Midterm 2: Chapters 1 & 10 Flashcards
What are the three types of muscle tissue?
- skeletal muscle
- smooth muscle
- cardiac muscle
_______: voluntary, skeleton.
skeletal muscle
_______: involuntary, hollow organs.
smooth muscle
_______: involuntary, heart.
cardiac muscle
the entire muscle is surrounded by and consists of?
- surrounded by epimysium
- consists of many bundles (fasciculi)
what is the fasciculi surrounded by and consist of?
- surrounded by perimysium
- consists of individual muscle cells (muscle fibers)
what is the muscle fiber surrounded by and consist of?
- surrounded by endomysium
- consist of myofibrils divided into sarcomeres
_________: fuses with tendon, conducts action potential, maintains pH, transports nutrients.
plasmalemma also referred to as the cell membrane.
_______: cytoplasm of muscle cell, has unique features: glycogen storage, myoglobin.
sarcoplasm
______: a protein inside the muscle cell that carries oxygen.
myoglobin
_________: a protein that carries oxygen within the blood system.
hemoglobin
_________: extensions of plasmalemma, carry action potential deep into muscle fiber.
transverse tubules (T-Tubules)
________: calcium (ca 2+) storage.
sarcoplasmic reticulum
_______: muscle -> fasciculus -> muscle fiber -> ? , sections known as sarcomeres.
myofibrils
______: basic contractile element of skeletal muscle, end to end for full myofibril length.
sarcomeres
what are the band parts of the sarcomeres referred to as?
~ a-bands: dark/blue stripes
~ I-bands: light/pink stripes
~ h-zone: middle of a-band
~m-line: middle of h-zone
what is the common boundary of the sarcomeres?
Z-disk (or Z-line)
______: show up lighter under microscope (red), I-bands contains only ?.
Actin (thin filaments)
Actin (thin filaments) actually composed of three proteins what are they?
- actin
- tropomyosin
- troponin
_____: contains myosin-binding site.
actin
_____: covers active site at rest.
tropomyosin
_____: anchored to actin, moves tropomyosin.
troponin
_____: two intertwined filaments with globular heads.
myosin (thick filaments)
______: protrude 360 degrees from thick filament axis, will interact with actin filaments for contraction.
globular heads
muscle fiber contraction starts with?
nervous system
____: innervates muscle fibers.
alpha-motor neurons
_____: single alpha-motor neuron + all fibers it innervates, more operating motor units = more contractile force.
motor unit
fibers contract through sequence of events:
“excitation contraction coupling”
What would the process of a muscle contraction?
- action potential (ap) starts in brain
- AP carries at axon terminal, releases ACh
- Ash crosses synapse, binds to Each receptors on plasmalemma
- AP travels down plasmalemma, T-tubules
- Triggers Ca 2+ release from sarcoplasmic reticulum
- Ca 2+ enables actin-myosin contraction
When the action potential arrives at SR from t-tubule what happens?
- SR sensitive to electrical charge
- causes mass release of Ca 2+ into sarcoplasm
what happens when Ca 2+ binds to troponin on actin?
- at rest, tropomyosin covers myosin-binding site
- troponin-Ca 2+ complex moves tropomyosin
- myosin binds to actin, forming a cross-bridge. allowing a contraction to occur
how muscles create movement is the process of?
actin-myosin contraction
____: no actin-myosin interaction at binding site, myofilaments overlap a little.
relaxed state
type II fibers consist of?
type IIa and type IIx
type II fibers in general?
- poor aerobic endurance, fatigue quickly
- produce ATP through anaerobic pathways
what are the characteristics of type IIa fibers?
- more force, faster fatigue than type I
- short, high-intensity endurance events
what are the characteristics of type IIx fibers?
- seldom used for everyday activities
- short explosive sprints (100 m)
________: myosin head pull actin toward sarcomere center (POWER STROKE), filaments slide past each other, sarcomeres, myofibrils, muscle fiber all shorten.
contracted state
according to the sliding filament theory what happens after power stroke ends?
- myosin detaches from active site
- myosin head rotates back to original position
- myosin attaches to another site farther down
according to the sliding filament theory process continues until?
- z-disk reaches myosin filaments
- AP stops, Ca 2+ gets pumped back into SR
_______: most influential in determining percentage
genetic factors
_____: can induce small (10%) change in fiber type, IIx -> IIa
training factors
______: muscles lose type II motor units
aging
what would be the other predictors for athletic success, since fiber type is not the sole predictor?
- cardiovascular function
- motivation
- training habits
- muscle size
muscle fiber recruitment is also referred to as?
motor unit recruitment
what does “muscle fiber recruitment” mean?
when a motor unit is recruited, ALL of its fibers are activated
what is the method for altering force production?
- less force: fewer or smaller motor units (type I)
- more force: more or larger motor units (type II)
what is the recruitment order?
- smallest (type I) motor units
- mid sized (type IIa) motor units
- largest (type IIx) motor units
T/F ? Motor units are recruited in the same order each time.
true
________: order recruitment of motor units directly related to size of a-motor neuron
principle of orderly recruitment (size principle)
_______: muscle produces force and changes length, joint movement produced.
dynamic contraction
what are the two subtypes of muscle contraction?
concentric and eccentric
______:
- muscle shortens while producing force
- sarcomere shortens, filaments toward center
concentric contraction
______:
- muscle lengthens while producing force
- cross-bridges form but sarcomere lengthens
- Ex.) lowering heavy weight
eccentric contraction
______:
- muscle produces force but does not change length
- joint angle does not change
- myosin cross-bridges form and recycle, no sliding
static (isometric) contraction
the amount of force developed depends on?
- number and type of motor units activated
- size of the muscle
- frequency of stimulation of each motor unit
- muscle fiber and sarcomere length
speed of contraction
when more force is generated and more motor units are activated what happens to type II and type II fibers?
- type I motor units = less fibers = less cross-bridges = less force
- type II motor units = less fibers = less cross-bridges = more force
single motor unit can exert varying levels of force dependent on _____ of stimulation.
frequency
_____: contractile response to single electrical stimulus.
twitch
_____: consecutive stimuli for greater force.
summation
_____: continued stimulation resulting in peak force
tetanus
process of varying levels is?
rate coding
what is the length-tension relationship?
fibers have optimal length for force production
- optimal sarcomere length = optimal overlap of actin/myosin
> maximizes cross-bridge interaction
-too short or too stretched = little or no force develops
what is the speed-force relationship?
ability to develop force also depends on speed of contraction
_____: maximal force development decreases at higher speeds.
concentric
_____: maximal force development increases at high speeds.
eccentric
what is the sensory-motor integration?
process of communication and traction between sensory and motor systems
> sensory stimulation can give rise to motor response
_____:
- fastest mode of response
> impulse does not travel up to the brain
- instant, preprogrammed response to a given stimulus
- only one response is possible
- occurs before conscious awareness
motor reflex
specific reflexes that help control muscle function involving two special structures:
- muscle spindles
2. Golgi tendon organs
what are muscle spindles?
- group of 4-20 small, specialized intramural muscle fibers
- different from normal (extrafusal) muscle fibers
- innervated by y-motor neurons
- sensory receptors for muscle fiber stretch
when stretched, muscle spindle sensory neuron stimulated … ?
- synapse in spinal cord with an a-motor neuron
- triggers reflex muscle contraction
- prevents further stretch
- stretch reflex
what are the Golgi tendon organs?
- sensory receptor embedded in tendon
> 5 to 25 muscle fibers attached to each GTO
> sensitive to tension in tendon
when stimulated by excessive tension, Golgi tendon organs … ?
- inhibit agonists, excite antagonists
- safety mechanism that prevents excessive tension in muscle/tendon
- reduce potential for injury
what should you know about “motor response” ?
- a-motor neuron carries AP to muscle
- AP spreads to muscle fibers of motor unit
_____:
- fewer fibers per motor unit
- extraocular muscles have innervation ratio of 1:15
fine motor control
_____:
- more fibers per motor unit
- gastrocnemius has innervation ratio of 1:2000
gross motor control
_____: fiber types not mixed within a given motor unit, either type I fibers or type II fibers
homogeneity of motor units
explain hypertrophy versus atrophy …?
- increase muscle size leads to an increase in muscle strength
- decrease in muscle size leads to a decrease in muscle strength
- but the association is more complex
strength gains result from?
- altered neural control
- increased muscle size
according to the mechanisms of muscle strength gain what is neural control?
- strength gain cannot occur without neural adaptations
> strength gain can occur without hypertrophy
> property of neuromotor system, not just muscle
what are the factors that are important to strength gains?
- increase motor unit synchronization and recruitment
- decrease autogenic inhibition
- reduced coactivation
according to the mechanisms of muscle strength gain what is synchronization and recruitment?
- motor units generally recruited asynchronously; not all engaged at the same instant
- resistance training -> synchronous recruitment
- synchronous recruitment -> strength gains
_____ = more motor units fire at the same time
- improves rate of force development
- increases capability to exert steady force
synchronicity
_____: normal intrinsic inhibitory mechanisms
- e.g., Golgi tendon organs
- inhibit muscle contraction if tendon tension too high
- prevent damage to bones and tendons
autogenic inhibition
training can _____ inhibitory impulses
- muscle can generate more force
decrease
_____:
- coactivation of agonists, antagonists
- normally antagonists oppose agonist force
- … may -> strength gain
reduced coactivation
_____: increase in muscle size.
hypertrophy
what are the two types of hypertrophy?
- transient hypertrophy and chronic hypertrophy (long term)
_____: (after exercise bout)
- due to edema formation from plasma fluid
- disappears within hours
transient hypertrophy
_____: reflects actual structural change in muscle
chronic hypertrophy (long term)
muscle hypertrophy is maximized by?
- high-velocity eccentric training
- disrupts sarcomere Z-lines (protein remodeling)
______ only training may limit muscle hypertrophy and strength gains.
concentric
fiber hypertrophy may occur as a result of?
- more actin, myosin filaments
- more myofibrils
- more sarcoplasm
- more connective tissue
resistance training leads to ______ in protein synthesis.
increase
(T/F) ? according to fiber hypertrophy muscle protein content is always changing, during exercise synthesis decreases, while degradation increases, after exercise synthesis increases while degradation decreases.
true
______: facilitates fiber hypertrophy
- natural anabolic steroid hormone
- massive doses of anabolic steroids + resistance training -> large increases in muscle mass
testosterone
_____:
- short-term increase in muscle strength
- neural factors critical in first 8 to 10 weeks
- due to increase voluntary ?
neural activation
_____:
- long-term increases in muscle strength
- ? major factor after first 10 weeks
- associated with significant fiber hypertrophy
- net increases protein synthesis takes time to occur
hypertrophy
atrophy and inactivity can lead to?
reduction or cessation of activity -> major change in muscle structure and function
- seen in: limb immobilization studies, detraining studies
what happens after a client or patient is immobilized?
- major changes after 6 hours
- lack of muscle use -> reduced protein synthesis
- first week: strength loss of 3 to 4% per day
- ( decreased size/atrophy)
- ( decreased in neuromuscular activity)
- reversible
- (recover when activity is resumed)
- (but recovery period longer than immobilization)
detraining can lead to?
- decreases in 1RM
- strength losses can be regained (~ 6 weeks)
- new 1 RM matches or exceeds old 1RM
once training goal is met, maintenance resistance program prevents detraining such as?
- maintain intensity (most potent)
- reduced training frequency
according to fiber type alteration the training regimen may not outright change fiber type, but?
- type II becomes more oxidative with aerobic training
- type I become more anaerobic with anaerobic training
according to the resistance trading for special populations: children and adolescents what would be considered a myth(s)?
- unsafe due to growth plate injuries
- ineffective before puberty due to. lack of hormones.
according to the resistance trading for special populations: children and adolescents what would be considered the truth?
- safe with proper safeguards
- children can gain both strength and muscle mass
- EMPHASIZE PROPER LIFTING TECHNIQUE!
(T/F) ? weight lifting or resistance training will be beneficial for the older population.
true
how can weight lifting help benefit the older population?
- helps restore age-related loss of muscle mass
- improves quality of life and health
- helps prevent falls
increases in strength dependent primary on neural adaptations
