1. Nutrients Every organism ( the cells) requires nutrients (macromolecules): The basic building blocks of all cell structures are built with these nutrients Almost all nutrients are also a source of energy (can be used by the mitochondria to produce useable energy in the form of ATP) Six basic nutrients are: 1) Carbohydrates4) Proteins 2) Lipids5) Minerals 3) Vitamins6) Water or (fibre) Nucleic acids = Nucleotides

2. The Digestive System An organism’s digestive system is responsible for acquiring the nutrients from food required by all body cells to survive. = maintaining HOMEOSTASIS

3. Overall Function of the Digestive System The digestive system has four basic functions: A) Ingestion B) Digestion C) Absorption D) Egestion

4. A) Ingestion Ingestion is the uptake of the appropriate size and kind of food Accomplished primarily by the mouth

5. B) Digestion Digestion is the breakdown of food into it’s nutrient components (carbohydrates, lipids, proteins, vitamins, and minerals). Digestion can be divided into two main processes: Mechanical digestion and Chemical Digestion

6. Mechanical Digestion Mechanical digestion is the physical breakdown of food into smaller pieces. Initiated by teeth and saliva Continued by hydrochloric acid and the sloshing action of the stomach

7. Chemical Digestion The chemical breakdown of food into its basic building blocks by enzymes (biological catalysts) Specific enzymes break down specific nutrients Carbohydrate digesting enzymes Protein digesting enzymes and Lipid digesting enzymes

8. C) Absorption Food nutrients need to be broken down completely for absorption: Carbohydrates - monosaccharides Proteins - amino acids Lipids - fatty acids and glycerol These building blocks are absorbed into the body (removed from the tube).

9. D) Egestion Anything that is left over is processed and removed (expelled) from the system.

10. The Human Digestive System The human digestive system is basically a long tube. It is composed of the: mouth, esophagus, stomach, small intestine and large intestine As well as the liver and pancreas (accessory organs) The overall function of any digestive system is to obtain nutrients.