Chapter 30 – Digestive and Excretory Systems

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Foods – these are necessary

• Carbohydrates

• Fats

• Proteins

• Vitamins

• Minerals

• water

Human Digestive System

Break it on down.

• The breaking down of food occurs two ways in the digestive system. Physical- your teeth chew food so you are able to swallow it. Chemical- changes actually change food in to different substances.

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.

•Saliva -Made by the salivary glands in the mouth; it is an enzyme that begins the chemical digestion of carbohydrates.

•Amylase- an enzyme in saliva and pancreatic juice that breaks down starch into simple sugars.

Teeth carry out mechanical digestion

• Take care of your teeth

Swallowed food passes into the esophagus then the stomach

•Peristalsis- the rhythmic muscles contraction that forces the food into the digestive system. –This occurs in the espophagus, stomach,

small intestine, large intestine, rectum, and pushes wastes out of the anus.

•Chyme- the soupy mixture of food and digestive enzymes in the stomach.

•Pepsin-stomach enzyme that digests protein.

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•Duodenum- the first short section of the small intestine immediately beyond the stomach.

• Villi-Fingerlike projection located in the lining of the small intestine. They are covered with nutrient absorbing cells that passes nutrients to the blood stream.

•Bile- made by the liver and stored in the gallbladder; it helps to break down large fat droplets into smaller ones.

•Colon-the section of the large intestine that runs from the cecum to the rectum.

•Rectum- it store the feces and the lower part of the large intestine, between the colon and the anal canal.

Digestive system problems:

• Food poisoning

• Parasites such as worms

• Viral infections (hepatitis)

• Eating disorders (anorexia and bulimia)

• Diarrhea and constipation

• Flatulence! (excuse me!)

The End