Your Digestive System

Structures and functions of the human digestive system

Human digestive system
The conjugation machinery of some bacteria and archaeal flagella is capable of transporting both DNA and proteins. In chemical digestion , enzymes break down food into the small molecules the body can use. My digestive problems are getting better. The gallbladder is a pear-shaped reservoir that sits just under the liver and stores bile. Harvard University Press, Cambridge, Mass. The liver has many functions, but two of its main functions within the digestive system are to make and secrete bile, and to cleanse and purify the blood coming from the small intestine containing the nutrients just absorbed.

Learn More

How does the Respiratory System Work?

Swallowing triggers its closing over the trachea to prevent food and fluids from draining into our lungs. Concentrated bile is released into the duodenum as needed to break down fats into an absorbable form. This duct collects donations from the liver and the gall bladder bile as it passes along to the duodenum of the small bowel. There are many sections to the large bowel — the appendix, caecum, ascending rising colon, transverse across colon, descending going down colon, sigmoid colon, the rectum and the anus.

The main purposes of the large intestine is to pass remaining essential nutrients into the bloodstream and the storage and elimination of waste left-overs. As the nutritional fluids are absorbed and transfered out to the bloodstream, the contents get more solid and compact. Sometimes a piece of food gets stuck in here like bubblegum causing an infection. This fluid enzyme helps to soften up the food, the first chemical action along the digestive trail.

It starts at the pyloric sphincter of the stomach and runs about 10 inches. The duodenum is largely responsible for the continuing food breaking-down process fats are bombarded with bile , with the jejunum and ileum mainly responsible for the transfer of nutrients into the bloodstream.

Both insulin and glucagon are produced by the pancreas. The duodenum is responsible for continuing to break down of food into liquid form and the jejunum and ileum mainly responsible for absorption of nutrients into the bloodstream. When the rectum becomes full, it triggers nerves that carry that message to the brain.

Make a Purse-string Sphincter or Valve In the digestive system, there are a number of places along the way that are designed to help regulate when, what direction, and how fast, food travels. Discussion Questions If a sphincter or valve did not close completely, what would you expect the contents to do?

The strongest stuff in the body! Is it poop yet? A muscular canal running from the pharynx to the stomach. The roof of the mouth is concave and is formed by the hard and soft palate. The hard palate is formed by the horizontal portions of the two palatine bones and the palatine portions of the maxillae, or upper jaws.

The hard palate is covered by a thick, somewhat pale mucous membrane that is continuous with that of the gums and is bound to the upper jaw and palate bones by firm fibrous tissue.

The soft palate is continuous with the hard palate in front. Posteriorly it is continuous with the mucous membrane covering the floor of the nasal cavity.

The soft palate is composed of a strong, thin, fibrous sheet, the palatine aponeurosis, and the glossopalatine and pharyngopalatine muscles. A small projection called the uvula hangs free from the posterior of the soft palate.

The floor of the mouth can be seen only when the tongue is raised. In the midline is a prominent, elevated fold of mucous membrane frenulum linguae that binds each lip to the gums, and on each side of this is a slight fold called a sublingual papilla , from which the ducts of the submandibular salivary glands open. Running outward and backward from each sublingual papilla is a ridge the plica sublingualis that marks the upper edge of the sublingual under the tongue salivary gland and onto which most of the ducts of that gland open.

The gums consist of mucous membranes connected by thick fibrous tissue to the membrane surrounding the bones of the jaw. The gum membrane rises to form a collar around the base of the crown exposed portion of each tooth. Rich in blood vessels, the gum tissues receive branches from the alveolar arteries; these vessels, called alveolar because of their relationship to the alveoli dentales, or tooth sockets, also supply the teeth and the spongy bone of the upper and lower jaws, in which the teeth are lodged.

We welcome suggested improvements to any of our articles. You can make it easier for us to review and, hopefully, publish your contribution by keeping a few points in mind.

Your contribution may be further edited by our staff, and its publication is subject to our final approval. Unfortunately, our editorial approach may not be able to accommodate all contributions. Our editors will review what you've submitted, and if it meets our criteria, we'll add it to the article.

Please note that our editors may make some formatting changes or correct spelling or grammatical errors, and may also contact you if any clarifications are needed. Read More on This Topic. Page 1 of Next page The teeth. Learn More in these related Britannica articles: As the embryo folds off, the endoderm is rolled in as the foregut and hindgut. Continued growth progressively closes both the midbody and the midgut.

The esophagus remains as a simple, straight tube. The stomach grows faster on its dorsal side, thereby forming…. Loss of teeth, which is often seen in elderly people, is more apt to be the result of long-term neglect than a result of aging itself.

The loss of teeth and incidence of oral disease increase with age, but, as programs of water…. In either event, pregnancy complicates their problems because the gastrointestinal disturbances that often…. Some brain cells may also participate as hunger receptors. This is especially true of cells in the lower parts of the brain such as the hypothalamus where some cells have been found to…. More About Human digestive system 5 references found in Britannica articles Assorted References embryological development In prenatal development: Digestive tube sensory reception In human sensory reception effects of aging In human aging: Digestive system pregnancy In pregnancy: Gastrointestinal tract In pregnancy: Articles from Britannica Encyclopedias for elementary and high school students.

Help us improve this article!

Free E-newsletter