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