DIGESTION ABSORPTION GI TRACT ANATOMY OF GI TRACT.
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Transcript of DIGESTION ABSORPTION GI TRACT ANATOMY OF GI TRACT.
DIGESTION
ABSORPTION
GI TRACT
ANATOMY OF GI TRACT
MOUTH
Chewing surface area of foodMixes fluid (saliva) in with foodTasteEase of swallowingCHO digestion (amylase) NO digestion of fibers and sugarsEpiglottis prevents choking
cartilage in throat to close off windpipe
NORMAL SWALLOW STAGES
ORAL PHASE- food bolus moves to back of mouth (voluntary)PHARYNGEAL PHASE – triggering of the swallow (reflexive stage)ESOPHAGEAL PHASE – actual swallow (reflexive)
DYSPHAGIA - SYMPTOMS
ORAL PHASE drooling pocketing facial droop inadequately chewed foods food falling out of the mouth excessive tongue movement
DYSPHAGIA CONT’D
PHARYNGEAL PHASE “Gurgling” voice food getting stuck nasal regurgitation delayed swallowing reflex coughing while eating or drinking
TEST OF SALIVARY SECRETIONS
GI TRACT
BOLUS – mouthful of swallowed foodPERISTALSIS –
powerful rhythmic waves propels food along circular and longitudinal muscles speed varies
PERISTALISIS
ESOPHAGUS TO STOMACHEsophagus diaphragmCardiac sphincter – 1 way valve between esophagus and stomachStomachCHO digestion stops in the stomachSaliva – is a protein and is digestedProblems:
Hiatal hernia GERD Heartburn – acidic stomach contents into
esophagus
HERNIA
GERD
STOMACH
Muscular, elastic, saclike, thickest walls, strongest muscles in GI tractParietal cells on wall release GastrinGastrin stimulates release of HCl (1.5-1.7 pH)HCl denatures proteinHCl activates pepsinogen (enzyme) pepsinPepsin large proteins smaller amino acidsDigestion of protein – little else
STOMACHChurning
circular longitudinal diagonal
Food mixed with water ~ 2 liters per dayChyme (“kime”) – very acidic
semiliquid mass of partly digested food and fluid Stomach protected by mucus membrane-from goblet cells
STOMACH
pH VALUES
STOMACH SURGERY
PYLORIC SPHINCTER
Circular muscle-1 way valve Opens 3 times/minuteWaits to re-open until chyme neutralizedChyme released in small squirtsNeutralized by bicarbonate from pancreas
SMALL INTESTINE
Three segments Duodenum Jejunum Ileum
Digestion completed for CHO, PRO, FatPancreatic enzymes-specific to need
proteases, lipases, carbohydrasesIntestinal enzymesBile (emulsifier)-livergallbladder
SMALL INTESTINE - ABSORPTION
Microvilli- fingerlike projectionsCrypts – secrete digestive enzymesSpecific areas for absorption of specific nutrients- absorption of most nutrientsAbsorbed into lymph or bloodBLOOD – liver via portal veinLYMPH – bloodstream via thoracic duct and subclavian vein
SMALL INTESTINAL VILLI
ABSORPTION OF NUTRIENTS
Diffusion – freely crosses cell membraneFacilitated diffusion – specific carriers required but no energyActive transport – requires carriers and energy
ILEOCECAL VALVE
One way valve between small and large intestine
ABSORPTION SITES
LARGE INTESTINEColon – three segmentsAscending colonTransverse colonDescending colonNormal bacterial action
Fiber kcals Vitamin K + others?
Absorption water and some minerals
LARGE INTESTINE FUNCTION
Food in large intestine 20-36 hoursWater reabsorbed – if not diarrheaHome for bacteriaFeces formed hereFew minerals absorbed
STOMAS
CROSS-SECTION
THE END
Rectum – semisolid waste (feces)Defecation – elimination of waste from body – “moving of bowels”Anus – terminal sphincter, opens to outside of body – YOU control this valve