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Elderly man has had a feeding tube inserted in his alimentary canal,…

- - - - Visceral peritoneum- membrane on external surface of most digestive organ
      - Parietal peritoneum- membrane that lines body wall
    - - potential space between the two peritoneums; contains a slippery fluid
    - - double layer of peritoneum
        
        holds organs in place and stores fat
        
        provides routes for blood vessels, lymphatics, and nerves
        
        Extends from body wall to digestive organs
      - Greater omentum
        
        drapes inferiorly from the greater curvature of the stomach
      - Lesser omentum
        
        runs from liver to the lesser curvature of the stomach
      - Falciform Ligament
        
        Suspends liver from diaphragm and anterior abdominal wall
      - Mesentery proper
        
        suspends most of small intestine from posterior abdominal wall
      - Mesocolon
        
        secures parts of large intestine to the posterior abdominal wall
    - - organs that are located within the peritoneum
        
        includes stomach, most of small intestine, and parts of large intestine
    - - located outside to peritoneum
        
        includes most of the pancreas, duodenum, and parts of large intestine
    - - functions in secretion, absorption, and protection against infection
      - simple columnar epithelium and mucus-secreting cells in most of tract
      - Also contains lymphoid follicles that help defend against microorganisms
    - - contains blood and lymphatic vessels
      - abundant elastic tissue that helps organs to regain shape after storing large meal
    - - contains inner circular muscle layer and outer longitudinal layers
      - Sphincters- thickened circular areas that act as valves
    - - replaces by adventitia in esophagus
      - retroperitoneal organs have both an adventitia and a serosa
    - - major regions
        
        cardial region- surrounds cardial orifice
        
        fundus- dome-shaped region beneath diaphragm
        
        body- the midportion
        
        pyloric region- terminates in pylorus, which is continuous with duodenum through pyloric valve
        
        greater curvature- convex lateral surface of stomach
        
        lesser curvature- concave medial surface of stomach
    - - subdivisions
        
        duodenum
        
        mostly retroperitoneal; 10.0 in long; curves around head of pancreas
        
        jejunum
        
        8 ft long; attached posteriorly by mesentery
        
        ileum
        
        12 ft long; attached posteriorly by mesentery
    - - Subdivision
        
        Cecum- first part of large intestine
        
        Appendix- contains masses of lymphoid tissue; part of MALT of immune system
        
        bacterial storehouse capable of recolonizing gut when necessary
        
        twisted shape of appendix makes it susceptible to blockages
        
        Colon- several regions, most are retroperitoneal
        
        ascending, transverse, and descending colon- travels up right side, across, and down left side of abdominal cavity
        
        Sigmoid colon- S-shaped portion that travels through pelvis
        
        Rectum- three rectal valves stop feces from being passed with gas
        
        Anal canal- last segment that opens to body exterior at anus; has two sphincters
        
        internal and external anal sphincter
        
        superficial venous plexuses of anal canal from hemorrhoids if inflamed
      - teniae coli- three bands of longitudinal smooth muscle in muscularis
      - Haustra- pocketlike sacs caused by tone of teniae coli
  - - - Protein
        
        any of a class of nitrogenous organic compounds that consist of large molecules composed of one or more long chains of amino acids and are an essential part of all living organisms
      - Carbohydrates
        
        any of a large group of organic compounds occurring in foods and living tissues and including sugars, starch, and cellulose.
      - Lipids
        
        any of a class of organic compounds that are fatty acids or their derivatives and are insoluble in water but soluble in organic solvents.
    - - Vitamins
        
        any of a group of organic compounds which are essential for normal growth and nutrition and are required in small quantities in the diet because they cannot be synthesized by the body.
      - Minerals
        
        chemical element required as an essential nutrient by organisms to perform functions necessary for life.
  - - - Process
        
        Begins mechanical breakdown by chewing
        
        Initiates propulsion by swallowing
        
        Starts the digestion of polysaccharides
        
        Ingests
      - Palate forms the roof of the mouth
        
        Hard palate
        
        formed by palatine processes of maxillae
        
        Soft palate
        
        Formed by mostly skeletal muscle; closes off nasopharynx during swallowing with help of downward projection uvula
      - Tongue
        
        composed of interlacing bundles of skeletal muscle
      - Salivary glands
        
        Saliva
        
        cleanses the mouth
        
        dissolves food chemicals for taste
        
        moistens food for compaction
        
        begins breakdown of starch with enzyme amylase
        
        minor salivary glands
        
        scattered throughout oral cavity
        
        major salivary glands
        
        parotid
        
        anterior to ear and external to masseter muscle
        
        submandibular
        
        medial to body of mandible
        
        sublingual
        
        anterior to submandibular gland under tongue
      - Teeth
        
        mastication
        
        process of chewing that tears and grinds food into smaller fragments
        
        primary dentition
        
        20 deciduous teeth
        
        erupt between 6 and 24 months of age
        
        32 permanent teeth
    - - Food passes from mouth into oropharynx and into laryngopharynx
      - Esophagus is a flat muscular tube that runs from laryngopharynx to stomach
        
        collapsed when not involved in food propulsion
        
        gastroesophageal sphincter surrounds cardial orifice
      - Major function of both organs is propulsion that starts with deglutition
        
        Buccal phase
        
        voluntary contraction of tongue
        
        Pharyngeal-esophageal phase
        
        involuntary phase controlled by the swallowing center in the brain stem
    - - Caphalic phase
        
        conditioned reflex triggered by aroma, taste, sight, though
      - Gastric Phase
        
        lasts 3-4 hours and provides two-thrids of gastric juice released
      - Intestinal Phase
        
        begins with a brief stimulatory component followed by inhibition
        
        Estergastric reflex
        
        duodenum inhibits acid secretion in stomach by short and long reflexes
        
        Enterogastrones
        
        duodenal enteroendocrine cells release two important hormones taht inhibit gastric secretion, secretin and cholecystokinin
    - - bile- yellow-green, alkaline solution containing:
        
        bile salts- cholesterol derivatives; function in fat emulsification and absorption
        
        bilirubin- pigment formed from heme; broken down by bacteria in intestine to stercobilin that gives brown color of feces
    - - functions to store and concentrate bile by absorbing water and ions
    - - secretion of insulin and glucagon by pancreatic islet cells
    - - Chyme from stomach contains partially digested carbohydrates and proteins and undigested fats
      - Enzymes for digestion
        
        substances such as bile, bicarbonate, digestive enzymes
      - Regulating chyme entry
      - After a meal, segmentation is most common motion
      - Between meals, peristaltic waves are initiated every 90-120 min
      - illeocecal valve control opens and admits chyme into larfe intestine when the force of segmentation and the motility in the ileum are increased
    - - residue remains in large intestine 12-24 hrs
      - motility of the large intestine
        
        mass movements- slow, powerful peristaltic waves activated 3-4 times per day
      - defecation reflex
        
        initiated by mass movements forcing feces towards rectum
  - - - Monosaccharides can be absorbed
      - starch digestion in intestine
        
        Pancreatic amylase breaks down starch or glycogen that escaped salivary amylase into oligosaccharides and disaccharides
        
        Brush border enzymes further break these into lactose, maltose, and sucrose; and then into monosaccharides
    - - Broken into
        
        Large polypeptides
        
        Small polypeptides and small peptides
        
        Finally into amino acid monomers, with some dipeptides and tripeptides
      - Protein digestion in intestine
        
        Pancreatic proteases cleave protein into smaller pepties
        
        Brush border enzymes break oligopeptides and dipeptides into amino acids
    - - Lipid digestion in intestine
        
        Emulsification - triglycerides and their breakdown products are insoluble in water
        
        Digestion- pancreatic lipases break down fat into free fatty acids and monoglycerides
        
        Micelle formation- products from digestion become coated with bile salts
        
        Diffusion- lipid products leave micelles and cross epithelial membrane via diffusion
    - - Nuclei of ingested cells in food contain DNA and RNA
        
        Pancreatic nucleases hydrolyze nucleic acid to nucleotide monomers
        
        Brush border enzymes break nucleotides down into free nitrogen bases, pentose sugars, and phosphate ions
    - - Vitamin absorption in small intestine
        
        Fat-soluble vitamins carried by micelles, absorbed by diffusion
        
        Water-soluble vitamins are absorbed by passive or active transport
        
        Vitamin B12 binds with intrinsic factor and is absorbed by endocytosis
      - Absorbed in large intestine
        
        Vitamin K and B vitamins from bacterial metabolism are absorbed
    - - Absorption of electrolytes - most ions are transported actively along small intestine
        
        usually amount in intestine is amount absorbed, regardless of nutrition state
        
        iron and calcium are exceptions as absorption is related to need
    - - absorption of water
        
        9 L water, most from GI tract secretions, enter small intestine
- - - - diffuclt swallowing
      - loss of appetite