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The Digestive System

The Digestive System. Ch. 30.3 . Feed Me!. Digestive system uses mechanical and chemical energy to break organic material Material is absorbed into the cells of our bodies; used to make energy or other molecules Mechanical: Grinding, smashing tearing, crushing Chemical:

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The Digestive System

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  1. The Digestive System Ch. 30.3

  2. Feed Me! • Digestive system uses mechanical and chemical energy to break organic material • Material is absorbed into the cells of our bodies; used to make energy or other molecules • Mechanical: • Grinding, smashing tearing, crushing • Chemical: • Enzymes and Acidic solutions

  3. The Mouth: Mechanical • Chewing: • Tearing and grinding food into small lumps; increase surface area for enzyme activity • Teeth: • Strongest bones in the body • Incisors; cutting food • Cuspids; tearing food • Molars; grinding food • Tongue: • Strongest muscle in the body • Pushes food down esophagus

  4. The Mouth: Chemical • Amylase: • Enzyme that breaks down starch into di and monosaccharaides • Taste buds: • Alert us to nutrients we need to consume • Sugar Sweet • Acids Sour • Toxins Bitter • Salts Salty • Protein Umami • Tonsils: • Protect body from bacteria take in through the mouth and nose

  5. The Esophagus • Swallowing pushes food down the esophagus to the stomach • Peristalsis: • Contractions of muscle waves move food in one direction • Food has to pass by the trachea (entrance to the lungs) so a small cartilage cover (epiglottis) blocks the opening • Eating too fast can send food “Down the Wrong Pipe”

  6. The Stomach: Mechanical • Walls of stomach contract to crush food and help mix food with digestive juices

  7. The Stomach: Chemical • Glands in stomach release Pepsin and HCl • Pepsin breaks down proteins into amino acids • HCl keeps the stomach at a pH 2! • Food can take up to 4 hours to digest • Why doesn’t HCl eat through the stomach? • Lining of stomach makes protective mucus

  8. Heart Burn and Stomach Ulcers • “Heart Burn” is when stomach acid gets into the esophagus and causes a burning feeling in the chest • Caused by spicy food • Stomach Ulcer is a hole in the stomach lining which can cause major health problems • Caused by high acidic levels

  9. The Small Intestine: Mechanical • 6 m long but only 2.5 cm wide • Peristaltic contractions move food through intestine and continue to break down food • Food is absorbed into the blood through villus • Liver and Gallbladder release bile which physically breaks globs of fat into smaller units

  10. The Small Intestine: Chemical • 3 pronged attack in the Duodenum (first 25cm) • Pancreas releases enzymes to break down carbohydrates, proteins, fats, and nucleic acids; also NaHCO3 to neutralize stomach acid • Liver releases enzymesto break down organic material • Gallbladder release mild acids to help enzyme activity

  11. The Large Intestine • Only 1.5m long but 6.5cm wide • Indigestible material is compacted as much water as possible is absorbed back into the body • Anaerobic bacteria produce vitamins B and K for us while digesting the material • After 18-24 hours, waste is removed from the body as feces • Passes through the last part of the digestive system, the rectum (the butt)

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