1. Unit 5 Notes: Oral Cavity, Esophagus & Stomach Details!

3. (1) Dig. In The Mouth Both Mechanical & Chemical Digestion Mechanical:
Teeth chewing + grinding breaks down food into smaller units
Chemical:
Enzymes in saliva breaks down parts of food

4. (2) Saliva & Digestion Saliva = Spit
Lubricates food for esophageal transfer
Contains an enzyme called AMYLASE…
Breaks down starch  maltose

6. (3) Saliva Reflexes Parasympathetic release of saliva Causes:
Pressure in mouth
Smell / Sight of food
Thinking about food
Emotional connection to food

8. (4) Bolus Bolus = chewed up food, mixed with saliva.
Bolus travels from mouth  esophagus.

11. (5) Deglutition Buccal Phase (Voluntary):
(A.K.A. – Swallowing)
Buccal Phase (Voluntary):
Tongue moves bolus into pharynx
Pharyngeal-Esophageal Phase (Involuntary):
Epiglottis closes over larynx
Bolus moves into esophagus

13. (6) In The Esophagus Bolus moves from esophagus  stomach
Food moves through esophagus using PERISTALSIS:
Peristalsis = Involuntary contraction of muscle
Wave-like contractions push food down
Like a tube of toothpaste!

16. (7) 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

19. (8) Dig. In The Stomach Mechanical Digestion: Chemical 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.

21. (9) 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

23. (10) Gastric Juice Contains… HCl = Hydrochloric Acid
Pepsin = Enzyme = Breaks down protein
Rennin = Enzyme = Breaks down protein
Muccin = Mucus = Lubricate Food Mass

24. (11) 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.

25. (12) 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