Download Chapter 25

Anatomy and Physiology, Sixth Edition
Rod R. Seeley
Idaho State University
Trent D. Stephens
Idaho State University
Philip Tate
Phoenix College
Chapter 25
Lecture Outline*
*See PowerPoint Image Slides for all figures and tables pre-inserted into PowerPoint without notes.
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Chapter 25
Nutrition, Metabolism,
Temperature Regulation
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Nutrients
• Chemicals used by body
• Classes
– Carbohydrates, proteins,
lipids, vitamins, minerals,
water
• Food Guide Pyramid
– USDA recommends
• Kilocalories
– Measure of energy supplied
by food and released through
metabolism
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Carbohydrates
• Monosaccharides
– Include glucose, fructose, galactose
• Disaccharides
– Include sucrose, maltose, lactose
• Polysaccharides (complex)
– Include starch, glycogen, cellulose
• Disaccharides and Polysaccharides
– Converted to glucose (used for energy or stored
as glycogen or fats)
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Lipids
• Triglycerides (95%): Used for energy to
produce ATP or stored in adipose tissue, liver
– Saturated fats: Meat fats, whole milk, cheese, eggs
– Unsaturated fats: Olive and peanut oil
• Cholesterol: Steroid found in liver, egg yolks
but not found in plants
• Phospholipids: Major components of plasma
membranes
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Proteins
• Chains of amino acids
– Kinds
• Essential: Must be obtained in diet
• Nonessential: Body can synthesize
• Functions
– Protection (antibodies), regulation (enzymes,
hormones), structure (collagen), muscle
contraction (actin, myosin), transportation
(hemoglobin, ion channels)
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Recommended Amounts
• Carbohydrates
– 60% of daily intake of kilocalories
• Lipids
– 30% or less of total daily kilocalories
• Proteins
– 10% of total kilocalories per day
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Vitamins
• Function as coenzymes or parts of coenzymes
• Organic molecules that exist in minute
quantities in food
– Essential vitamins must be obtained by diet
• Classifications
– Fat soluble: Vitamins A,D,E,K
– Water-soluble: B and C
25-8
Minerals
• Inorganic
• Necessary for normal metabolic functions
• Functions
– Establish resting membrane potentials, generate
action potentials, add strength to bones and
teeth, buffers, involved in osmotic balance
• Obtained from animal and plant sources
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Metabolism
• Total of all chemical changes that occur in
body
– Anabolism: Energy-requiring process where
small molecules joined to form larger
molecules
– Catabolism: Energy-releasing process where
large molecules broken down to smaller
• Energy in carbohydrates, lipids, proteins is
used to produce ATP through oxidationreduction reactions
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Catabolic and Anabolic Reactions
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Cellular Metabolism
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Carbohydrate Metabolism
• Glycolysis
– Breakdown of glucose into 2 pyruvic acid
molecules
• Phases
–
–
–
–
Input of ATP
Sugar cleavage
NADH production
ATP and pyruvic acid production
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Glycolysis
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Glycolysis
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Anaerobic Respiration
• Breakdown of glucose
in absence of oxygen
– Produces 2 molecules
of lactic acid and 2
molecules of ATP
• Phases
– Glycolysis
– Lactic acid formation
• Cori cycle
– Process of converting
lactic acid to glucose
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Aerobic Respiration
• Breakdown of glucose in presence of
oxygen to produce carbon dioxide, water,
38 ATP molecules
– Most of ATP molecules to sustain life are
produced this way
• Phases
– Glycolysis, acetyl-CoA formation, citric acid
cycle, electron-transport chain
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Aerobic Respiration
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Electron-Transport Chain
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Lipid Metabolism
• Adipose triglycerides are
broken down and released
as free fatty acids
• Free fatty acids are taken
up by cells and broken
down by beta-oxidation
into acetyl-CoA which
– Can enter citric acid
cycle
– Can be converted to
ketone bodies
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Protein Metabolism
• New amino acids are formed by
transamination, transfer of an amine group
to keto acid
• Amino acids are used to synthesize
proteins
– If used for energy, ammonia is produced as a
by-product of oxidative deamination
• Ammonia is converted to urea and excreted
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Amino Acid Metabolism
• Once absorbed in body, amino acids quickly taken up by cells
• Amino acids are used to synthesize proteins or as a source of energy
• Amino acids not stored in body
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Amino Acid Reactions
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Interconversion of Nutrient
Molecules
• Glycogenesis
– Excess glucose used to form glycogen
• Lipogenesis
– When glycogen stores filled, glucose and amino acids
used to synthesize lipids
• Glycogenolysis
– Breakdown of glycogen to glucose
• Gluconeogenesis
– Formation of glucose from amino acids and glycerol
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Interconversion of Nutrient
Molecules
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Metabolic States
• Absorptive state
– Period immediately after eating when nutrients
absorbed through intestinal wall into circulatory
and lymphatic systems (about 4 hours after
each meal)
• Postabsorptive state
– Occurs late in morning, afternoon, night after
absorptive state concluded
– Blood glucose levels maintained by conversion
of other molecules to glucose
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Absorptive State
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Postabsorptive State
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Metabolic Rate
• Total amount of energy produced and used
by body per unit of time
– Estimated by amount of oxygen used per minute
• Components
– Basal metabolic rate
• Energy used at rest, 60% of metabolic rate
– Thermic effect of food
• Energy used to digest and absorb food, 10%
– Muscular activity
• Energy used for muscle contraction, 30%
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Body Temperature Regulation
• A balance between heat gain and loss
– Heat is produced through metabolism
– Heat is exchanged through radiation,
conduction, convection, evaporation
• The greater the temperature difference
between body and environment, the greater
the rate of heat exchange
• Regulated by a “set point” in hypothalamus
25-30
Heat Exchange
25-31
Temperature Regulation
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