Horse
the smallest contractile response (contraction and relaxation) of muscle that occurs in response to a single stimulus
twitch
muscle shortens as it maintains tension (as in lifting a weight)
isotonic concentric contraction
the minimum amount of stimulus to cause contraction
increasing the number of motor units responding to a single stimulus, increasing tension in muscle fiber
recruitment
muscle lengthens while maintaining tension (as in lowering a weight)
isotonic eccentric contraction
what phase of muscle twitch?
2 msec delay; time for excitation-coupling to occur
latent period
the force generated during the latent period
internal tension
which phase of muscle twitch is this?
the rise in tension through crossbridge cycle
contraction phase
increase in tension when a muscle fiber is unable to relax between twitches. twitches overlap and produce a contraction
summation
what phase of muscle twitch?
decline in tension. (Ca2+ is pumped back into SR)
relaxation
no change in muscle length, no movement
isometric
how is the ratio of different fiber types determined?
genetically
which fibers make ATP aerobically?
Slow Twitch
relating to muscle fatigue...
what inhibits Ca2+ release from SR, inhibits troponin’s sensitivity to Ca2+ thereby inhibiting force.
ADP/Pi accumulation
what is the ability to maintain high intensity for more than 4-5 minutes? (determined by VO2max)
endurance
disorder of muscle tissue:
autoimmune disease
antibodies attack neuromuscular junctions and bind ACh receptors together in clusters causing weakness. –No stimulus
myasthenia gravis
The demand for oxygen exceeds the availability of oxygen
EPOC (excess post exercise oxygen consumption)
"oxygen debt"
what are the 3 systems for ATP generation in skeletal muscle fiber?
endurance exercise/muscle fatigue contributes to 3 things..
fuel depletion
loss of electrolytes
central fatigue triggered by ammonia, inhibiting somatic motor neurons in the brain
muscle tissue disorder:
–hereditary diseases (mutation in protein gene)
what are the 6 factors that contribute to the contraction strength of twitches?
Length – tension relationship
• how stretched muscle was before it was stimulated
Fatigue
Temperature
• warmed-up muscle contracts more strongly
• enzymes work more quickly
Stimulus frequency
• Stimuli arriving closer together produce stronger twitches
Concentration of Ca+2
• Calcium in sarcoplasm can vary the frequency
Hydration
• state of hydration of muscle affects overlap of thick & thin filaments
the point at which the rate of O2 consumption reaches a plateau and increases no further with added workload.
which fibers work aerobically and anaerobically?
fast twitch
additional oxygen is required to do ...? (4 things)
Discuss the two broad types of exercise that affect muscles differently and how they improve muscle fitness.
Resistance exercise: contraction of muscles against a load that resists movement. Growth results from cellular enlargement, not division. Muscle fibers synthesize more myofilaments and the myofibrils grow thicker. Myofibrils split longitudinally when they reach a certain size, so a well conditioned muscle has more myofibrils than a poorly conditioned one
Endurance (aerobic) exercise: improves the fatigue resistance of muscles by enhancing the delivery and use of oxygen. Improves skeletal strength by increasing the RBC count, and oxygen transport capacity of the blood; and enhances the function of the cardiovascular, respiratory, and nervous systems