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metabolism
- every chemical reaction works to generate ATP
- major reactions are oxidation/reduction reactions
- stored energy is released/transferred to other substances
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oxidation
- electrons or hydrogen ions removed from a molecule
- gives up energy
- generate ATP
- almost all ATP comes from oxidation of food
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reduction
- electrons or hydrogen ions are added to a molecule
- gain energy
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glycogenesis
- production of glycogen from glucose
- anabolic
- glycogen is stored
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glycogenolysis
stored glycogen converted back to glucose
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gluconeogenesis
- glucose forms from non-carbs (usually fat)
- occurs when no glucose is available and all glycogen is used up
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carbohydrate metabolism
- poly/disacharrides -> monosaccharides -> glucose
- gluose enters cell through facilitated diffusion with the help of insulin
- energy needed: glucose oxidized to make ATP
- energy not needed: glucose converted to glycogen and store in liver/skeletal muscle until needed
- glucose releases 36-38 ATP released
- 3 steps: glycolosis, krebs cycle, electron transport chain
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glycolysis
- occur in the cytoplasm outside of the mitochondria
- glucose is split into 2 molecules of pyruvic acid
- can occur aerobically or anaerobically
- controlled by enzymes
- steps 1-3:
- --cell invests 2 ATP
- --glucose (C6-H12-O6) enters cell (facilitated diffusion w/ insulin)
- --glucose is phosphorylated
- --glucose becomes fructose
- --fructose is phosphorylated
- steps 4-5:
- --fructose splits into G3P and DHP
- step 6:
- --G3P and DHP oxidized
- steps 7-10:
- --2 PA (C3) molecules produced
- --4 ATP released (net 2 gained by cell), 32-34 remain
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phosphorylated
a phosphate group attaches to glucose to make it bigger so it cannot slide out of cell
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phosphofructokinase
- enzyme that catalyzes step 3 of glycolysis
- controls the speed of glycolysis
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lactic acid
- if no O2 present, PA becomes lactic acid
- will stay in the cell until O2 is present or will go to the liver to convert back to PA
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acetyl coenzyme A formation
- PA must be converted before entering the Krebs Cycle
- no ATP generated
- steps:
- --PA (C3) is decarboxylized, CO2 is removed
- --C2 acetyl group is formed
- --coenzyme A is added
- --acetyl coenzyme A (C2) is formed
- --32-34 ATP remain
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krebs cycle
- series of oxidation/reduction reactions
- occurs in the outer membrane of the mitochondria
- steps:
- --acetyl coenzyme A (C2) + oxaloacetic acid (C4) -> citric acid (C6)
- --citric acid is oxidized
- --end result - 4C02, 2 GTP (ATP), 6 NADH + H+, 2 FADH
- --6 NADH + H+ and 2 FADH are reduced coenzymes, 30-32 ATP remain
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electron transport chain
- series of reactions where reduced coenzymes release all ATP into the cell
- occurs in inner membrane of mitochondria
- involes electron carrier molecules
- coenzymes release ATP at each turn
- H20 forms at the end
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lipid metabolism
- triglycerides -> fatty acid + glycerol
- glycerol -> G3P -> moves through glycolysis
- fatty acid -> beta oxidations -> acetyl coenzyme A -> enters Krebs Cycle
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ketogenesis
- ketone bodies are formed in the liver from excess acetyl coenzyme A
- condition is called ketosis
- liver eventually converts ketone bodies back into ACOA
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lipogenesis
extra glucose converted to fat
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protein metabolism
- protein -> amino acids
- protein should be the last source for energy
- amino acids must be deaminated
- amino group -> liver -> NH3 (ammonia) -> NH4 (ammonium) -> urea -> pee
- remaining amino acid will enter pre-Krebs
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essential amino acids
- 10 amino acids that the body does not produce
- must come from the diet
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non-essential amino acids
10 amino acids produced by the body
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transamination
the process by with the body produces amino acids
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metabolic rate
production of heat or energy from food
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basal metabolic rate
- measurement of how fast the body breaks down food and generates ATP
- depends on age, surface area, and gender
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homeotherms
- humans maintain a constanst body temp within a range
- temp is lowest in the AM
- heat produced = heat lost
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fever
produce more heat than is lost
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hypothermia
lose more heat than is produced
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heat production
- skeletal muscle contraction: generates most heat
- T4 (thyroxine): increase MR which increases body temp
- SNS stimulation: in emergency, body temp increases
- vasoconstriction: shivering, goose bumps send blood to inside of body
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heat loss
- radiation: body heat transferred to cooler substances NOT in direct contact
- conduction: body heat transferred to cooler substance in direct contact
- convection: body heat transferred to a gas that is a lower temp
- evaporation: body heat transferred to a liquid then a vapor
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