Post on 04-Jan-2016
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Digestive System
Nutrients
• Substances in food that provide raw materials and energy the body needs to live
• Our digestive system turns the chemical energy in these nutrients into energy we can use
Functions of the Digestive System
• Digests food into molecules the body can use (physical or chemical change)
• Absorbs nutrient molecules and carries them around the body (physical change)
• Eliminates waste material from unused nutrients
Digestion
• Process by which your body breaks down food into small nutrient molecules– Mechanical– Chemical
Mechanical Digestion
• Food is physically broken down into smaller pieces
• Begins in the mouth– Teeth– Movement of
smooth muscles
Chemical Digestion
• Chemicals produced by the body break foods into their smaller nutrients– Mouth– Stomach
Absorption
• Process by which nutrient molecules pass through the wall of your digestive system into your blood– The lining of the small intestine is covered
in villi that aid in absorption
Elimination
• Materials that are not absorbed leave the body as waste
• The waste material left over after food is digested must leave the body to prevent illness
Organs of the Digestive System
• Mouth Rectum• Esophagus Anus• Stomach Pancreas• Small intestine Gall
Bladder• Large intestine Liver
Mouth
• Digestion begins in the mouth– Mechanical – teeth– Chemical - saliva
Esophagus• Muscular tube that connects your
mouth to your stomach– moves food down into your stomach
using involuntary muscle
contractions (peristalsis)– Lined with mucus that
allows food to slide down
The Stomach
• J-shaped muscular pouch• Most mechanical digestion takes place
in the stomach• Chemical digestions also takes place
– Stomach secretes digestive juice (enzymes) that break down food
• Average adult stomach holds 2 liters• Mucus keeps the acids from burning a
hole in your stomach
Stomach
Modeling• Place the marble in the end of the tube
and squeeze it down into the balloon.
Modeling• What do you think this could be a model
of?
– What is the tube?– What is the balloon?– What is the marble?– What is the soap?
esophagusstomachfood
saliva and mucus
Small Intestine• Where most of the chemical digestion
takes place • Where most of the absorption takes
place• Covered in villi which
enlarge the surface area
Small Intestine
Liver• Breaks down medicines and other
chemicals• Produces bile that breaks up fat
particles• The gall bladder
stores bile
Pancreas• Produces enzymes that flow into the
small intestine• Secretes insulin• Causes diabetes when it does not make
insulin
Large Intestine
• Last section of the digestive tract• Where water is absorbed• Vitamin K is made by bacteria in the
large intestine
Rectum and Anus
• Rectum – end of the large intestine, forms the solid waste– elimination
• Anus – muscular opening at the end of the rectum– elimination
Which cell parts are like the digestive system?
Which one makes energy?
Which one helps get rid of waste?
mitochondria
lysosomes
Which one allows materials to pass in and out?
cell membrane
The digestive System Interacts with:
The digestive system depends on the muscular system to move the food through and for mechanical digestion, the circulatory system to move the absorbed nutrients around the body and the respiratory system to supply it with oxygen