1. Digestive System
Purpose & Teeth

2. 1. Purpose – To break food down physically and chemically to be absorbed and used by the body.
2. Types of Systems
a. Simple Diffusion – Some organisms will diffuse nutrients directly into their body from the environment. (i.e. Hydra, or tapeworm)
b. Incomplete digestive system - Food enters through an opening into a saclike gut, waste leaves through the same opening! (i.e. flatworms like the planarian, jellyfish, sea anemones)
Hydra
Tapeworm

3. c. Complete Digestive Systems - A tubular gut with openings at both ends. Food enters one end and specialized areas are dedicated to digesting and absorbing food. The waste leaves through a separate hole. (i.e. Most complex vertebrates like us.)
Ruminants – hoofed animals with 4 chambered stomachs to better digest plants.

4. 3. Food is made out of 6 general nutrients: Water, Vitamins, Minerals, Fat “lipids”, Proteins and Carbohydrates. *Water, Vitamins and Minerals do not have to be digested or changed, just released from food and used. 4. Mechanical digestion – The physical breaking/mashing of food into smaller pieces. Done primarily by the teeth, but also by the muscular contractions of the stomach and small intestines. *A full grown adult has 32 teeth to aid in the process (counting wisdoms) *Peristalsis – the muscular contractions that move food through the system, also mechanically mashes and churns food. *The mixed and churned food (from the stomach on) is called “chyme”.

5. 5. Teeth – Bone like structures implanted in sockets of the jaw
5. Teeth – Bone like structures implanted in sockets of the jaw. (2 sets / life) 6. Structure a. Divided into crown – part you can see and the root – part embedded in jaw bone. b. Front teeth have one root, back teeth have 2 or three roots. Molars – Made for grinding and gnashing. Pre Molars “Bi-Cuspids” - Grinding Canines or “Cuspids” – Ripping & tearing! Incisors – Made for cutting

6. c. Teeth are “sewed” in the jaw bone by periodontal ligaments – tough fibers and tiny blood vessels, and “glued” in by cementum. d. Enamel – Hard outer covering of the tooth. e. Dentin – Living cells under the enamel that senses hot and cold. f. Dental Pulp – Very inner of the tooth that is made of blood vessels and nerves.

7. Caries is Latin for rotten
7. Dental Caries – When bad bacteria release acids that eat through the enamel and a cavity forms
Caries is Latin for rotten

8. 8. Root Canal – Often needed to fix a cavity. a
8. Root Canal – Often needed to fix a cavity. a. enamel is drilled out b. Infected dental pulp is removed c. Filling material fills the dental cavity d. A crown then restores/protects the surface