The Digestive System
The Digestive System
https://www.youtube.com/watch?v=s06XzaKqELk
3 Functions of the Digestive System● Digestion
○ The process by which the digestive system breaks down food into molecules that the body can use■ Mechanical
● Foods are physically broken apart into smaller pieces (Chewing)
■ Chemical● Chemicals produced by your body
break large molecules into small ones (Enzymes)
3 Functions of the Digestive System
● Absorption○ The process by which nutrients pass through the
lining of your digestive system into your blood■ Blood
● Transports the nutrients throughout body● Elimination
○ Materials not absorbed are eliminated from the body as wastes
Structures of the Digestive System
● Mouth● Pharynx● Esophagus● Stomach● Small Intestine● Large Intestine● Liver● Gallbladder● Pancreas
Structures of the Digestive System● Mouth
○ Mechanical Digestion■ Teeth tear, crush, and grind your food■ Tongue pushes food around
○ Chemical Digestion■ Enzymes in saliva begin to breakdown starches■ Moistens food so it can be swallowed
● Pharynx○ Upper portion of the throat○ Junction between digestive tract and respiratory system
● Epiglottis○ Seals off trachea(windpipe) preventing food from entering the lungs
Structures of the Digestive System
● Esophagus○ Muscular tube that connects the
pharynx to the stomach■ Peristalsis
● Muscle contractions push food through esophagus to stomach
● Continue throughout the digestive system
Structures of the Digestive System
● Stomach○ Muscular pouch in the abdomen
■ Mechanical Digestion● Layers of muscle produce churning motion● Mixes food with fluids like a washing machine
■ Chemical Digestion● Gastric juice containing hydrochloric acid is released ● Hydrochloric acid helps break down food● Pepsin (enzyme) breaks down proteins and converts to amino acids● Stomach lining is coated with mucus● Mucus protects stomach lining from contact with hydrochloric acid
○ Peptic Ulcer - hole in stomach lining● Chyme
○ Thick liquid that moves to the small intestine
Structures of the Digestive System● Small Intestine
○ 20 foot long tube, where most chemical digestion and absorption of nutrients takes place
● Liver○ Produces bile, a substance that physically breaks up
large fat droplets that clump together
● Gallbladder○ Stores and releases bile into the small intestine
● Pancreas○ Secretes enzymes into the small intestine
○ Enzymes break down carbohydrates, protein, and fats
○ After enzymes break down food, nutrients can be absorbed
Structures of the Digestive System● Villi
○ Millions line the small intestine○ Finger like projections that absorb nutrients○ Nutrients pass from villi to your blood, where
they are transported throughout the body
● Large Intestine○ Undigested material and unabsorbed water is
pushed to the large intestine○ 5 feet long○ Water is absorbed into blood○ Waste material is compressed and pasted to the
rectum