Digestive System

30.2 & 30.3

Digestive System

• Functions:– Convert food into small

molecules that can be used by cells.• Amino acids• Fatty acids• Monosaccharides• Nucleotides• Vitamins• Electrolyes• Water

4 Phases of Digestion

• Ingestion

• Digestion– Mechanical

– Chemical

• Absorption

• Elimination

Mouth• Ingestion• Mechanical Digestion• Chemical Digestion• Accessory Organs– Teeth, Tongue, Salivary

glands

EsophagusEpiglottis

Peristalsis

Upper Digestive TractSummary: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: