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An elderly male patient has multiple bypass in his digestive system due to…

- - - - chyme is the result from a chemical breakdown of bolus
    - - segmentation
        
        rhythmic constrictions to churn and mix chyme
      - peristalsis
        
        alternating waves of contraction and relaxation to move food
      - physical mechanical breakdown
        
        physically breaking down chyme into smaller fragments
    - - parietal cells
        
        hydrochloric acid (HCl)
        
        denatures protein, activates pepsin, breaks down plant cell wall, and kills many bacterias
        
        intrinsic factor
        
        required for absorption of vitamin B12 in small intestines
        
        B12 is needed for the maturation of red blood cells
        
        lack of intrinsic factor leads to pernicious anemia
      - chief cells
        
        pepsinogen (inactive)
        
        Pepsin (active)
        
        activated by HCl and by pepsin (positive feedback mechanism)
        
        pH 1.5 - 2.5
        
        enzyme that digests protein into smaller amino acids
      - enteroendocrine cells
        
        secrete chemical messengers (like gastrin)
      - Gastric secretion regulation
        
        Gastric phase
        
        stimulated by: distension, peptides, and low acidity
        
        inhibited by: excessive acidity in stomach and emotional stress
        
        chemical stimuli activates enteroendocrine G cells to secrete gastrin
        
        gastrin binds to receptors on parietal cells
        
        release of HCl from parietal cells
        
        gastrin stimulates enteroendocrine cell to release histamine
        
        Intestinal phase
        
        stimulated by: partially digested food entering small intestine
        
        inhibited by: distension of duodenum, or presence of acidic, fatty, or hypertonic chyme
        
        protect intestine from too much chyme or acidity
        
        enterogastric reflex
        
        duodenum inhibits acid secretion in stomach by short and long reflexes
        
        enterogastrones
        
        duodenal enteroendocrine cell release secretin and cholecystokinin (CCK)
        
        brief release of intestinal gastrin
        
        encourages gastric glands
        
        Cephalic (reflex) phase
        
        triggered by: aroma, taste, sight, thought
        
        inhibited by: loss of appetite and depression
        
        vagus nerve stimulates gastric glands
  - - - site where bile and pancreatic juices is released to digest chyme
        
        regulation of bile and pancreatic secretions
        
        stimulated by neural and hormonal controls
        
        Duodenal mucosa cells secrete secretin (hormonal) in response to acidic chyme
        
        bile secretion increases
        
        duodenal mucosa cells secrete CCK (hormonal) in response to fatty chyme
        
        enterohepatic circulations returns large amounts of bile salt
        
        duodenal mucosa cells sescrete secretin (hormonal) in response to acidic chyme
        
        increase in pancreatic secretion
        
        brush border enzymes bound to plasma membrane perform final digestion of chyme
        
        digests proteins, carbohydrates, and nucleic acids
      - duodenal glands secrete alkaline mucus to neutralize acidic chyme
      - regulating chyme entry into small intestine
        
        chyme delivery has to be slow when entering the small intestines
        
        chyme is usually hypertonic, has to be slow to prevent ocmotic loss of water from blood
        
        increase the low pH of chyme
        
        chyme has to mix with bile and pancreatic juices for digestion
        
        enterogastric reflex and enterogastrones control movement of chyme into duodenum to prevent it from overflowing
    - - absorbs most nutrients, electrolytes, and water
        
        absorbed through enterocytes
    - - circular folds (about 1 cm deep)
        
        villi (about 1 mm high)
        
        microvilli
        
        cytoplasmic extensions of mucosa to provide more surface area for absorption
        
        contains brush border enzymes
        
        fingerlike projections of mucosa that absorbs nutrients to dense capillary beds and lacteals
        
        force chyme to move slowly to create more time for nutrient absorption
  - - - secretes mucus that aid in food passage
  - - - Contains:
        
        bile salts: cholesterol derivatives (fat emulsification and absorption)
        
        Bilirubin: pigment formed from heme
        
        cholesterol, triglycerides, phospholipids, and electrolytes
      - Gallbladder: stores and concentrate bile by absorbing water and ions
        
        released to small intestine only with contraction
      - flows through hepatopancreatic ampulla with pancreatic juices
        
        flows into duodenum through major duodenal papilla
  - - - contains:
        
        watery, alkaline solutions (pH8) to neutralize acidic chymes
        
        electrolytes
        
        digestive enzymes
        
        proteases (for proteins)
        
        Amylase (for carbohydrates)
        
        Lipases (for lipids)
        
        Nucleases (for nucleic acids)
      - flows through hepatopancreatic apulla with bile
        
        flow to duodenum through major duodenal papilla
  - - - functions:
        
        fermentaion of indigestible carbohydrates and mucin
        
        vitamin synthesis: synthesize B complex and vitamin K to produce clotting factor in the liver
- - - - pancreatic amylase
        
        starch and disaccharides that escaped salivary amylase broken down into oligosaccharides and disaccharides
        
        brush border enzymes
        
        oligosaccharides and disaccharides broken down into monosaccharides
      - starch and disaccharides broken down into oligosaccharides and disaccharides
  - - - pancreatic proteases
        
        brush border enzymes
        
        breaks down oligopeptides and dipeptides into amino acids
        
        break down large polypeptides into small polypeptides and small peptides
      - breaks down protein into large polypeptides
  - - - micelles formation
        
        pancreatic lipases
        
        breaks down fat into free fatty acids and monoglycerides
        
        products from digestion
        
        prevent lipids from floating on surface of chyme, allows enterocytes to absorb more efficiently
      - breaks down large fat globules into small ones (emulsification)
  - - - brush border enzymes
        
        breaks down nucleotides into free nitrogenous bases, pentose sugars, and phosphate ions
      - hydrolyze nucleic acid to nucleotide monomers
  - - - fat soluble vitamins (A, D, E, K)
        
        carried by micelles
        
        absorbed by diffusion
      - water soluble vitamins (C,B)
        
        absorbed by passive or active transport
      - Vitamin B12
        
        binds with intrinsic factor
        
        absorbed by endocytosis
    - - Vitamin K and B
        
        absorbed from the product of bacterial metabolism
- - - - no pepsin
        
        cannot breakdown protein into large polypeptides
        
        difficulty breaking down proteins into amino acids through only pancreatic proteases and brush enzymes
        
        HCl and pepsinogen/pepsin needs to be inserted to digest protein
    - - affects with immune system
    - - the patient will have difficulty to know if he is full
  - - - cannot mature red blood cell
        
        leads to pernicious anemia
        
        intrinsic factor needs to be inserted in his feeding tube
- - - - weaker absorption of these nutrients
        
        Pancreatic juice should be inserted in the feeding tube
    - - no emulsification and lipid digestion
        
        no micelles formation
        
        no fat soluble vitamin absorptions
        
        difficulty of enterocytes to absorb nutrients
  - - - weaker nutrient absorption than before
  - - - weaker bile and pancreatic secretions
        
        CCK and secretin should be inserted in the feeding tube
- - - - slower fat emulsification and digestion
        
        slower absorption of lipids
        
        bile should be inserted in the feeding tube