9/25c Metabolic Pathways for Aerobic Exercise (Biomedical Sciences) Flashcards
muscles are metabolic machines and what is their reason for being?
convert chemical energy into mechanical work
- Catabolism of fuel
- ATP
- Force Production
- Movement
intimate relationship between muscles and capillaries
there are many capillaries that lie within the muscles running throughout everything!
Different muscle types:
Type I
Type IIa
Type IIx
Type I muscle fibers
-slow oxidative
-slow contraction speed
-slow relaxation speed
-few fibers
-high concentration myoglobin (makes them red)
-high structural capillary density
-fatigue very slowly
-low glycolytic
-high oxidative
-high mitochondrial
POSTURAL MUSCLES
Type IIx muscle fibers
-lowest capillary density structure
-high concentration glycolytic enzymes
-lowest concentration oxidative enzymes
-lowest mitochondrial content
-Fastest contraction speed
-lowest concentration myoglobin (whitest/leanest meat)
-Fatigue very easily
-many fibers
POWER MUSCLES
Type IIa muscle fibers
-low capillary density structure
-high concentration glycolytic enzymes
-low concentration oxidative enzymes
-low mitochondrial content
-Fast contraction speed
-lower concentration myoglobin (white meat)
-many fibers
POWER MUSCLES
ATP function
adenine with 3 phosphate groups > hydrolysis > ADP + Phosphate + ENERGY (used to produce mechanical work)
ATP + H2O > ADP + Pi + Free Energy
resting skeletal muscle requirements of ATP?
- ion pumps (Na+-, K+, Ca++, SERCA)
- RNA and protein synthesis
- Fuel Storage
- Transport of substances
- signaling to regulate cell processes
- 1mmol/kg/min
Contracting skeletal muscle requirements of ATP
– All those in resting
– Myosin ATPase - enzyme that breaks down ATP in order to power contraction
-240mmol/kg/min
throughout the entire range of muscle metabolic activity level what is the ATP level?
it stays at 8mM
- the concentration doesn’t change even when there is a really high consumption rate
- Pathways for ATP regeneration
3 pathways whereby ATP is regenerated
- Phosphocreatine
- Anaerobic Glycolysis
- Oxidative Phosphorylation
Phosphocreatine reaction and its function
ADP + PCr + H+ ATP + Cr
TEMPORAL BUFFER and Spatial buffer
-rapid reaction, supplies about 10 seconds worth of energy at max effort
-takes 1 second to get to peak capacity
-HIGH power, LOW capacity
-ATP and ADP don’t diffuse rapidly through the cell, but PCr and Cr do, so they shuttle phosphate groups from mitochondria to the ATPase where they are broken down
-Cr is synthesized in the liver and absorbed in the diet
what is phosphocreatine imperative for?
the initial transition between rest and exercise
anaerobic glycolysis key factors
- Glucose/glycogen broken down into lactate in the absence of oxygen
- Moderate power and capacity (not as rapid as PCr), lasts on the order of minutes
- associated with acidosis
- takes 5 seconds to get to peak output
- important during heavy exercise (>60% VO2max)
- when oxygen is insufficient to support oxidative phosphorylation
process of anaerobic glycolysis
Glycolysis leads to 2 possible endpoints
- pyruvate that enters TCA cycle -> Oxidative phosphorylation
- OR pyruvate gets broken into lactate
Steps for Anaerobic Glycolysis (two sources of glucose)
A.
1. Glucose in the blood (5mmol)
2. glucose transporters move glucose into the muscle in response to: insulin and/or exercise
3. Glucose goes right into glycolysis then pyruvate and lactate (acidosis)
B.
- Glycogen stored in muscle (carbohydrate stored in muscle)
- glycogen is broken down through glycolysis
- pyruvate + lactate is the end result (acidosis)