nutrition and metabolism dietary sources of major nutrients basics of cellular respiration ...
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Nutrition and Metabolism Dietary Sources of Major
Nutrients
Basics of Cellular Respiration
Metabolism of Carbos, Fats, and Protein
Central Role of the Liver in Digestion/Metabolism
Cholesterol and Lipid Transport
Absorptive and Postabsorptive States
Developmental Aspects of Metabolism
Sources of Nutrients in the Diet
Macronutrients: Carbohydrates, Protein, Lipids, H2O
Micronutrients: Vitamins, Minerals
Major protein source
some vitamins
Major source of vitamins & minerals
Major source of carbohydrates & B vitamins
Major source of minerals and
vitamins A and D, some protein
Major source of lipids and
fat soluble vitamins A,D,E, K
Figure 24.1b
Red meat, butter:use sparingly
Vegetables inabundance
Whole-grainfoods atmost meals
Daily excercise and weight control
(b) Healthy eating pyramid
Dairy or calcium supplement: 1–2 servings
White rice, white bread,potatoes, pasta, sweets:
use sparingly
Fish, poultry, eggs:0–2 servings
Nuts, legumes:1–3 servings
Fruits:2–3 servings
Plant oilsat most
meals
Nutrition and Metabolism Dietary Sources of Major
Nutrients
Basics of Cellular Respiration
Metabolism of Carbos, Fats, and Protein
Central Role of the Liver in Digestion/Metabolism
Cholesterol and Lipid Transport
Absorptive and Postabsorptive States
Developmental Aspects of Metabolism
In biological systems, the electrons are often associated with hydrogen atoms. Biological oxidations are often dehydrogenations.
Oxidation-Reduction is Important in Energy Production
Figure 5.10
Sugars, amino acids, fatty acids
Or FAD+ FADH2
The Energy Stored in ATP Can Be Used to Perform Work in the Cell
• The energy released by ATP breaking down into ADP and P can power a variety of needs in the cell
ADP P
PADP
Energized ATP:
Discharged ATP:
X Y+Z
Powering the synthesis of molecule Z by coupling oxidation to reduction:
Metabolic Pathways Involved in Cellular Respiration
Overall Equation for Cellular Respiration
34
An oxidation of glucose to reduce ADP to ATP
glucose
NAD
NADH2 pyruvates
mitochondrion
Cell membrane
CO2
CO2
CO2
O2
Glycolysis
Krebs Cycle
H 2OATP fuels
construction/synthesis reactions inside the cell
Acetyl CoA
4 ATP(substrate-
level phosphorylat
ion)
2 ATP(substrate-level phosphorylation)
30 ATP(oxidative
phosphorylation)
ATP Synthase
ElectronTransportChain and ATP Synthase
Linking Step
C6H12O6 + O2 CO2 + H2O + 34ATP sugar oxygen carbon dioxide water usable energy
Aerobic Cellular Respiration
Nutrition and Metabolism Dietary Sources of Major
Nutrients
Basics of Cellular Respiration
Metabolism of the Three Macronutrients: Carbohydrates, Fats, and Protein
Central Role of the Liver in Digestion/Metabolism
Cholesterol and Lipid Transport
Absorptive and Postabsorptive States
Developmental Aspects of Metabolism
Fat Metabolism
acetone and
acetoacetic acid =
ketosis/acid-osis
in
liver
Body cells remove fat and cholesterol to build membranes, steroid hormones, adipose cells, and myelin sheaths
Oxidation of Fats (ß-Oxidation) for ATP
• Fat catabolism yields 9 kcal per gram (vs 4 kcal per gram of carbohydrate or protein)
• Fats must first be broken down to acetic acid, then in mito. to H2O, CO2, and ATP
• Ketones (acetoacetic acid and acetone can accumulate, producing acidosis/ketosis)
Fat metabolism handled mostly by the liver
• Some fats used to make ATP
• Used to synthesize lipoproteins, thromboplastin, and cholesterol
• Release breakdown products to the blood
Protein Metabolism
deamination
urea
Figure 24.3
Stage 1 Digestion in GI tract lumen to absorbable forms.Transport via blood totissue cells.
Stage 2 Anabolism (incorporation into molecules) and catabolism of nutrients to form intermediates within tissue cells.
Stage 3 Oxidative breakdown of products of stage 2 in mitochondria of tissue cells. CO2 is liberated, and H atoms removed are ultimately delivered to molecular oxygen, formingwater. Some energy released isused to form ATP.
Catabolic reactionsAnabolic reactions
Glycogen
PROTEINS
Proteins Fats
CARBOHYDRATES
Glucose
FATS
Amino acids Glucose and other sugars Glycerol Fatty acids
Pyruvic acid
Acetyl CoA
Infrequent CO2
NH3
H
Krebscycle
Oxidativephosphorylation
(in electron transport chain)
O2
H2O
Three Macronutrients Used for ATP Production
Nutrition and Metabolism Dietary Sources of Major
Nutrients
Basics of Cellular Respiration
Metabolism of Carbos, Fats, and Protein
Central Role of the Liver in Digestion/Metabolism
Cholesterol and Lipid Transport
Absorptive and Postabsorptive States
Developmental Aspects of Metabolism
Role of the Liver in Metabolism
Produces blood proteins (albumin, clotting proteins) and lipoproteins Degrades hormones
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Liver Modifications on Glucose Levels Glycogenesis (making glycogen)
• Glucose molecules are converted to glycogen
• Glycogen molecules are stored in the liver
Glycogenolysis (breaking glycogen)
• Glucose is released from the liver after conversion from glycogen
Gluconeogenesis (rebuilding glucose)
• Glucose is produced from amino acids and glycerol
• Protects against damaging effects of hypoglycemia
Roles of Cholesterol in the Body
Vitamin D synthesis
Keeping membranes fluid
Steroid Hormone Synthesis
Cholesterol Transport Cholesterol and fatty acids cannot freely circulate in
the bloodstream
They are transported by chylomicron lipoproteins (lipid-protein complexes)
• Low-density lipoproteins (LDLs) transport cholesterol to body cells; are increased by dietary saturated and trans-fat
Triglycerides broken down by fat and muscle tissue (lipoprotein lipase) into fatty acids and glycerol
• High-density lipoproteins (HDLs) transport from body cells to the liver for breakdown; are increased by exercise, and limited coffee, smoking, and saturated fats/trans fats
Healthy Ratios in the Blood
• Total Cholesterol/HDL < 5
• LDL/HDL < 2.5
Total cholesterol (mg/dL)Under 200 - desirable 200-239 - borderline highOver 240 - highLDL cholesterol (mg/dL)Below 100 - optimal100-129 - near optimal130-159 - borderline high160-189 - highAbove 190 - very highHDL cholesterol (mg/dL)Below 40 - low60 or above - high
Nutrition and Metabolism Dietary Sources of Major
Nutrients
Basics of Cellular Respiration
Metabolism of Carbos, Fats, and Protein
Central Role of the Liver in Digestion/Metabolism
Cholesterol and Lipid Transport
Absorptive and Postabsorptive States
Developmental Aspects of Metabolism
Absorptive and Postabsorptive States Absorptive (fed) state
• During and shortly after eating; absorption of nutrients
• Muscle and fat tissue: lipoprotein lipase hydrolyzes lipids of chylomicrons in muscle and fat tissues; most glycerol and fatty acids are converted to triglycerides for storage
• Liver: Excess amino acids are deaminated and used for ATP synthesis or stored as fat in the liver
• Insulin facilitates glucose uptake, glycogenesis, triglyceride genesis, and protein synthesis
Postabsorptive (fasting) state
• When the GI tract is empty; energy sources are supplied by breakdown of reserves
• Liver: lipolysis, glycerol then fuels glycogenolysis
• Skeletal muscle: glycogenolysis; protein catabolism if starving
• Fat tissue: lipolysis tissues and the liver
• Glucagon facilitates glycogenolysis and gluconeogenesis in the liver, fat tissue lipolysis
Developmental Aspects of the Digestive System Fetal Development
• The alimentary canal is a continuous tube by the fifth week of development
• Digestive glands bud from the mucosa of the alimentary tube
• The developing fetus receives all nutrients through the placenta
Birth and Infancy
• In newborns, feeding must be frequent, peristalsis is inefficient, and vomiting is common
• Congenital conditions include cleft palate, phenylketonuria, tracheoesophageal fistula
• Teething (eruption of teeth) begins around age six months
Metabolism decreases with old age
Middle age digestive problems
• Ulcers
• Gall bladder problems
Old Age
• Fewer digestive juices
• Peristalsis slows
• Diverticulosis and cancer are more common
brain damage and
retardation in infancy
Tracheoesophageal Fistula
PKU
Nutrition and Metabolism Dietary Sources of Major Nutrients
Basics of Cellular Respiration
Metabolism of Carbos, Fats, and Protein
Central Role of the Liver in Digestion/Metabolism
Cholesterol and Lipid Transport
Absorptive and Postabsorptive States
Developmental Aspects of Metabolism