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sarcoplasmic reticulum (SR)
the muscle fiber's version of smooth endoplasmic reticulum; function is to temporarily store calcium
transverse tubules, formed by inward extensions of the sarcolema; main function is to allow electrical signals to move deeper into the cell
a T tubule sandwiched between two sacs of sarcoplasmic reticulum; allows electrical impulse traveling along T tubule to stimulate the membranes of adjacent sacs of the sarcoplasmic reticulum
bundles of very fine cytoskeletal filaments that extend lengthwise along skeletal muscle fiber and almost fill the sarcoplasm
dark strips called "A bands", light H zone runs across the midsection of each dark A band; light stripes called "I bands", dark Z disk extends across the center of each light I band
makes up almost all the thick filament, "heads" are chemically attratcted to actin molecules, "heads" are known as cross bridges when attached to actin
globular protein that forms two fibrous strands twisted around each other to form the bulk of the thin filament
motor neurons connect to the sarcolemma at the motor endplate; is a synapse where neurotransmitter molecules transmit signals
the neurotransmitter released into the synaptic cleft that diffuses across the gap, stimulates the receptors, and initiates an impulse in the sarcolemma
thick (myosin) filaments are held together and stabilized by protein molecules that form a middle line (proteins built up)
the segment that includes the Z disk and the ends of the thin filaments where they do not overlap the thick filaments (light, and only acton)
the middle region of the thick filaments where they do not overlap the thin filaments (only myosin)
composed of a protein called titin, they anchor the ends of the thick filaments to the Z disk
nerve cell that carries signals from the central nervous system to muscle or gland cells
The theory explaining how muscle contracts, based on change within a sarcomere, the basic unit of muscle organization, stating that thin (actin) filaments slide across thick (myosin) filaments, shortening the sarcomere; the shortening of all sarcomeres in a myofibril shortens the entire myofibril
creatine phosphate (CP)
a unique high energy molecule stored in muscles, is tapped to regenerate ATP while the metabolic pathways are adjusting to the suddenly higher demands for ATP
cellular respiration that uses oxygen, sequentially releasing energy and storing it in ATP
a hemoprotein that receives oxygen from hemoglobin and stores it in the tissues until needed
red muscle fibers that are slow to contract but have the ability to continue contracting for long periods of time
very similar to fast fibers, although they have a greater resistance to fatigue.
product of anaerobic respiration that accumulates in muscle tissue during exercise and causes a burning sensation
somatic motor neuron
Stimulate skeletal muscle to contract, one neuron sends branches to multiple muscle fibers
process of recording the strength of muscle contraction as a result of electrical stimulation
the latent period
during which phase of the twitch contraction, is there a triggering of the release of calcium ions into the sarcoplasm
gradual, steplike increase in the strength of contraction, the muscle responds with less forceful contractions and relaxations phase becomes shorter
multiple wave summation
if a series of stimuli come in rapid enough succession, the muscle does not have time to relax completely before the next contraction phase
A simple automatic action of the spinal cord not requiring involvement of the brain, such as the knee-jerk reflex
graded strength principle
skeletal muscles contract with varying degrees of strength at different times
the maximal strength that a muscle can develop is directly related to the initial length of its fibers
a contraction in which the tone or tension within a muscle remains the same as the length of the muscle changes, aka dynamic tension
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