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) Carbohydrates 4) Proteins 2) Lipids 5) Minerals 3) Vitamins 6) Water or (fibre) Nucleic acids = Nucleotides 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 Overall Function of the Digestive System • The digestive system has four basic functions: • A) Ingestion • B) Digestion • C) Absorption • D) Egestion A) Ingestion • Ingestion is the uptake of the appropriate size and kind of food • Accomplished primarily by the mouth 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 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 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 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). D) Egestion • Anything that is left over is processed and removed (expelled) from the system. 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.