The Digestive System Chapter 29

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

Activity: Enzymes at Work Chew the saltine cracker 25 times and record the answers to the following questions: Chew the saltine cracker 25 times and record the answers to the following questions: 1) Was there a change in the taste as you chewed it? What was the change? 1) Was there a change in the taste as you chewed it? What was the change? 2) What do you think caused the change in the taste? 2) What do you think caused the change in the taste?

Nutrition Ingestion Ingestion Digestion Digestion Absorption Absorption Elimination Elimination

Nutrition Ingestion Food Ingestion Food Digestion Food-->Nutrients Digestion Food-->Nutrients Absorption Nutrients Absorption Nutrients Elimination Waste Elimination Waste

Macromolecules Carbohydrates Carbohydrates Proteins Proteins Fats Fats Nucleic acids Nucleic acids

CHEMISTRY OF DIGESTION HYDROLYSIS: WATER AND ENZYMES BREAK DOWN LARGER MOLECULES INTO SMALLER UNITS HYDROLYSIS: WATER AND ENZYMES BREAK DOWN LARGER MOLECULES INTO SMALLER UNITS –PROTEINS TO AMINO ACIDS –CARBOHYDRATES TO SINGLE SUGARS –FATS TO 1 GLYCEROL AND 3 FATTY ACIDS

HYDROLYSIS

Human Digestion Mechanical Digestion- Chops & grinds food into smaller pieces Mechanical Digestion- Chops & grinds food into smaller pieces Chemical Digestion- Breaks the chemical bonds within macromolecule, producing smaller subunits. Chemical Digestion- Breaks the chemical bonds within macromolecule, producing smaller subunits.

title Alimentary tract –Mouth –Esophagus –Stomach –Small intestine Duodenum Jejunum Ileum –Lg. Intestine (appendix) Accessory Structures –Salivary glands –Liver –Gall bladder –pancreas

Online Activities Phsuccessnet.com Phsuccessnet.com –Activity 29.1 –Activity 29.2

Digestion Occurs in a Tube

Mouth Mechanical Digestion (teeth/ tongue) Mechanical Digestion (teeth/ tongue) Chemical Digestion Chemical Digestion –Salivia– produces amylase  Breaks down carbohydrates

Pharynx Bolus of food travels down throat Bolus of food travels down throat Epiglottis Epiglottis

Esophagus Peristalsis pushes food down tube into the stomach. Peristalsis pushes food down tube into the stomach.

Stomach Rugae Rugae Gastric juices (mucus, HCl, enzymes) meet bolus. Gastric juices (mucus, HCl, enzymes) meet bolus. –Proteins digested here. Bolus --- Chyme Bolus --- Chyme Sphincters Sphincters 2-6 hours to empty 2-6 hours to empty

Small Intestine Long & narrow Long & narrow Absorption of most nutrients takes place here. Absorption of most nutrients takes place here. Duodenum (breakdown of fats, proteins, and carbs) Duodenum (breakdown of fats, proteins, and carbs) Villi absorb nutrients. Villi absorb nutrients.

Villi

Large Intestine (Colon) Wide & short Wide & short Water is absorbed into body. Water is absorbed into body. Feces- undigested waste leaves in hours Feces- undigested waste leaves in hours Appendix Appendix

Liver/ Gall Bladder Bile breaks down fats in the duodonem. Bile breaks down fats in the duodonem. Liver makes bile. Liver makes bile. Gall bladder stores it. Gall bladder stores it.

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

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