Download Organs of the Digestive System

Organs of the Digestive System
The digestive system is generally divided into two main categories:
organs of the alimentary canal (aliment = “nourish”) and accessory
digestive organs. The alimentary canal, also called the gastrointestinal (GI)
tract or gut, is a continuous muscular tube that runs from the mouth to
the anus. The internal space of this tube is called the lumen. The GI tract
is involved with the digestion of food –its breakdown into smaller
fragments – and the absorption of digested food fragments from the
lument through the alimentary canal wall and into the bloodstream. The
accessory digestive organs contribute to secretions to the GI tract, but
the food doesn't pass through these organs.
Digestive System organs. This work by Cenveo is licensed under a Creative Commons Attribution 3.0 United
States .
Different digestive system organs are responsible for different digestive
processes and functions. These functions include: extracting nutrients
from food and removing waste. The processes by which these occur are
called ingestion, motility of
food
through
the
GI
tract
lumen, mehcanical and chemical digestionof the food, absorption and
breakdown of products, defecation to remove residues.
Organ
Major Functions
Other Functions
Mouth
Ingests food; Mechanical
chewing of food; Salivary
amylase begins chemical
breakdown of starch;
Swallows food and propels
it into pharynx
Salivary mucus
Pharynx
Propels bolus from oral
cavity to esophagus
Mucus lubricates
food passageways
Esophagus
Peristaltic waves
propel
food bolus to stomach
Mucus lubricates
food passageways
Stomach
Peristaltic waves combine
food withgastric juice and
move it into
theduodenum; Pepsin begins
protein digestion; Absorbs
some fat-soluble
substances (e.g., alcohol,
aspirin)
Hydrochloric
helps
dissolve food;
Release of flavors
stimulates tastebuds
allowing us to
appreciate its
taste; Saliva moistens
food, and tongue
helps create
a bolus that can be
swallowed; Saliva
cleans and lubricates
the teeth and oral
cavity
neutralizes
ingested pathogens
and stimulates
protein-digesting
enzymes; Mucus
lubricates and
protects the
stomach; Intrinsic
acid
Organ
Major Functions
Other Functions
allows vitamin
B12 to be absorbed
in intestines
factor
Small
intestine
Mixes contents with
digestive juices for
digestion and
absorption;Brush-border
enzymes digest food;
Absorbs breakdown
products of
carbohydrates, protein,
fat, and nucleic acid
digestion, along with
vitamins, water, and
electrolytes
Alkaline mucus
helps
Large
intestine
Enteric bacteria
digest some
food residue and vitamins;
Absorbs most residual
water, electrolytes, and
vitamins produced by
enteric bacteria; Propels
feces toward
rectum; Defecation reflex
eliminates feces
Residues are
concentrated and
temporarily stored
prior to defecation;
Mucus smoothes
passage of feces
through colon
neutralize
acidic chymefrom the
stomach
Organ
Major Functions
Other Functions
Accessory
organs
Liver: produces bile; Gall
bladder: stores and
concentrates
bile; Pancreas: produces
enzymes that digests food
Gall bladder releases
bile, which
emulsifies fat and
stimulates the
digestion of fat and
the absorption of
fatty acids,
monoglycerides,
cholesterol,
phospholipids, and
fat-soluble vitamins;
Bicarbonaterich pancreatic
juice helps neutralize
acidic chyme (from
the stomach) and
provide optimal
environment for
enzymatic activity