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A vascular smooth muscle has several receptors that allow it to respond to signals from the sympathetic nervous system or to sympathetic stimuli. These receptors are alpha-1, alpha-2, and beta-2 receptors. When the neurotransmitter norepinephrine binds to the alpha-1 receptors, contraction of the...
Journal of PhysiologyLangley, J.N. (1909) On the contraction of muscle, chiefly in relation to the presence of “receptive” substances. Part IV. The effect of curare and of some other substances on the nicotine response of the sartorius and gastrocnemius muscles of the frog. J. Physiol. ...
Understanding muscle contraction goes to the heart of one of the fundamental questions posed by classical philosophy, namely the nature of the pi nu epsilon upsilon mu alpha psi nu chi iota kappa omicron nu. The nature of 'understanding' has altered greatly during the last two millenia, ...
If embryonic heart cells are separated into a Petri dish and kept alive, each is capable of generating its own electrical impulse followed by contraction. When two independently beating embryonic cardiac muscle cells are placed together, the cell with the higher inherent rate sets the pace, and ...
The wave of contraction that allows the heart to work as a unit, called a functional syncytium, begins with the pacemaker cells. This group of cells is self-excitable and able to depolarize to threshold and fire action potentials on their own, a feature calledautorhythmicity; they do this ...
Understanding muscle contraction goes to the heart of one of the fundamental questions posed by classical philosophy, namely the nature of the pi nu epsilon upsilon mu alpha psi nu chi iota kappa omicron nu. The nature of 'understanding' has altered greatly during the last two millenia, particul...
5: Myosin heads bind to actin and execute power strokes leading to muscle contraction. Repolarization of the sarcolemma along the T-tubules shifts the DHPRs back to their resting state of blocking Ca2+ efflux from the SR, while the SR Ca2+ ATPase (SERCA) found on the SR membrane quickly ...
In effect, the muscle cell runs out of energy and fluid and becomes hyperexcitable, resulting in a forceful contraction. This spasm may involve part of a muscle, the whole muscle, or even adjacent muscles. Overuse as a cause of skeletal muscle spasms is often seen in athletes who are doing...
(which in this region corresponds to the pectoral fascia) and theperimysium, allowing muscular contraction to be modulated by ‘peripheral’ demands. This mechanism describes a possible anatomical basis for peripheral motor coordination. A similar structure can also be found in thedorsal regionbetween...