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| How many muscles does the human body contain? |
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Definition
over 400
40-50% of body weight |
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| Function of skeletal muscle (3) |
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Definition
Force production for locomotion and breathing
Force production for postural support
Heat production during cold stress |
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| Surrounds fascicles (bundles of muscle fibers) |
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Definition
| surrounds individual muscle fibers |
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Definition
| just below endomysium (bottom layer of connective tissue covering muscle |
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Definition
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Definition
Play role in muscle growth and repair
More nuclei allow for greater protein synthesis
Important for adaptations to strength training |
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Definition
| cytoplasm surrounding each nucleus |
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Definition
| contain contractile proteins (actin and myosin) |
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z line
m line
h zone
a band
I band |
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Definition
storage sites for calcium
terminal cisternae |
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Definition
| extend from sarcolemma to sarcoplasmic reticulum |
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Definition
| Junction between motor neuron and muscle fiber |
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Definition
| pocket formed around motor neuron by sarcolemma |
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Term
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Definition
| gap between neuron and muscle fiber |
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Term
| What is released from the motor neuron to the motor end plate and why? |
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Definition
Ach (acetylcoline)
causes an end-plate potential (EPP) |
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Term
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Definition
end-plate potential
causes depolarization of muscle fiber |
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Term
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Definition
| actin moves over myosin and crossbridges deliver power stroke to shorten muscle |
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Term
| What happens to ATP during a contraction of muscle |
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Definition
| Myosin ATPase breakes down ATP as fiber contracts |
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Term
| Excitation-Contraction Coupling |
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Definition
| Depolarization of motor end plate is coupled to muscular contraction |
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Term
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Definition
Decline in muscle power output (lower force generation and velocity of muscle shortening)
2 types: high intensity, low intensity |
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Term
| High-intensity exercise muscle fatigue |
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Definition
about 60 secs
build-up of lactate, H+, ADP, P, and free radicals lowers amount of cross bridges that can bind to actin |
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Term
| Long-duration exercise muscle fatigue |
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Definition
2-4 hours in length
Build-up of free radicals, electrolyte imbalance, and glycogen depletion |
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Term
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Definition
Spasmodic, involuntary muscle contrations
2 theories: Electrolyte depletion and dehydration theory
Altered neuromusular control theory |
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Term
| Electrolyte depletion and dehydration theory |
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Definition
| water and sodium loss from sweating causes spontaneous contractions |
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Term
| Altered neuromusular control theory |
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Definition
| abnormal activity in muscle spindle and golgi tendon organ fires motor neurons |
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Term
| Biochemical properties of muscle fiber types |
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Definition
oxidative capacity
Type of myosin ATPase |
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Definition
how much oxygen the muscle can receive
effected by:
number of cailllaries, mitochondria, and amount of myoglobin |
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Term
| Contractile properties of muscle fiber types |
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Definition
Maximal force production
Speed of contraction
Muscle fiber efficiency |
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Definition
| force per unit of cross-sectional area |
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Term
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Definition
(Vmax)
Myosin ATPase activity |
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Term
| How can you type muscle fibers? |
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Definition
Stain them with stain that detects ATPase
Lightest uses least O2, Darkest used most O2 |
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Term
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Definition
slow twitch fibers
slow-oxidative fibers |
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Term
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Definition
Intermediate fibers
fast-oxidative glycolytic fibers |
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Definition
Fast twitch fibers
fast-glycolytic fibers |
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Term
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Definition
| 50-50 fast and slow twitch fibers |
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Term
| Power athlete fiber types |
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Definition
| Higher percentage of fast fibers |
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Term
| Endurance athletes fiber types |
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Definition
| Higher percentage of slow twitch fibers |
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Term
| Isometric muscle contration |
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Definition
Muscle exerts force without changing length
pulling against immovable object
Postural muscles |
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Term
| Isotonic (dynamic) muscle contraction |
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Definition
2 types:
Concentric
Eccentric |
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Term
| Concentric muscle contraction |
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Definition
muscle shortens during force production
going against gravity |
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Term
| Eccentric muscle contraction |
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Definition
Muscle produces force but length increase
going with gravity
associated with mucle fiber injury and soreness |
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Term
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Definition
| Contraction as the result of a single stimulus |
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Term
| Latent period in muscle twitch |
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Definition
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Term
| Contraction period in muscle twitch |
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Definition
Tension is developed
40 ms |
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Term
| Relaxation period in muscle twitch |
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Definition
Lasts 50 ms
Release of muscle tension |
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Term
| Why is their more speed of shortening in fast fibers? |
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Definition
SR releases Ca at a faster rate
Higher ATPase activity |
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Term
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Definition
| More motor units or faster motor units = more force |
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Term
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Definition
ideal length for force generation
increased cross-bridge formation |
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Term
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Definition
muscle loss from aging
10% muscle mass lost between 25-50yrs
40% lost between 50-80years |
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Term
| What happens to muscle fiber types during aging |
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Definition
| less fast twitch more slow twitch |
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Term
| What can delay age-related muscle loss? |
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Definition
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Term
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Definition
rapid loss of muscle mass
50% of cancer patients
20% of cancer deaths |
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Term
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Definition
Hereditary defects in muscle protein
loss of muscle fibers and weakness |
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Term
| Duchene muscular dystrophy |
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Definition
most common in childhood
progression varies based on specific disease type |
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Term
| Force-velocity relationship |
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Definition
at any absolute force, speed of movement is greater in muscle with higher percent of fast-twitch fibers
Maximum velocity of shortening is greatest at the lowest force (true for fast and slow twitch) |
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Term
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Definition
| addition of muscle twitches |
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Term
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Definition
| individual contractions are fused in a sustained contraction |
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| Factors of force generation during muscular contraction |
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Definition
types and number of motor units recruited
initial muscle length
nature of motor units' neural stimulation |
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Term
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Definition
as speed of movement increases, peak force generated decreases.
amount of power generated by a muscle group increases as a function of movement velocity |
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