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Cell excitability is the change in membrane potential that is necessary for cellular responses in various tissues. The resting potential forms the basis of cell excitability and these processes are fundamental for the generation of graded and action potentials. Normal and pathological activities in the heart and brain can be modelled as ...
Cell excitability (biology) This page was last edited on 24 January 2020, at 17:36 (UTC). Text is available under the Creative Commons ...
Dolf Zillmann began developing excitation-transfer theory in the late 1960s through the early 1970s and continued to refine it into the 21st century. [1] The theory itself is based largely on Clark Hull's notion of residual excitation (i.e., drive theory), Stanley Schachter's two factor theory of emotion, and the application of the three-factor theory of emotions.
Nerve excitability studies have established a number of biophysical differences between human sensory and motor axons. [6] Even though the diameters and conduction velocities of the most excitable motor and sensory fibers are similar, sensory fibers have significantly longer strength-duration time constants. [11]
As an action potential (nerve impulse) travels down an axon there is a change in electric polarity across the membrane of the axon. In response to a signal from another neuron, sodium- (Na +) and potassium- (K +)–gated ion channels open and close as the membrane reaches its threshold potential.
Chronaxie is the tissue-excitability parameter that permits choice of the optimum stimulus pulse duration for stimulation of any excitable tissue. Chronaxie (c) is the Lapicque descriptor of the stimulus pulse duration for a current of twice rheobasic (b) strength, which is the threshold current for an infinitely long-duration stimulus pulse.
Overexcitability is a term introduced to current psychology by Kazimierz Dąbrowski as part of his theory of positive disintegration (TPD). Overexcitability is a rough translation of the Polish word 'nadpobudliwość', which is more accurately translated as 'superstimulatability' in English.
As a rule, premature ectopic beats (i.e. with a shorter than the prevailing preceding R-R' interval) indicate increased myocyte or conducting tissue excitability, whereas late ectopic beats (i.e. with a prolonged preceding R-R' interval) indicate proximal pacemaker or conduction failure with an escape 'ectopic' beat.