ANATOMY & ANATOMY & PHYSIOLOGY OF THE PHYSIOLOGY OF THE DIGESTIVE SYSTEMDIGESTIVE SYSTEM

The organs of the digestive system can be The organs of the digestive system can be separated into two main groups: those separated into two main groups: those forming the alimentary canal and the forming the alimentary canal and the accessory digestive organs. accessory digestive organs.

THE ALIMENTARY CANAL THE ALIMENTARY CANAL The alimentary canal also called the The alimentary canal also called the Gastrointestinal Tract performs the Gastrointestinal Tract performs the digestive functions that are to ingest, digestive functions that are to ingest, digests, absorbs, and defecates. The digests, absorbs, and defecates. The organs of the alimentary canal are organs of the alimentary canal are described as follows:described as follows:

MOUTHMOUTHThe mouth, buccal cavity, or oral cavity is The mouth, buccal cavity, or oral cavity is the first portion of the the first portion of the alimentary canalalimentary canal that receives food and begins digestion that receives food and begins digestion by mechanically breaking up the solid by mechanically breaking up the solid food particles into smaller pieces and food particles into smaller pieces and mixing them with mixing them with salivasaliva. The . The oral mucosaoral mucosa is the is the mucous membranemucous membrane epithelium epithelium lining the inside of the mouth.lining the inside of the mouth.

PHARYNXPHARYNXThe pharynx is the part of the The pharynx is the part of the neckneck and and throatthroat situated immediately situated immediately posteriorposterior to to (behind) the (behind) the mouthmouth and and nasal cavitynasal cavity, and , and cranialcranial, or superior, to the , or superior, to the esophagusesophagus, , larynxlarynx, and , and tracheatrachea. Both . Both foodfood and and airair pass through the pharynx, a flap of pass through the pharynx, a flap of connective tissue called the connective tissue called the epiglottisepiglottis closes over the trachea when food is closes over the trachea when food is swallowed to prevent swallowed to prevent chokingchoking or or aspirationaspiration..

ESOPHAGUSESOPHAGUS

The esophagusThe esophagus sometimes known as the sometimes known as the gullet, is an gullet, is an organorgan in which consists of a in which consists of a muscularmuscular tube through which food tube through which food passes from the passes from the pharynxpharynx to the to the stomachstomach. . Food is passed through the esophagus Food is passed through the esophagus by using the process of by using the process of peristalsisperistalsis..

STOMACHSTOMACHThe stomach lies between the The stomach lies between the esophagusesophagus and the and the duodenumduodenum. It is on . It is on the left side of the the left side of the abdominal cavityabdominal cavity. The . The top of the stomach lies against the top of the stomach lies against the diaphragmdiaphragm. The connection between the . The connection between the stomach and the esophagus is called the stomach and the esophagus is called the cardiac sphincter. The cardiac sphincter cardiac sphincter. The cardiac sphincter prevents food from passing back to the prevents food from passing back to the esophagus. The other end of the esophagus. The other end of the stomach empties into the stomach empties into the

duodenum. The duodenum is the first duodenum. The duodenum is the first section of the small intestine. The pyloric section of the small intestine. The pyloric sphincter separates the stomach from the sphincter separates the stomach from the duodenum. Stomach is responsible for the duodenum. Stomach is responsible for the second phase of digestion, and performs second phase of digestion, and performs three vital functions: stores food, breaks three vital functions: stores food, breaks down food into a chyme, and slowly down food into a chyme, and slowly empties chyme into the small intestine.empties chyme into the small intestine.

SMALL INTESTINESMALL INTESTINE

The small intestine is the part of the The small intestine is the part of the gastrointestinal tractgastrointestinal tract (gut) following the (gut) following the stomachstomach and followed by the and followed by the large intestinelarge intestine, and is where the vast , and is where the vast majority of majority of digestiondigestion and absorption of and absorption of food takes place. The small intestine is food takes place. The small intestine is divided into three structural parts in the divided into three structural parts in the following manner: following manner: DuodenumDuodenum, , JejunumJejunum, , and and IleumIleum. .

LARGE INTESTINELARGE INTESTINEThe large intestine is the last part of the The large intestine is the last part of the digestive systemdigestive system and the final stage of the and the final stage of the alimentary canalalimentary canal. Its function is to absorb . Its function is to absorb water from the remaining indigestible food water from the remaining indigestible food matter, and then to pass useless matter, and then to pass useless waste materialwaste material from the body. The large from the body. The large intestine consists of the intestine consists of the cecumcecum and and coloncolon. It . It starts in the right starts in the right iliac regioniliac region of the of the pelvispelvis, just , just at or below the right at or below the right waistwaist, where it is joined to , where it is joined to the bottom end of the the bottom end of the small intestinesmall intestine. From . From here it continues up the here it continues up the abdomenabdomen, then across , then across the width of the abdominal cavity, and then it the width of the abdominal cavity, and then it turns down, continuing to its endpoint at the turns down, continuing to its endpoint at the anusanus

THE ACCESSORY ORGANSTHE ACCESSORY ORGANS

The accessory organs (teeth, tongue, and The accessory organs (teeth, tongue, and several large digestive glands) assist the several large digestive glands) assist the process of digestive breakdown in various process of digestive breakdown in various ways.ways.

SALIVARY GLANDSSALIVARY GLANDSThe glands are found in and around the mouth and The glands are found in and around the mouth and the throat. The major salivary glands are the parotid, the throat. The major salivary glands are the parotid, submandibular, and sublingual glands. They all submandibular, and sublingual glands. They all secrete saliva in mouth, the parotid through tubes secrete saliva in mouth, the parotid through tubes that drain saliva, called salivary ducts, near the that drain saliva, called salivary ducts, near the upper teeth, submandibular under the tongue, and upper teeth, submandibular under the tongue, and the sublingual through many ducts in the floor of the the sublingual through many ducts in the floor of the mouth. Besides these glands, there are many tiny mouth. Besides these glands, there are many tiny glands called minor salivary glands located in the glands called minor salivary glands located in the lips, inner cheek area (buccal mucosa), and lips, inner cheek area (buccal mucosa), and extensively in other linings of the mouth and throat. extensively in other linings of the mouth and throat. Salivary glands produce the saliva used to moisten Salivary glands produce the saliva used to moisten your mouth, initiate digestion, and help protect your your mouth, initiate digestion, and help protect your teeth from decay.teeth from decay.

TEETHTEETH

Teeth are small whitish structures found Teeth are small whitish structures found in the in the jawsjaws (or mouths) that are used to (or mouths) that are used to tear, scrape, and chew or masticate tear, scrape, and chew or masticate foodfood..

PANCREASPANCREASThe pancreas is a The pancreas is a glandgland organorgan in the in the digestivedigestive and and endocrine systemendocrine system of of vertebratesvertebrates. It is both an endocrine gland . It is both an endocrine gland producing several important producing several important hormoneshormones, , including including insulininsulin, , glucagonglucagon, and , and somatostatinsomatostatin, as well as an , as well as an exocrine glandexocrine gland, secreting , secreting pancreatic juicepancreatic juice containing containing digestivedigestive enzymesenzymes that pass to the that pass to the small intestinesmall intestine. . These enzymes help in the further These enzymes help in the further breakdown of the breakdown of the carbohydratescarbohydrates, , proteinprotein, , and and fatfat in the in the chymechyme..

LIVER AND GALLBLADDERLIVER AND GALLBLADDER

A liver is a soft, pinkish-brown, triangular organ. It is A liver is a soft, pinkish-brown, triangular organ. It is located in the located in the right upper quadrantright upper quadrant of the of the abdominal cavityabdominal cavity, resting just below the , resting just below the diaphragmdiaphragm. . The liver lies to the right of the stomach and overlies The liver lies to the right of the stomach and overlies the the gallbladdergallbladder. The liver is a vital organ that has a . The liver is a vital organ that has a wide range of functions, a few of which are wide range of functions, a few of which are detoxification, protein synthesis, and production of detoxification, protein synthesis, and production of biochemicals necessary for biochemicals necessary for digestiondigestion. The liver plays . The liver plays a major role in a major role in metabolismmetabolism and has a number of and has a number of functions in the body, including functions in the body, including glycogenglycogen storage, storage, decompositiondecomposition of red blood cells, of red blood cells, plasma proteinplasma protein synthesis, synthesis, hormonehormone production, and detoxification. production, and detoxification.

The liver is also the largest gland in the The liver is also the largest gland in the human body. It lies below the diaphragm human body. It lies below the diaphragm in the thoracic region of the abdomen. It in the thoracic region of the abdomen. It produces bile, an alkaline compound produces bile, an alkaline compound which aids in digestion, via the which aids in digestion, via the emulsification of lipids. It also performs emulsification of lipids. It also performs and regulates a wide variety of high-and regulates a wide variety of high-volume biochemical reactions requiring volume biochemical reactions requiring highly specialized tissues. highly specialized tissues.

The gallbladder or cholecyst, is a small The gallbladder or cholecyst, is a small non-vital non-vital organorgan which aids in the digestive which aids in the digestive process and concentrates process and concentrates bilebile produced in produced in the the liverliver. The gallbladder is a hollow organ . The gallbladder is a hollow organ that sits in a concavity of the that sits in a concavity of the liverliver known known as the gallbladder fossa. It is divided into as the gallbladder fossa. It is divided into three sections: fundus, body, and neck. three sections: fundus, body, and neck. The neck tapers and connects to the The neck tapers and connects to the biliarybiliary tree tree via the via the cystic ductcystic duct, which then , which then joins the joins the common hepatic ductcommon hepatic duct to become to become the the common bile ductcommon bile duct..

GIT with Duodenal ulcerGIT with Duodenal ulcer