● When a stimulus is applied at a site on the `color{violet}("polarised membrane")` , the membrane at the site A becomes freely `color{brown}("permeable to" Na^+)` .
● This leads to a `color{violet}("rapid influx")` of`color{violet}( Na^+)` followed by the reversal of the polarity at that site, i.e., the outer surface of the membrane becomes `color{violet}("negatively charged")` and the `color{violet}("inner side")` becomes `color{violet}("positively charged.")`
● The `color{violet}("polarity of the membrane")` at the site A is thus reversed and hence `color{brown}("depolarised. ")`
● The `color{violet}("electrical potential difference")` across the `color{violet}("plasma membrane")` at the site A is called the `color{brown}("action potential")`, which is in fact termed as a `color{brown}("nerve impulse.")`
● At sites immediately ahead, the `color{violet}("axon")` (e.g., site B) membrane has a `color{violet}("positive charge")` on the outer surface and a `color{violet}("negative charge")` on its`color{violet}(" inner surface.")`
● As a result, a `color{violet}("current flows")` on the `color{violet}("inner surface")` from site A to site B
● On the `color{violet}("outer surface")` current flows from site B to site A to complete the `color{violet}("circuit of current flow")`.
● Hence, the `color{violet}("polarity")` at the site is reversed, and an `color{violet}("action potential")` is generated at site B.
● Thus, the `color{violet}("impulse (action potential)")` generated at site A arrives at site B.
● The sequence is repeated along the length of the `color{violet}("axon")` and consequently the `color{violet}("impulse")` is conducted.
● The rise in the stimulus-induced `color{violet}("permeability to" Na^+)` is extremely `color{brown}("short lived.")`
● It is quickly followed by a `color{brown}("rise in permeability to" K^+)`.
● Within a `color{violet}("fraction of a second," K^+)` diffuses outside the membrane and restores the `color{violet}("resting potential")` of the membrane at the site of excitation and the `color{violet}("fibre")` becomes once more `color{brown}("responsive to further stimulation.")`
● When a stimulus is applied at a site on the `color{violet}("polarised membrane")` , the membrane at the site A becomes freely `color{brown}("permeable to" Na^+)` .
● This leads to a `color{violet}("rapid influx")` of`color{violet}( Na^+)` followed by the reversal of the polarity at that site, i.e., the outer surface of the membrane becomes `color{violet}("negatively charged")` and the `color{violet}("inner side")` becomes `color{violet}("positively charged.")`
● The `color{violet}("polarity of the membrane")` at the site A is thus reversed and hence `color{brown}("depolarised. ")`
● The `color{violet}("electrical potential difference")` across the `color{violet}("plasma membrane")` at the site A is called the `color{brown}("action potential")`, which is in fact termed as a `color{brown}("nerve impulse.")`
● At sites immediately ahead, the `color{violet}("axon")` (e.g., site B) membrane has a `color{violet}("positive charge")` on the outer surface and a `color{violet}("negative charge")` on its`color{violet}(" inner surface.")`
● As a result, a `color{violet}("current flows")` on the `color{violet}("inner surface")` from site A to site B
● On the `color{violet}("outer surface")` current flows from site B to site A to complete the `color{violet}("circuit of current flow")`.
● Hence, the `color{violet}("polarity")` at the site is reversed, and an `color{violet}("action potential")` is generated at site B.
● Thus, the `color{violet}("impulse (action potential)")` generated at site A arrives at site B.
● The sequence is repeated along the length of the `color{violet}("axon")` and consequently the `color{violet}("impulse")` is conducted.
● The rise in the stimulus-induced `color{violet}("permeability to" Na^+)` is extremely `color{brown}("short lived.")`
● It is quickly followed by a `color{brown}("rise in permeability to" K^+)`.
● Within a `color{violet}("fraction of a second," K^+)` diffuses outside the membrane and restores the `color{violet}("resting potential")` of the membrane at the site of excitation and the `color{violet}("fibre")` becomes once more `color{brown}("responsive to further stimulation.")`