The Digestive SystemThe Digestive SystemChapter 29Chapter 29

Think about sliding a warm, tasty slice Think about sliding a warm, tasty slice of cheese pizza into your mouth. You of cheese pizza into your mouth. You take a bite, chew, and swallow. You take a bite, chew, and swallow. You probably aren't saying to yourself, probably aren't saying to yourself, "There, I'm providing my cells with "There, I'm providing my cells with nutrients." However, that's exactly what nutrients." However, that's exactly what you're doing. But first, your digestive you're doing. But first, your digestive system must disassemble the pizza into system must disassemble the pizza into basic building blocks that your cells can basic building blocks that your cells can use.use.

Activity: Enzymes at WorkActivity: Enzymes at Work

Chew the saltine cracker 25 times Chew the saltine cracker 25 times and record the answers to the and record the answers to the following questions:following questions:

1) Was there a change in the taste as 1) Was there a change in the taste as you chewed it? What was the you chewed it? What was the change?change?

2) What do you think caused the 2) What do you think caused the change in the taste? change in the taste?

NutritionNutrition

IngestionIngestion DigestionDigestion AbsorptionAbsorptionEliminationElimination

NutritionNutrition IngestionIngestion FoodFood DigestionDigestion Food--Food-->Nutrients>Nutrients

AbsorptionAbsorptionNutrientsNutrients

EliminationElimination WasteWaste

MacromoleculesMacromolecules

CarbohydratesCarbohydrates ProteinsProteins FatsFats Nucleic acidsNucleic acids

CHEMISTRY OF DIGESTIONCHEMISTRY OF DIGESTION

HYDROLYSISHYDROLYSIS: WATER AND : WATER AND ENZYMES BREAK DOWN LARGER ENZYMES BREAK DOWN LARGER MOLECULES INTO SMALLER UNITSMOLECULES INTO SMALLER UNITS– PROTEINS TO AMINO ACIDSPROTEINS TO AMINO ACIDS– CARBOHYDRATES TO SINGLE SUGARSCARBOHYDRATES TO SINGLE SUGARS– FATS TO 1 GLYCEROL AND 3 FATTY FATS TO 1 GLYCEROL AND 3 FATTY

ACIDSACIDS

http://nhscience.lonestar.edu/biol/dehydrat/dehydrat.html

HYDROLYSISHYDROLYSIS

Human DigestionHuman Digestion

Mechanical Digestion- Mechanical Digestion- Chops & Chops & grinds food into smaller piecesgrinds food into smaller pieces

Chemical Digestion- Chemical Digestion- Breaks the Breaks the chemical bonds within chemical bonds within macromolecule, producing smaller macromolecule, producing smaller subunits.subunits.

titleAlimentary tract

–Mouth

– Esophagus

– Stomach

– Small intestine

• Duodenum

• Jejunum

• Ileum

– Lg. Intestine

• (appendix)

Accessory

Structures

– Salivary

glands

– Liver

– Gall bladder

– pancreas

Online ActivitiesOnline Activities

Phsuccessnet.comPhsuccessnet.com– Activity 29.1Activity 29.1– Activity 29.2Activity 29.2

Digestion Occurs in a TubeDigestion Occurs in a Tube

MouthMouth

Mechanical Digestion (teeth/ tongue)Mechanical Digestion (teeth/ tongue) Chemical Digestion Chemical Digestion

– Salivia– produces Salivia– produces amylaseamylase Breaks down carbohydratesBreaks down carbohydrates

PharynxPharynx

Bolus of food travels down throatBolus of food travels down throat EpiglottisEpiglottis

EsophagusEsophagus

PeristalsisPeristalsis pushes food down tube pushes food down tube into the stomach.into the stomach.

StomachStomach

RugaeRugae Gastric juices (mucus, HCl, enzymes) Gastric juices (mucus, HCl, enzymes)

meet bolus.meet bolus.– Proteins digested here.Proteins digested here.

Bolus --- ChymeBolus --- Chyme Sphincters Sphincters 2-6 hours to empty2-6 hours to empty

Small IntestineSmall Intestine

Long & narrowLong & narrow Absorption of most Absorption of most

nutrients takes nutrients takes place here.place here.

Duodenum Duodenum (breakdown of fats, (breakdown of fats, proteins, and proteins, and carbs)carbs)

Villi absorb Villi absorb nutrients.nutrients.

VilliVilli

Large Intestine (Colon)Large Intestine (Colon)

Wide & shortWide & short Water is absorbed into body.Water is absorbed into body. Feces- undigested waste leaves in Feces- undigested waste leaves in

12-24 hours12-24 hours AppendixAppendix

Liver/ Gall BladderLiver/ Gall Bladder

Bile breaks down fats in the Bile breaks down fats in the duodonem.duodonem.

Liver makes bile.Liver makes bile. Gall bladder stores it.Gall bladder stores it.

PancreasPancreas

Secretes pancreatic juices into Secretes pancreatic juices into duodonem.duodonem.– Neutralizes chyme.Neutralizes chyme.– Breaks down carbs, proteins, and lipids.Breaks down carbs, proteins, and lipids.

ReteachReteach

Describe what happens to the Describe what happens to the carbohydrates in a piece of pizza as carbohydrates in a piece of pizza as they travel through the digestive they travel through the digestive system.system.