Question

total information about conduction of nerve starting from intro upto conclusion

Answer 1

neurones are excitable cells because their membranes are in a polarized state. different types of Ion channels are present on the neural membrane these ion channels are selectively permeable to ions when the neurone is not conducting an impulse that is in resting state the axon membrane is comparatively more Permeable to potassium and nearly impermeable to sodium ions similarly the membrane is impermeable to negatively charged proteins present in axoplasm. consequently, the axoplasm inside the axon contains high concentration of potassium ions and negatively charged proteins and low concentrations of sodium ions. incontrast the fluid outside the axon contains low concentrations of potassium and high concentration of sodium forming a concentration gradient. these ionic gradient across the resting membrane are maintained by active transport of Ions by the Sodium Potassium pump which transports 3 sodium ions out words for to potassium ions into the cell. as a result the outer surface of the axonal membrane possesses positive charge while its inner surface becomes negatively charged therefore is polarized. the electrical potential difference across the resting plasma membrane is called the resting potential. when is stimulus is applied at the site on the polarized membrane the membrane at the site becomes freely permeable to sodium ions this leads to a rapid influx of sodium ions followed by the reversal of polity at the site that is outer surface of the membrane becomes negatively charged and inside becomes positively charged the polarity of the membrane at site is therefore reversed and hence depolarized. the electrical potential difference across the plasma membrane at the site is called action potential which is in fact termed as nerve impulse at sites immediately ahead the axon membrane has a positive charge on the outer surface and a negative charge on its inner surface from site a to site b. an outer surface current flows from site B to site a to complete the circuit of current flow. Hence polarity at the site is reversed and action potential is generated at site b. thus the impulse generated at site A arrives at site B. the sequence is repeated along the length of axon. that is how the nerve impulse is conducted the rise in stimulus induced permeability of sodium ions is extremely short lived it is quickly followed by a rise in permeability to potassium ions within a fraction of second potassium diffuses outside the membrane and restore the resting potential of the membrane at site of exitation and the fibres become once more responsive to the further stimulation

Answer 2

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A nerve impulse is the electric signals that pass along the dendrites to generate a nerve impulse or an action potential. An action potential is due to the movement of ions in and out of the cell. It specifically involves sodium and potassium ions. They are moved in and out of the cell through sodium and potassium channels and sodium-potassium pump.

Conduction of nerve impulse occurs due to the presence of active and electronic potentials along the conductors. Transmission of signals internally between the cells is achieved through a synapse. Nerve conductors comprise relatively higher membrane resistance and low axial resistance. The electrical synapse has its application in escape reflexes, heart and in the retina of vertebrates. They are mainly used whenever there is a requirement of fast response and timing being crucial. The ionic currents pass through the two cell membrane when the action potential reaches the stage of such synapse.

Mechanism of Transmission of Nerve Impulse

The axon or nerve fibres are in the form of a cylinder wherein the interior of the axon is filled with axoplasm and the exterior is covered with axolemma. The nerve fibres are immersed in ECF. The solution is in the ionic form that is present in axoplasm and extracellular fluid or ECF.

Outside the axon, the negatively charged chloride ions are neutralized in the presence of positively charged sodium ions. Negatively charged protein molecules are neutralized in the presence of potassium ions within the axoplasm. The membrane of a neuron is -ve inside and +ve outside. Resting potential would be the difference in charge. The difference in charge might vary from seventy to ninety millivolts, as a result, the membrane would be polarized. Sodium potassium pump operates to keep resting potential in equilibrium.

The pump is placed on the axon membrane. Now the potassium ions are pumped from ECF to axoplasm and sodium ions are pumped from axoplasm to ECF.

The sodium-potassium pump stops operating when a stimulus is applied to a membrane of a nerve fibre. The stimulus could be either electrical, chemical or mechanical. The potassium ions rush outside the membrane and sodium ions rush inside the membrane as a result negative charges are present outside and positive charges are present inside.

The nerve fibres are either depolarized or they are said to be in the action potential. The action potential travelling along the membrane is called the nerve impulse. It is around + 30 mV. The sodium-potassium pump starts to operate once the action potential is completed. As a result, the axon membrane will obtain a resting potential by repolarization.