Chapter 3 Flashcards
ATP
adenosine triphosphate
- without it, muscular activity would not be possible
- composed of: adenine( a nitrogen-containing base) ribose, (a five-carbon sugar), (adine+ribose=adenosine), and three phosphate groups.
- large amounts of energy in the chemical bonds of the two terminal phosphate groups
- When the third phosphate on the ATP is separated from adenosine by ATPase, energy is released
Bioenergetics
the flow of energy in the biological system
*primarily concerns the conversion of food into biologically usable forms of energy
catabolic
breakdown of large molecules into smaller molecules
anabolic
building-up process, small to large
metabolism
constant state of anabolism and catabolism
ADP
adenosine diphosphate, removal of one phosphate group from ATP
AMP
adenosine monophosphate, removal of two phosphate groups from ATP
Phosphagen system
system to replenish ATP
- an anaerobic process, occurs in the absence of oxygen
- primary source of ATP for short-term, high-intensity activities, and at the start of all exercise types
- Relies on chemical reactions of ATP and creatine phosphate, which involve ATPase and creatine kinase
- Myotin ATPase increases rate of breakdown of ATP to for ADP and inorganic phosphate (P) and energy…=catabolic reaction
- Creatine kinase increases rate of synthesis of ATP from creatine phosphate and ADP by supplying phosphate that combines with ADP to form ATP…=anabolic reaction
- cannot supply energy for long-duration activities
- type II muscles contain greater concentrations of phosphagens than type I
- Creatine kinase activity regulates breakdown of creatine phosphate: ^^in ADP promotes creatine kinase activity, ^^^in ATP inhibits it.
- activity remains elevated if exercise intensity remains high
Glycolysis
system to replenish ATP
*fast and slow glycolysis; both are also anaerobic
*breakdown of carbohydrates, glycogen (muscle) or glucose (blood)
*enzymes for glycolysis are located in the cytoplasm of the cells (sarcoplasm of muscle cells)
*fast glycolysis: pyruvate is converted to lactate, providing ATP at a faster right than slow gly…
Glucose+2Pi + 2ADP –>
2lactate +2ATP+ H20
- controlled by energy demands of cell
- high rate=fast g
- low rate=slow g
*slow glycolysis:
Glucose+2Pi +2 ADP + 2 NAD(+) –>2pyruvate + 2ATP +2NADH +2H20
- stimulated during intense muscular activity by ADP, P, ammonia, and a sligh decrease in pH, and AMP
- If glycogen is not being broken down into glucose quickly enough and the supply of free glycose has already been depleted, glycolysis will be slowed
Oxidative system
system to replenish ATP
- an aerobic process, requires oxygen
- for activities of a lower intensity but longer duration (10 mile bike-ride or swimming laps for an hour)
Carbs
only energy source which can be metabolized without the direct involvement of oxygen
Rate-limiting step
Slowest reaction in the series
Phosphofructokinase
PFK is the primary factor in the regulation of the rate of glycolysis
Lactate
converts into lactic acid, associated with muscle fatigue
- as PH decreases (becomes acidic) it inhibits glycolytic reactions, decrease in available energy
- normal level in blood is 0.5 to 2.2 mmol/L at rest.
- normally return to preexercise values within an hour after activity, cool down helps it go faster
- peak blood lactate concentrations occur approximately 5 min after the cessation of exercise
Glyconeogenesis
formation of glucose
- lactate is used in this process during extended exercise and recovery
- clearance of lactate indicates a person’s ability to recover
Cori cycle
When lactate is transported in the blood to the liver, and then turned to glucose
Lactate Threshold
the exercise intensity or relative intensity at which blood lactate begins an abrupt increase above the baseline concentration
- shows increase reliance on anaerobic mechanisms
- begins at untrained peeps 50-60% of maximal oxygen uptake, and trained peeps 70-80%
Onset of blood lactate accumulation
OBLA- second point of inflection in lactat accumulation curve
occurs when the concentratoin of blood lactate is near 4 mmol/L. correspond to when large motor units are recruited (typically type II fibers)
Oxidative system
primary source of ATP at rest and during aerobic activities, uses carbohydrates and fats as substrates
ex:yoga, water aerobics, walking, etc.
protein is normally not metabolized except during long term starvation bouts (>90min)
at rest, 70% of ATP is produced from fats and 30% from carbs
- during activity, shifts from fats to carbs during high intensity aerobic activities
- shift back to fats during prolonged, submaximal, steady-work
Kerbs cycle
*If oxygen is present in sufficient quantities, then pyruvate is transported to mitochondria and then converted to CoA
- cycle produce stwo ATPs indirectly from guanine triphosphate (GTP) for each molecule of glucose
- six molecules of NADH are produced and two molecules of reduced flavin adenine dinucleotide (FADH2)
- different if fat or protein enters the kerbs cycle
Electron Transport Chain
ETC, molecules from krebs cycle are used to produce ATP from ADP.
*ETC uses the NADH and FADH2 molecules to rephosphorylate ADP to ATP
- NADH can produce three molecules of ATP
- FADH2 can produce two molecules of ATP
Fat Oxidation
tricglyercids broken down by hormone-sensitive lipase
Beta oxidation
free fatty acids are broke down to acetrylcoA and hydrogen atoms
Protein Oxidation
not a significant source of energy
*amino acids are converted into glucose (gluconeogenesis)
*provides 3%-18% of energy source during prolonged activity
*waste prodcuts are eliminated through the formation of urea and small amounts of ammonia»>urine
(ammonia is toxic and associated with fatigue)
Oxidative Sstem Regulation
If NAD+ and FAD+ are not available to accept hydrogen, Kerbs cycle is reduced
Also when GTP accumulates
All three energy systems are active at a given time; however, the extent to which each is used depends primarily on the intensity on the activity, and secondarily on its duration
Exercise Intensity
level of muscular activity that can be quanitified in terms of power output,
power-amount of physical work performed for a particular duration of time
Effect of Event Duration on Primary Energy Used
0 to 6 s very intense=phosphagen
6 to 30 s intense-phosphagen and fast glycolysis
30 s to 2 min heavy- fast glycolysis
2 to 3 min moderate-fast gly and oxidative system
>3 min light Oxidative system
Energy substrates
molecules that provide starting materials for bioenergetic reactions. fatigue is associated with deplition of phosphagens and glycogen
ex:
phosphagens, glucose, glycogen, lactate, free fatty acids, amino acids
Phosphagens
- more rapidly depleted as a result of high-intensity anaerobic exercise than aerobic exercise
- Creatine decreases by 50-70% to almost elimination
- ATP do not decrease by more than about 60%
Glycogen
*Limited stores are available
*Stored in muscle and liver
*Anaerobic training can increase resting muscle glycogen concentration
*Muscle concentration important during high-intensity
*Liver concentration important during low-intensity
*repletion is related to postexercise carbohydrate ingestion (.7-3.0 of carb per kilogram of body is ingested following every 2 hours after exercise)
*
Selective muscle fiber glycogen depletion
more depletion in type II muscle fibers
Oxygen Uptake
measure of a person’s ability to take in and use oxygen.
high oxygen uptake, more fit of a person
Oxygen Deficit
anaerobic contribution to the total energy cost of exercise
Oxygen debt
postexercise oxygen uptake
aka EPOC: excess postexercise oxygen consumption
EPOC
EPOC: excess post exercise oxygen consumption
- oxygen uptake above resting values used to restore the body to the pre-exercise condition
- Oxygen deficit may influence size of EPOC, but they are not equal
