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Summation, which includes both spatial summation and temporal summation, is the process that determines whether or not an action potential will be generated by the combined effects of excitatory and inhibitory signals, both from multiple simultaneous inputs (spatial summation), and from repeated inputs (temporal summation).
Temporal summation: When a single synapse inputs that are close together in time, their potentials are also added together. Thus, if a neuron receives an excitatory postsynaptic potential, and then the presynaptic neuron fires again, creating another EPSP, then the membrane of the postsynaptic cell is depolarized by the total sum of all the ...
Temporal summation refers to successive excitatory stimuli on the same location of the postsynaptic neuron. Both types of summation are the result of adding together many excitatory potentials; the difference being whether the multiple stimuli are coming from different locations at the same time (spatial) or at different times from the same ...
Depiction of smooth muscle contraction. Muscle contraction is the activation of tension-generating sites within muscle cells. [1] [2] In physiology, muscle contraction does not necessarily mean muscle shortening because muscle tension can be produced without changes in muscle length, such as when holding something heavy in the same position. [1]
Therefore, in order to achieve threshold and generate an action potential, the postsynaptic neuron has the capacity to add up all of the incoming EPSPs based on the mechanism of summation, which can occur in time and space. Temporal summation occurs when a particular synapse is stimulated at a high frequency, which causes the postsynaptic ...
A fused tetanic contraction is the strongest single-unit twitch in contraction. [6] When tetanized, the contracting tension in the muscle remains constant in a steady state. This is the maximal possible contraction. [3] During tetanic contractions, muscles can shorten, lengthen or remain constant length. [7]
In muscle cells, for example, an action potential is the first step in the chain of events leading to contraction. In beta cells of the pancreas , they provoke release of insulin . [ a ] Action potentials in neurons are also known as " nerve impulses " or " spikes ", and the temporal sequence of action potentials generated by a neuron is called ...
When necessary, the maximal number of motor units in a muscle can be recruited simultaneously, producing the maximum force of contraction for that muscle, but this cannot last for very long because of the energy requirements to sustain the contraction. To prevent complete muscle fatigue, motor units are generally not all simultaneously active ...