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Digestive system

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DEPARTMENT: PHARMACYFACULTY :( B.H.M.S) 1st semester ASSIGNMENT: ANATOMYTOPIC: DIGESTIVE SYSTEMSUBMITED TO: Dr.KANWALSUBMITED BY: TAYYEBA AZAMDIGESTION:Definition:The process, by which large, complex, insoluble, organic food substances are broken down into smaller, simple, soluble molecule by the action of enzymes, is known as digestion.DIGESTIVE SYSTEM:Definition:Arrangement of organs which involved in the process of digestion; in a proper way, makes a system, called as digestive system. Synonyms:Digestive system is also known as Alimentary canal OR Gastro-intestinal track (GIT).More About GIT: It is about 5-7m long. GIT is one way tube, having two opening, i.e. Mouth and Anus lined by mucous membrane.

ORGANS OF GIT:Oral cavity: It is divided into following parts:a) Lips b) Teethc) Gums d) Tonguee) Cheeksf) Palate (soft and hard)g) Mucous membrane. Pharynx Esophagus Stomach Small intestine Large intestine Rectum AnusAssociated Glands: Salivary glands:[Parotid Gland, Sublingual gland, Submandibular] Liver Gall bladder PancreasMain Function of GIT: Ingestion Propulsion Digestion Absorption EliminationTHE ORAL CAVITY:Lips, teeth, gums, tongue, cheeks, palate are formed oral cavity.Structure of Oral Cavity: Wide cavity, supported by bones of skull. Externally, bounded by lips and cheeks. Internally, by gums and teeth. Lateral walls made up muscles of cheeks Superiorly, roof made from palate. Inferiorly, floor made from tongue.Structure of Tooth: Humans have two sets of teeth: a) Deciduous or milk teeth (20 in numbers) b) Permanent (32 in numbers) Each tooth consist of 3 main parts: a) Neckb) Crownc) RootFunctions of Teeth: Functionally divided into four categories:a) Incisor: cutting and biting.b) Canines: pointed teeth to tearing.c) Premolar: grinding.d) Molar: grinding and crushing.

Functions of Oral Cavity: LIPS: helps in ingestion of food. CHEEKS: secretion of mucous and sometimes modified to form saliva. GUMS: fixation of teeth. TONGUE: act as spoon, mixing saliva with food. PALATE: formed roof of oral cavity.

Associated Glands Of Oral Cavity:Salivary Glands: Three types of salivary glands:a) Parotid: Located below.b) Submandibular: Located under the angle of jaw.c) Sublingual: Located under the mucous membrane of mouth.Functions of Glands: Lubrication of food. Purifies and moisturize the oral cavity. Secretion of digestive enzyme.

PHARYNX: Muculo-membranous passage of GIT. It measures about 12-14cm long. It pushes down the bolus into esophagus.Parts of Pharynx: It consist of 3 parts; a) Naso pharynxb) Oropharynxc) Laryngeopharynx Only Oropharynx is associated with digestive system.

ESOPHAGUS: Some time called as FOOD PIPE. Long muscular tube which connects pharynx to the stomach. It measure about 25cm long It located in thorasic cavity infront of vertebral column. Esophagus started from 6th cervical vertebrae to the 11th vertebrae.Parts of Esophagus: According to its position in body, divided into the following parts:a) Cervical part: Lies with trachea.b) Thorasic part: Lies between trachea and vertebral column.c) Abdominal part: Covered with peritoneum located at the level of 10th thorasic vertebrae.Functions: Propulsion of food by the help of peristaltic waves.

STOMACH: It is hollow, muscular sac like organ Most dilated part of alimentary canal.Position: It is located between end of esophagus and beginning of small intestine and diaphragm.Structure: Divided into four main regions;a) Cardia: Surrounded the superior opening of stomach.b) Fundus: Rounded portion superior to and to left of the cardia.c) Body: Inferior to fundus is the large central portion of the stomach.d) Pyloric Part: It is the part of stomach connected with duodenum.

INTERNAL STRUCTURE: It contains 3 types of cell:a) Chief or peptic orzymogenic cells: These are typical type of protein-synthesizing cells and source of digestive enzyme like Pepsinogen.b) Oxyntic or parital cell: 1. They activated the inactivated digestive enzyme into pepsin.2. They may secrete HCL of PH 1.5-2.5.3. They also kill microbes.c) Mucous Cells: 1. It secrete mucous.2. It lubricates the food.Functions of stomach: Temporary storage of food. It secretes gastric juice. Chemical digestion takes place by pepsin which converts protein to polypeptides. Mechanical breakdown by smooth muscle layer which performing peristaltic movement. Absorption of some chemicals and water take place.

SMALL INTESTINE:It is long coiled tube, which almost fills the whole abdominal cavity.Location: It is located in abdominal cavity it is continuity as the stomach at the pyloric sphincter and leads to large intestine.Structure: divided into following; Duodenum Jejunum IleumI. Duodenum:It is the shortest and widest part of small intestine.Importance: The secretion of gall bladder and pancreas are released into duodenum by a Hepatopancreatic duct.II. Jejunum:It is thicker and more vascular then ileum.III. Ileum:It is the last and longest part of small intestine.Importance; It have finger like microscopic projection called Villi.

Villi: Tiny finger like projection of mucosal layer. Visible to naked eye. Large and numerous in duodenum but smaller and fewer in ileum. Their walls are richly supplied with blood vessels and lymph vessels.Functions of Small Intestine:Completion of digestion of carbohydrates, protein, and fats in the enterocytes of the villi.

LARGE INTESTINE:It is the second intestinal part, not coiled but has segmented. Location: It covers all nine regions of abdomen. Structure: Part of large intestine is divided into Caecum, ascending colon, transverse colon, descending colon, sigmoid colon.

Caecum: It is the first part of colon. Blind ended pouch. It gives a 10cm long finer like projection called Vermiform appendix. Vermiform appendix is fine tube, closed at one end which leads from the Caecum.Ascending colon: It is 15cm long It passes upward from Caecum to the level of liver where it is curve acutely to the left.Transverse colon: It is 50cm long. Loop of colon that extent across the abdominal cavity infront of duodenum and stomach.Descending colon: It is about 25cm long. It passes down the left side of the abdominal cavity then curves towards midline.Sigmoid Colon: Begins at the inlet of lesser pelvis, where it continues with descending colon. It forms a loop which varies greatly in length average about 4cm. S- Shaped curve in pelvis, that continues downward to become the rectum.

Functions of Large Intestine: In the large intestine absorption of water take place. Minerals, salts, vitamins and drugs are also absorbed by blood capillaries in large intestine. The large intestine is heavily colonized by certain types of bacteria, which synthesize vitamin K and Folic acid

RECTUMIt is the last portion; it is slightly dilated, continues with sigmoid colon and terminates in anal canal.It is about 13cm long Functions:Rectum stores feaces for some time when feaces enter into rectum it bring about a desire for defecation, process called egestion.

PANCREAS: It is soft, lobulated gland. It is both exocrine and endocrine gland.Location: It is situated transversely behind the stomach between the spleen and duodenum.

Struct ure:It is leaf like shape, present in oblique position. It consist of three parts:a) Head: Broad extremity called head which directed downward.b) Body: Head connected to main part, the body by a slightly constricted neck.c) Tail: Left extremity is transverse and terminates closely to spleen.

Function: Its function both as endocrine gland and exocrine gland.As Endocrine Pancreas: The endocrine part of pancreas consists of group of specialized cells called Islet of Langerhans. The islet has no duct, so hormones diffuses directly into blood. The endocrine pancreas secretes two types of hormones which control blood glucose level.a. Glycogen by A cell.b. Insulin by B cell.As Exocrine Pancreas: The exocrine pancreas is a lobulated, branched part surrounded and partially divided into lobules. Each lobule is derived by a tiny duct and these unite eventually to form a pancreatic duct. Pancreatic duct secretes Pancreatic juice into duodenum which contain enzymes that help in digestion of carbohydrates, protein and fats.

LIVER: It is the largest gland of whole body. Structure: consist of 4 lobes: Lobes of Liver: Liver is divided into two main lobe i.e. Right and Left lobe. Left is further divided into two lobes and is much smaller than right lobe. The Quadrate and Caudate lobes are part of left lobe.Functions: Carbohydrate metabolism. Protein metabolism. Fat metabolism. Dotoxification of drugs. Storage of vitamins A, D, E, K, B12. Secretions of Bile. Production of heat.

GALL BLADDER: The gallbladder is a hollow organ that present just beneath the right lobe of the liver. Humans can live without a gallbladder. Structure: Anatomically, the gallbladder is divided into three sections: Fundus Body neckFunction: The secretion of gallbladder is Bile.