dilation.

Dilatation: The enlargement of the obstructed vessel with a balloon catheter, esophageal dilation, and dilatation and curettage of the cervix are the example of dilatation.

Conclusion

Dilation and dilatation are two terms used interchangeably to describe different enlargements in the anatomical structures of the body. Dilation is the enlargement of the anatomical structures within their normal dimensions under the influence of autonomic nervous system. However, dilatation is the enlargement of anatomical structures beyond their normal dimensions under the influence of pathological or surgical factors. Therefore, the main difference between dilation and dilatation is the features of both types of enlargements.

Reference:

1. “What is Dilation? – Definition & Meaning.” Study.com, Available here.
2. “Dilatation pathologic.” Biology-Online Dictionary, Available here.
3. “Dilatation and curettage.” Biology-Online Dictionary, Available here.

Image Courtesy:

1. “Vasoconstriction and Vasodilation” By Elizabeth2424 – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “Dilation and curettage” By Fred the Oyster – Own work (CC BY-SA 3.0) via Commons Wikimedia