Download Human Digestion

Nutrition
Why do we eat?
 The foods we eat provide the nutrients our
bodies need for energy, growth, and tissue
repair.
 Digestion is the process of breaking down
food in order to extract the nutrients and
make them useable by the body.
Types of Nutrients
(You should know these!)
 Micronutrients- vitamins & minerals
 Macronutrients- proteins, fats, carbohydrates
And water…
Four Stages of Digestion
1. Ingestion
2. Digestion
3. Absorption
4. Egestion
Four Stages of Digestion
1. Ingestion
taking substances into the body
through the mouth
2. Digestion
3. Absorption
4. Egestion
Four Stages of Digestion
1. Ingestion
2. Digestion
The breaking-down of large, insoluble
food molecules into small water-soluble
molecules.
3. Absorption
4. Egestion
Digestion…
begins in the mouth
1)MECHANICAL DIGESTION
The teeth breaks up food &
the tongue moves it around
Digestion…
begins in the mouth
2) CHEMICAL DIGESTION
saliva
amylase: an enzyme that
digests starch
mucin: a protein present in
mucus that protects soft lining of digestive system
and lubricates food for easier swallowing
buffers: neutralize acid to prevent tooth decay
anti-bacterial chemicals: kill bacteria that enter
mouth with food
Which type of digestion is the
following?
1.
Chewing a saltine? -
2. Saliva breaking the saltine down into molecules of
glucose? 3. Your tongue breaking pieces of a hamburger apart?
4. Pepsin (an enzyme) in your stomach breaking the
hamburger into amino acids?
Digestion…
then moves to the esophagus
 The esophagus
is a muscular
tube that carries
food and liquids
from the mouth
to the stomach.
Esophagus
Food moves through the
Esophagus to the
Stomach by Peristalsis
 Peristalsis: a series of
involuntary wave-like
muscle contractions
which move food along
the digestive tract
Digestion…
then moves to the stomach
The stomach stores
swallowed food and
liquid, mixes the food
and liquid with
digestive juice it
produces, and slowly
empties its contents,
called chyme, into the
small intestine.
Four Stages of Digestion
1. Ingestion
2. Digestion
3. Absorption
movement of digested food molecules
through the wall of the intestine into
the blood
4. Egestion
Absorption…
begins in the small intestine
 The walls of the
small intestine
absorb the digested
nutrients into the
bloodstream. The
blood delivers the
nutrients to the rest
of the body.
Small intestine
Structure: 3 sections
1. duodenum = mostly digestion
2. jejunum = absorption of
nutrients & water
3. ileum = absorption of
nutrients & water
Absorption…
and finishes in the large intestine
 The large intestine
absorbs water and
any remaining
nutrients and
changes the waste
from liquid into
stool.
Rectum
Last section of colon (large intestine)
Stores feces (undigested material) for
elimination
 mainly cellulose
from plants
 roughage or fiber
Four Stages of Digestion
1. Ingestion
2. Digestion
3. Absorption
4. Egestion
passing out of food that has not been
digested, as feces, through the anus
Egestion…
The elimination or
removal of
undigested or waste
material from a cell
or organism.