1. Digestive System

2. Digestion The breaking down of food molecules for use by body cells
Types:
Mechanical— physically breaking down large food particles into smaller food particles
Chemical— chemical reactions that break down into usable molecules

3. Digestive Functions Ingestion: taking food into the body
Movement: transportation of food throughout the body
Deglutition: swallowing
Peristalsis: moves material through digestive tract; wave like contractions of smooth muscle
Absorption: bringing usable molecules into the bloodstream
Mixing: combining substances together to form one mass
Churning: to make a substance through agitation
Secretion: lubricate, liquefy, digest
Defecation: elimination of unused substances

4. Names of Digestive System
Continuous tube from the mouth to anus
Approximately 30 feet long
Known as:
Digestive system
Gastrointestinal (GI) tract
Alimentary canal

5. Four Layers of Tissues Mucosa: innermost, mucous membrane
Submucosa: vascular, holds mucosa in place
Muscularis: smooth muscle to move food
Serosa: outermost layer continuous with the mesentery

7. Mouth
Oral cavity: opening surrounded by hard & soft palate, teeth, cheeks, tongue
Lips: lined with mucous membrane and covered with skin
Labial frenulum— attaches lips to gums
Uvula— prevents food from entering the nasal cavity when swallowing

8. Mouth Tongue— skeletal muscle covered with mucous membrane
Shapes chewed food with saliva into a ball— bolus
Lingual frenulum— limits tongue movement
Papillae— cover surface and sides of tongue

9. Salivary Glands Parotid: under skin in front of ears
Submandibular: under base of tongue and below mandible
Sublingual: under anterior portion of the tongue
Saliva: 99.5% water, 0.5% other stuff
Salts—to buffer chemicals
Mucin—with forms mucous with matter
Lysozyme—kill bacteria
Amylase—starch digesting enzyme

10. Teeth

11. Teeth
Dentin-is a tissue that is calcified and consists of tiny tubules or tubes. It is the second layer of the tooth and is normally covered by enamel and covers the pulp, making up the majority of the tooth's structure.
Enamel - the first layer of tooth that is visible in the mouth, is a porous, calcified substance made from crystalline calcium phosphate. Enamel appears to be a soft beige to white color, yet it is semi-translucent allowing the color of the dentin layer to penetrate through. Enamel is also the hardest substance in the body.
Pulp- the most vital part of the tooth, the pulp originates in the center of the tooth, underneath the enamel layer and dentin layer, in the pulp chamber. The pulp contains blood vessels, connective tissue, and large nerves. The pulp, also commonly referred to as the nerve, branches out and continues down each root through the canals of the tooth and stops just shy of the apex, or tip of the tooth.
Crown- visible portion of tooth
Root- portion of tooth underneath the gum
Periodontal membrane (aka periodontal ligament)- connective tissue deep to the cementum that connects to bones or cartilages, serving to support and strengthen the joint between the tooth and the gum
Cementum- a layer of tough, yellowish, bone-like tissue that covers the root of a tooth. It helps hold the tooth in the socket

12. Teeth Ability to chew food—mastication 2 sets of teeth in lifetime
Deciduous teeth-baby teeth
Permanent teeth-32 adult teeth
Types of teeth
Incisors
Canines
Premolars
Molars

13. Digestion in Mouth Mechanical: mastication Chemical: salivary amylase
AKA chewing
Chemical: salivary amylase
Breaks down starch

14. Pharynx Common pathway for food and air
Skeletal muscle lined by mucous membrane

15. Esophagus Muscular tube that lies closed behind the trachea
Transports food to stomach
Secretes mucous to lubricate and aid transport

16. Deglutition (swallowing)
Voluntary stage: tongue pushes bolus into pharynx
Pharyngeal stage: involuntary; soft palate & uvula close off nasal passage, epiglottis seals the larynx; breathing is interrupted
Esophageal stage: food is pushed down by waves of muscular movements called PERISTALSIS