lecture 10 nutrition and metabolism
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Lecture 10 nutrition and metabolismTRANSCRIPT
Copyright 2010, John Wiley & Sons, Inc.
Chapter 20
Nutrition and Metabolism
Copyright 2010, John Wiley & Sons, Inc.
Nutrients Nutrients are chemicals the body uses for
growth, maintenance, and repair Essential nutrients: ones needed in the diet
because the body cannot make sufficient amounts to meet body needs.
There are six major types of nutrients: carbohydrates, lipids, proteins, minerals, vitamins, and water.
Copyright 2010, John Wiley & Sons, Inc.
Healthy Eating 4 Cal/ gram for protein or carbohydrate 9 Cal/gram for lipids Experted-suggested dietary calories:
50-60% Calories from carbohydrate Should be <15% monosaccharides
<30% from fats (mostly triglycerides) Should be < 10% from saturated fats
12-15% from protein
Copyright 2010, John Wiley & Sons, Inc.
Guidelines for Healthy Eating Eat a variety of foods Maintain a healthy weight Choose foods low in fat, saturated fat, and
cholesterol Eat plenty of fruits, vegetables, and grains Use sugars in moderation Use sodium in moderation: < 2.3 grams/day Use alcoholic beverages in moderation only:
1 drink/day for women; 2 drinks/day for men
Copyright 2010, John Wiley & Sons, Inc.
My Pyramid Introduced in 2005 by USDA Web: http://www.mypyramid.gov/ Personalized approach to healthy food
choices Based on gender, age, and activity Food from each of 6 bands needed each day Example: healthy, moderately active 18-year-old
Female requires about 2000 Calories/day Male requires about 2800 Calories/day
Steps a reminder of daily activity needed
Copyright 2010, John Wiley & Sons, Inc.
My Pyramid
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Categories of Nutrients Carbohydrates, proteins, lipids
Calories for energy + building materials. Water Minerals
Ca, P, K, S, Na, Cl, Fl, Mg, Fe, Cr, I, Mn, Co, Cu, Zn, Se. Table 21.1
Vitamins: essential or dietary provitamins Lipid-soluble: A, D, E, K Water-soluble: B vitamins and C Functions: Table 20.2
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Categories of Nutrients: Six Carbohydrates, proteins, lipids
Give calories for energy + building materials. Minerals: inorganic (Table 20.1)
Ca, P, K, S, Na, Cl, Fl, Mg, Fe, I, Mn, Co, Cu, Zn, Se, Cr
Electrolytes, components of skeleton, enzymes Vitamins: organic (Table 20.2)
Lipid soluble: A, D, E, K Water soluble: B group, C Many function as coenzymes
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Metabolism Facilitated by enzymes and coenzymes
NAD+ from B vitamin niacin FAD from riboflavin (B2)
Sequence of enzymatic steps is a pathway Two categories
Anabolism: synthesis of more complex chemicals Catabolism: breakdown with energy release
40% cellular functions (ATP) 60% heat
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Metabolism
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MetabolismInteractions Animation
Introduction to Metabolism
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Metabolism
Copyright 2010, John Wiley & Sons, Inc.
Carbohydrate Metabolism Glucose: the body’s preferred source for ATP
production Possible uses of glucose
Used immediately for ATP production Stored as glycogen in liver or skeletal muscle Leftover: forms triglycerides in adipose tissue
Enters cells by facilitated diffusion Insulin increases rate of transport
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Glucose Catabolism Overall catabolism of glucose
Glucose + 6 O2 36-38 ATP + 6 CO2 + 6 H2O 1. Glycolysis (in cytosol)
Glucose pyruvate + ATP + NADH + H+
Anaerobic cellular respiration2. Transition step (in mitochondria):
Pyruvate acetyl CoA + CO2 + NADH + H+ 3. Krebs cycle (in mitochondria): aerobic
CO2 + ATP + NADH + H+ + FADH2 4. Electron transport chain (in mitochondria): aerobic
NADH + H+ + FADH2 + O2 ATP + H2O
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Glucose Anabolism and Regulation of Blood Glucose Levels When blood glucose is high
Glucose + ATP glycogen (in liver, muscle) Effect: blood glucose level is lowered
When blood glucose is low Hormones glucagon and epinephrine stimulate
Glycogen breakdown to glucose Hormones: glucagon and cortisol stimulate
Gluconeogenesis in liver cells by Glycerol (from fat) glucose Some amino acids glucose
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Glucose Anabolism and Regulation of Blood Glucose Levels
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Lipid Metabolism Lipolysis (catabolism): triglycerides
glycerol + fatty acids Glycerol glycolysis or gluconeogenesis Fatty acids acetyl-CoA (2-carbon) Krebs
cyle ATP Liver converts some acetyl-CoA ketone bodies Diabetics can form excessive ketone bodies acetone
(causes sweet breath) + acidosis (with possible coma and death)
Lipogenesis (anabolism) Excess fats, carbohydrates, or proteins fats
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Lipid Metabolism
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Lipid Transport in Blood Lipids are not water soluble so need
protein coating lipoproteins Types of lipoproteins
Chylomicrons: carry dietary fat to adipose Very low-density lipoproteins (VLDL)
Made in liver; transport fat to adipose tissue Converted to LDLs
Low-density lipoproteins (LDL): “bad” Carry 75% of cholesterol to cells for use there
High-density lipoproteins (HDL): “good” Remove excess cholesterol and transport to liver for
disposal
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Protein Metabolism Catabolism: protein breakdown
Deamination in liver to remove NH2 NH3
Liver converts toxic NH3 urea urine Rest of amino acid Krebs cycle ATP
Anabolism: protein synthesis to form many different proteins in the body Essential amino acids (10): must come in diet Nonessential amino acids (10): can be made in
the body by modifications of essential amino acids
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Metabolism and Body Heat Gain Heat is one form of energy Measured in calories
1 calorie (cal) = energy needed to raise 1 g of water 1oC
For foods use kilocalories (1000 cal) = Calorie Heat is produced (gained) from catabolism
Rate of production = metabolic rate Basal metabolic rate (BMR) = heat produced from
catabolism when resting and fasting BMR for adult :1200-1800 Cal/day
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Metabolism and Body Heat Metabolic rate is affected by the following
Exercise: rate can increase 15-20 times Hormones: thyroid is primary Nervous System: ANS can increase Body temperature: warming increases Ingestion of food: gives 10-20% increase Age: metabolic rate of child higher than adult’s Gender, pregnancy, climate, sleep, malnutrition
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Body Heat Loss Must be continuous as catabolism constantly
produces heat Routes of heat loss
Radiation: loss of body heat to air Conduction: loss of body heat to surface, such as
cold metal seat Convection
Loss of body heat to air moving from a fan or from breeze outside shower curtain
Evaporation Conversion of water to vapor as in sweating; helps
prevent overheating with exercise
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Control of Body Temperature Balance regulated by hypothalamus
Detects changes in temperature (“thermostat”) Warming mechanisms
Sympathetic vasoconstriction heat loss Epinephrine metabolism Increased muscle tone metabolism
Can lead to shivering heat from muscles TSH thyroid gland thyroid hormone in
blood metabolism Cooling mechanisms
The reverse + sympathetic-stimulated sweating
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End of Chapter 20
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