What Are The Functions Of Digestive System – The job of the digestive system is to break down the food you eat, release nutrients, and absorb those nutrients into the body. Although the small intestine is the workhorse of the system, where most of the digestion takes place, and where most nutrients are absorbed into the blood or lymph, each member of the digestive system plays an important role in this process (Fig. 1). .
Figure 1. Components of the digestive system. All digestive organs play an important role in the continuous digestion of life.
What Are The Functions Of Digestive System
Like all body systems, the digestive system does not work in isolation; It works in conjunction with other body systems. Consider, for example, the relationship between the digestive and cardiovascular systems. Arteries deliver oxygen and processed nutrients to the digestive organs and veins drain the digestive tract. This intestinal vein, which forms the portal system of the liver, is unique; They do not return blood directly to the heart. Instead, this blood is sent to the liver where its nutrients are released for processing before the blood completes its return to the heart. At the same time, the digestive system provides nutrients to the heart muscle and nerve tissue to support its function. The relationship between the digestive and endocrine systems is also important. Hormones secreted by several endocrine glands, as well as endocrine cells of the pancreas, stomach, and small intestine, help control digestion and nutrient metabolism. Instead, the digestive system provides nutrients to stimulate endocrine function. Table 1 provides a quick overview of how these other systems contribute to the functioning of the digestive system.
Definition Of Small Intestine
Lymphoid tissue associated with the mucosa and other lymphatic tissues protects against the entry of pathogens; Lactose absorbs lipids; And lymphatic vessels transport lipids into the bloodstream
The easiest way to understand the digestive system is to divide its organs into two main parts. The first group is the organs that make up the digestive tract. The accessible digestive organs comprise the second group and are important for breaking down food and regulating the absorption of nutrients into the body. Manual digestive organs, despite their name, are essential to the functioning of the digestive system.
Also called the gastrointestinal (GI) tract or intestine, the alimentary canal (aliment- = “nutrition”) is a one-way tube that is approximately 7.62 meters (25 ft) long in life and approximately 10.67 meters (35 ft) long. . When measured after death, when the smooth muscle tone is lost. The main function of the digestive organs is to nourish the body. This tube starts from the mouth and ends in the anus. Between these two points, channels such as the pharynx, esophagus, stomach, and small and large intestines are modified to meet the functional needs of the body. Both the mouth and the anus are open to the external environment; Therefore, food and waste in the alimentary canal are technically considered outside the body. Only through the process of absorption of nutrients in food can they enter and nourish the “internal space” of the body.
Each digestive organ helps break down food (Figure 2). In the mouth, the teeth and tongue initiate mechanical digestion, while the salivary glands initiate chemical digestion. When a food product enters the small intestine, the gallbladder, liver, and pancreas release enzymes—such as bile and enzymes—important to continue digestion. Together, these are called accessory organs because they arise from the cells of the developing intestinal lining (mucosa) and add to their function; In fact, you cannot live without their essential help, and many major diseases are the result of their damage. Even after development is complete, they maintain a connection with the intestine through the duct.
Chapter 14 The Digestive System
Along its length, the digestive tract consists of four identical tissue layers; The details of their structure vary according to their specific functions. Starting from the lumen and moving outward, these layers are the mucosa, submucosa, muscularis, and serosa, which is continuous with the mesentery (see Figure 2).
Figure 2. Layers of alimentary canal. The wall of the digestive tract consists of four basic tissue layers: mucosa, submucosa, muscularis, and serosa.
The mucosa is called the mucous membrane, because mucus production is a characteristic of the intestinal epithelium. The membrane consists of the epithelium, which is in direct contact with the ingested food, and the lamina propria, a layer of connective tissue similar to the dermis. Additionally, the mucosa contains a thin layer of smooth muscle, called the muscularis mucosa (not to be confused with the muscular layer, described below).
– In the mouth, pharynx, esophagus, and rectal canal, the epithelium is primarily a nonkeratinized, stratified squamous epithelium. In the stomach and intestines, it is a simple columnar epithelium. Note that the epithelium is in direct contact with the lumen, the space inside the digestive tract. Among the epithelial cells are goblet cells, which secrete mucus and fluid into the lumen, and enteroendocrine cells, which secrete hormones into the interstitial space between the cells. Epithelial cells have a very short lifespan, averaging only a few days (in the mouth) to a week (in the gut). This rapid renewal process helps maintain the health of the alimentary canal despite wear and tear due to constant contact with food.
Bioelectric Neuromodulation For Gastrointestinal Disorders: Effectiveness And Mechanisms
– In addition to loose connective tissue, the lamina propria contains numerous blood and lymphatic vessels that transport nutrients absorbed through the digestive tract to other parts of the body. The lamina propria also exerts an immune function by hosting clusters of lymphocytes, forming the mucosa-associated lymphoid tissue (MALT). These clusters of lymphocytes are particularly large in the distal ileum where they are known as Peyer’s patches. When you consider that the digestive tract is exposed to food-borne bacteria and other foreign substances, it is not difficult to understand why the immune system is found within the body to defend itself against pathogens. developed as a way.
– This thin layer of smooth muscle is constantly under tension, pulling the mucosa of the stomach and small intestine into unstable folds. These coatings dramatically increase the surface area for digestion and absorption.
As the name suggests, the submucosa is located just below the mucosa. A dense layer of connective tissue, it connects the mucosa above it to the muscles below. These include blood and lymphatic vessels (which transport absorbed nutrients), and the proliferation of submucosal glands that release digestive secretions. In addition, it serves as a conduit for a dense network of nerve branches, the submucosal plexus, which is described below.
The third layer of the digestive tract is the muscularis (also called muscularis externa). The muscles in the small intestine consist of two layers of smooth muscle: an inner circular layer and an outer longitudinal layer. The contraction of this layer promotes mechanical digestion, delivers more food to the digestive chemicals, and moves the food along the passageway. In the proximal and distal regions of the digestive tract, including the mouth, pharynx, anterior part of the esophagus, and the external rectal sphincter, the muscles are made up of skeletal muscles, which help you swallow and defecate. Gives voluntary control. The basic two-layered structure found in the small intestine is modified in adjacent and distant organs. The stomach is equipped for its turning function by adding a third layer, the oblique muscles. Although the colon has two layers like the small intestine, its longitudinal layer is divided into three narrow parallel bands, the tenia coli, that make it look more like a series of pouches than a simple tube.
Human Digestive System
The serosa is the part of the digestive tract that is superficial to the muscles. Located just inside the abdominal cavity in the area of the digestive tract, it consists of a layer of visceral peritoneum that covers a layer of soft connective tissue. Instead of serosa, the mouth, nerves, and esophagus have a dense covering of collagen fibers called the adventitia. These tissues hold the digestive tract close to the ventral surface of the vertebral column.
Once food enters the mouth, it is detected by receptors that send impulses along the sensory neurons of the cranial nerves. Without these nerves, not only would your food taste good, but you wouldn’t be able to feel the food or the texture of your mouth, and you wouldn’t be able to stop yourself from chewing while chewing, a motor act. Cranial nerve division
The inner nervous system of most parts of the digestive system is provided by the enteric nervous system, which runs from the esophagus to the anus, and contains approximately 100 million motor, sensory, and interneurons (unique to all other parts of this system. nervous system). These interneurons are grouped into two plexuses. Myenteric plexus (Plexus of Auerbach) is located in the muscular layer of the digestive tract and is responsible for movement, especially the rhythm and force of muscle contraction. The submucosal plexus (Meissner’s plexus) is located in the submucosa layer and is responsible
