Digestive System
30.2 & 30.3
Digestive System
• Functions:
– Convert food into small
molecules that can be
used by cells.
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Amino acids
Fatty acids
Monosaccharides
Nucleotides
Vitamins
Electrolyes
Water
4 Phases of Digestion
• Ingestion
• Digestion
– Mechanical
– Chemical
• Absorption
• Elimination
Mouth
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Ingestion
Mechanical Digestion
Chemical Digestion
Accessory Organs
– Teeth, Tongue, Salivary
glands
Esophagus
Epiglottis
Peristalsis
Upper Digestive Tract
Summary:
Mouth
Esophagus
Stomach
• Mechanical Digestion
– chyme
• Chemical Digestion
– Pepsin
– HCl
– Mucus
Cardiac
Sphincter
Small Intestine
• Chemical Digestion
• Absorption
• Assisted by Accessory
Organs
Villi
Accessory Organs of the S.I.
• Liver
– Bile separates fat into
smaller droplets
– Mechanically breaks
down fats so enzymes
can digest fat into fatty
acids faster
• Gall bladder
– Stores excess bile
Accessory Organs of S.I.
• Pancreas
– Secretes hormones to
regulate blood sugar
– Secretes enzymes into
small intestine that help
digest proteins, sugars,
fats and nucleic acids
– Secretes bicarbonate
ions into small intestine
to raise pH of acidic
chyme
Enzymes and Chemical Digestion
Large Intestine
• Absorption
• Elimination
Lower Digestive Tract
• Summary: