1 / 16

The Digestive System

The Digestive System. 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.

elisha
Télécharger la présentation

The Digestive System

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. The Digestive System

  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; 32 in a normal mouth • Incisorscutting food; 8 • Caninestearing food; 4 • Premolars grinding food; 8 • Molarsgrinding food ; 12 • Tongue: • Strongest muscle in the body • Pushes food down esophagus • Taste food • Wet area for chemical digestion

  4. Smile! • How many sets of teeth do we have? • 2; milk teeth (fall out) and permanent teeth • Wisdom teeth last molars to form (may never form) • Ruins teeth placement in many people (mouth too small) • Removed surgical • Parts of a tooth: • Crown part of tooth above gums • Gums flesh around jaw bone • Enamel hard outer layer; easily scrubbed away if weakened • Dentine soft, bone-like middle of tooth • Root blood vessels/nerves keeping tooth alive • Cement strong material holding tooth to jaw

  5. Tooth Pain is the WORST Pain • Why do we brush our teeth? • Reduce bad breath • Reduce tooth decay • Reduce gum disease • What causes all these? • Bacteria living on our teeth; eating mashed food • Bacteria produce acid as they eat; slowly breakdown enamel • Plaque sticky layer of food and bacteria • Cavity holes in teeth from tooth decay • Pulp cavity decay reaches root; extremely painful!

  6. The War Against Plaque! • How can we reduce tooth decay? • Fluoride in water and toothpaste • Strengthens enamel of teeth by resisting bacteria acid • Not done in Asia…Thoughts? • Brush BEFORE meals, not after • After meals your mouth acidity is much higher, so the enamel is weak; must wait 30 mins! • Brushing after can make teeth decay faster • Brush your gums • Bacteria can hide in space between gums and teeth

  7. The Mouth: Chemical • Salivary glands: • Hidden under tongue • Release mucus (watery solution) and enzymes to help breakdown food • Amylase: • Enzyme that breaks down starch into di and monosaccharaides • Bolus: • Ball of mashed food • Taste buds: • Alert us to nutrients we need to consume • Sugar Sweet • Acids Sour • Toxins Bitter • Salts Salty • Protein Umami

  8. The (O)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”

  9. The Stomach: Mechanical • Walls of stomach contract to crush food and help mix food with digestive juices • Pyloric Sphincter muscular ring at exit of stomach that lets a small amount of digested food (chyme) through at a time • Why? • Too much acidic liquid in the intestine at one time will damage it

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

  11. 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

  12. The Small Intestine: Chemical • Duodenum (first 25cm) • Pancreas releases enzymes to: • Amylase: Starch  Maltose • Trypsin: Proteins Peptides • Lipase: Fats Fatty Acids • NaHCO3 to neutralize stomach acid • Liver releases bile to: • Break apart fat globs (emulsify) • Neutralize pH • Gallbladder releases extra bile when needed • Ileum second round of enzymes to finish digestion; absorption

  13. The Small Intestine: Mechanical • 6 m long but only 2.5 cm wide; covers 9m2How does this fit inside you? • Villi folds on the intestine membrane; one cell thick so absorption can occur • Peristaltic contractions move food through intestine and continue to break down food • Food is absorbed into the blood through villus • Lacteals absorb fatty acids/glycerols into lymph which carries it to blood in heart • Capillaries absorb sugars and amino acids • Hepatic portal vein transfer food molecules to liver

  14. You Ate It, Now Use It • After absorption, food molecules are assimilated • Assimilation to become a useful part of a cell or organ • Liver • Glycogen is made from excess blood glucose • Amino acids used to make proteins • Fatty acids/glycerols are made into fat • Form cholesterol from fat • Excess amino acids deaminated

  15. Liquid Waste • Excess water, vitamins, minerals, drugs and toxins are removed as urine • Most of urine is Urea • Deamination excess amino acids cannot be stored, so liver removes the amino group (NH2) to make sugars and fats • NH2 becomes ammonia (NH3) • NH3 joins CO2 to make Urea • Urea is toxic, so it is filtered from the blood by the kidneys

  16. 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) • Anus releases feces (egestion)

More Related