Transcript Human Digestive System

Human Digestive System
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Digestive System
• Organ system made of GI (gastrointestinal) Tract.
This is a one way tube.
• Peristalsis is a regular muscular contraction that
moves the food through the GI Tract.
• Begins with digesting food
• Breaks down food
• Moves through digestive tract
• Absorbs digested food and water
• Eliminates waste materials
• Small molecules like vitamins, minerals and water
can be absorbed without being digested.
• Large molecules like carbs, lipids, and proteins
need to be digested before they can be absorbed
into the cells.
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Oral Cavity
(Mouth)
• Contains teeth, tongue, and salivary glands
• Teeth mechanically break down food into small
pieces
• Salivary glands secrete saliva
• Saliva contains amylase (enzyme) which starts to
chemically break down food
• The tongue moves food backwards into esophagus for
swallowing
• Epiglottis covers trachea so breathing is not blocked
• Peristalsis moves food from esophagus to stomach
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Your Mouth
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• Esophagus dumps food into
the stomach.
• Muscles churn food – more
mechanical digestion.
• Gastric glands produce HCl
(hydrochloric acid) and gastric
protease (enzyme).
• This acidic environment
begins the chemical digestion
of proteins.
• Food leaves after 2-4 hours.
• Food leaves the stomach and
enters the small intestine.
Mrs. Degl
Stomach
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Small
Intestine
– Peristalsis finishes mechanical
digestion
– The liver, gallbladder, and pancreas
secrete substances into the small
intestine.
– The liver produces bile, which
passes into the gallbladder, which
then passes into the small intestine,
where it breaks down fats into tiny
droplets. This process is called
emulsification.
– Pancreatic juice produces enzymes
to finish chemical digestion of fats,
proteins and carbohydrates.
– The end products of digestion (fatty
acids, glycerol, and glucose) are
absorbed through the lining of the
small intestine, which is covered in
villi.
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•Villi (singular is villus) are finger like projections in the small
intestine.
•Each villus contains a lacteal and capillaries.
•A lacteal is a small vessel of the lymphatic system.
•Fatty acids and glycerol are absorbed into the lacteals and then
transported to the blood.
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Large
Intestine
• Undigested and indigestible
foods move here from the small
intestine.
• Water is reabsorbed into the
cappilarities here.
• Bacteria live here (produce
methane)
• Remaining solid waste in is
stored here until peristalsis can
remove it through the rectum
(anus). This is called
elimination.
• The colon is attached to the
large intestine.
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Nutrition
The foods you eat provide the energy your body needs to function.
Just like you need to put fuel in your car or recharge your cell
phone battery, your body needs to be fed energy-providing foods
every day. The main form of energy for your body is carbohydrates.
Your body has the easiest time digesting carbohydrates like sugar
and starch. Carbohydrates are broken down into individual
glucose, fructose or galactose units. Glucose is your body’s
favorite form of energy. If you don’t get enough carbohydrates,
your body can make glucose from protein or fat -- and if you get
too many carbohydrates, your body is very good at storing them as
fat.
For more info see www.mypyramid.gov
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Food Pyramid
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Digestive Disorders
•Ulcer – an open sore in the lining of the stomach or intestines.
This can be caused by an excess of HCl . They are painful and
can bleed.
•Constipation - when someone has difficulty eliminating feces.
This can be caused by too much water being removed from the
feces in the large intestine, a reduction of peristalsis, or
insufficient roughage in ones diet.
•Diarrhea – this the frequent elimination of watery feces. This can
be caused by decreased water absorbed in the large intestine.
Prolonged diarrhea can cause dehydration.
•Appendicitis – This is an inflammation of the appendix
•Gallstones – These are small hardened cholesterol deposits that
from in the gallbladder and when they block the flow of bile they
cause severe pain.
For more info click here
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