muscle physiology 4 Flashcards
what are the 2 ways force can be increased?
- Increase number of motor units being activated
- Increase rate of contractions per second
at a low frequency is there tetanus?
NO, only twitches
what are things you need to contract a muscle rapidly?
- Rapid release of Ca+ (Larger SR = faster release)
- ATP hydrolysis needs a very active ATPase isoform
- Fast product release step (fast myosin isoform)
how many ATP are used in a contraction sequence? when is each used?
2!
- Provides energy for crossbridge movement
- ATP binding to myosin breaks myosin-actin bond
When maximal response is obtained with the maximal recruitment, how can you increase the force even further?
Increase the frequency of nerve stimulation to the motor units and have the muscles go into wave summation and tetany
________ contraction happen when tehre is enough force to overcome inertia and muscle shortens as it contracts (bicep curls, leg curls, etc)
Concentric
_________ contractions occur when you are decelerating an object or body part and lowering a load gently
Eccentric
_______ contraction happens when contraction velocity remains constant but force can vary
Isokinetic/isovelocity
Higher energy level = higher VO2 threshold = _______ O2 debt created
higher
O2 debt can be up to ___x basal consumption
O2 debt can be up to 6x basal consumption
½ O2 debt is repaid in ____, the rest can take hours
30s
Sprinters use mainly ________ ATP generation… why?
anaerobic respiration
because the inability of O2 to reach the leg muscles and activate aerobic enzymes
Long distance runners use more _____ (carbohydrates or fat? why?
fat! because Beta-oxidation of fatty acids yields way more ATP
what are the 2 types of fatigue?
muscle, central/physiological
most muscular activities involve __________ mechanisms
feed forward
________ is a fatigue state in which Ca+ does not readily re-enter SR
Contracture
_________ is associated with muscle fatigue and are mostly caused by metabolic changes
Tetanic contraction
how does rigor mortis work?
when you die, you have depolarization of the cells which release Ca+ → Ca+ binds troponin, displaces tropomyosin → myosin binds actin → cell is dead/no more energy production → NO ATP to detach myosin → muscle stays contracted!
what is the max efficiency of muscle contraction?
30%
________ is the basal metabolism in resting state
_________ is the heat over resting heat produced during contraction
Resting heat
Initial heat
________ is what heat is produced in excess of resting heat after the contraction has stopped
Recovery heat
how long does metabolism increase after strenuous exercise?
1 hour
how many waves of macrophages come into the muscle? what do they do?
2!
1st wave: Remove debris
2nd wave: repair fibers
________ blocks sensory inhibitory impulses from muscles leading to unopposed contraction. what does this cause?
Tetanus
-Causes constitutive muscle contraction
_________ blocks activity of ACHesterase. what does this cause?
Organophosphate
-Constitutive muscle contraction
_______ inhibits muscle contraction by blocking nicotinic ACH receptor activity. what does this cause
Curare
-paralysis
___________ prevents fusion of vesicle with membrane at axon terminal and thus the release of ACH. what does this cause?
Botulin
-paralysis
what can large doses of Ryanodine cause?
paralysis
