The Digestive System Chapter 3 Section 1. Digestive System Organs that break down food so it can...
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Transcript of The Digestive System Chapter 3 Section 1. Digestive System Organs that break down food so it can...
The Digestive SystemChapter 3 Section 1
Digestive System• Organs that break down food so it can be used by the body.• Food passes through a long tube called the digestive tract.• Mouth, pharynx, esophagus, stomach, small intestine, large
intestine, rectum, anus• There are other organs in the digestive system that food
doesn’t pass through:• Liver, gallbladder, pancreas, salivary glands
Digestion• Breaking down food- 2 possible ways:• Mechanical digestion: breaking, crushing, mashing food. (smaller
pieces)• Chemical digestion: breaking apart large molecules into smaller
nutrient molecules. (chemically different molecule)• Enzymes help break apart large molecule chains into smaller
nutrients
• 3 types of nutrients• Carbohydrates sugar (glucose) Energy• Proteins amino acids Build body materials• Fats fatty acids Storage and energy
Mouth• Teeth are used to chew food (mechanical digestion)• Saliva has enzymes that begin breaking down carbs into sugars
(chemical digestion)• Tongue helps push food into the esophagus- a tube coming off
the pharynx (along with the trachea)• Epiglottis: covers the trachea when you swallow.• Peristalsis: a wave of muscle contraction that pushes food
along the digestive tract.
Stomach• A saclike, muscular organ at the end of the esophagus• Muscles contract to squeeze food (mechanical digestion)• Glands produce enzymes and acid to break food into nutrients
(chemical digestion)• Stomach acid also kills any bacteria.• Chyme- the soupy mixture of broken down food and digestive
juices• Stomach stores food for a while and slowly lets it out into the
small intestine.• Sphincter- ring of muscle that opens and closes like a valve• Cardiac (lower esophageal)- esophagus into stomach• Pyloric- stomach into small intestine
Pancreas & Small Intestine• Pancreas- secretes digestive enzymes into the small intestine
and produces hormones to regulate blood sugar levels.• Small intestine is about 20 feet long, but is only 1 inch in
diameter.• Most digestion and absorption occur in small intestine.• Villi- Fingerlike projections that increase the surface area and
are covered with nutrient absorbing cells that put nutrients into bloodstream.
Liver & Gallbladder• Liver is a large (football size), reddish-brown organ that helps
with digestion:• Produces bile which breaks up (emulsifies) fats• Stores nutrients and regulates absorption into blood• Removes toxins
• Gallbladder: Stores bile for release into small intestine
Large Intestine
• Large intestine is only about 5 feet long, but is 2.5 inches in diameter.
• Materials that couldn’t be absorbed are pushed into the large intestine.
• Large intestine stores, compacts, and eliminates indigestible wastes from the body.
• Water is absorbed from the mixture and the liquid becomes semi-solid material called feces or stool (aka. poop).
• Fiber helps keep materials moving in digestive system.• Rectum- Stores feces until it can be passed out of the body
through the anus (another sphincter)
Diagram