Muscle Phys III Flashcards
what protects motor units against fatigue?
Asynchronys Fatigue
Why might you recruit all motor units at once?
power lifting
What are the three phases of a muscle twitch
latent, contraction, relaxation
period of muscle twitch before the contraction starts
Latent
period of muscle twitch where cross bridge cycling occurs and tension is developing
contraction
period of muscle twitch where the muscle begins to relax after a twitch
relaxation
the active process of generating a force within a muscle by cross bridge activity
contraction
the force exerted by muscle on an object
muscle tension
the weight or force exerted by an object on a muscle
load
muscle changes length BUT tension remains constant throughout
Holding a baby in a constant position
Isotonic Contraction
muscle shortens - doing work
concentric
muscle contracts as it lengthens
- muscle being stretched by external force, resisting stretch
eccentric
tension develops at CONSTANT muscle LENGTH
- occurs in muscles that act to remain posture, stabilize joints, etc. or when the load is more than tension
(A person trying to lift up a car– muscles are contracted, but length is not changing)
Isometric contraction
Sources of ATP production in muscle cells
- Creatine Phosphate (CP)
- Anaerobic Glycolysis Pathway
- Aerobic Pathway
A type of very fast ATP production
Problem: it is a 1:1 ratio, low product yield. Can be depleted very quickly (very short amount of time)
Creatine Phosphate (CP)
in order to produce muscle contractions you need ___
ATP
Why do people use creatine supplementation
increase creatine in muscle cells which then produces more Creatine phosphate, which yields more ATP
- good for powerlifters and sprinters
- Rate of ATP production is fast
What is the very fast ATP production that goes through glucose rapidly
Anaerobic Glycolysis
1 gulcose produces 2 ATP (low yield, but produces more than CP) what pathway is it?
Anaerobic Pathways
glucose is derived from?
Glycogen
fast contractions for a short amount of time.. what pathway?
Anaerobic Pathways
does Anaerobic Pathways need oxygen?
No
the pathway that is important in recovery
Aerobic pathway
why does the Aerobic pathway need oxygen?
it is dependent on the cardiovascular and respiratory system
Does Aerobic pathway have a high or low yield of ATP?
Very high! 1 glucose = 36 ATP BUT takes a long time
occurs when exercising muscle can no longer respond to stimulation with same degree of contractile activity
muscle fatigue
point in a graph where anaerobic glycolysis and aerobic metabolism cross
Anaerobic Threshold
does creatine phosphate pathway need oxygen?
No
the motion during the bicep curl when the load is raised in an arc towards the body is what type of contraction (shortening the muscle)
isotonic concentric
After a dumbbell curl while lowering the dumbbell is the result of (muscle becoming long again)
eccentric contraction
aiming a bow is a type of what contraction
isometric
muscle has not shortened. sarcomeres shorten, generating force, but elastic elements stretch, allowing muscle length to remain the same
isometric contraction
sarcomeres shorten more but, because elastic elements are already stretched, the muscle must shorten
isotonic contraction
supplies about 10 seconds worth of energy and is used for short bursts of exercise, such as a 100-meter sprint
CP pathway
for endurance you would use this type of ATP pathway
aerobic
Adenosine inhibits supraspinal dopaminergic neurons
- supraspinal dopinergic transmission is associated with increased arousal, motivation, spontaneous motor activity, and prolonged exercise time
central fatigue
what are the 4 stages of cross-bridge cycling
- Crossbridge Formation (activated myosin head attaches to actin)
- Power stroke (ADP released, myosin head pivots, pulls z disc forward)
- myosin head release (detachment from actin)
- reactivation of myosin head (reset)
z lines move closer and closer to the m line
each myosin head allows binding sites for two things: what are they?
Actin (top)
ATP (bottom)
during the powerstroke phase of the crossbridge cycle what occurs?
ADP and Pi (phosphate group) are released. pulls the z disc closer to the m line
ATP is binded to myosin head until what occurs?
until a new ATP molecule binds
After death, our bodies can no longer replenish ATP reserves, which leads to .
ATP decreased but myosin heads increase. muscles get stiffer and stiffer. muscles running out of ATP
Rigor Mortis
how does a myosin head allow weight lifting - generate enough tension ?
it depends on teamwork. Not a single myosin head does it.
Huge number of individual myosin heads undergo crossbridge cycling, which allows the ability to generate high tension force
each thick filament pulls inward __ thin filaments
6 thin filaments
importance of calcium in crossbridge cycling– what are the 2 important proteins?
- tropomyosin (long protein)
- Troponin (short)
what protein covers all the myosin binding sites on actin
tropomyosin
calcium binds to troponin molecules and changes the structure of tropomyosin. Myosin heads are now free and not covered and they now can perform what?
cross bridge
