2. (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
3.
4.
5. (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
6.
7. (3) Release of Gastric Juice
• Gastrin (hormone) released from GCells 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
8.
9. (4) Gastric Juice
Contains…
• HCl = Hydrochloric Acid
• Pepsin = Enzyme = Breaks down
protein
• Rennin = Enzyme = Breaks down
protein
• Muccin = Mucus = Lubricate Food
Mass
10. (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.
11. (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
