The salivary glands, liver , gallbladder , and pancreas are major accessory organs that have a role in digestion. These organs secrete fluids into the digestive tract. Digestion and absorption occur in the digestive tract. After the nutrients are absorbed, they are available to all cells in the body and are utilized by the body cells in metabolism.
The digestive system prepares nutrients for utilization by body cells through six activities, or functions. The first activity of the digestive system is to take in food through the mouth.
Bile is stored in the gallbladder until it is needed. The pancreas makes enzymes that help digest proteins, fats, and carbs. It also makes a substance that neutralizes stomach acid. These enzymes and bile travel through special pathways called ducts into the small intestine, where they help to break down food.
The liver also helps process nutrients in the bloodstream. From the small intestine, undigested food and some water travels to the large intestine through a muscular ring or valve that prevents food from returning to the small intestine. By the time food reaches the large intestine, the work of absorbing nutrients is nearly finished. The large intestine's main job is to remove water from the undigested matter and form solid waste poop to be excreted. Reviewed by: Larissa Hirsch, MD. Larger text size Large text size Regular text size.
What Is the Digestive System? Almost all animals have a tube-type digestive system in which food: enters the mouth passes through a long tube exits the body as feces poop through the anus Along the way, food is broken down into tiny molecules so that the body can absorb nutrients it needs: Protein must be broken down into amino acids.
Starches break down into simple sugars. Birds do not have teeth in their oral cavity and do not carry out mastication of food. The beaks of the birds are adapted to grind the food and hence different species of birds have different shapes of beaks. The absorption of nutrients occurs in the small intestine and the waste is eliminated from the opening called the cloaca. Ruminants like sheep, bovine, goats, etc. This adaptation is to digest the cellulose , which is the major component of the plant-based ruminant diet.
The stomach is divided into four chambers:. The abomasum is considered to be equivalent to the mono-gastric stomach or true stomach due to the presence of gastric secretions. In the rumen and reticulum, the stomach is rich in microbial flora that aids in the breakdown of cellulose in the food.
In these chambers, fermentation of the ingested food also occurs, resulting in the generation of a high volume of gases. These gases are periodically expelled out by the animal. The ruminants regurgitate the food material or the cud from the reticulum chamber and chew it again and this cud is then transferred to the third chamber, the omasum. In omasum removal of water occurs.
From the omasum, the food material is then transferred to the abomasum for digestion by the enzymes and gastric secretions and is eventually transferred to the small intestine.
The absorption of nutrients occurs in the small intestine while the elimination of the waste occurs via the large intestine. In contrast to the ruminants, pseudo-ruminants like camel have a three-chamber stomach.
The rumen is absent in camels. Omasum, abomasum, and reticulum are the three compartments of the stomach of the camel. Interestingly, camels have an enlarged cecum. Cecum in camel is rich in microbial flora and is responsible for the digestion of the plant-based roughage, which forms the major part of the diet of camels.
The alimentary canal in insects like cockroaches starts at the mouth and ends at the anus and is subdivided into three parts-. Fishes do not possess a large intestine; however, they have a short rectum. The alimentary canal of fishes has an oral cavity to ingest food followed by an esophagus to transfer the food to the stomach for digestion. The nutrients are absorbed in the intestine and eliminate the waste from the vent equivalent to anus.
The intestine is classified as the proximal intestine and distal intestine in fishes. Try to answer the quiz below to check what you have learned so far about alimentary canal. The Alimentary Canal. Eds Academic Press, pp , doi. Alimentary Tract. In: Principles of Regenerative Medicine. Atala A. Eds Academic Press, , 3rd ed. Human digestion—a processing perspective. Journal of the science of food and agriculture, 96 7 , — Intraluminal pH of the human gastrointestinal tract. Danish medical bulletin, 46 3 , — Physiology, Gastrointestinal.
In: StatPearls [Internet]. Gastrointestinal Physiology and Function. Handbook of experimental pharmacology, , 1— Changes, functional disorders, and diseases in the gastrointestinal tract of elderly. Nutricion hospitalaria, 26 4 , — Structure, development and evolution of the digestive system.
Cell Tissue Res , — A typical eukaryotic cell is comprised of cytoplasm with different organelles, such as nucleus, endoplasmic reticulum, G.. This tutorial investigates perception as two people can interpret the same thing differently.
Know more about human perc.. This study guide tackles plant roots in greater detail. It delves into the development of plant roots, the root structur.. Different pregnancy and birth control and contraception strategies are described. Read this tutorial to learn each of th.. Molecules move within the cell or from one cell to another through different strategies. Transport may be in the form of.. Cell respiration is the process of creating ATP.
The stomach then further liquefies the food and adds digestive acids. From there the stomach contents are slowly released into the small intestine.
The small intestine is where most of the digestion and absorption of nutrients takes place. There are millions of tiny finger-like projections lining the small intestine called villi pronounced: "VILL-ee".
0コメント