HOW NUTRIENTS BECOME YOU
Chapter 3
Food Science
FOOD, NUTRIENTS, AND ENERGY
Food plays more roles than satisfying hunger
 The food you eat becomes a part of you
 Nutrients from food are your body’s source of fuel
and building materials
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SIX NUTRIENT GROUPS
There are six groups of nutrients your body needs
 Each nutrient has a specific job to perform for the
body
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Carbohydrates (compound)
Fats (compound)
Proteins (compound)
Vitamins (compound)
Minerals (elements)
Water (compound)
CHEMISTRY OF NUTRITION
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Learning about health and nutrition requires SOME
knowledge of chemistry
Elements: simplest substance from which all matter
is formed
Matter: is anything that takes up space and has a
measurable quantity.
Atom: smallest part of an element that can enter into
a chemical reaction
Molecule: smallest amount of a substance that has
all the characteristics of the substance
Molecules are made up of two or more atoms that are
bonded together
Having some knowledge of chemistry will help you
grasp how nutrients interact in your body
FUNCTIONS OF NUTRIENTS
Build and Repair body tissues
 Regulate all body processes
 Provide energy
 When your body is performing all of these
functions in harmony, your potential for optimum
wellness increases
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Find and highlight on the periodic table the elements essential to human health.
(There are 20).
ENZYMES
In chemical digestion, food is mixed with
powerful acids and enzymes.
 Enzymes: a type of protein produced by cells that
cause specific chemical reactions.
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http://www.youtube.com/watch?v=SyVcyTfOaohttp://www.youtube.com/watch?v=uSkLR50
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THE DIGESTIVE SYSTEM
Digestion is the process by which your body breaks
down food and the nutrients in food, into simpler
substances.
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http://www.youtube.com/watch?v=SyVcyT-fOao
THE PROCESS OF DIGESTION
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Digestion: process by which your body beaks down
food, the nutrients in the food, into simpler
substances. The blood then carries these substances
to the cells to use in growth, repair, and maintenance.
Digestion occurs through mechanical and chemical
means
Mechanical digestion: happens as food is crushed
and churned
Chemical digestion: food is mixed with powerful
acids and enzymes.
Enzymes: type of protein produced by cells that case
specific chemical reactions. i.e. cause food particles to
break apart into simpler substances.
Gastrointestinal (GI) Tract: As food is digested, is
passes through a muscular tube leading from the
mouth to the anus. 25-30 feet in length.
IN THE MOUTH
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Mastication: chewing, first step in the digestive
process, prepares food for swallowing
Chewing food well aids digestion because the body
can break down small food particles faster than large
food particles
About 9,000 taste buds that cover the surface of the
tongue. This taste sensation along with good food
odors and the thought of food triggers salivary glands
in the mouth. (Produces saliva)
Saliva is mixture of about 99% water with a few
chemicals (salivary amylase-found only in the mouth)
helps to digest starches in foods.
Without saliva, your mouth is dry and food seems to
have little taste.
Saliva moistens, softens, and dissolves food. Also
helps to clean teeth and neutralize mouth acids.
IN THE ESOPHAGUS
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As you chew, the muscles in your mouth and tongue form
the food into a small ball. Your tongue moves this ball of
food to the back of your mouth and you swallow.
Tube that helps food pass from the mouth to the stomach
Only one of two tubes in the throat. (Trachea/windpipe) is
the other.
Epiglottis is a flap of skin that keeps the trachea closed
when you swallow and keeps food from entering the
windpipe
Breathing automatically stops when you swallow food to
help prevent choking
Peristalsis: a series of squeezing actions by the muscles in
the esophagus move food through the tube. Peristaltic
action occurs throughout the esophagus and intestine to
help mechanically move and churn food.
STOMACH (GASTRIC)
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When you eat, the stomach produces gastric juices in order to prepare
for the food
Gastric juices: contains hydrochloric acid, digestive enzymes, and
mucus.
Mucus: thick fluid that helps soften and lubricate food (helps prevent
the stomach from its strong acidic juices
Chyme: mixture of gastric juices and chewed food
Acid in the stomach is almost as strong as battery acid found in a car
Protein digestion begins in the stomach
Pepsin: major gastric enzyme that begins to chemically break down
protein
Most people can hold about one quart of food in their stomach
Food generally remains there for 2-3 hours, depending on the type of
food.
Liquids leave before solids
Carbohydrates and proteins digest faster than fats
From the stomach, it moves to the small intestine
SMALL INTESTINE
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95% of digestion occurs in the small intestine
Coiled in the abdomen in circular folds.
3 sections (duodenum-12 inches, the jejunum-4 feet,
and the ileum-5feet).
When stretched, it is about 20 feet in length and 1
inch in diameter.
5-14 hours for food to travel from the mouth through
the small intestine
Needs less acidic environment than the stomach to
perform its work.
Pancreas: long elongated gland behind the stomach,
helps create the correct environment (secretes bonate,
which neutralizes the hydrochloric acid)
Pancreas: Produces digestive enzyme that helps
digestion take place in the small intestine.
SMALL INTESTINE (CONTINUED)
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Liver: involved in the chemical digestion
Large gland above the stomach
 Produces Bile (helps disperse the fat in the waterbased digestive fluids so they can be broken down.
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LARGE INTESTINE
Large Intestine is sometimes called the colon
 About 3-3 ½ Feet long (5 to 6 feet stretched)
 Main job of large intestine is to reabsorb water
 When liquid enters the large intestine, it is
referred to as chyme
 Chyme usually stays in the colon 1-3 days before
being expelled
 Feces: solid wastes that result from digestion
 The end of the large intestine is called the rectum
 Feces is expelled through the anus
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ABSORPTION OF NUTRIENTS
Absorption: passage of the nutrients from the
digestive tract into the circulatory or lymphatic
system
 Villi: tiny, fingerlike projections that give the
lining of the small intestine a velvet-like texture
 Microvilli: microscopic hears that help catch
nutrient particles on villi
 Water soluble nutrients: can be dissolved in
water
 Fat-soluble nutrients: can be dissolved in fat
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METABOLISM
Metabolism: all chemical changes have occurred
and cells produce energy and material needed to
sustain life
 Cells make compounds that are used for energy.
Some are stored for later.
 ATP (adenosine triphosphate): source of
immediate energy fond in muscle tissue.
Chemical break down ATP to release energy
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FACTORS AFFECTING DIGESTION &
ABSORPTION
Eating Habits
 Emotions
 Food Allergies
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Reaction to the immune system to certain proteins
found in food.
Protein that stimulates the immune system to
produce antibodies is called an allergen.
Physical Activity
DIGESTIVE DISORDERS
Diarrhea: frequent expulsion of watery feces
 Constipation: occurs when chyme moves very
slowly through the large intestine
 Indigestion: difficulty in digesting food
 Heartburn: burning pain in the middle of the
chest (has nothing to do with the heart-caused by
acid)
 Ulcer: open sore in the lining of the stomach or
small intestine
 Gallstones: small crystals that form from bile in
the gallbladder
 Diverticulitis: disorder in which many
abnormal pouches form in the intestinal wall
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