1. Organ Systems

2. Organization Individual body units: cells Similar cells work together as: tissues 4 main types of tissue: Epithelial, connective, muscle, nervous Different tissues form an: organ Heart, stomach, kidney, small intestine Organs work together forming: organ systems Digestive system, Nervous System, Endocrine System, Excretory System

3. System What is a system? Organ system: group of organs that has related structures or functions

4. Organ Systems Organ SystemMajor OrgansMajor Function Digestive Esophagus, stomach, intestines, liver, pancreas Mechanical and chemical breakdown of food Respiratory Lungs, trachea, blood vessels Gas exchange; bring in O 2, rid body of CO 2 Circulatory Heart, blood vessels; arteries, veins, capillaries Transportation of nutrients, gases & wastes, defence against infection

5. Digestive System Breaks down food Nutrients are absorbed Transported by circulatory system Cells require nutrients for:  Growth, maintenance and repair

6. 4 Stages of Food Processing Ingestion – taking in nutrients Digestion – breakdown of complex molecules into smaller components Absorption – taking up of digested molecules by cells Egestion – removal of food waste materials from the body

7. Gastrointestinal Tract Human digestive system – one long tube, open at both ends Is food ever really ‘in’ your body?

8. Digestive System Pathway Mouth – Esophagus – Stomach – Small Intestine – Large Intestine – Rectum – Anus Ingestion Digestion Absorption Egestion

9. Enzymes/Secretions Many important enzymes/secretions play a role in the digestive system Enzymes Amylase (mouth) – breakdown carbohydrates Pepsin (stomach) – begins digestion of proteins Secretions Bile salts (liver) – break fat into smaller globules Sodium bicarbonate (pancreas) – raises pH of chyme (2.5 – 9.0) so intestines protected

10. Absorption of Nutrients Primarily takes place in small and large intestines Glucose, amino acids, fatty acids, glycerol Nutrients absorbed by small intestine Finger-like projections called villi increase surface area of small intestine x 10… Each villus has a capillary network, nutrients travel through circulatory system and delivered to cells