Fichas
2a. Exercise Physio - Part 1
Fichas del conjunto (45)
- 1How is exercise fueled?Chemical Energy --> Mechanical Work
- 2How much of your bodily mass is made up of skeletal muscle?30-50%
- 3How much of your work is translated to cross-bridging and heat loss25% Cross-Bridging
75% heat loss - 4What comprises a motor unit?the Alpha-motor neuron and all the innervated fibers
- 5What is innervation ratio?# of fibers/ neuron
classified as Small or Large - 6What are small motor units composed of?Type 1 motor neurons
(less force generation and more finesse) - 7What are Large motor units composed of?Type 2 fibers
(more force generation, rapid contraction, gross movements....fatiguable) - 8Major structure of Motor units?Compartmentalized vs Interspersed
- 93 things that affect force generation1). how many motor units recruited;
2). frequency of motor neuron firing;
3). progressive recruitment of larger/stronger motor unites - 10What is the size principle and why does it occurSmaller neurons get recruited before larger ones b/c they have a higher membrane resistance due to smaller cross sectional area
- 11What is the rate coding principle?faster the motor neuron fibers the faster the muscle fibers twitch and the stronger the contraction (till tetanus occurs) helps make a smooth transition as more Motor Units are incorporated (prevent jerky motion
- 12Cross Sectional Arealarger cross sectional area results in greater contraction force (larger/more myofibrils containing sarcomeres)
- 13Axis of FibersLong Fibers: Parallel to the axis of shortening (fast, weak contraction).
Short Fibers: at an angle to the axis of shortening (slow, strong contraction) - 14When a single motor nerve fires, which of the following are activated?All of the fibers innervated by the nerve
- 15True or False: When a motor nerve reaches threshold to fire an action potential, all of the muscle fibers it innervates contractT
- 16Steps (1-3) of the Cross Bridging Cycle1). ATP Binds myosin head, actin – myosin dissociation;
2). ATP --> ADP causes myosin head to relax
3). Myosin head (APD + Pi bound) binds actin - 17Steps 4 + 5 of Cross bridging4. Pi released with concomitant power stroke
5. ADP is released while myosin remains bound to actin - 18When is the inorganic phosphate released?During the power stroke
- 19Three types of Muscle FibersType I (slow twitch)
Type IIa (fast oxidative)
Type IIb (fast glycolytic) - 20Where is SERCA 1 locatedType II muscles
- 21Where is SERCA 2 locatedType 1 muscles
- 22Muscles are classified based on what?Myosin Heavy Chain complex (MHC)
- 23Physio of "The Twitch"Action potential arrives from motor nerve -> NMJ -> Ach release --> action on Nicotinic Type 1 receptors --> Voltage gated channels open and sarcolemma is depolarized (All-or-none, just like nerve
- 24TetanusAbsolute Max force a motor unit can generate
- 25Which muscle types have fused and unfused tetanic forcesType I = unfused
Type II = fused - 26Differences in motor neuron sizeType I is small.
Type II is large - 27Differences in Nerve Conduction VelocityType I is slow
Type II is fast - 28Differences in contraction speedType I: slow
Type II: Fast - 29Differences in fatigue resistanceType I: High
Type IIa: Intermediate
Type IIb: Low - 30Differences in force productionType I: Low
Type IIa: Intermediate
Typ IIb: high - 31Differences in Capillary DensityType I: High
Type IIa: Intermediate
Type IIb: Low - 32Differences in Myoglobin contentType I: High
Type II: Low - 33Differences in Mitochondrial DensityType I: High
Type IIa: Intermediate
Type IIb: Low - 34Differences in Fiber DiameterType I: Small
Type IIa: Medium
Type IIb: High - 35Differences in Anerobic Enzyme ContentType I: Low
Type II: High - 36Max Force per Cross Sectional Area25 Newtons/cm2
- 37Ability to generate force depends on:The # or diameter of fibers in the motor units
- 38True or False: All of the muscle fibers a motor neuron innervates are the same fiber type.False
- 39Concentric ShorteningShortening of the sarcomeres. Force developed by sarcomeres:
ex: Picking up coffee - 40Isometric ShorteningShortening of the sarcomeres with no change in external length
ex: holding coffee or start of arm wrestling - 41Eccentric CompressionLengthening of sarcomeres (while generating force) and increasing joint angle
Force developed by cross bridges is less than the load
ex: Attempting to hold the coffee cup while someone else pours lead into it. - 42Which contraction type would cause the most intense sensation of “burning” during contractionIsometric
Because there is no muscle pump action, metabolites and waste products (particularly protons) are not flushed away thus the build up contributes to a sensation of burning – NOT LACTIC ACID - 43Which contraction type would cause the most discomfort 24-48 hours after contractionEccentric contraction
Because the sarcomeres have been stretched, passive tension is most prevalent and limit is breaking point (refer to 19-9B) of series elastic elements. This causes damage to the muscle fibers and connective tissue and is known as DOMS – delayed onset muscle soreness. - 44Push v PullMuscles only pull. To push, there must be specific contraction of bony levers
- 45Axes of muscle fibersParallel -- rapid, lower tension
Oblique -- slower, greater tension