Peristalsis

Peristalsis Movement

Peristalsis is a series of wave-like contractions of the muscles that are involved in the food movement and in the movement of other liquid particles in the digestive tract to various processing organs that are located in the digestive system.

The process of peristalsis is initiated from the esophagus when food that is completely chewed is swallowed which includes the reflexive action of the longitudinal and circular muscles greatly in the digestive sites and some other times in hollow tubes that are present in progressive wave-like contractions. It occurs in the esophagus, intestines, and stomach and the waves could be long, short, continuous or continual that transit within the complete length of the organs, basis their location.

Importance Of Peristalsis

Peristalsis is a wave-like motion which brings about the movement of food and liquid through muscle contractions. It is an involuntary action of the muscles and hence cannot be under one’s conscious to control. But, the muscles that are involved in peristalsis, the smooth muscles, function when they are triggered to do so.

 

Esophageal Peristalsis

The Esophagus
Peristaltic waves in esophagus start from the upper position of the tube and pass into the complete length and impel the food into the stomach. This could be termed as Esophageal Peristalsis. The food particles left behind the esophagus begins with the secondary peristaltic waves that eliminate leftover particles. A single wave moves along the complete length of the tube. In cud-chewing animals like cattle, sheep, giraffes, and camels the reverse peristalsis happens such that the food is brought again to the mouth for chewing.

The peristaltic waves get disappeared after the stomach gets filled. The excess fats present in the food particles stop these movements until it gets diluted with gastric juices. These waves help in mixing the stomach content and drive the food into the small intestine. Normally, two to three waves exist at once in separate areas of the stomach.

Intestinal Peristalsis

Intestinal Peristalsis

The stimulation of smooth muscle tissues for the existence of food particles in the small intestine is responsible for contractions that travel from the restorative point in both directions is termed as Intestinal Peristalsis.

Usually, they are found in the small intestine and move in varying distances. These expose food to the intestinal wall for immersion and keep moving forward.

Peristalsis In The Urinary Tract

Peristalsis not only helps in the movement along the esophageal, digestive tract and the intestines but it also brings about movement of urine. Peristalsis is observed in two of the urinary tract tubes to bring about the motion of liquids right from the kidneys up to the bladder. The liquid, due to the peristaltic movement, eliminates from the body through structures called the urethra in the form of urine.

Gastric Juices

The stomach releases gastric juices as soon as we ingest food into the mouth. These gastric juices bring about the action of dissolving food upon arriving at the stomach which initiates the digestion process.

The food that is chewed and swallowed is referred to as bolus. It blends with the gastric juices that are secreted by the specialized glands that are situated in the stomach lining which include the cardiac glands which are present at the upper part of the stomach, the oxyntic glands situated in the main body of the stomach and the pyloric gland situated in the lowest part of the stomach.
Every gland contains specialized cells that produce particular components which are collectively called as the gastric juices. The neck cells produce mucus and bicarbonate, hydrochloric acid is produced by parietal cells, pepsinogen is secreted by chief cells, several hormones are responsible to secrete enteroendocrine cells.
Gastric juices are composed of the following constituents – electrolytes, water, hydrochloric acid, mucus, enzymes, and intrinsic factor.

Reverse Peristalsis

It is a wave of intestinal contraction in a direction that is reversed to the normal, following which the contents present in the tube are forced in a backward direction, known as antiperistalsis.  It is the converse of the contractions of the involuntary smooth muscles and occurs as a precursor to the action of vomiting. Irritation of the stomach, in particular, food poisoning, triggers the emetic center of the brain which in response flags an immediate vomiting reflex.

 

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Further Reading:

Biology

Digestive System In Humans – Process Of Digestion

Micturition – The Process Of Urination


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