The Digestive System

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The Digestive System

• 6th, 7th, 8th Grade Health

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Digestive System
Warm-up

• What is the function of the Respiratory System?
• Name the parts of the Respiratory System?

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Learning Objectives

• To recognise the organs involved in digestion
• To understand the major functions of each body
  part in the digestive process
• To understand the four major phases of digestion
• To understand the functions of different enzymes.

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Major Functions of the Digestive System

• Break down ingested food
• Put nutrients into the bloodstream
• Remove waste from the body

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Organs of the Digestive System

• Mouth- teeth, salivary glands, tongue
• Esophagus
• Stomach
• Small Intestine
• Large Intestine
• Pancreas
• Liver
• Gall bladder

Accessory Organs
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Mouth

• Digestion begins here!
• Teeth and tongue are used in mechanical
  digestion- physical breakdown of food
• Saliva and enzymes begin chemical digestion-
  chemical breakdown of food

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Esophagus

• Muscular tube that connects mouth to stomach
• Moves food downward by peristalsis, or muscular
  contractions
• Epiglottis seals off windpipe during swallowing
  to prevent choking

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Stomach- Mechanical and Chemical Digestion

• Muscular pouch that expands to hold your food
• Hydrochloric acid (HCl) and the enzyme pepsin
  combine to form gastric juice

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Stomach- Mechanical and Chemical Digestion

• A gummy coating of mucus protects the stomach
  lining from the strong chemicals
• Chyme, a thick liquid containing partially
  digested food, is produced here

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Small Intestine

• Most chemical digestion occurs here!
• Inner surface is covered in villi and microvilli,
  millions of tiny finger-like projections that
  absorb nutrient molecules from the chyme
• The villi create a large surface area, so as
• many nutrients as possible can be absorbed

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Other Facts of the Small Intestine

• Longest portion of the digestive tract
• Tube that is 20- 25 feet long
• Food stays in your small intestine for 4 to 8
  hours

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Liver

• Makes bile to break up fat
• Stores nutrients, like vitamins and sugars until
  your body needs them
• Breaks down toxins

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Gallbladder

• Temporarily stores bile and releases it into the
  small intestines
• Storage tank for bile (a greenish-yellow liquid)
• Helps your body break down and use fats
• Located under your liver
• Shaped like a pear

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Pancreas

• Makes digestive enzymes
• Makes hormones that regulate sugar levels
• Helps you digest food by breaking down sugars

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Large Intestine

• No digestion occurs here
• Water is absorbed from remaining food
• Bacteria feed on material passing through and
  produce Vitamins (K) vital to our health
• Waste material, feces, is prepared for
  elimination from the body

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Other Facts of the Large Intestine

• Tube that is 5 feet long
• Gets waste from small intestine
• Waste stays for 10 to 12 hours

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Rectum

• Stores feces until they can be expelled through
  the anus.

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Large Intestine
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Videos

• http//www.neok12.com/video/Digestive-System/zX455
  9475700465170435873.htm
• http//kidshealth.org/kid/htbw/DSmovie.html

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Some more videos

• http//www.youtube.com/watch?vP5lyQUtq1KQ
• http//kidshealth.org/kid/htbw/_bfs_DSmoviesource.
  html
• http//www.youtube.com/watch?vq3986Yfl5cU
• http//kitses.com/animation/swfs/digestion.swf

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The End!