Anus Definition, Parts and Function

Human Anus

The human anus is a part of the digestive system. It is present at the posterior most end of the alimentary canal. The primary job of anus is to regulate the discharge of waste and indigestible substances out of the body. It can hold excretory materials from going out of the body till the time an individual finds an appropriate place for defecation. Given below is the comprehensive and biological anus definiton:

Anus Definition - Anus Diagram

Anus Definition

According to a comprehensive anus definition, "playing an important role in the excretion of digestive wastes, the anal opening constitutes the posterior most part of the gastrointestinal system". Two round muscular structures line the anus. These muscular structures assist in the opening and closing of the anal aperture.

Anus Definition Biology:

The anal definition biology lets you know details about the structure and function of this organ of gastrointestinal system. The opening and closing of the hole is under the voluntary control of an individual. It is not completely functional in the human babies. However, as the child advances towards maturity, it comes under their deliberate command. On the attainment of puberty in an individual, pubis hair starts to grow around the anal opening.

Did you ever imagine, “How would your social life be if you were unable to hold and prolong feces before you reach toilet for defecation”? However, when you prolong defecation for an extended duration, the excretory matter goes backwards into colon. There is further absorption of fluids, salts and any other useful substances. You will learn about the details of the things related to anus definition in the succeeding parts of the article.

Anus Function

As the anus definition reveals, the major anus function is the accomplishment of excretory process. But it also has close association with sexuality. The knowledge of anal anatomy makes it easy for you to understand the anus function. The following information will be very useful.

Role in Excretion:

  • The internal and external sphincters play a key role in excretion. The internal involuntary sphincter operates under the command of autonomous nervous system. You can deliberately open or forcefully contract the external sphincter.
  • Holding feces back is a very important anus function. Otherwise, you won’t be able to hold the bowels for some time in order to reach the place of defecation.
  • The capacity of rectal storage and sensation of waste products arriving in the region inspire the need for their removal.

Anal Diagram and Steps for Excretion:

Looking at the anus diagram, you can easily understand different steps for excretion. Different nearby parts of anus experience physical changes as waste matter reaches there. Here is a brief discussion of the step by step procedure for excretion.

Anus Diagram
  • First Step: As the waste, semi-solid substances fill the rectum and anal canal, the surrounding walls stretch to accommodate it.
  • Second Step: The nerve endings present at the region deliver the stimulus to the brain. The brain processes this stimulus to generate an appropriate response.
  • Third Step: When the responding signal reaches the target place, it induces the desire for defecation in the individual. Afterwards, the individual takes appropriate action accordingly.

Role in Sex:

Role in sexuality is a secondary anus function. It happens so due to proximity of anus with the sensitive parts of male and female genitals. It is noteworthy that anal sex leads to intense sexual arousal.

Anus Anatomy:

Here is interesting information related to anus anatomy. Two layers of muscles surround this ring-shaped structure. They form the internal anal sphincter and external anal sphincter. However, both of these are not under your deliberate command. That is, the interior one is involuntary while the voluntary actions control the external sphincter.

They vary in their length while running along the anal canal. The internal muscle extends up to 4 centimeters and the external one reaches the maximum size of 10 centimeter or more. The outer muscular layer retracts during the process of defecation. Further, it is two strata, viz. deeper stratum and the superficial one (the main portion).

Anus Disease:

Anus DiseaseAn anal disease can seriously affect the regulation of the process of excretion. The researchers have discovered various conditions of anal aperture. They not only disturb the excretory function of your digestive system, but are also the cause of great embarrassment for the victim in social life.

Some of the disorders are infectious. The others may be viral or cancerous. Still there are some that arise due to mechanical reasons. Some of the most frequently occurring ailments of excretory orifice include anal abscesses, anal fistula, hemorrhoids, anal fissures, and so on.

Anal Itching:

The diagnostic symptoms of the acute and chronic conditions of anus may include pain, anal itching, intense sensation of burning, bleeding, cramps, inflammation, bowel obstruction, release of pus, chills, fever, and so on.

Finally, let’s talk about the treatment of anal disease. The suggestion and application of treatment strategy depends upon the type and severity of the condition and may involve medication, diet supplementation, or surgical removal of the infected part. However, if you take preventive measures in advance and, in case of attack of the disease, consult your health care provider immediately, you can save your life from all such hassles.

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