anatomy unit 3 notes: the stomach
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Anatomy Unit 3 Notes: The StomachTRANSCRIPT
Unit 3 Notes: The Stomach
(1) About The Stomach• Stomach can contain up to 1.5L of food without
pressure changes.
• Stomach composed of excess tissue Folds of Tissue = Rugae– Folds allow the stomach to expand– Folds also contain secretion glands
• Food sits in the stomach for 3-4 hours.
(2) Dig. In The Stomach• Mechanical Digestion:
–Peristaltic churning of stomach muscle breaks apart bolus.
–Triggered by release of serotonin from rugae.
• Chemical Digestion:–Gastric Juice contains enzymes and acid
that breaks down bolus.
(3) Release of Gastric Juice• Gastrin (hormone) released from
G-Cells within Rugae:–Triggered by smell + taste of food–Triggered by increase in pH
• Gastrin stimulates the release of HCl: –HCL decreases the pH.–HCL metabolizes proteins + carbs.–Small & Large Intestine also stimulated
when gastrin released.
(4) Gastric JuiceContains…• HCl = Hydrochloric Acid • Pepsin = Enzyme = Breaks down protein• Rennin = Enzyme = Breaks down protein• Muccin = Mucus = Lubricate Food Mass
(5) Protein Metabolism• Proteins take a lot of Gastric Juice to
Metabolize.
• Breaking Down Proteins releases H+ ions.
• Decreases pH of stomach.
• G-Cells stop releasing gastrin HCl stopped.
(6) Leaving The Stomach• The mass leaving the stomach is called
“Chyme”:– Mostly liquid Liquids leave first!– Solids are left behind until broken down
• Approximately 3mL of food leaves at one time….– Food Exits the Pyloric Sphincter– Chyme dumped into Small Intestine