3. Chemical Reactions in theChemical Reactions in the
BodyBody
• Energy metabolism
• How body obtains & uses energy from food
• Cells
• Liver cells
• Anabolism
• Requires energy
• Catabolism
• Releases energy
6. Chemical Reactions in theChemical Reactions in the
BodyBody
• Transfer of energy in reactions – ATP
• Released during breakdown of glucose, fatty
acids, and amino acids
• Form of phosphate groups
• Negative charge – vulnerable to hydrolysis
• Provides energy for all cell activities
• Coupled reactions
• Efficiency
• Heat loss
8. Chemical Reactions in theChemical Reactions in the
BodyBody
• Enzymes
• Facilitators of metabolic reactions
• Coenzymes
• Organic
• Associate with enzymes
• Without coenzyme, an enzyme cannot
function
9. Breaking Down Nutrients forBreaking Down Nutrients for
EnergyEnergy
• Digestion
• Carbohydrates – glucose (& other
monosaccharides)
• Fats (triglycerides) – glycerol and fatty acids
• Proteins – amino acids
• Molecules of glucose, glycerol, amino acids,
and fatty acids
• Catabolism
• Carbon, nitrogen, oxygen, hydrogen
10. Breaking Down Nutrients forBreaking Down Nutrients for
EnergyEnergy
• Two new compounds
• Pyruvate
• 3-carbon structure
• Can be used to make glucose
• Acetyl CoA
• 2-carbon structure
• Cannot be used to make glucose
• TCA cycle and electron transport chain
11. Simplified Overview of Energy-Simplified Overview of Energy-
Yielding PathwaysYielding Pathways
12. Breaking Down Nutrients forBreaking Down Nutrients for
Energy – GlucoseEnergy – Glucose
• Glucose-to-pyruvate
• Glycolysis
• 2 pyruvate molecules
• Hydrogen atoms carried to electron transport
chain
• Pyruvate can be converted back to glucose
• Liver cells and kidneys (to some extent)
13.
14. Breaking Down Nutrients forBreaking Down Nutrients for
Energy – GlucoseEnergy – Glucose
• Pyruvate’s options
• Quick energy needs – anaerobic
• Pyruvate to lactate
• Slower energy needs – aerobic
• Pyruvate to acetyl CoA
15. Breaking Down Nutrients forBreaking Down Nutrients for
Energy – GlucoseEnergy – Glucose
• Pyruvate-to-lactate
• Pyruvate accepts hydrogens
• Converts pyruvate to lactate
• Occurs to a limited extent at rest
• Produces ATP quickly
• Mitochondrial ability
• Accumulation of lactate in muscles
• Effects
• Cori cycle
17. Breaking Down Nutrients forBreaking Down Nutrients for
Energy – GlucoseEnergy – Glucose
• Pyruvate-to-Acetyl CoA
• Pyruvate enters mitochondria of cell
• Carbon removed – becomes carbon dioxide
• 2-carbon compound joins with CoA becoming
acetyl CoA – irreversible
• Acetyl CoA pathways
21. Breaking Down Nutrients forBreaking Down Nutrients for
Energy – Glycerol & Fatty AcidsEnergy – Glycerol & Fatty Acids
• Glycerol-to-pyruvate
• Glycerol can be converted
• Glucose
• Pyruvate
• Fatty acids-to-Acetyl CoA
• Fatty acid oxidation
• 2-carbon units at a time then join with CoA
• Hydrogens and electrons carried to electron
transport chain
23. Fats Enter the Energy PathwayFats Enter the Energy Pathway
24. Breaking Down Nutrients forBreaking Down Nutrients for
Energy – Amino AcidsEnergy – Amino Acids
• Deamination of amino acids
• Amino acids-to-energy
• Several entry points in energy pathway
• Converted to pyruvate (glucogenic)
• Converted to acetyl CoA (ketogenic)
• Enter TCA cycle directly (glucogenic)
• Amino acids-to-glucose
26. Final Steps of EnergyFinal Steps of Energy
MetabolismMetabolism
• TCA Cycle
• Inner compartment of mitochondria
• Circular path
• Acetyl CoA
• Oxaloacetate – made primarily from pyruvate
• Carbon dioxide release
• Hydrogen atoms and their electrons
• Niacin and riboflavin
27.
28. Final Steps of EnergyFinal Steps of Energy
MetabolismMetabolism
• Electron transport chain
• Captures energy in ATP
• Series of proteins
• Electron “carriers”
• Inner membrane of mitochondria
• Electrons passed to next carrier
• Join oxygen at end of chain – water released
• ATP synthesis
29. Final Steps of Energy
Metabolism
• kCalorie-per-gram secret
• Fat provides most energy per gram
• Carbon-hydrogen bonds
• More ATP = more kcalories
30.
31. Feasting – Excess EnergyFeasting – Excess Energy
• Metabolism favors fat formation
• Regardless of excess from protein, fat, or
carbohydrates
• Excess protein
• Excess carbohydrate
• Excess fat – most direct and efficient
conversion
• Fuel mix
32. Transition from Feasting toTransition from Feasting to
FastingFasting
• Glucose, glycerol, and fatty acids are used
then stored
• Fasting state draws on these stores
• Glycogen and fat are released
• Basal metabolism
• Fasting versus starving
34. Fasting – Inadequate EnergyFasting – Inadequate Energy
• Carbohydrate, fat, and protein are all
eventually used for energy
• Begin with release of glucose and fatty acids
• Acetyl CoA
• Low blood glucose levels signal
• Fat breakdown
• Release of amino acids from muscles
35. Fasting – Inadequate EnergyFasting – Inadequate Energy
• Adaptation: making glucose
• Nervous system and red blood cells
• Amino acids yielding pyruvate
• Breakdown of body proteins
• Adaptation: creating an alternate fuel
• Use fat to fuel brain
• Ketone bodies
• Slows the rate of body protein breakdown
• Ketosis induces a loss of appetite
37. Energy Balance – FastingEnergy Balance – Fasting
• Adaptation: conserving energy
• Hormones
• Reduces energy output
• Supports weight loss but not fat loss
• Symptoms of starvation
• Physical symptoms
• Psychological symptoms
38. Low-Carbohydrate DietsLow-Carbohydrate Diets
• Metabolism similar to fasting
• Uses glycogen stores first
• Gluconeogenesis when glycogen is depleted
• Body tissues used somewhat even when
protein provided in diet
• Urine monitoring
• Ketosis
41. Alcohol in the BodyAlcohol in the Body
• Potential health
benefits
• Alcohols
• Glycerol
• Ethanol
• Lipid solvents
• Moderation
• Definition of “drink”
• Proof
42. AlcoholAlcohol’s Influence’s Influence
• Alcohol’s special privileges
• No digestion
• Quick absorption
• Slowing absorption
• Stomach
• Alcohol dehydrogenase
• Small intestine
• Priority over nutrients
43. AlcoholAlcohol’s Influence’s Influence
• In the liver
• Liver cells
• First to receive alcohol-laden blood
• Alcohol dehydrogenase
• Disrupts liver activity
• Can permanently change liver cell structure
• Rate of alcohol metabolism
• Acetaldehyde
• Acetate
45. AlcoholAlcohol’s Influence’s Influence
• In the liver
• Niacin coenzyme
• Glycolysis
• TCA cycle
• Electron transport chain
• Development of fatty liver
• Damage to central nervous system
• Inflammation of joints
• Amino acid and protein metabolism
47. AlcoholAlcohol’s Influence’s Influence
• In the liver
• Immune system functioning
• Alcohol interferes with drug metabolism
• Microsomal ethanol-oxidizing system (MEOS)
48. AlcoholAlcohol’s Influence’s Influence
• In the brain
• Sedates inhibitory nerves
• Acts as central nervous system depressant
• Blood alcohol levels and brain responses
• Death of liver and brain cells
• Depression of antidiuretic hormone (ADH)
• Loss of body water
• Loss of important minerals
53. Alcohol’s Damage
• Malnutrition
• Can contribute to body fat and weight gain
• 1 ounce of alcohol represents 0.5 ounce of fat
• Central obesity
• Substituted energy
• 7 kcalories per gram
• Nutrient displacement
• B vitamins
• Wernicke-Korsakoff syndrome
54. AlcoholAlcohol’s Effects’s Effects
• Short-term effects
• Excessive drinking
• Heavy drinking
• Binge drinking
• Long-term effects
• Third leading preventable cause of death in
U.S.
• Sobering up
