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stomach cancer/feeding tube insertion and gall bladder removal (downstream…
stomach cancer/feeding tube insertion and gall bladder removal
upstream causes
feeding tube insertion into alimentary canal (due to stomach cancer)
this BYPASSES the mouth, esophagus, stomach, and duodenum
Mouth: contains the enzyme salivary amylase, lysozyme, IgA antibodies, and defins
esophagus: submucosa mucus aids food passage
stomach: HCl denatures proteins, pepsin carries out enzymatic digestion of proteins, secretion of intrinsic factor (B12 absorption)
duodenum: endocrine cells release Secretin and cholecystokinin to inhibit gastric secretion
gall bladder removal
no place for bile to be stored
downstream effects
what can not occur in patients digestive system
deglutition (swallowing)
HCl of stomach can't denature protein, activate pepsin, break down plant cell walls, and kills bacteria
liquid foods needed
Mechanical breakdown: mechanical processes that include chewing, mixing food with saliva by the tongue, churning food in stomach **(segmentation still ongoing in small intestine)
normal production of intrinsic factor may be impaired
pernicious anemia can develop
ingestion; can't use mouth to chew
salivary amylase and mucus not added to food- intestines have to do more work to break down starches
nutrients
Standard formulas
are the most commonly used by G-tube patients.
The carbohydrate component is typically glucose polymers, such as maltodextrin, modified starches, and all varieties of sugar.
The fats are typically heat- or chemically-extracted from plant sources. They could also include fish oils or modified oils such as MCT oils taken from coconut and palm oils.
contain proteins that haven’t been broken down (intact proteins) and polysaccharides. The proteins are normally extracted from cow’s milk, soybeans, or protein isolates derived from other food sources.
gall bladder removal
sinse bile isn't being stored and is flowing to the intestine anytime the liver produces it, you should try to avoid fatty, greasy, and sugary foods
these foods can cause painful gas, bloating, and diarrhea (bile free flowing into your intestine works like a laxative)
Anatomy
GI tract
stomach
Cardial region (cardia): 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 (sphincter controlling stomach emptying)
Greater curvature: convex lateral surface of stomach
Lesser curvature: concave medial surface of stomach
pyloric sphincter
cells
chief
enteroendocrine
parietal
small intestine
ileocecal valve
subdivisions
Jejunum: ~8 ft long; attached posteriorly by mesentery
Ileum: ~12 ft long; attached posteriorly by mesentery; joins large intestine at ileocecal valve
Duodenum: mostly retroperitoneal; ~10.0 in long; curves around head of pancreas; has the most features of interest
smaller structures
vili
microvili
circular folds
intrstinal crypts
peyers patches
duodenal glands
cells
goblet cells
enteroendocrine cells
enterocytes
paneth cells
alkaline mucus produced by intestinal glands and bicarbonate rich juice ducted in from pancreas help neutralize help neutralize acidic chyme and provide proper environment from enzymatic activity
esophagus
joins stomach at cardial orifice
runs from layryngopharynx to stomach
gastroesophageal (cardiac) sphincter
esophageal glands
large intestine
teniae coli
haustra
subdivisions
Colon: several regions, most are retroperitoneal (except transverse and sigmoid) ; ascending, transverse, descending, and sigmoid
Rectum: three rectal valves stop feces from being passed with gas (flatus)
Appendix: contains masses of lymphoid tissue; part of MALT of immune system
Anal canal: last segment that opens to body exterior at anus; has two sphincters
internal (smooth muscle)
external (skelatal muscle)
Cecum: first part of large intestine
copius mucous released by goblet cells ease passage of feces thru colon
pharynx
oropharynx
laryngopharynx
mucus produces helps to lubricate food passageways (same as esophagus)
anus
mouth
hard palate
soft palate
tongue
filiform papillae
intrinsic salivary glands
teeth
basic nutrients essential for survival
fats
vitamins
proteins
minerals
carbohydrates
water
Physiology
organs
small intestine
bile produced by liver emulsifies fats
vili: Fingerlike projections of mucosa (~1 mm high) with a core that contains dense capillary bed and lymphatic capillary called a lacteal for absorption
microvili: Microvilli; Cytoplasmic extensions of mucosal cells that give a fuzzy appearance called the brush border that contains membrane-bound enzymes called brush border enzymes, which are used for final digestion of proteins, carbohydrates, and nucleic acids
Enterocytes: make up bulk of epithelium
In villi: absorb nutrients and electrolytes; brush border enzymes bound to the plasma membranes;
In crypts: produce intestinal juice, watery mixture of mucus that acts as carrier fluid for absorbing nutrients from chyme
gobelt cells: mucus secreting cells
Enteroendocrine cells: source of enterogastrones, e.g., CCK and secretin
Paneth cells: secrete antimicrobial agents (defensins and lysozyme)
Duodenal glands in submucosa of the duodenum secrete alkaline mucus to neutralize acidic chyme
stomach
mucus protects stomach from self-digestion
intrinsic factor produced is importantfor intestinal absorption of B12
HCl produced is a bacteriostatic agent activates protein digesting enzymes
temporary storage tank that starts chemical breakdown of protein digestion; Converts bolus of food to paste-like chyme
chief cells secrete pepsinogen: inactive enzyme that is activated to pepsin by HCl and by pepsin itself (a positive feedback mechanism)
Parietal cells secrete Hydrochloric acid (HCl): pH 1.5–3.5; denatures protein, activates pepsin, breaks down plant cell walls, and kills many bacteria
Enteroendocrine cells secrete chemical messengers. Some are paracrines (e.g., histamine) while others are hormones (e.g., gastrin)
esophagus
tranports swallowed food from laryngyopharynx to stomach
large intestine
Residue remains in large intestine 12–24 hours
No food breakdown (digestion) occurs except what enteric bacteria digest
Absorbs vitamins made by bacterial flora, water, and electrolytes (largely NaCl)
Major functions of large intestine is propulsion of feces to anus and defecation
pharynx
allows passage of food, fluids, and air
anus
defaction
mouth
The mouth (1) ingests, (2) begins mechanical breakdown by chewing, (3) initiates propulsion by swallowing, and (4) starts the digestion of polysaccharides
Buccal phase: voluntary contraction of tongue; Pushes the food bolus into the oropharynx
Pharyngeal-esophageal phase: involuntary phase controlled by the swallowing center in the brain stem
mucus in saliva helps dissolve food so it can be tasted and moistens it so tongue can compact it into bolus that can be swallowed. Saliva cleans and lubricates oral cavity and teeth
enzymes involved in digesting different nutrients
carbs
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 (glucose, fructose, galactose)
Starch and disaccharides are broken down to oligosaccharides and disaccharides; Begins in mouth with
**salivary amylase
proteins
Digestion begins in stomach when pepsinogen is converted to pepsin at pH 1.5–2.5; Becomes inactive in high pH of duodenum
Pancreatic proteases cleave protein into smaller peptides,
Brush border enzymes break oligopeptides and dipeptides into amino acids
lipids
pancreatic lipases break down fat (triglyceride) into free fatty acids and monoglycerides
nucleic acids
Pancreatic nucleases hydrolyze nucleic acid to nucleotide monomers
pancreatic lipases break down fat (triglyceride) into free fatty acids and monoglycerides
brush border enzymes break nucleotides down intro free nitrogenous bases, pentose sugars, and phosphate ions