1. OBJ: Given video, notes, activity sheet SWBAT explain the functions of the digestive system and the role of the mouth esophagus and stomach play in digestion with 70% accuracy. BRING IN TEXTBOOK DN: Distribute SMSD Review Sheets (**EXAM**) HW Check- Skin Booklet; Video: Digestive System ACT: Introduction to Digestion (notes) Text, read p. 60-65; Work on Digestive Process Begins Booklet HW: Complete Digestive Process Begins Booklet; Work on SMSD Review Sheets; SMSD EXAM, Wednesday, Feb 25; Winter Recess NYSSAE 2008 Exam (on scantron, due Feb 23)

2. Digestive Process Begins Notes Digestive System Functions: 1. breakdown food into nutrient molecules 2. absorption of nutrient molecules (into Circulatory System) eliminate solid waste (Excretory System) Absorption: nutrient molecules pass through wall of small intestine into bloodstream (Circulatory System)

3. Digestion Notes Digestion: breakdown food into nutrient molecules. Two (2) types of digestion: –Mechanical Digestion: physical breakdown by chewing (mouth) and churning (stomach) –Chemical Digestion: chemicals (enzymes, acids) breakdown food. Example: enzymes in mouth breakdown starch into sugars, acids in stomach breakdown proteins

4. Digestion Notes Mouth: digestion begins; saliva contains water, DNA, enzymes (which breaks down starches). Teeth physically breaks down food. Teeth Types: incisors: cut into pieces canines: tear, slash into pieces molars: crush and grind into powder Enzyme: protein that speed up chemical reactions

6. Digestion Notes Esophagus: muscular tube connecting mouth to stomach. Epiglottis: flap (sheet) of tissue which seals off trachea (windpipe) to lungs. Peristalsis: involuntary muscular contractions that push food toward stomach and through intestines.

7. Digestion Notes Stomach: holds/stores food; where digestion begins (protein breakdown): mostly mechanical digestion (churning) but some chemical digestion (acids, enzymes) occurs. Digestive Juice: HCL acid and pepsin (enzyme). Pepsin: enzyme that breaks down protein. HCL Acid: chemical that breaks down solid food into paste (chyme); kills bacteria Mucus: covers stomach wall which protects stomach against ulcers (= holes in stomach wall)

8. Mouth Esophagus Stomach Liver Gallbladder Pancreas Small Intestine Large Intestine Rectum Anus Digestion Begins Final Digestion & Absorption

10. Digestion Notes Stomach cells are quickly replaced if damaged or worn. Chyme: solid food is broken down into thick liquid paste Next Lesson: in small intestine, final digestion and absorption occurs