THE NUTRITION FUNCTION I.
The digestive system.
The nutrition function.
Taking in of nutrients (found in food) which are
organic substances and mineral ions, containing
raw materials or energy for growth and tissue
repair, absorbing and assimilating them.
In multicellular organisms, several systems take
part in this function.
Endocrine and nervous
system also participate.
Digestive System Processes.
Ingestion : Intake of food into the body through
Digestion: The process of break-down of
large, insoluble food molecules into small, water
soluble molecules using mechanical and chemical
Absorption : The process of passing digested food
molecules across the wall of the intestine into the
blood or lymph.
Assimilation : The movement of digested food
molecules into the cells of the body where they are
used, becoming part of the cells.
Egestion : Passing out of undigested food, in
the form of faeces, through the anus.
Enzymatic reactions to
improve digestion of
Digestive System Organization
• Accessory glands.
Digestive System Organization
– Direct link/path between
– Shape varies.
– Secrete mucus (ˈmjuːkəs) or
• Small intestine
• Large Intestine
Digestive System Organization.
Not part of the path of
food, but play a critical
liver, gall bladder, and
Epiglottis is a
structure at the
back of the
closes over the
CHEWING: Teeth mechanically break down food into
SALIVATION: Tongue mixes food with saliva (contains
amylase (ˈæmɪleɪz), which helps break down starch).
SWALLOWING: the tongue push the bolus towards the
Saliva (səˈlaɪvə) is a
watery liquid released
by salivary glands.
Starts digestion of
Eases the bolus into
It is a common passageway for air and food.
It participates in swallowing
2.Moves food from the
throat to the stomach
If acid from the
stomach gets in here
(cardia at the entering
of the stomach stops
J-shaped muscular bag that stores the food
you eat, and digests it.
Mixes food with digestive juices that
contain enzymes to break down proteins
(pepsine) and lipids.
HYDROCHLORIC ACID in the stomach
kills bacteria, and supports enzyme’s work.
It absorbs water, alcohol and some drugs.
Food in the stomach is called chyme
(kaɪm), once it has mixed with gastric
The stomach takes around 4 hours to do it’s
job on the food, depending on what kinds
of food are digested.
Small intestines are roughly 7
meters long, finishing in the
Intestine walls have finger-like
projections called villi, to increase
The villi are covered in microvilli
which further increases surface
Nutrients from the food pass into the bloodstream through
the small intestine walls.
Establishes an optimal pH for
Secretes digestive enzymes.
80% ingested water.
When the chyme mixes with intestinal
juices, and secretions from liver and
pancreas, it transforms into chyle (kaɪl).
The first part of
Bile juice from
Directly affects digestion by
Bile helps digest fat.
• Filters out toxins and waste including
drugs and alcohol.
Bile does not contains any enzymes.
Bile contains bile salts which acts on
Bile salts break fats up into smaller fat
droplets which can be more easily
digested by lipase.23
Stores bile from the
liver, releases it into
the small intestine.
Bile is realeased
through the ampulla of
Fatty diets can cause
enzymes to digest
Regulates blood sugar
by producing insulin, a
Pancreatic juice also
neutralizes the acid
liquid from the
After digestion, simpler molecules are obtained:
Glycerol and fatty acids.
Those nutrients are absorbed through the small
intestine inner layer. Capillaries collect them.
About 1’5 m long.
Accepts what small intestines
Absorbs more water.
Portions of the large intestine,
The rectum is the short term storage which holds
feces before it is expelled).
Write the name of each colored organ:
How’d you do?
Pink: Small Intestine
Brown: Large Intestine
Green: Gall Bladder
References and Links
Inner body: http://www.innerbody.com/
Your Digestive System and How It Works
Digestive system diagram comes from this site
The Real Deal on the Digestive System
Pancreas: Introduction and Index
Your Gross and Cool Body - Digestive System