Over view of the digestive system
Two groups of organs compose the digestive system:
-The gastrointestinal tract and the acessory igestive organbs
the gi tract is a continous tube that extends form the mouth to the anus,
the gi tract contains food from the mouth to the anus
the gi tract contains food from the time it is eaten until it is digested and abosrbed or eliminated from the body
orangs in this tract: mouth pharynx asophogus stomach small intestine and large intestine.
Acessory digestive system: the teeth tongue, salivary glands, liver, gallbladder and pancreas
teeth: brerak down food
tongue: chewing and swallowing
6 basic processes of the digestive systemL
THE LAYERS OF THE GI TRACT AND THE OMENTUM.
layers from inside out: mucos, submucose muscularis and serosa
mucosa-inner lining, mucous membrane.
It is composed of a layer of areolar ct called the lamina propria and a thin layer of smooth muscle called the muscularis mucosae. The muscularis mucose create folds in the mucosaa that increase the surface area for digestion and absorbtion.
Submucosa- the submucosa consisits of areolar t that binds the mucosa to the muscularis. It contains many blood and lymphatic vessels that receive absorbed food molecules. Also located in the submucoses are networks of neurons that are part of the enteric nervous system. They control the the secretions of the organs in the gi tract.
Muscularis: as its name implies the muscularis of the gi tract is a thick layer of muscle. In the mouth the pharyn and upper esophogus it consists of muscle. In the mouth pharyn and upper esophogus it consits in part of the skeletal muscle that produces voluntary swallowing. Skeletal muscle also forms the external anal sphincter, which permits voluntary control of defecation. Ens neurons in the muscularis control the frequ4ency of the contraction
serosa: the outermost layer around the organs of the gi tract below the diaprhram is a membrane composed of simple squamos epithelium and areolar ct the serosa secreted a slippery watery fluid that allows the tract to glide easily againt other organs. The serosa is also called the visceral pwritoneum. The greater omentum drapes over ther transverse colon and small intestine like a fatty apron
the mesentry binds the small intestine to the posterior of the abdominal wall.
Peritonitis: the acute inflamation of the perioneum by infectious microbes.
cheeks and lips are covered with mucous memebrane on the inside.
The hard palate which consists of maxille and palatine bones forms most of the roof of the mouth. The rest is formed by the muscular soft palat. Hanging down from the soft palate is a projection called the uvula. During swallowing the uvula moves upward with the soft palate which prevents entry of swalloed foods and liquids into the nasal cavity.
the tongue forms the floor of the oral cavity. It is and acessory digestive organ composed of skeletal muscle covvered with mucous membrane.
Maneuver food, shape and force it to the back of the mouth for later swallowing.
Thje lingiual frenelum a fold of mucous membrane in the midline of the undersurface of the tongue, limits the movement og the tongue posteriorly. The upper surface and sides of the tongue are covered with projections called papillae, some of which contain taste buds.
the three pairs of salivar glands are acessory organs of digestion that lie outside of the mouth and release their secretions into ducts emptying into the oral cavity.
The paotid glands are located inferior and anterior to the ars nbetween the skin and the masseter muscle.