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An elderly patient with stomach cancer had a feeding tube inserted into…

- - - - large intestine
        
        This has unique features not seen anywhere
        
        Teniae coli: three bands of longitudinal smooth muscle in muscularis
        
        Haustra: pocketlike sacs caused by tone of teniae coli
        
        Subdivisions of large intestine
        
        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 (except transverse and sigmoid) Ascending, transverse, and descending colon: travels up right side, across, and down left side of abdominal cavity
        
        Superficial venous plexuses of anal canal form hemorrhoids if inflamed
        
        Rectum: three rectal valves stop feces from being passed with gas (flatus))
        
        Anal canal: last segment that opens to body exterior at anus; has two sphincters; internal (smooth muscle) and external anal sphincter (skeletal muscle)
        
        Digestive process in large intestine
        
        Residue remains in large intestine 12–24 hours. No food breakdown (digestion) occurs except what enteric bacteria digest.Large intestine absorbs vitamins made by bacterial flora, water, and electrolytes (largely NaCl).Major functions of large intestine is propulsion of feces to anus and defecation
        
        Motility of the large intestine: Mass movements: slow, powerful peristaltic waves activated 3-4 times per day. Gastrocolic reflex (initiated by presence of food in stomach) and amount of fiber increase the strength of contractions. Descending colon and sigmoid colon act as storage reservoir.
        
        Defecation reflex initiated by mass movements forcing feces toward rectum. Parasympathetic signals stimulate contraction of the sigmoid colon and rectum and relaxation of the internal anal sphincter. Conscious control allows relaxation of external anal sphincter, and muscles of rectum contract to expel feces. Assisted by Valsalva’s maneuver: closing of glottis, contraction of diaphragm abdominal wall muscles cause increased intra-abdominal pressure. Involuntary defecation occurs in infants because they have not yet gained control of their external anal sphincter
      - small intestine
        
        This is the major organ of digestion and absorption
        
        Duodenum: mostly retroperitoneal, it has most features of interest
        
        Jejenum: this is attached posteriorly by mesentery
        
        Ileum: This is attached posteriorly by mesentery, joins large intestine at ileocecal valve
        
        Motility of small interstine
        
        After a meal, segmentation (mechanical breakdown) is most common motion.Mixes chyme with pancreatic and brush border enzymes and bile
        
        Between meals, peristaltic waves (propulsion) are initiated every 90–120 minutes. Meal remnants, bacteria, and debris are moved toward large intestine
        
        Ileocecal valve control opens and admits chyme into large intestine when the force of segmentation and the motility in the ileum are increased Ileocecal valve flaps close when chyme exerts backward pressure this prevents regurgitation into ileum. The mechanism for all of these involve long and short reflexes and hormones
      - esophagus
        
        The esophagus is a flat muscular tube that runs from laryngo pharynx to stomach, collapsed when not involved in food propulsion Pierces diaphragm and joins stomach at cardial orifice. Keeps orifice closed when food is not being swallowed.It contains Esophageal mucosa contains stratified stratified squamous epithelium ,Changes to simple columnar at stomach Submucosa has mucus-secreting esophageal glands that aid in food passage.it has adventitia instead of serosa.
      - pharynx
        
        function of pharynx include
        
        Food passes from mouth into oropharynx and then into laryngopharynx
        
        Allows passage of food, fluids, and air
        
        Stratified squamous epithelium lining with mucus-producing glands
        
        External muscle layers consists of two skeletal muscle layers
        
        Inner layer of muscles runs longitudinally
        
        Outer pharyngeal constrictors encircle wall of pharynx
      - mouth (buccal cavity)
        
        consists of
        
        (1) ingests, (2) begins mechanical breakdown by chewing, (3) initiates propulsion by swallowing, and (4) starts the digestion of polysaccharides
        
        Bounded by lips anteriorly, cheeks laterally, palate superiorly, and tongue inferiorly
        
        Palate forms the roof of the mouth and has two distinct parts
        
        Hard palate: formed by palatine bones and palatine processes of maxillae
        
        Mucosa is slightly corrugated to help create friction against tongue
        
        Soft palate: formed by mostly skeletal muscle; closes off nasopharynx during swallowing with help of downward projecting uvula
        
        Tongue composed of interlacing bundles of skeletal muscle. functions include
        
        gripping, repositioning, and mixing of food during chewing
        
        Forms bolus – compact mixture of food and saliva
        
        Initiates swallowing and aids in speech and sense of taste
        
        Superior surface bears papillae, peglike projections of underlying mucosa
        
        Filiform papillae: gives tongue roughness to provide friction; only one that does not contain taste buds; gives tongue a whitish appearance
        
        Teeth
        
        Crown: exposed part above gingiva (gum), Covered by enamel, the hardest substance in body. it is heavily mineralized with calcium salts and hydroxyapatite crystals
        
        Root: portion embedded in jawbone; number varies between teeth
      - Anus
        
        The anus is the opening at the far end of the digestive tract through which stool leaves the body. The anus is formed partly from the surface layers of the body, including the skin, and partly from the intestine. The anus is lined with a continuation of the external skin. A muscular ring (anal sphincter) keeps the anus closed until the person has a bowel movement.
  - - - Teeth, tongue, and gallbladder
      - Digestive glands: produce secretions that help break down foodstuffs
      - Salivary glands, liver, and pancreas