the digestive system
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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.

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Presentation Transcript
feed me
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
the mouth mechanical
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
smile
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
tooth pain is the worst pain
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!
the war against plaque
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
the mouth chemical
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
the o esophagus
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”
the stomach mechanical
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
the stomach chemical
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
heart burn and stomach ulcers
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
the small intestine chemical
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
the small intestine mechanical
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
you ate it now use it
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
liquid waste
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
the large intestine
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)
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