Digestive System PDF

Digestive System - - Taking the food, trying to break ot down, using that energy from the food and defacating it. Part of this is part of the GI process. Anatomy of the Oral System: Absorption o Trodd and of ig it edal of canducts intoDefecation o Elimination of indigestible substances from body as...

Digestive System - - Taking the food, trying to break ot down, using that energy from the food and defacating it. Part of this is part of the GI process. Anatomy of the Oral System: Absorption o Trodd and of ig it edal of canducts intoDefecation o Elimination of indigestible substances from body as feces 1. Oral Cavity a. Salivary Glands b. Tonsils 2. Pharynx 3. Esophagus 4. Stomach 5. Small Intestine a. Duodenum b. Iileum c. Jejunum 6. Large intestine 7. Anus Histology of the Digestive Tract: ▪ Digestive process Ingestion o Taking in food through the mouth Propulsion (movement of food) o Swallowing o Peristalsis - propulsion by alternate contraction relaxation; not affected by gravity. Mechanical digestion o Chewing o Churning in stomach. o Mixing by segmentation. Chemical digestion o By secreted enzymes: see later. ▪ ▪ ▪ Mucosa o Inner most layer ▪ Epithelium ▪ Lamina propria ▪ Muscularis mucosa (between mucosa and submucosa) Submucosa o Contain most of them Blood Vessels Muscularis o Intestinal Wall o Conducts contraction and relaxation (Peristalsis) ▪ Outer longitudinal layer ▪ Inner circular layer Serosa or Adventitia o Outher most layer - Prevent the intestine from being intangled during the movement of intestine. Nervouse Control of the G.I.T. Function Lining of the peritoneal Cavity: Two parts: Viceral (serosa) peritonium - Lining Directly attached to the organ. Parietal peritonium - Lines the inner surfaces of the body wall Autonomic Control - In the G.I tract muscles would all be smooth muscle under involuntary control o Parasympathetic ▪ Rest and digest ▪ Enhance the action o Sympathetic ▪ Fight or flight ▪ Decrease acrion of the smooth muscle Enteric Mesenteries - Double sheet of the peritonela membrane Stabilizes the position of the attached organs - Plexus is scattered over the intestinal area. Smooth muscle at middle third of esophagus up to the rectum. o Meissner’s Plexus o Auerbach’s plexus Somatic Tongue: - Skeletal muscle at voluntary control. Present mainly in the oral cavity, 1/3 of esophagus, and anal sphincter. Moves food in the mouth in the middle, Participates in speech and swallowing. Papillae o Filiform ▪ Provide Frcition o Fungiform ▪ Located on the side and apex. o Circumvallate ▪ Back of the tongue o Foliate ▪ On the sides at the back of the tongue. (Nice to know) Oral Cavity: Teeth o Incisors, Canines, Premolar and Molars Frenulum o Having short Frenulum would result to inhibiting the tongues movement therefore are tonguetied. Hard Palte Soft Palte Uvula o Under the vagosnerve stimulation. o Stimulation results to Gag Reflux. Salivary Glands o Inflammation of the Parotid Gland is called Mumps. o Parasympathetic stimulates saliva. Functions of Saliva 1. Prevents bacterial Infection. 2. Lubrication 3. Ocntains salivary amylase that breaks down starch into disacchrarides. 4. Helps to form bolus for deglutition 5. Parasympathetic input casues salivary production; sympathetic lessens this. Gastroesophageal Reflux Disease (GERD) - Pharynx - A common pathway for air and food. Regions: - Nasopahraynx Oropharaynx Laryngopharynx - Stomach - Esophagus - 10 inches long. Conducts food by peristalsis. Runs from pharynx to stomach through the diaphragm. Goes through the diaphragm to join stomach at gastroesopgageal sphincter (Cardioesophageal Sphincter). Swallowing process: 1. Buccal Phase 2. Pharangeal phase 3. Esophageal phase In a healthy Esophageal sphincter, it closes but if it is faulty, allows reflux of acidic components of stomach causing gerd. Pain in the epigastric area. - Storage tank for food. Mechanical partial breakdown of food. o Churning Chemical breakdown of proteins begins. Delivers chyme to the small intestine for complete digestion. Produces 2-3l/day of gastric juice (HCI, Enzymes- and mucus) Anatomy of Stomach: Opening - Gastroesophageal (Cardiac) Sphincter Pyloric Sphincter Parts: - Cardiac Fundus - Body Antrum Greater and lesser curvature; attachment site for omentum (Holds stomach in place) Nice to know: In shorter or more obese people have high horzontal position. In taller or thinner people have elongated vertically (J shaped) Histology: Layers: - Serosa or Visceral Peritoneum Muscularis Submucosa Mucosa o Contaisn Rugae or Rugal Folds. (Increase stomach area) Danger: Perforation of the Stomach wall followed by peritonitis and hemorrhage. Secretions of the Stomach: Chyme a. Makes stomach more acidic. Intrinsic Factor a. Binds Vit B12 and helps absorb it. b. Failure of B12 Absorbtion leads to Pernicious Anemia. HCI: Parietal Cells a. Kills bacteria. b. Stops C6H12H6 digestion by inactivating salivary amylase. Pepsinogen: Chief Cells (Produces Pepsinogen) a. Aids breakdown of protein. *Small frequent feeding is advised to prevent acid from reacting to the wound of the stomach. Small Intestine: Diseases and Disorders Heartburn o GERD result Hiatal Hernia o Certain area in the stomach protudes in the diaphragm leaving juces to go into esophagus. Vomiting o Reverse peristalsis; Backflow of food. o Reverse movement of food, brought about by a signal from the medulla. Gastirc Ulcers (Peptic Ulcer Disease) o Wound inside the stomach o Erosion of the stomach uscle o Caused by H.pylori Bacteria o Aggravated by: Hypersecretion of HCI or pepsin Hyposecretion of Mucus Dietary/smoking/ stress factors Segmentarion mix chyme with digestive juices: a. Bring food into contact with mucosa for absorption. Complete the digestion or Carbohydrates, proteins, and lipids (Fats start in small intestine) Absorbs about 90% of nutrients and water that pass through the digestive system. *By-product is the waste product therefore no more use. Site of greatest amount of digestion and absorption of nutrients and water Small caliber but long 6 meters longs (21 ft) but 1 inch in diameter. Gradual decrease in diameter thickness of wall, number of circular folds and villi the farther you go in the Intestine. Villi and microvilli is present it is for absorption. Duodenum - 25 cm Called the Mixing bowl. Received chyme from the stomach and digestive secretions from the pancrease and liver- - Function of the Large intestine: Jejunum - 1 m long Bulk of Chemical Digestion and nutrient absorption Ileum - 2m Longest part Ends at the Ileocecal vavlve prevent backflow of poop. Ileocecal Junction - - Close link between terminal ileum and cecum by ileocecal ligaments — Functional Valve. Prevents backflow of cecal contents Keeps small intestinal bacterial concentrations at usual low levels. *First part of the Colon (LI) and appendix is on the Right - Something to do with immunity Found in the intestinal wall of the small intestine. - Large Intestine: - Extends from Ileocecal Junction to anus (5ft. in length) Haustral Churing, peristalsis and mass peristalsis drive contents of the colon to the rectum. Bacteria converts proteins to Amino acids to produce Bvits and Vid K. Absopt water, ions and vitamins Forming feces Defecating (emptying rectum) Anatomy of the Large Intestine: Payers Patches (Tonsils of the Intestine) - Larger in diameter but shorter. REAbsirption of water Movement of fecal material sluggish (18-24 hrs) Eliminates indigestible food from the body as feces. Does not participate in Food Digestion. *Unusual stool means there is something wrong with your large intestine. (eg: Loose stool means the intesinte did not absorp water properly) Cecum o 1st part o Blind sac, Vermiform appendix. Colon o Ascending - t o Transverse o Descending o Signoidal colon Rectum o Straight muscular tube o Holding areas before release of fecal material o The last 15 cm (6in) Anus o Not airtight therefore sometimes leaks. (LBM) o Internal anal sphincter (Smooth Muscle) - Involuntary o External Sphincter (Skeletal Muscle) – Voluntary Things to remember: Colon: - - Large diameter thinner wall Have Puches or Hasutra permit the colon to expand and elongate. Tenia coli: Longitudinal bands of muscularis externa (3) along the outer surface, muscle tone within the teniase coli creates the hausta. o Follow tenia coli to find appendix. Omental Appendices; Teardrop shaped sacs of fat on the serosa— - Function: - - - Rectum - Forms last 15 cm of the digestive tract. Expandable organ for temporary storage of feces. Anus or Anal Orifice is the exit of the anal canal. Disorders: Diarrhea - - Results when water ins not sufficently absorbed by large intestine (Can be due to bacteria) *LBM is different from Diarrhea since LBM is secondary to an organism affecting our boy while diarrhea can be stress induced. Constipation - Result when too much water is absorbed by the large intestine. Accessory Gland of the Digestive system: - Not part of the Tract. Liver - Largest Gland in the body Located on the right side of the body under the diaphragm Consist of 4 lobes; suspended from the diaphragm and abdominal wall by the falciform ligament. Connected to the gall bladder via the common hepatic duct - Bile Production: 600-1000 ml/day. o Bile salts emulsify (Breakdown) fats. Storage o Gylcogen, fat, vitamins, copper and iron. Detoxification o Detoxifies drugs and alcohol. Phagocytosis o Kupffer cells phagocytize wornout and dying Red and WBC, some bacteria. Synthesis o Albumins, Fibrinogen, globulins, heparin, clotting factors. Gallbladder - - 4 inches long Stores Bile and concentrats it to performs its action on the digestive process. Bile exits through the cystic duct then into the common bile duct. *Bile breakdowns fats. Gallstones: - Predipitated cholesterol Block cystic duct. Occur because of drastic dieting. Pancrease - At the C-lope of the duodenum Secret enzymes at the c lope Produces digestive enzymes that break down all categories of food. Enxymes are secreted at the duodenum (Duodenal Papillia) Alkaline fluid introduces with enzymes nuetralizes acidic Chyme. - Have both endocrine and excorine functions— Pancreatic secretions: - Pancreatic Trypsin = digest protein Pancreatic Amylase = Continues digestion of starch Pancreatic Lipase = Digest lipids. Sodium Bicarbonate = Protects the duodenum by nuetralizing acid from the stomach. Additional Info: