Unit 3 Notes: Digestion Basics, The Mouth,

and The Esophagus

• 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.

(1) Digestion Basics

(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

(3) Saliva & Digestion• Saliva = Spit• Lubricates food for esophageal

transfer• Contains an enzyme called

AMYLASE…–Breaks down starch maltose

(4) Saliva Reflexes• Parasympathetic release of saliva

• Causes:–Pressure in mouth–Smell / Sight of food–Thinking about food–Emotional connection to food

(5) Bolus• Bolus = chewed up food, mixed

with saliva.

• Bolus travels from mouth esophagus.

(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

(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!