Flashcards in Muscular System Deck (69)
Calcium complex that modifies the position of tropomyosin
First step of Muscle Fiber Contraction
Nerve impulses (action potential) travels down motor neurons to a neuromuscular junction
Where a motor neuron connects to skeletal muscle
A nerve fiber and all of the muscle fibers that it innervates
Second Step of Muscle Fiber Contraction
Acetylcholine (ACh) is released from the neurons and bind to the muscle fibers. (Synaptic vesicles of the neuron contain ACh, a neurotransmitter, where it binds with receptor on the sarcolemma)
Third Step of Muscle Fiber Contraction
Binding of ACh stimulates impulses down the T-tibules causing calcium to be released from the sarcoplasmic reticulum
Fourth Step of Muscle Fiber Contraction
Calcium complex (troponin) modifies tropomyosin, exposing binding site
Fifth Step of Muscle Fiber Contraction
Myosin head binds with actin (thanks to ADP + P)
Sixth Step of Muscle Fiber Contraction
ADP + P are released, resulting in a power stroke
Seventh Step of Muscle Fiber Contraction
Additional ATP allows for myosin head to return to resting position and calcium to be pumped back into sarcoplasmic reticulum
Method of detecting changes in ions associated with muscle contraction
Difference in charge from place to place - can be detected on surface of skin
A nerve fiber and all of the muscle fibers it stimulates - "all or none"
Motor Unit Recruitment
Increases the strength of contraction by increasing the number of motor units in use
Fatigue sets in when...
...you have recruited same motor units for a while and depleted energy (ATP)
Muscle twitch is...
A single motor unit contraction, caused by infrequent electrical impulses, and lasts a fraction of a second.
Increase in muscle contraction until maximum sustained contraction (tetanus) is reached, and lasts until fatigue (muscle relaxes despite stimulation due to depletion of energy reserves).
Maximal sustained contraction
Decrease in a muscle's ability to generate force, when the muscle relaxes despite stimulation due to depletion of energy reserves.
Four sources of ATP for muscle contraction...
Stored in muscle fibers
Fastest way to acquire ATP but only sustains cell for seconds; builds up when a muscle is resting (anaerobic).
Fast-acting but results in lactate build-up (anaerobic)
Not an immediate source of ATP, but best long term source (aerobic)
Protein that transports oxygen directly to mitochondria of muscle cells
Fast Twitch Fiber Characteristics
Creatine-Phosphate pathway and fermentation for ATP
Fewer blood vessels
Slow Twitch Fiber Characteristics
Cellular Respiration for ATP
More blood vessels
Fast Twitch Muscle Characteristics
Slow Twitch Muscle Characteristics
Sudden, involuntary muscle contractions that are usually painful