Ch 2: Fuel for Exercise: Quiz 1 Flashcards
Bioenergetics
ATP Formation
Energy
the capacity to perform work
Laws of Thermodynamics
- Energy is never created or destroyed; it only changes from one form to another
- Entropy is always increasing in the universe
2nd Law of Thermodynamics
- Everything tends to disorder. To reorder part of universe, we must put energy into it.
- No system is 100% efficient. Some energy is lost as heat. Heat lost to outside not used productively. We can look at amount of heat produced as the inefficiency of the system.
- We measure energy in the body as a measure of the amount of heat produced in the kilocalorie
1 kilocalorie
energy needed to raise the temperature of 1 kg of water from 14.5 to 15.5 C
Coupled Reactions
- linked reactions, with energy made in one reaction being used to drive a second reaction
- Oxidation-reductions (REDOX) reactions are an important type of coupled reaction
Energy transfer in the body
- occurs via release of energy trapped within chemical bonds of various molecules
- chemical bonds containing relatively large amounts of potential energy are often called “high energy” bonds
- endergonic reactions
- exergonic reactions
- in body, energy is usually released in many small, controlled steps, as opposed to 1 single reaction
endergonic reactions
require energy be added to reactants
exergonic reactions
give off energy
Oxidation
removing an electron from an atom or molecule
Reduction
addition of an electron to an atom or molecule
REDOX
oxidation and reduction always coupled
Often, REDOX reactions involve the transfer of H+ atoms rather than free electrons.
- hydrogen atom contains 1 electron, so an atom or molecule that loses a hydrogen atom loses an electron and is oxidized, the molecule that gains the hydrogen (and electron) is reduced.
- two molecules play important roles in the transfer of hydrogens, NAD+ and FAD+. Reduced forms are NADH+, H+ and FADH2
Enzymes
- speed up chemical reactions by lowering activation energy
- “Lock and Key Mechanism”
- not used up in reaction
- enzyme activity measured by rate at which substrates converted to products (influenced by several factors, especially temperature and pH)
Catabolism
big molecule to small molecules
Anabolism
small molecules to big molecule
Coenzyme
- complex, non-protein, organic molecules that associate closely with an enzyme
- an enzyme dependent on a coenzyme will not function optimally without enough coenzyme.
- B vitamins and Mg+ are coenzymes for many enzymes of carbohydrate, fatty acid and amino acid metabolism
- without coenzyme, metabolism slows
carbohydrate
- 1:2:1 ratio of C, H, & O
- glucose
- sucrose (disaccharide) [glucose + fructose]
- polyssacharides
- 4.1 kcal/g CHO
polysaccharides
plant form -cellulose (fiber) -starch animal form (glycogen) -glucose polymer -storage (muscles, liver) -glycogenesis-glycogen synthase -glycogenolysis-glycogen phosphorylase
Fats (Lipids)
- greater C/O ratio that CHO
- large stores (store more fat than carbohydrate)
- 9.4 kcal/g fat (most efficient fuel to use)
- harder to activate (slowest/hardest to use)
- prolonged, low intensity exercise
- triglycerides
triglycerides (storage fats)
- 1 Glycerol + 3 Free Fatty Acids (FFAs)
- Lipolysis-lipases
Saturated or Unsaturated fats are better? and Why?
Unsaturated fats are better because there is a smaller calorie content. Big health component-cell membrane,etc. More fluid
Proteins
- long chains of amino acids (aa’s)
- must break into aa’s and remove N before using for energy (happens during urea cycle)
- 2-3% of energy at rest
- 5-10% in prolonged submax exercise
- 4.1 kcal/g protein
High Energy Phosphates
-ATP= 1 adenine + 1 ribose + 3P
-Making ATP requires much energy. We link exergonic reactions to endergonic ones to form ATP
-Synthesis (ADP + Pi + E–> ATP)
-Breakdown
(ATP —> ADP + Pi + E) By ATPase. Energy used to do bodily work
Bioenergetics
- Muscle cells store limited amounts of ATP
- Metabolic Pathways produce ATP rapidly
- Aerobic vs. Anaerobic
Aerobic
requires oxygen
Anaerobic
doesn’t require oxygen
Basic Energy Systems
- ATP-PCr system
- Glycolytic System
- Oxidative System
ATP-PCr System
“phosphagen system”
cytoplasm
anaerobic
Glycolytic System
cytoplasm
anaerobic
Oxidative System
aerobic
mitochondria
Red Blood Cells
carries oxygen
anaerobic (no cytoplasm)
ATP-PCr/Phosphagen System
Phosphocreatine (PCr)- high-energy molecule in muscle used to reform ATP
Sources: Food; red meat/meat. Fish (best source) Body manufactures creatine in liver and kidney
- Anaerobic
- Cytoplasm
- Simplest (one reaction/one enzyme)
- Quickest
- Provides energy at onset of exercise and to sustain high intensity muscular activity for - 10 sec.
can’t make phosphocreatine until you are in recovery
ATP-PCr System
limitation: muscle cells store only small amounts of PCr.
need ATP to form PCr
- can’t do until recovery
- 50-70% restored in 30 sec
- Full recovery in 10-30 min.
creatine supplementation
- quicker recovery
- most studies show more work when exercise is repeated
Control of ATP-PCr System Creatine Kinase (CK)
PCr breakdown catalyzed by CK
CK controls rate of ATP production
- negative feedback system
- when ATP levels decreases (ADP increases) CK activity increases
- when ATP levels increase, CK activity decreases
Glycolytic System
- anaerobic
- cytoplasm
- ATP yield: 2 to 3 mol ATP/ 1 mol substrate
- duration: 15 s to 2 min
