The document discusses the basics of digestion, including the organs involved and their functions. It then focuses on digestion that occurs in the mouth, including both mechanical and chemical breakdown of food. Mechanical digestion is done by teeth chewing and grinding food into smaller pieces, while chemical digestion starts as enzymes in saliva begin breaking down parts of the food, such as the enzyme amylase breaking down starch into maltose. The chewed up food mixed with saliva forms a bolus that then travels from the mouth to the esophagus, using both voluntary and involuntary swallowing processes. In the esophagus, the bolus moves to the stomach through peristalsis, which are involuntary, wave-like contractions that push

1. Unit 5 Notes:
Digestion Basics, The Mouth,
and The Esophagus

2. (1) Digestion Basics
• Organs:
– Oral Cavity
– Esophagus
– Stomach
– Small Intestine
– Large Intestine
• Functions:
– Metabolize biomolecules.
– Absorb useful nutrients into blood stream.
– Excrete waste, irritating or non-useful compounds.

4. (2) 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

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

7. (4) Saliva Reflexes
• Parasympathetic release of saliva
• Causes:
–Pressure in mouth
–Smell / Sight of food
–Thinking about food
–Emotional connection to food

9. (5) Bolus
• Bolus = chewed up food, mixed
with saliva.
• Bolus travels from mouth 
esophagus.

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

14. (7) 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!