Chapter 30 – Digestive and Excretory Systems

Foods – these are necessary Carbohydrates Fats Proteins Vitamins Minerals water

Human Digestive System

Digestion starts in the mouth Saliva starts mixing food with saliva - saliva comes from salivary glands in the cheeks and under the tongue. - saliva moistens food, mixes food with mucus, and adds enzymes that break down starch into sugars.

Teeth carry out mechanical digestion Take care of your teeth

Swallowed food passes into the esophagus then the stomach Peristalsis is responsible for pushing food in one direction through the rest of the digestive system after the mouth. This occurs in the espophagus, stomach, small intestine, large intestine, rectum, and pushes wastes out of the anus.

Digestive system problems: Food poisoning Parasites such as worms Viral infections (hepatitis) Eating disorders (anorexia and bulimia) Diarrhea and constipation Flatulence! (excuse me!)

Excretory System Animals produce waste products that must be removed from their body. Most animals have a system that deals with nitrogen-rich wastes from the breakdown of proteins and nucleic acids. Ammonia (NH3) is toxic. In addition, it helps maintain homeostasis – balancing osmotic action and pH.

Human Excretory System

                                                                                                              

Excretory System Problems Kidney stones – crystalized mineral salts and uric acid salts in the urine. Stones block flow of urine and cause excrutiating pain. Kidney failure - can be caused by long-term diabetes, infections, physical injuries, chemical poisoning. Causes toxic materials to build up to lethal levels. Dialysis or kidney transplant is the treatment.

The End