Download Use food products in two ways

 Chapter 16 - Nutrition and
Metabolism
 Nutrition - food (nutrients) we eat
 Need balance - carbohydrates, fats,
proteins (vitamins & minerals)
 Malnutrition - deficiency or imbalance in
consumption of nutrients
 Metabolism - the “use of foods,” after they
have been digested, absorbed, & circulated
to cells
 Use food products in two ways 
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energy source
building blocks for complex chemical
compounds
 Assimilation - occurs when food
molecules enter cells & undergo
chemical changes
 Catabolism - chemical reactions that
release energy from food

body’s only source of energy
 Anabolism - chemical reactions that build
food molecules into more complex
chemical compounds
 Role of the Liver 
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Bile -secreted to help move fats (lipids)
Help maintain normal glucose conc.
Synthesize blood proteins (plasma proteins prothrombin, fibrinogen, albumin)
Detoxifies bacterial products & some drugs
Stores iron, Vitamin A & D
Blood flow from GI tract goes to liver 1st
 Carbohydrate Metabolism 
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Preferred energy source
Compound made of glucose which body likes
to use 1st for energy
 Three series of chemical reactions that occur
in sequence for catabolism of glucose:
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1. Glycolysis - changes glucose to pyruvic acid
(in cytoplasm), anaerobic, energy is released
2. Citric acid cycle - pyruvic acid to carbon
dioxide (in mitochondria), aerobic, energy is
released
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3. Electron transfer system • Located in mitochondria
• Transfers most of glucose energy to ATP
(adenosine triphosphate), some as heat
• ATP - served as direct energy source for
cellular work in all living organisms
• ATP - not stored - used almost immediately
• When ATP used - it changes to a reusable form
(ADP) & releases energy - ADP attached to
more carbohydrate breakdown products >
forms more ATP
• Only enough ATP is produced to met cellular
 Glycogenesis - glucose anabolism
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Occurs in liver & muscle cells
Process of joining glucose molecules
together > glycogen (animal starch)
 Constant Glucose Blood Levels 
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Stays between 70 - 110 mg / 100ml blood
(even if we have or have not eaten)
Hormones help regulate carbohydrate
metabolism to control blood glucose
• Insulin - helps glucose into cells (<
blood levels)
 Fat Metabolism 
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Also primary source of energy
Used if glucose not available - fats can goes into
citric acid cycle for energy
If not needed - anabolized to form triglycerides stored in adipose tissue
 Protein Metabolism 
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Used for energy only in very small amounts
(normally)
Anabolism - amino acids (20) used to make
proteins (Essential - must be in diet, Nonessentialcan be missing from diet, body can make)
 Vitamins 
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Organic compounds needed in small amt.
for normal metabolism throughout the
body
Make enzymes work properly
Most are not made in body (must come
from diet)
Body stores fat-soluble Vit. -A, D, E, K
in the liver
Water-soluble (Vit. Bs, C) - need
continuous supply from diet
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Avitaminosis - deficiency of vitamins
• Scurvy - deficiency Of Vit. C, < collagen
fiber production & maintenance = body
falls apart (connective tissue problems)
Hypervitaminosis - vitamin excess
• Vit. A - Hair loss, skin dry, anoxexia,
vomiting
• More common with fat-soluble vit.
 Minerals - inorganic elements or salts
found naturally in the earth - proper amt.
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Enzymes activation, many chemical reactions
(Na & Ca: muscle & nerve conduction)
 Metabolic Rates  Basal metabolic rate (BMR) - rate at
which food is catabolized under basal
conditions (resting but awake, not
digesting food, not adjusting to temp.)
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Number of calories of heat that must be
produced per hour by catabolism to keep
body alive, awake, & comfortably warm
 Total metabolic rate (TMR) - total amt.
of energy used by body / day
 Calories = TMB (no weight gain)
 Body Temperature 
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60% energy from food > heat (not ATP)
Hypothalamus regulates body temp.by negative
feedback mechanisms (^ temp. > more blood to
skin)
Normal 97-100 degrees F
Heat lost from skin:
• Radiation - flow of heat away from blood
• Conduction - transfer to skin > external envir.
• Convection - transfer to air(flowing away from skin)
• Evaporation - water (sweat) vaporization
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Heat Conserved - vasoconstriction