Anatomy unit 4 digestive and excretory systems stomach notes
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Transcript of Anatomy unit 4 digestive and excretory systems stomach notes
Unit 5 Notes: The Stomach
(1) About The Stomach• Stomach can contain up to 1.5L of food without
pressure changes.– Feelings of discomfort come from irritants + too
much food
• 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– Depends on Amount & Type of food
(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 release of HCl = Decreasing pH:–Proteins & Carbohydrates
Metabolized–Small & Large Intestine stimulated
(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