Food is one of the most essential basic needs. It is made up of nutrients, micronutrients, such as vitamins and minerals, and macronutrients, such as carbohydrates, proteins and fats. A balanced diet, consisting of a variety of these nutrients is the foundation of good health. While consuming the necessary daily intake of carbohydrates, high-quality proteins, heart-healthy fats, vitamins, minerals and water is essential towards maintaining the body’s overall well-being and function, staying healthy and productive could not be achieved without one important structure: the digestive system.
What is the digestive system?
The digestive system is a collective group of organs which function together to convert food into energy and provide basic, fundamental nutrients in order to nourish the entire body. Food is delivered through a long tube inside the body known as the alimentary canal, best referred to as the gastrointestinal tract, or the GI tract. The gastrointestinal tract consists of the oral cavity, or mouth, pharynx, esophagus, stomach, small intestines, and large intestines. Along with the gastrointestinal tract, there are various important accessory organs which additionally help the human body to digest foods, however, these do not have food pass through them. Accessory organs of the digestive system include the teeth, the tongue, salivary glands, liver, gallbladder, and the pancreas.
Digestive System Anatomy
Food begins its course through the digestive system at the mouth, also known as the oral cavity. As a matter of fact, digestion is considered to begin here as soon as you take the first bite of a meal. Within the mouth are numerous accessory organs which aid in the digestion of food: the teeth, the tongue, and the salivary glands. Teeth chop food into smaller pieces, to allow for an easier digestion, which are then moistened by saliva to begin the process of breaking the food down, before the tongue and other muscles of the mouth push the food into the pharynx.
- Teeth. The teeth are 32 small, hard organs located along the anterior and lateral edges of the mouth. Each tooth is created from a bone-like material called dentin and coated in a layer of enamel, the hardest substance in the human body. Teeth are living organs that also contain blood vessels and nerves under the dentin in a soft region, best referred to as the pulp. The structure of the teeth is made for cutting and grinding food into smaller pieces.
- Tongue. The tongue is located on the inferior section of the mouth only posterior and medial to teeth. It’s a small organ composed of several pairs of muscles coated in a thin but strong, bumpy, skin-like layer. The outside of the tongue contains many papillae designed for grasping food as it’s moved by the tongue’s muscles. The taste buds on the surface of the tongue distinguish flavor molecules in food and link to nerves in the tongue to deliver taste information to the brain. The tongue can also help push food toward the posterior area of the mouth for swallowing.
- Salivary Glands. Surrounding the mouth are three varieties of salivary glands. The salivary glands are sets of accessory organs that produce a watery secretion known as saliva. Saliva helps to moisten food and starts the digestion of food. The body also uses saliva to continue lubricating food as it moves through the mouth, pharynx, and esophagus.
The pharynx, or throat, is a funnel-shaped tube connected to the back end of their mouth. The pharynx is responsible for the delivery of a mass of chewed food from the mouth to the esophagus. The pharynx also has a significant role in the respiratory system, as air from the nasal cavity passes through the pharynx on its way to the larynx and finally the lungs. Since the pharynx serves two different functions, it includes a flap of tissue called the epiglottis which behaves as a switch to effectively route food into the esophagus and air into the larynx.
The esophagus is a muscular tube which connects the pharynx to the stomach, that is part of the upper gastrointestinal tract, or upper GI tract. By means of a series of contractions, referred to as peristalsis, it transports the eaten masses of chewed food along its span. At the inferior end of the esophagus is a muscular ring known as the lower esophageal sphincter or cardiac sphincter. The role of the sphincter is to shut off the end of the esophagus and keep food from passing backwards into the esophagus, and instead maintain it in the stomach.
The stomach is a muscular sac that’s located on the left side of the abdominal cavity, just inferior to the diaphragm. In an average individual, the stomach is about the size of their two fists placed alongside each other. This major organ plays the role of serving as a sort of storage tank for foods so the body has enough time to digest large meals properly. The stomach also contains hydrochloric acid and digestive enzymes which continue the digestion of food that began from the mouth. When it leaves the stomach, food is the consistency of a liquid or paste.
Made up of three segments, the duodenum, the jejunum and the ileum, the small intestine is a long, thin tube about 1 inch in diameter and approximately 10 feet long which is part of the lower gastrointestinal tract, or lower GI tract. It is located only inferior to the stomach and takes up nearly all the space in the abdominal cavity. The entire small intestine is coiled like a hose and the interior surface is filled with lots of ridges and folds. These folds are utilized to make the most of the digestion of food and absorption of nutrients. The small intestine continues the process of breaking down food with the help of accessory organs. Contractions known as peristalsis are also at work within this organ. By the time food leaves the small intestine, approximately 90 percent of nutrients are extracted from the food which entered it.
Liver and Gallblader
The liver is a roughly triangular accessory organ of the digestive system found to the right of the stomach, just inferior to the diaphragm and superior to the small intestine. The liver weighs about 3 pounds and is the second largest organ in the human body. The liver has many different functions, but its primary purpose is the production of bile and its secretion into the small intestine for digestion. Another of its important functions include the cleansing and purification of the blood flowing from the small intestine, which contains the absorbed nutrients. The gallblader is a small, pear-shaped organ found just posterior to the liver. The gallbladder is used to store and recycle surplus bile from the small intestine, through a channel known as the cystic duct, so that it might be re-utilized for the digestion of subsequent meals.
The pancreas is a large gland situated just inferior and posterior to the stomach. It is approximately 6 inches long and shaped like short, lumpy snake with its “head” attached into the duodenum and its “tail” pointing towards the left wall of the abdominal cavity. The pancreas secretes digestive enzymes into the small intestine to complete the digestion of foods. These enzymes break down carbohydrates, proteins and fats from the food we eat.
The large intestine, best referred to as the colon, is a long, thick tube about 2.5 inches in diameter and approximately 5 feet long. It is made up of the cecum, the ascending colon, the transverse colon, the descending colon, and the sigmoid colon, which connects to the rectum. It is located only inferior to the stomach and wraps across the lateral and superior border of the small intestine. The large intestine absorbs water and also contains many symbiotic bacteria which aid in the breaking down of wastes to extract small quantities of nutrients. Stool, or waste left over from the digestive process, is passed through the colon by means of peristalsis, or contractions, first in a liquid state and ultimately in solid form as the water is removed from the stool. Stool, or feces, in the large intestine exits the body through the anal canal, to begin the process of elimination.
In conclusion, the digestive system is ultimately essential to effectively break down the food we consume to provide our body with energy and basic nutrients. Unfortunately, however, as with other systems of the body, gastrointestinal diseases can alter the healthy function of the digestive system. The gastrointestinal tract may appear normal but may not be working properly. Symptoms can vary widely on the individual depending on the problem. We will discuss the common issues affecting the gastrointestinal tract, or GI tract, including the colon as well as rectum and anal problems, in the following series of articles. The scope of our information is limited to chiropractic and spinal injuries and conditions. To discuss the subject matter, please feel free to ask Dr. Jimenez or contact us at 915-850-0900 .
By Dr. Alex Jimenez
Additional Topics: Wellness
Overall health and wellness are essential towards maintaining the proper mental and physical balance in the body. From eating a balanced nutrition as well as exercising and participating in physical activities, to sleeping a healthy amount of time on a regular basis, following the best health and wellness tips can ultimately help maintain overall well-being. Eating plenty of fruits and vegetables can go a long way towards helping people become healthy.