Digestive System Chapter 14 Digestion the physical chemical

Digestive System Chapter 14

Digestion: the physical & chemical breakdown of food into fundamental components • Useable: nutrients • Unusable: waste

Digestive overview • primary function is digestion of food & absorption of nutrients

Anatomy of GI tract • the walls of the tract composed of 4 layers of tissue – 1. mucosa – 2. submucosa

Anatomy of GI tract • 3. muscularis

Anatomy of GI tract • 4. serosa

Anatomy of GI tract

Muscularis of stomach

Movement of GI tract • peristalsis • segmentation

• peristalsis • segmentation

Digestion is a 4 part process • Ingestion • Digestion • Absorption • Elimination

Ingestion • food is taken into body by mouth

Swallowing reflex

Digestion • physical & chemical breakdown of food into absorbable molecules – stomach

Indigestion/heartburn

Digestion, continued • physical & chemical breakdown of food into absorbable molecules – small intestine – pancreas – liver

Absorption – mostly occurs in small intestine – villi, – microvilli

Small intestine

How are nutrients absorbed? • broken down proteins (amino acids) & simple sugars

How are nutrients absorbed? • small broken down fat

How are nutrients absorbed? • water • vitamins & minerals

More about our fabulous liver • hepatic portal system • it has many, many other functions that help maintain homeostasis including

Elimination

What causes gas & the toots?

A few words about poop • Composition, on average is about. . .

Obesity (epidemic? ? )

Obesity, continued • Hormone leptin

Health effects of obesity • Body has a harder time maintaining homeostasis & some effects are: