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 TEXTBOOKDN: 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)

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)

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

Digestion Notes• Mouth: digestion begins; saliva contains

water, DNA, enzymes (which breaks down starches). Teeth physically breaks down food.

Teeth Types:incisors: cut into piecescanines: tear, slash into piecesmolars: crush and grind into powder

Enzyme: protein that speed up chemical reactions

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.

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 bacteriaMucus: covers stomach wall which protects stomach against ulcers (= holes in stomach wall)

MouthEsophagus

Stomach

LiverGallbladderPancreas

Small IntestineLarge Intestine

RectumAnus

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Digestion NotesStomach 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