Nutrition
                                  The  body needs proteins, carbohydrates, fats, vitamins and minerals.  Vitamins are organic molecules that are  needed for chemical reactions.  the body  cannot produce on its own and must derive it from food.  Minerals are inorganic molecules that are  needed for many body structures, and also must be taken from food.
                                The Digestive System
                                  The  digestive system is an organ system for the uptake, digestion, and absorption  of food.  The mouth and trachea are for  uptake.  The stomach is for storage and  digestion.  The small intestines are for  absorption of nutrients into the blood, and are folded to increase surface  area. The large intestines are for absorption of water to concentrate  waste.  The rectum is for excretion of  waste.
                                The Excretory System
                                  The excretory system is for  removing waste from the body.  The  kidneys filter the blood to decide what the body needs or has too much of.  The ureter and bladder are for storage of  waste to be excreted as urine.