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Digestive SystemDigestive System
Job of Digestive SystemJob of Digestive System
Break down food (macromolecules) into nutrients & energy
Review: MacromoleculesReview: MacromoleculesWhat macromolecules do we eat?Proteins: Meat, Nuts Lipids: Oils, FatsCarbohydrates: Breads, Sugars
Review: Food EnergyReview: Food EnergyWhich macromolecule is our main energy source?
Carbohydrates
Which macromolecule stores the most energy?
Lipids
Review: Food Energy (cont.)Review: Food Energy (cont.)
The Food PyramidThe Food Pyramid
NutritionNutrition
Nutrients: Anything that promotes growth
Vitamins (Vitamin C) Minerals (Iron) Macromolecules
Two Types of DigestionTwo Types of Digestion
Mechanical – physically breaking food into smaller pieces (mouth)
Chemical – food molecules are broken down by acids and enzymes (stomach, small intestines)
Digestive SystemDigestive System
Tracking a Piece of FoodTracking a Piece of Food
1. Mouth2. Esophagus3. Stomach4. Small Intestine5. Large Intestine6. Rectum 7. Anus
SwallowingSwallowing
Peristalsis: wavelike movement of muscles pushes food through digestive tract
My food went down the My food went down the “wrong pipe!”“wrong pipe!”
2 tubes in throat: trachea & esophagus
esophagus connects mouth to stomach How does food know which tube to go down?
epiglottis
3 Jobs of Stomach3 Jobs of Stomach
1. Store food & liquid2. Mix food & digestive
juices (HCl)3. Empty into small
intestine
Digestive JuicesDigestive JuicesAssist in breaking down of food
Ex. Enzymes
Acid Reflux
Small IntestineSmall IntestineAbsorbs greatest amount of nutrients
Covered with tiny finger-like projections – villi
~20 ft long!
VilliVilli
Increase surface area
for better absorption (like a towel)
Large IntestineLarge IntestinePrepares waste for removal by absorbing water
~5 ft long!
Digestion: ‘Helper’ OrgansDigestion: ‘Helper’ OrgansSalivary Glands: produce saliva – starts breaking down carbohydrates
Pancreas: produces enzymes & regulates
glucose levels
Liver:Produces bile
Filters blood
Digestion: ‘Helper’ Organs Digestion: ‘Helper’ Organs (cont.)(cont.)
Gall Bladder: stores bileHelps digest fatty foods
Digestion: ‘Helper’ Organs Digestion: ‘Helper’ Organs (cont.)(cont.)
