GI System Introduction PDF

Gastrointestinal System (Overview) Copyright © McGraw-Hill Education. Permission required for reproduction or display. Digestive System  Ingestion Digestion Functions Abso...

Gastrointestinal System (Overview) Copyright © McGraw-Hill Education. Permission required for reproduction or display. Digestive System  Ingestion Digestion Functions Absorption Elimination Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Copyright © McGraw-Hill Education. Permission required for reproduction or display. Pharynx (throat) Oral cavity Salivary (mouth) glands Esophagus Stomach Pancreas Small Liver intestine Gallbladder Large intestine Appendix Rectum Anus Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Layers of Digestive System Digestive system is one large tube from mouth to anus plus the accessory organs 1. Mucosa: - innermost layer - secretes mucus 2. Submucosa: - above mucosa - contains blood vessels, nerves, small glands Copyright © McGraw-Hill Education. Permission required for reproduction or display. 3. Muscularis: - above submucosa - longitudinal, circular, and oblique muscles 4. Serosa/adventitia: - outermost layer - peritoneum is present called serosa - no peritoneum then called adventitia (Ex. Esophagus) Copyright © McGraw-Hill Education. Permission required for reproduction or display. Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Peritoneum Layer of smooth epithelial tissue Mesenteries: ✓ Connective tissue of organs in abdominal cavity Lesser Omentum: ✓ Mesentery connecting lesser curvature of stomach to liver and diaphragm Greater Omentum: ✓ Mesentery connecting greater curvature of stomach to transverse colon and posterior body wall Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Visceral Parietal Peritoneal Peritoneum peritoneum peritoneum cavity Lesser Mesentery Greater omentum of small intestine omentum Peritoneum Mesentery Lesser and Greater Omentum Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Oral Cavity First part of digestive system Contains stratified squamous epithelia Salivary glands: - Produce saliva which contains enzymes to breakdown carbohydrates into glucose - Cleanse mouth. - Dissolve and moisten food. Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Amylase: Salivary enzyme that breaks down carbohydrates. Lysozyme: Salivary enzymes that are active against bacteria. Tongue: House taste buds and mucus Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Tongue 25-15 Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Teeth 25-17  Teeth 32 teeth in normal adult Incisors, canine, premolars, molars, wisdom 20 primary teeth (baby teeth / deciduous teeth) Each tooth has crown, cusp, neck, root Center of tooth is pulp cavity, surrounded by dentin. Enamel is hard covering protects against abrasions Cavities are breakdown of enamel by acids from bacteria Copyright © McGraw-Hill Education. Permission required for reproduction or display. Teeth & Gingiva  Figure 16.5 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Palate Palate: roof of oral cavity Hard palate: anterior part Soft palate: posterior part Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Palate and Palatine Tonsil Hard palate Soft palate Uvula Palatine tonsil 25-23  Salivary Glands Salivary Glands: - includes submandibular, sublingual, parotid - produce saliva contains enzymes to breakdown food - mumps is inflammation of parotid gland Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Salivary Glands Parotid Sublingual Submandibular Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Pharynx Throat Connects mouth to esophagus Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Pharynx Nasopharynx Oropharynx Laryngopharynx Pharynx  Esophagus Tube that connects pharynx to stomach Transport food to stomach Joins stomach at cardiac opening Heartburn: - Occurs when gastric juices regurgitate into esophagus. - Caused by caffeine, smoking, or eating or drinking in excess. Copyright © McGraw-Hill Education. Permission required for reproduction or display. Surface Projection of Esophagus Esophagus  Swallowing Voluntary phase: bolus (mass of food) formed in mouth and pushed into oropharynx Pharyngeal phase: swallowing reflex initiated when bolus stimulates receptors in oropharynx Esophageal phase: moves food from pharynx to stomach Peristalsis: wave-like contractions moves food through digestive tract Copyright © McGraw-Hill Education. Permission required for reproduction or display. Copyright © McGraw-Hill Education. Permission required for reproduction or display. Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Stomach Located in abdomen. Storage tank for food. Can hold up to 2 liters of food. Produces mucus, hydrochloric acid, peptides, intrinsic factors. Contains a thick mucus layer that lubricates and protects epithelial cells on stomach wall form acidic pH (2). Copyright © McGraw-Hill Education. Permission required for reproduction or display. 5 Groups of Epithelial Cells in Stomach 1. Surface Mucous Cells ▪ Inner surface of stomach, produces mucus 2. Mucous Neck Cells ▪ Produce mucus 3. Parietal Cells ▪ Produce hydrochloric acid & intrinsic factors 4. Endocrine Cells ▪ Produce gastrin & histamine 5. Chief Cells ▪ Produce pepsinogen that is converted to pepsin by hCl Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Secretions of the Stomach 1. Hydrochloric Acids ▪ Produce pH of 2 that kills microorganisms & activates the enzyme, pepsin. 2. Pepsin ▪ Breaks covalent bonds of protein to form smaller peptide chains. 3. Mucus ▪ Lubricates & protects stomach wall from damaging effects of acidic chime & pepsin. 4. Intrinsic Factor ▪ Bind with Vit B12 to be readily absorbed in small intestines. Copyright © McGraw-Hill Education. Permission required for reproduction or display. Stomach Virtual Dissection  Stomach Esophagus Cardia Fundus Body Pyloris Duodenum  3 muscular layers: Outer longitudinal, middle circular, and inner oblique to produce churning action. Rugae: Large folds that allow stomach to stretch. Chyme: Paste-like substance that forms when food begins to be broken down. Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Pyloric opening: Opening between stomach and small intestine. Pyloric sphincter: Thick, ring of smooth muscle around pyloric opening. Hunger pangs: Stomach is stimulated to contract by low blood glucose levels usually 12-24 hours after a meal. Copyright © McGraw-Hill Education. Permission required for reproduction or display. Copyright © McGraw-Hill Education. Permission required for reproduction or display. Regulation of Stomach Secretions Parasympathetic stimulation, gastrin, histamine increase stomach secretions Cephalic phase (“get started”): - 1st phase. - Stomach secretions are initiated by sight, smell, taste, or food thought. Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Gastric phase (“go for it”): - 2nd phase - partially digested proteins and distention of stomach promote secretion Intestinal phase (“slow down”): - 3rd phase - acidic chyme stimulates neuronal reflexes and secretions of hormones that inhibit gastric secretions by negative feedback loops Copyright © McGraw-Hill Education. Permission required for reproduction or display. Copyright © McGraw-Hill Education. Permission required for reproduction or display. Stomach  Movement in Stomach Mixing waves: - weak contraction - thoroughly mix food to form chyme Peristaltic waves: - stronger contraction - force chyme toward and through pyloric sphincter Hormonal and neural mechanisms stimulate stomach secretions Stomach empties every 4 hours after regular meal, and 6-8 hours after high fatty meal Copyright © McGraw-Hill Education. Permission required for reproduction or display. Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Small Intestine Measures 6 meters in length Major absorptive organ Chyme takes 3-5 hours to pass through Contains enzymes to further breakdown food Contains secretions for protection against chyme acidity Contains absorptive cells, goblet cells, granular cells, endocrine cells Copyright © McGraw-Hill Education. Permission required for reproduction or display. Gross Anatomy of Small Intestine Duodenum and Ileum  Parts of Small Intestine Duodenum: - 25 cm long - contains microvilli and many folds - contains bile and pancreatic ducts Jejunum: 2.5 meters long and absorbs nutrients Ileum: 3.5 meters long Copyright © McGraw-Hill Education. Permission required for reproduction or display. Copyright © McGraw-Hill Education. Permission required for reproduction or display. Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Liver Anatomy Weighs about 3 lbs; produces bile In right upper quadrant of abdomen under diaphragm Right, left, caudate, quadrate lobes Porta: gate where blood vessels, ducts, nerves enter and exit Receives blood from hepatic artery Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Lobules: divisions of liver with portal triads at corners Portal triad: contain hepatic artery, hepatic portal vein, hepatic duct Hepatic cords: - between center margins of each lobule - separated by hepatic sinusoids (blood channels) Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Hepatic sinusoids: contain phagocytic cells that remove foreign particles from blood Central vein: - center of each lobule - where mixed blood flows towards - forms hepatic veins Copyright © McGraw-Hill Education. Permission required for reproduction or display. Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Liver Ducts Hepatic duct: transport bile out of liver Common hepatic duct: formed from left and right hepatic duct Cystic duct: - joins common hepatic duct - from gallbladder Common bile duct: formed from common hepatic duct and cystic duct Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Gallbladder Small sac on inferior surface of liver Stores and concentrates bile Copyright © McGraw-Hill Education. Permission required for reproduction or display. Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Functions of Liver Digestive and excretory functions Stores and processes nutrients Detoxifies harmful chemicals Synthesizes new molecules Secretes 600 to 1000 ml of bile each day Bile: dilutes and neutralizes stomach acid and breaks down fats 90% of bile salts are reabsorbed in ileum Copyright © McGraw-Hill Education. Permission required for reproduction or display. Copyright © McGraw-Hill Education. Permission required for reproduction or display. FUNCTION EXPLANATION Bile neutralizes stomach acid & emulsify Digestion fats for fat digestion. Bile contains excretory products, such as Excretion cholesterol, fats, bile pigments (bilirubin), that results from hgb breakdown. Liver cells remove sugar from the blood & Nutrient store it in the form of glycogen; they also Storage store fat, vitamins (A, B12, D, E, K), copper, & iron. Copyright © McGraw-Hill Education. Permission required for reproduction or display.  FUNCTION EXPLANATION Liver cells can convert amino acids to Nutrient lipids or glucose; fats to Conversion phospholipids, & Vitamin D to its active form. Detoxification Liver cells remove ammonia from of Harmful blood & convert to urea to be Chemicals eliminated in urine. Synthesis of Liver synthesizes blood proteins such New as albumins, fibrinogen, globulins & Molecules clotting factors. Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Pancreas Located posterior to stomach in inferior part of left upper quadrant Head near midline of body Tail extends to left and touches spleen Endocrine tissues have pancreatic islet that produce insulin and glucagon Exocrine tissues produce digestive enzymes Copyright © McGraw-Hill Education. Permission required for reproduction or display. Copyright © McGraw-Hill Education. Permission required for reproduction or display. Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Large Intestine Function is to absorb water from indigestible food Contains cecum, colon, rectum, anal canal Cecum: - joins small intestine at ileocecal junction - has appendix attached Appendix: 9 cm structure that is often removed Copyright © McGraw-Hill Education. Permission required for reproduction or display. Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Colon: - 1.5 – 1.8 meters long - contains ascending, transverse, descending, sigmoid regions Rectum: straight tube that begins at sigmoid and ends at anal canal; muscular tunic is thicker than the rest of digestive tract Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Anal canal: last 2-3 cm of digestive tract Food takes 18-24 hours to pass through large intestines. Feces is product of water, indigestible food, and microbes Microbes synthesize vitamin K Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Mass Movements 🡪 several strong contractions every 8 to 12 hours to propel the colon contents Defecation Reflex 🡪 occurs when feces distend the rectal wall; internal anal sphincter relaxes Valsalva Maneuver 🡪 can voluntarily initiate defecation by increasing abdominal pressure Copyright © McGraw-Hill Education. Permission required for reproduction or display. Copyright © McGraw-Hill Education. Permission required for reproduction or display. Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Digestive Process 1. Digestion: breakdown of food occurs in stomach and mouth 2. Propulsion: moves food through digestive tract includes swallowing and peristalsis 3. Absorption: primarily in duodenum and jejunum of small intestine 4. Transport: requires carrier molecules & include facilitated diffusion, cotransport, & active transport Copyright © McGraw-Hill Education. Permission required for reproduction or display. Copyright © McGraw-Hill Education. Permission required for reproduction or display. Copyright © McGraw-Hill Education. Permission required for reproduction or display.  GASTROINTESTINAL ASSESSMENT Physical Assessment 1. Family history of the ff: ◼ Gallbladder disease, gallstones, liver dysfunction, jaundice, irritable bowel disorder, ulcerative colitis or Crohn’s disease, stomach ulcers, hemorrhoids, any cancers of the GI tract, GERD, pancreatitis, hernias, etc. 2. Past abdominal history  GASTROINTESTINAL ASSESSMENT 3. Eating habits ◼ Appetite ◼ Food intolerance ◼ Bowel habits 4. Nutritional assessment 5. Dysphagia or heartburn (pyrosis)  GASTROINTESTINAL ASSESSMENT 6. Nausea/ vomiting ◼ hematemesis may be caused by irritation or tears of the esophagus, stomach or duodenal ulcerations, and with esophageal varices. 7. Abdominal pain 8. Medications ◼ NSAIDs, such as aspirin, acetaminophen, naproxen, ibuprofen, and some antibiotics.  GASTROINTESTINAL ASSESSMENT GI Symptom Assessment: 1. Heartburn (Pyrosis) = is a substernal burning sensation that often radiates to the neck and is experienced within one hour of eating or one to two hours after reclining. ◼ Described as a burning in the throat, neck, and suprasternal or substernal area.  Heartburn ▣ Causes: activities that increase intraabdominal pressure (e.g., bending, lifting, exercise, straining during bowel movement, or Valsalva maneuver); ingesting irritating foods (spicy foods).  GASTROINTESTINAL ASSESSMENT 2. Painful swallowing (Odynophagia) = pain experienced when a person swallows, is associated with erosion of the esophagus. ◼ Causes: medication-induced esophagitis (antibiotics [tetracycline, doxycycline] and some antiviral agents), esophageal erosion, immunocompromised patients with Candida, herpes, and cytomegalovirus infections (often found in patients undergoing chemotherapy), or with HIV or AIDS.  GASTROINTESTINAL ASSESSMENT 3. Difficulty swallowing (Dysphagia) ◼ Causes:Schatzki’s ring (which is mucosal ring at the lower esophagus), ethyl alcohol, scleroderma, achalasia (failure of the LES to relax).  GASTROINTESTINAL ASSESSMENT 4. Indigestion (dyspepsia) = is an uncomfortable feeling in the upper abdominal region. Term used to describe imprecise complaints, such as epigastric pain, gnawing, bloating, fullness, early satiety, belching, heartburn, burning and nausea. ◼ The most common symptom that patients complain to their health care provider.  Dyspepsia ▣ Alarming symptoms include weight loss, anemia, bleeding, persistent vomiting, and dysphagia. ▣ Two types of dyspepsia: ◼ Nonulcer dyspepsia = associated with GERD, medication, alcohol ingestion, DM, Helicobacter pylori gastritis. ◼ Dyspepsia secondary to peptic ulcer disease.  GASTROINTESTINAL ASSESSMENT 5. Nausea = is a vague, unpleasant sensation of queasiness or feeling sick to the stomach, accompanied by pallor, sweating, and increased saliva production. There is usually distaste for food and the urge to vomit.  GASTROINTESTINAL ASSESSMENT 6. Vomiting (emesis) = or retching, is the forceful expulsion (reverse peristalsis) of stomach contents through the mouth that involves the muscles of the chest and stomach. ◼ Is centrally controlled and stimulated by afferent vagal fibers, vestibular system, and the chemoreceptor trigger zone.  Emesis ▣ Causes: medications, food poisoning, GI infection, intestinal obstruction, appendicitis, cholecystitis, pregnancy, motion sickness ▣ Complication: ◼ Boerhaave syndrome = rupture of the esophagus with subsequent mediastinitis ◼ Mallory-Weiss tear = tear occurring at the esophagogastric junction.  GASTROINTESTINAL ASSESSMENT 7. Regurgitation = is an effortless return of gastric contents into the mouth. 7. Hiccups (hiccoughs) = caused by a sudden contraction of the diaphragm. ◼ Cause: gastric distension due to carbonated beverages, aerophagia (air swallowing), extreme hot or cold liquids, or ethyl alcohol ingestion.  GASTROINTESTINAL ASSESSMENT 9. Gastrointestinal gas = this is a general category of symptoms associated with belching, bloating, borborygmus (hyperactive bowel sounds), abdominal pain, cramps, and flatulence (gas formed within the GI tract and expelled via the rectum) ◼ Prevention: eating slowly, not using a straw when drinking, not drinking carbonated beverages, not smoking, and not chewing gum.  Gastrointestinal Gas ▣ Lactase deficiency (lactose intolerance) = inability to metabolize lactose that would result to increased intestinal gas production. ▣ Foods known to produce large amounts of gas during digestion: ◼ Beans, Brussels, sprouts, broccoli, cabbage, onions. ABDOMINAL ASSESSMENT  Physical Assessment of the Abdomen ▣ Patient should be lying supine; with an emptied bladder. ▣ Abdomen should be exposed, patient’s head should be resting on a pillow ▣ Knees should be bent to relax the abdomen ▣ Use warm hands to avoid eliciting muscle guarding. ▣ The room should be warm, with suitable lighting.  Physical Assessment of the Abdomen Four-quadrant method = involves the use of an imaginary line drawn vertically from the sternum to the pubis through the umbilicus, and a second line drawn perpendicular to the first horizontally across the abdomen through the umbilicus. Physical Assessment of the Abdomen  Physical Assessment of the Abdomen ▣ Inspection: ◼ Cutaneous angiomas = spider angiomas occur with portal hypertension ◼ Cullen’s sign = is a faint bluish color around the umbilicus secondary to hemoperitoneum (intraabdominal bleeding) ◼ Marked pulsations in epigastric area = highly suggestive of abdominal aortic aneurysm (AAA).  Physical Assessment of the Abdomen ▣ Auscultation: ◼ Use the diaphragm of the stethoscope. ◼ Sequence: RLQ, RUQ, LUQ, and LLQ ◼ Listen at least 5 minutes for abdominal sounds 🢭 Normal: sounds heard every 5-20 sec (5-35 gurgles per min) 🢭 Hypoactive: 1 or 2 sounds in 2 min (normal the first few hours after general anesthesia)  Auscultation ▣ Hyperactive: 5-6 sounds heard in less than 30 sec (also called borborygmi) ▣ Absent: none heard for at least 5 min (may signal paralytic ileus, peritonitis, or an obstruction) ▣ Bruit = a swishing or buzzing sound and indicates turbulent blood-flow suggestive of aortic aneurysm  Physical Assessment of the Abdomen ▣ Percussion = purpose is to elicit either of two sounds: 🢭 Tympani (drum-like) = is produced over air-filled structures 🢭 Dullness = is produced over solid structures (mass), ascites (excessive accumulation of fluid in the abdominal cavity), or a full bladder ▣ Sequence: RLQ, RUQ, LUQ, and LLQ  Percussion ▣ Normal: tympani is the predominant sound that results from the presence of air in the stomach and small intestines. ◼ Liver cannot be percussed (although it may be 1-2cm below the costal region) ◼ Spleen is not normally percussed.  Physical Assessment of the Abdomen ▣ Palpation ◼ Sequence: RLQ, RUQ, LUQ, and LLQ ◼ Light palpation = is used to detect tenderness or cutaneous hypersensitivity, muscular resistance, masses, and swelling. Keep fingers together and press gently with the pads of fingertips depressing about 1 cm.  Palpation ▣ Deep palpation = is used to delineate abdominal organs and masses (tumors). ◼ Two-hand method = one hand is placed on the top of the other. Fingers of the top hand apply pressure to the bottom hand. Fingers of the bottom hand feel for organs and masses.  Palpation ▣ Never palpate over areas where bruits are auscultated. ▣ Spleen is never palpable. If it is palpable, do not continue. ▣ Gallbladder is unusually palpable.  Palpation ▣ Murphy’s sign = patient is asked to breathe in while the examiner’s fingers are held under the liver border. Patient guards the movement by an Inspiratory arrest secondary to painful contact with the fingers. (+) murphy’s sign confirms cholecystitis. ▣ Rovsing’s sign = is elicited by palpating the LLQ and paradoxically causes pain felt in the RLQ. (+) rovsing’s sign indicated appendicitis. ▣ Rebound tenderness = is elicited when pain is felt in RLQ.  Physical Assessment of the Rectum and Anus ▣ Digital rectal examination = used to assess nodules, tenderness, BPH and external hemorrhoids. ◼ Gloved and lubricated index finger is placed against the anus while the patient strains. The finger is inserted into the rectum as far as possible. END 1- 4. What are the 4 major functions of the nervous system? 5. Salivary enzyme that breaks down carbohydrates? 6. What do you call a mass of food formed in mouth and pushed into oropharynx? 7. Tube that connects pharynx to stomach and transport food to stomach 8. A paste-like substance that forms when food begins to be broken down. 9. Pain experienced when a person swallows, is associated with erosion of the esophagus. 10 - 13. What are the four physical assessment techniques used for abdominal assessment. 14. Type of palpation using one hand method. 15. Type of palpation using two hand method.