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