Nutrition is the study of how food affects
the function of living organisms.
Food contains nutrients.
Nutrients provide the energy and materials
If organism’s cells are not provided with
nutrients, the cells will not function
Poor diet = poor cells
Six Categories of Nutrients
Glucose is main source of carbohydrates
Glucose is easily converted to ATP.
Glucose is found in fruits, vegetables,
grains, and dairy foods.
Many foods contain cellulose also known
as “fiber.” Important for helping push food
through the digestive tract.
Energy from food is measured in
Provide twice as much energy as carbohydrates.
1) Making cell membranes
2) Hormone production
3) Myelin production
4) Protect organs and insulate body
Take long time to digest.
Too much fat in diet= excess energy = fat
Saturated fats (solid, contain single bonds)
contain LDL cholesterol and build up on arteries.
Proteins made of amino acids.
20 different amino acids.
Body can make 12/20 amino acids.
The other eight must come from food are
called “essential amino acids.”
Proteins are materials needed for…
1) growth and repair.
2) skin and muscles.
3) regulatory (enzymes- insulin) and transport
functions (hemoglobin– RBC).
Most important nutrient.
Lubricates areas of body (blood, lymph,
Coolant for body.
Solvent for digestion.
Provides fluid environment for cells.
Body needs intake 1L of water a day.
Inorganic (not made by living things).
Plants absorb minerals.
Animals eat plants to get minerals.
Minerals are only needed in trace amounts
by the body.
Iron (hemoglobin RBC)
Calcium (bones and teeth)
Sodium/Potassium (nerve and muscle
Organic (made by living things).
Help regulate body processes.
Most obtained from food.
Vitamin K- made by bacteria in digestive tract.
Vitamin D- synthesized by skin cells when
exposed to sunlight.
2 types vitamins…
1) Fat soluble- can be stored in fatty
tissues for future use (A, D, E, K)
2) Water soluble- dissolve in water and can
not be stored by body (C, B)
Importance of Various Vitamins
A, C, D, E, K, Folic Acid, B12
Helps RBC mature
The Digestive System
System is responsible for breaking down food
so that nutrients can be absorbed by the
The “alimentary canal” is the pathway which
food travels while it is digested.
The Alimentary Canal
* The liver, pancreas, and gallbladder are parts of
the digestive system but are not parts of the
Chemical digestion –saliva contains
enzyme amylase that digests
Mechanical digestion- chewing
Tube from back throat
Trachea (lungs) and
esophagus are next to
Epiglottis prevents food
from going down the
food down esophagus.
Hydrochloric acid and
pepsin (enzyme) break
down proteins to
Stomach lining contains
Mucus protects stomach
from acid (ulcers).
Sphincter muscles (cardiac
and pyloric) control what
enters and leaves the
and proteins are broken
All lipids are digested here.
Connected to liver and
Liver and Pancreas
Makes and secretes
bile (needed digest
Bile is stored in the
Detoxifies drugs and
enzymes into small
acid as it enters the
Small Intestine (cont.)
After all nutrients are
digested, they are
absorbed. This is the
major job of this
S.I. contains lots of
lipids have been
removed from food by
the time it gets here.
Water is absorbed
Vitamins are absorbed.
Feces is undigested
food passes out rectum