muscles 4 Flashcards
What two things is muscle performance considered in terms of?
Force and Endurance
muscle performance and force
- power, strength
- max alt of tension produced by a muscle or muscle group
endurance and muscle performance
amt of time during which an indiv. can performa particular activity
Factors that determine performance capabilities of a skeletal muscle
- types of muscle fiber present in the muscle
- physical conditioning or training
Type I fibers
- slow fibers
- slow twitch oxidative fivers
Type II-A fibers
- intermediate fibers
- fast twitch oxidative fibers
- fast fibers w/ greater endurance capability
Type II-B
- fast fibers
- fast twitch glycolytic fibers
- greater capacity for anaerobic metabolism
slow fibers (red)
- half the diameter of fast fibers
- take 3x as long to contract after stimulation
- abundant mitochondria
- extensive capillary supply
- high concentrations of myoglobin
- can contract for long periods of time
what does abundant mitochondria do in slow fibers?
allows aerobic respiration, oxidative metabolism
what does high concentrations of myoglobin do in slow fibers
-greater oxygen reserve and oxygen diffusion, more readily available
fast fibers (white)
- large in diameter
- contain densely packed myofibrils
- large glycogen reserves
- relatively few mitochondria
- produce rapid, powerful contractions of short duration
- fatigue rapidly
what do small amounts of mitochondria do in a fast fiber?
causes anaerobic, glycolytic metabolism
intermediate fibers
- fast fibers that gain greater resistance to fatigue
- additional capillary supply
- more mitochondria
- smaller diameter
- not as dependent on anaerobic metabolism
- can be trained
How is the percentage of slow and fast fibers determined?
genetically and can vary considerably among muscles
Which fibers can change due to training?
fast with intermediate properties
hypertrophy
increase in diameter of muscle with use
atrophy
decrease in diameter of muscle
does the number of muscle fibers change under normal conditions?
no, we don’t produce new muscle cells
why does change in diameter of muscles change?
- increase or decrease depending on level of activity over time
- increased activity leads to synthesis of more actin and myosin myofilaments
- decreased activity leads to loss of actin and myosin filaments
what does long term disuse of muscles lead to?
irreversible atrophy in muscle if muscle cells die
physical conditioning, anaerobic endurance
time period in which muscular contractions are sustained by glycolysis after depleting ATP/CP
physical conditioning, aerobic endurance
time period in which muscle can continue to contract while supported by activities after depleting ATP/CP reserves
physical conditioning, improve anaerobic endurance
- frequent brief, intensive workouts
- increase muscle mass
- ATP/CP reserves
- glycogen reserves
- ability to tolerate lactic acid buildup
physical conditioning improve aerobic endurance
sustained low levels of activity
- increase bloody supply to muscles
- improve cardiovascular activity
What happens to muscles with age?
- decrease in size, strength and endurance of muscles
- skeletal muscle becomes less elastic
- tolerance for exercise decreases
- ability to recover from muscular injuries decreases
why do muscles decrease in size and strength with age?
- reduction in size decreases the number of myofibrils
- decrease in endurance due to less ATP, CP, glycogen, and myoglobin
Why does skeletal muscle become less elastic with age?
develop increasing amounts of fibrous connective tissue (fibrosis)
Why does tolerance for exercise decrease with age?
- Muscles fatigue more quickly
- reduction in thermoregulatory ability, thus are subject to over heating
Why does the ability to recover from injuries decrease with age?
- number of satellite cells decreases with age
- repair capabilities become more limited, more scar tissue (fibrous tissue) formation occurs
Primary muscle disorders
result from problems with the muscular system itself
- muscle trauma
- muscle infections
- inherited disorders
- tumors
Secondary disorders
result in problems originating in
- nervous system disorders
- nutritional or metabolic problems
- cardiovascular disorders
Muscular system disorders
1) muscle spasm
2) muscle spasticity
3) muscle flaccidity
4) muscle atrophy
5) myositis
6) strain
7) paralysis
muscle spasm
(cramp) strong sudden usually painful, unwanted contraction
muscle spasticity
excessive muscle tone
muscle flaccidity
very low muscle tone
muscle atrophy
deterioration or wasting due to disuse, immobility, or interference with normal motor neuron innervation
myositis
muscle inflammation
-polymyositis and dermatomyositis= autoimmune
strain
tears in muscle tissue
-sparin tears in ligament or tendon or joint capsule
paralysis
loss of voluntary motor control
-flaccid or spastic
nervous system disorders that affect the coordination or control of muscle contraction
- blockage of release of ACh (botulism
- Interference with binding of ACh to receptors
- Interference with AChE activity
- loss of motor neuron (polio)
- loss of motor neuron axon-peripheral nerve damage
- excessive stimulation of motor neuron (e.g. tetanus)
flaccid paralysis examples
- blockage of release of ACh (botulism
- Interference with binding of ACh to receptors
- loss of motor neuron (polio)
- loss of motor neuron axon-peripheral nerve damage
spastic paralysis examples
-Interference with AChE activity
excessive stimulation of motor neuron (e.g. tetanus)
inherited muscular disorders
- Muscular dystrophies
- myotonic dystrophy
muscular dystrophies
muscle structure is compromised, problem with how muscle proteins are structured
- duchennes MD
- early onset
myotonic dystrophy
chromosome 19 disorder
-typically onset is after puberty
Muscle trauma
- minor trauma
- major trauma
- new muscle cel production from satellite cells-limited ability
- scar tissue formation
- compartment syndrome
minor muscle trauma
damage to myofibrils, sarcolemma from excessive activity
major muscle trauma
laceration, crushing, deep bruise, muscle tear (strain)
