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What are the functions of muscle contraction? ****
i) body movement
ii) stabilization of body position
iii) movement of substances through the body
iv) generating heat to maintain body temperature
muscles that assist the agonist by stabilizing the origin bone or by positioning the insertion bone during the movement
Components of sarcomere
i) Z line
ii) A band (doesn't change)
iii) H zone (changes)
iv) I band (changes)
Stages of sliding filament theory.*****
1) first, tropomyosin covers an active site on the actin preventing the myosin head from binding
2) second, in presence of calcium ions, troponin pulls the tropomyosin back, exposing the active site and thus allowing the myosin to bind
3) power stroke
4) ATP attaches to the myosin head
5) ATP splits to inorganic phosphate and ADP
bending of myosin to low energy state via the expulsion of ADP and phosphate from the myosin head, which leads to shortening of sarcomere
Role of action potential in muscle contraction
AP initiates muscle contraction. AP of the neuron releases Ach in the neuromuscular synapse. The Ach activates ion channels in the sarcolemma of the muscle cell creating an AP. AP travels via T-tubules to the sarcoplasmic reticulum, which increases its permeability to calcium. At the end of each cycle, calcium is actively pumped back into the sarcoplasmic reticulum.
small tunnels in the muscle membrane which allows action potential to spread through the muscle cell more rapidly
specialized endoplasmic reticulum of the muscle cell, whose lumen is filled with calcium ions
neuron and the muscle fibers that it innervates
- independent of each other
- small motor units are usually the first ones to be activated
Types of skeletal muscles***
i) slow oxidative (type I) fibers,
ii) fast oxidative (type II A) fibers and,
iii) fast glycolytic (type II B) fibers
oxygen storing protein with one subunit
- stores oxygen inside muscle cells
- capable of storing only one molecule of oxygen
Type I fibers
- contains large amounts of myoglobin and mitochondria
- split ATP as slow rate
- slow to fatigue, but also have slow contraction velocity
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