The Human
Digestive
System
The Human Digestive System
 The
digestive system of humans consists of a
digestive tract and several accessory organs which
work together to help the body gain nutrients from
food.
 The organs form a tract through the body which
function to mechanically and chemically digest the
food for absorption.
 The accessory organs assist in the digestion of food
into its component nutrients which can then be
absorbed.
pharynx
tongue
salivary
glands
esophagus
liver
gall bladder
common bile duct
lower esophageal
sphincter
stomach
pancreas
pancreatic duct
duodenum
pyloric sphincter
transverse colon
descending colon
ascending colon
small intestines
cecum
rectum
anus
Organ
Structure
•
Oral Cavity
•
Contains the tongue, which is a large
Function
•
muscle in the mouth that has taste
and chewing to break down
buds in structures called papillae
and taste food
Also the location of teeth and exit
•
point of salivary glands
•
Esophagus •
Long muscular tube leading to the
This is mechanical digestion of
food
•
Muscles around the tube push
stomach
the food bolus down towards
Lined with both circular and
the stomach
longitudinal muscles
•
Secretes mucin (a lubricant)
•
Food bolus enters through the lower
•
•
Secretes mucous and acid
•
Contains folds called rugae
•
Chyme exits through the pyloric
sphincter into the small intestines
This movement is known as
peristalsis
•
esophageal sphincter
Stomach
Tongue and teeth aid in mixing
Churning of the stomach helps
to mechanically digest food.
•
Hydrochloric acid aids in
chemical breakdown of food.
•
The enzyme pepsin chemically
breaks down protein.
Organ
Structure
•
First part of the small intestine after
•
are released by the pancreas and
sphincter
•
Ducts release secretions here
•
Consists of the duodenum, the
jejunum, and the ileum
•
Very long tube with many folds
gall bladder to help with chemical
digestion
•
Absorption of nutrients through villi
and microvilli which provide
called villi and microvilli
•
Muscles move chyme around to
mix it with digestive enzymes that
chyme moves through the pyloric
Duodenum
Small
Intestines
Function
increased surface area
Connects to the large intestines
through the ileocecal valve
•
Colon
Larger diameter and shorter length
than small intestine
•
•
breakdown products from
Contain bacteria that assist in
bacteria
digestion
Rectum
and Anus
•
Last tube of the digestive tract
before exit of waste products
through the anal sphincter
Absorption of water and
•
Storage of undigested waste
before controlled elimination
Organ
Structure
• Glands located above and
Salivary
Glands
below the oral cavity which
release liquids into the mouth
through salivary ducts
Liver
• Large organ located above
the stomach
• Small sack under the liver that
Gall
Bladder
is connected to the liver and
the duodenum through the
common bile duct
Function
• Produces saliva and the
enzyme amylase which breaks
down some carbohydrates
• Produces bile which breaks
down globs of fat
• Storage of bile before it is
release into the duodenum
through the bile duct
• Located behind the stomach
Pancreas
and connected to the
duodenum through the
• Production of enzymes to break
down fats and proteins