Major Organs Of The Digestive System And Their Functions – Click Prefixes, Combined Forms, and Suffixes to reveal a list of word parts to remember for digestion.

The digestive system works constantly, yet people rarely appreciate the complex functions it performs in a choreographed biological symphony. Think about what happens if you eat an apple. Sure, you taste the apple when you bite into it, but for hours afterward, you don’t notice that your digestive system is working until something goes wrong and you have a stomach ache. You may be walking or studying or sleeping, forgetting all about the apple, but your stomach and intestines are busy digesting it and absorbing its vitamins and other nutrients. By the time any waste material is expelled, the body has used up everything from the apple. In short, whether you notice it or not, the organs of the digestive system perform their specific functions, allowing the food you eat to be used to keep you going.

Major Organs Of The Digestive System And Their Functions

This chapter examines the structure and functions of these organs and explores the mechanics and chemistry of the digestive process. The function of the digestive system is to break down the food you eat, release its nutrients, and absorb those nutrients into the body. Although the small intestine is the functional area of ​​the system, where most digestion takes place and where most released nutrients are absorbed into the blood or lymph, each organ of the digestive system contributes significantly to this process (see Figure 12.1. ).

Anatomy Final Review

Figure 12.1 Components of the digestive system. All digestive organs play an integral role in the life-sustaining process of digestion. Medical Gallery of Blossen Medical 2014. ISSN 2002-4436., CC BY 3.0, via Wikimedia Commons.

Now that you’ve memorized the word part, see if you can break down and define the following digestive terms.

You can eat upside down. Food does not need gravity to reach your stomach. Peristalsis, a wave-like muscle movement, pushes food along.

Also called oral cavity (or buccal cavity). The structure of the mouth is illustrated in Figure 12.2.

Facts About The Digestive System

The oral vestibule is a pocket-like area formed by the gums and teeth on the inside of the mouth and the cheeks and lips on the outside. The main open area of ​​the mouth, or oral cavity proper, runs from the gums and teeth to the gums.

When you are chewing, you don’t have trouble breathing at the same time. The next time you have food in your mouth, notice that the arched shape of the roof of your mouth allows you to handle both digestion and breathing at the same time. This arch is called the palate. The anterior part of the palate acts as a wall (or septum) between the oral and nasal cavities as well as a rigid shelf against which the tongue can push food. It is formed by the maxillary and palatine bones of the skull and, given its bony structure, is known as the hard palate. If you run your tongue across the roof of your mouth, you will notice that the hard palate ends in the oral cavity and the tissue becomes more fleshy. This part of the scalp, known as the soft palate, is made up mostly of skeletal muscle. So you can subconsciously manipulate the soft palate—for example, yawn, swallow, or sing (see Figure 12.2).

Figure 12.2 3D medical animation mouth. Includes the uvula, teeth, tongue, soft palate, and palatoglossal arch. https://www.scientificanimations.com, CC BY 4.0. via Wikimedia Commons

A fleshy bead called the uvula descends in the center of the posterior edge of the soft palate. Although some have suggested that the ovary is a vestigial organ, it serves an important purpose. When you swallow, the soft palate and ovaries move upward, helping to prevent food and liquids from entering the nasal cavity. Unfortunately, it can also contribute to the noise produced by snoring. Two muscular folds extend from the soft palate downwards, on either side of the ovary. These two folds contain the palatine tonsils, clusters of lymphoid tissue that protect the pharynx. Lingual tonsils are located at the base of the tongue.

Definition Of Digestive System

You may have heard that the tongue is the strongest muscle in the body. Those who make this claim cite its strength in proportion to its size. Although it is difficult to measure the relative strength of different muscles, it is undeniable that the tongue is a workhorse, facilitating ingestion, mechanical digestion, chemical digestion (lingual lipase), sensation (taste, texture and temperature of food), swallowing. , and singing.

Figure 12.3 Tongue. This view of the tongue shows the location and type of papillae. OpenStax, CC BY 4.0, via Wikimedia Commons.

The mucous membranes of the mouth and tongue contain many small salivary glands. These minor exocrine glands continuously secrete saliva, either directly into the oral cavity or indirectly through ducts, even while you sleep. In fact, an average of 1 to 1.5 liters of saliva is produced per day. There is usually enough saliva to moisten the mouth and teeth. Secretion increases when you eat, because saliva is needed to moisten food and start the chemical breakdown of carbohydrates. A small amount of saliva is also secreted by the labial glands in the lips. In addition, buccal glands in the cheeks, palatal glands in the palate, and lingual glands in the tongue help ensure an adequate supply of saliva to all parts of the mouth.

The pharynx (pharynx) is involved in both digestion and respiration. It takes in food and air through the mouth and air through the nasal cavity. When food enters the pharynx, involuntary muscle contractions close the airways. A short tube of skeletal muscle with a mucous membrane, the pharynx leads from the oral and nasal cavities to the opening of the esophagus and larynx. It has three subdivisions. The superior one, the nasopharynx, is involved only in breathing and speech. The other two subdivisions, oropharynx and laryngopharynx, are used for both breathing and digestion. The oropharynx begins inferior to the nasopharynx and is continuous below the larynx. The inferior border of the larynx connects to the esophagus, while the anterior border connects to the larynx, allowing air to flow into the bronchial tree.

Parts Of The Digestive System

The esophagus is a muscular tube that connects the pharynx to the stomach. It is approximately 25.4 cm (10 in) in length, lies posterior to the trachea, and remains collapsed when not involved in swallowing. As you can see in Figure 12.4, the esophagus passes through the mediastinum of the thorax in a mostly straight path. To enter the abdomen, the esophagus enters a diaphragm called the esophageal hiatus.

Figure 12.4 Esophagus. The upper esophageal sphincter controls the movement of food from the pharynx to the esophagus. The lower esophageal sphincter (LES) controls the movement of food from the esophagus to the stomach. From Betts, et al., 2021. Licensed under CC BY 4.0.

The upper esophageal sphincter controls the movement of food from the pharynx into the esophagus. The upper two-thirds of the esophagus consists of smooth and skeletal muscle fibers. A series of contractions called peristalsis pushes it through the esophagus and into the stomach. Before the opening of the stomach is an important ring-shaped muscle called the lower esophageal sphincter (LES). Sphincters are muscles that close the tube when the sphincter contracts and opens when it relaxes. This sphincter opens to allow food to enter the stomach and closes to keep it there.

The stomach has four main parts: cardia, fundus, body, and pylorus (see Figure 12.5). The cardia (or heart region) is the point where the esophagus joins the stomach and through which food passes into the stomach. Above and to the left of the cardia, located below the diaphragm, is the dome-shaped fundus. Below the fundus is the body, the main part of the stomach. The funnel-shaped pylorus connects the stomach to the duodenum.

What Is Stomach Cancer?

Figure 12.5 Abdominal region. The stomach consists of four major regions: cardia, fundus, body, and pylorus. Farlex, from 2021.

Chyme from the stomach enters the small intestine, the primary digestive organ in the body. Not only is this where most digestion takes place, practically all absorption also takes place. The longest part of the alimentary canal, the small intestine is about 3.05 m (10 ft) long in the living (but twice as long in the cadaver due to loss of muscle tone). Since it is five times longer than the large intestine, you may wonder why it is called “small”. In fact, its name comes from its relatively small diameter of only 2.54 cm (1 inch) compared to 7.62 cm (3 inches) for the large intestine. As we shall soon see, in addition to its length, the folds and projections of the lining of the small intestine serve to give it an enormous surface area,

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