Oral Cavity cont Teeth Function in MASTICATION Work with tongue, saliva, and palate to form BOLUS. Bolus is swallowed at pharynx, prevented from entering trachea by epiglottis and passed to esophagus Automatic Propulsion of food (PERISTALSIS) begins!
What is Gastric Juice?A collection of chemicals produced by a variety of cells liningthe gastric pits!Examples: CELL TYPE SECRETIONMucus Neck Cells mucusParietal Cells HClChief Cells Pepsinogenl PepsinEnteroendocrine Cells Hormones
So How’s It All Related?Bolus enters stomach through cardiac sphincterStomach distends (stretches)Receptors detect stretch stimulusGastrin secretedGastrin stimulates secretion of HCl by Parietal CellsHCl stimulates conversion of pepsinogen (produced bychief cells) to pepsin!
The Effect of It All?Stomach Distension/Muscle Contraction: Completion of Mechanical DigestionAcidic Environment: Bolus ChymePepsinogen mPepsin:
PART IIISMALL INTESTINEACCESSORYSTRUCTURESLIVERGALL BLADDERPANCREAS
Small IntestineThree Regions:Duodenum~1 ftJejunum~8 ftIleum~12 ft
Digestive Processesof the Small IntestineCHEMICAL DIGESTION OF…CARBOHYDRATESPROTEINSLIPIDSNUTRIENT ABSORPTION!!
Microscopic Anatomy of theSmall Intestine Mucosa Circular folds (“plicae circulares”) Slow propulsion of chyme Villi Finger-like projections w/ capillaries in center Microvilli Small projections of cells that absorb nutrients (aka absorptive cells)
Destructionremoved dailyOld, worn out RBC’s of RBC’s~120 days:RBC’s collect in spleenMacrophages in spleen break down RBC’sFe in heme gets recycledRemainder of heme broken down to bilirubinBilirubin binds to plasma albumin, sent to liverLiver sends bilirubin to intestineLeaves body in feces