A nerve impulse, also known as an action potential, is an electrical signal that travels along the nerve cells or neurons in the nervous system.
It is the fundamental mechanism through which neurons communicate with each other and transmit information.
Nerve impulses are crucial for processing sensory input, generating motor output, and enabling higher cognitive functions such as learning and memory.
Here’s an overview of how a nerve impulse is generated and transmitted:
1. Resting state:
Neuron at resting membrane potential, around -70 mV.
2. Stimulus and depolarization:
External stimulus cause local depolarization; if threshold is reached, voltage-gated Na+ channels open, leading to a rapid increase in membrane potential.
3. Propagation:
Nerve impulse travels along the axon as depolarization opens voltage-gated Na+ channels in adjacent regions.
4. Repolarization:
Voltage-gated K+ channels open, allowing K+ ions to exit, restoring membrane potential back to resting state.
5. Refractory period:
Neuron enters a period where generating another action potential is difficult or impossible, ensuring unidirectional propagation of nerve impulses.
6. Synaptic transmission:
It triggers neurotransmitter release at the synaptic terminal, influencing the postsynaptic neuron’s membrane potential.
Here is the diagram illustrating the process of nerve impulse transmission: