Introduction to Digestive System:
Chemical digestion also occurs in the mouth with chemicals called enzymes that chemically break down the food. The pancreas is also the main source of enzymes for the digestion of fats and proteins. Tenesmus of GI origin usually is associated with inflammatory disease of the rectum and anus. Lipase is further produced in the pancreas where it is released to continue this digestion of fats. It starts at the duodenal bulb and ends at the suspensory muscle of duodenum. The epiglottis is a flap of elastic cartilage attached to the entrance of the larynx.
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The digestive tract begins this involuntary process once food is consumed. Saliva begins the breakdown of food, and other enzymes in the digestive tract extend this process. As digestion continues, the food is propelled from organ to organ through muscular contractions called peristalsis. The connection between all of these organs and their fluids requires a delicate balance that can easily be disrupted by numerous factors, including diet, stress, disease, and more.
Other problems are connected to serious conditions that affect portions of the digestive system, including:. Whiteheads, blackheads, pimples, and pustules are just a few of the many types of blemishes that can appear on the skin. Find out what causes…. Recent research shows that diet can play a role in acne development. These 7 foods can all cause acne. Your underarms should be a shade similar to the rest of your skin. If they're darker, it may be a sign of an underlying condition. Here's what to look….
If you're wondering how to get an even skin tone, there are plenty of remedies that can help. Sallow skin refers to skin that has lost its natural complexion. The highly modified parasitic genus Enderoxenos has no digestive tract at all, and simply absorbs the blood of its host through the body wall.
The buccal mass is the first part of the digestive system, and consists of the mouth and pharynx. The mouth includes a radula , and in most cases, also a pair of jaws. The pharynx can be very large, especially in carnivorous species. Many carnivorous species have developed a proboscis , containing the oral cavity, radula, and part of the oesophagus. At rest, the proboscis is enclosed within a sac-like sheath, with an opening at the front of the animal that resembles a true mouth.
When the animal feeds, it pumps blood into the proboscis, inflating it and pushing it out through the opening to grasp the gastropod's prey.
A set of retractor muscles help pull the proboscis back inside the sheath once feeding is completed. The radula is a chitinous ribbon used for scraping or cutting food.
Several herbivorous species, as well as carnivores that prey on sessile animals, have also developed simple jaws, which help to hold the food steady while the radula works on it. The jaw is opposite to the radula and reinforces part of the foregut.
The purely carnivorous the diet, the more the jaw is reduced. There are often pieces of food in the gut corresponding to the shape of the jaw. Drawing of the jaw of the Kerry Slug Geomalacus maculosus. Drawing of the jaw of Macrochlamys indica. Drawing of the jaw of Newcomb's snail. Salivary glands plays primary role in the anatomical and physiological adaptations of the digestive system of predatory gastropods.
The mouth of gastropods opens into an oesophagus , which connects to the stomach. Because of torsion, the oesophagus usually passes around the stomach, and opens into its posterior portion, furthest from the mouth. In species that have undergone de-torsion, however, the oesophagus may open into the anterior of the stomach, which is therefore reversed from the usual gastropod arrangement. In Tarebia granifera the brood pouch is above the oesophagus.
There is available an extensive rostrum on the anterior part of the oesophagus in all carnivorous gastropods. Some basal gastropod clades have oesophageal gland. In most species, the stomach itself is a relatively simple sac, and is the main site of digestion.
In many herbivores, however, the hind part of the oesophagus is enlarged to form a crop , which, in terrestrial pulmonates , may even replace the stomach entirely. In many aquatic herbivores, however, the stomach is adapted into a gizzard that helps to grind up the food. The gizzard may have a tough cuticle , or may be filled with abrasive sand grains.
In the most primitive gastropods, however, the stomach is a more complex structure. In these species, the hind part of the stomach, where the oesophagus enters, is chitinous , and includes a sorting region lined with cilia. In all gastropods, the portion of the stomach furthest from the oesophagus, called the "style sac", is lined with cilia.