Download Human Digestive System

DIGESTION ANIMATIONS
 https://www.youtube.com/watch?v=bo2A
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 https://www.youtube.com/watch?v=08Vy
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 https://www.youtube.com/watch?v=Mq9f
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Cool Facts
 Your intestines will grow to at least 25 feet as
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an adult. Be glad you're not a full-grown horse
their coiled-up intestines are 89 feet long!
Food sloshing in the stomach can last 3-4 hours
It takes 3 hours for food to move through the
intestine
Food drying up and hanging out in the large
intestine can last 18 hours to 2 days!
Americans eat over 2 billion pounds of
chocolate a year.
In your lifetime, your digestive system may
handle about 50 tons!!
Human Digestive
System
Structures
 The GastrointestinaI tract (GI), also called the
alimentary canal is the system of organs that take in
food, digest it to extract nutrients and expels the
waste. These organs are the mouth, pharynx,
esophagus, stomach, small intestine and large
intestine.
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Major Functions:
 Ingestion
 Digestion
 Absorption
 Defecation
or Excretion
Following the Trail
 The process begins in the mouth.
 Chewing initiates mechanical breakdown of food
and is followed by secretion of saliva, which
moistens and lubricates food for swallowing.
 Saliva also contains amylases (enzymes), which
start the chemical breakdown of carbohydrates.
 The swallowing reflex begins in the pharynx
and initiates rhythmic waves of smooth muscle
contractions called peristalsis.
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Peristaltic contractions transport food to the
stomach and allow a person to swallow even if
he/she are upside down.
Human Digestive System
 Digestion is the ability to process food in the body into a form
that can be absorbed and used or excreted.
 Digestion involves three principle processes:
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Mechanical digestion: takes place in the mouth, your teeth
chew the food
Chemical digestion: using chemicals to digest/ break
down food, this takes place in your mouth and stomach
where acid and enzymes mix with the food.
Absorption: pulling nutrients out of the food, occurs in the
small intestine
 Accessory organs: Organs that help with
digestion but are not part of the digestive tract.
These organs are the tongue, salivary glands,
liver, gall bladder, and pancreas.
Human Digestive System
Diagram
Mouth
Pharynx
Esophagus
Liver
Stomach
Large Intestine
Small Intestine
Villi
Following the Trail II
 The stomach contains an extra layer of
muscle that aids in mechanically mixing
and churning food into a semiliquid form
called “chyme.”
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Chemical digestion begins with proteins
through the action of hydrochloric acid (HCl)
and the enzyme, pepsin.
Only water and a few substances, such as
aspirin and alcohol, are absorbed by the
lining of the stomach.
Following the Trail III
 As food enters the small intestine secretions from the
liver, gall bladder and pancreas are added .
 The small intestine completes digestion of
food materials by absorbing nutrients into
the blood stream
 The lining of the small intestine consists of
tiny folds or fingerlike projections, called
villi, which, in turn, are covered by microvilli
which increase surface area
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The villi contain capillaries and lymphatic
vessels for the absorption of nutrients
Microvilli have brush border enzymes to
hydrolyze lactose and sucrose.
Cross-Section of
small intestine
Villi
Microvilli
The large intestine does not
contain villi and it plays no
role in digestion
Only water and vitamin K are
absorbed from the large intestine
 Undigested or unabsorbed food is
eliminated through the rectum and
then anus.
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Nutrition
 Food materials are broken down to usable nutrients and
absorbed into the bloodstream.
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They are used by the body for metabolism, building and repair
Some nutrients are stored within the body
 Nutrients include carbohydrates, proteins, lipids, vitamins,
minerals and water.
 Carbohydrates
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Must be broken down into monosaccharides
Body’s main source of energy.
Nutrition II
 Proteins
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Broken down to amino acids
Supply the raw materials for growth and repair.
The body requires 20 amino acids, 10 of which it cannot
make and must obtain
 Lipids are reduced to fatty acids and glycerol
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They are used to make steroid hormones, cell membranes
Store energy
Nucleic acids are reduced to nucleotides.
 DNA
and RNA
 The genetic material of all cells.
Where does each nutrient
get broken down?
CarbDigestion
Mouth,
Throat,
Esophagus
Stomach
Small
Intestine
Protein
Digestion
Nucleic Acid
Digestion
Fat
Digestion
Polysacch.
Into
Disacch.
Polypepties DNA, RNA
into smaller into
proteins
nucleotides
Disacch.
Small
Into
proteins
Monosacch. into amino
acids
Nucleotides
into nitrogen
base, sugar
and phospate
Fat into
glycerol,
fatty acids
and
glycerides
What enzymes break down
each nutrient?
Protein
Carb Digestion Digestion
Nucleic Acid
Digestion
Salivary
amylase
Peptidases
Nucleotidases
(amino acids
are connected
by “peptide”
bonds)
(nucleotides
are building
block of DNA
and RNA)
(amylose is
starch, a
polysacch)
Fat Digestion
Bile salts and
Lipase
(fats are made
of lipids)
Nutrition III
 Vitamins are organic molecules that aid
in the regulation of body processes
 Vitamin C: healthy teeth, gums and
blood vessels; improves iron
absorption and resistance to
infection
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Vitamin K: for normal blood clotting and
synthesis of proteins found in plasma,
bone, and kidneys
 Water
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Required for metabolism and chemical
reactions within the body
Transport of substances around the body
Regulation of body temperature.
Approximately two-thirds of the body
weight is water.