Unit III The Digestive System and The Excretory System Chapter 23-25-Digestive System Chapter 26-Excretory System
Warm-UP Can you trace the flow of food into the mouth and through the alimentary canal? Start with mouth and end with anus.
Digestive System-Background Functions, Alimentary Canal, and layers
Functions
What is being digested? Lipids/fats Carbohydrates protein Nucleic acids
What is Digestion? Mechanical digestion- physical breakdown of food- making food smaller Ex. Chewing and churning of stomach
What is Digestion? Chemical digestion- using chemicals to break down food Ex. Enzymes
What is Digestion? Absorption- passing nutrients into blood from digestive system
What is the Digestive System? AKA-alimentary canal or gastrointestinal tract (GI tract) 9 meter tube Include primary organs- mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum, anus Include accessory organs- liver, gall bladder, pancreas, salivary glands, secrete substances which help
What are the 4 layers of the wall of the digestive system? 1. Mucosa- 2. Submucosa- 3. Muscular- 4. Serosa-
1. Mucosa- inner most, secretes mucous, protects tissue below it, helps with secretion and absorption
2. Submucosa- contains gland, blood, lymph vessels and nerves Nourishes tissue and carries away absorbed materials
3. Muscular- contains involuntary smooth muscle Rhythmically mix food with secretions via peristalsis- muscles propel food movement forward
4. Serosa- outermost visceral peritoneum- protects underlying tissues and secretes fluid to lubricate outer surface