What defines an impulse in the context of neuronal communication?

An impulse in the context of neuronal communication is defined as a self-propagating electrochemical signal. This refers specifically to the action potential, which is a rapid rise and subsequent fall in voltage or membrane potential across a cellular membrane, particularly in neurons. When a neuron is stimulated by a sufficient stimulus, it reaches a threshold that triggers the opening of voltage-gated sodium channels. This allows sodium ions to flow into the neuron, causing depolarization.

The self-propagating aspect means that once initiated, the action potential travels down the axon without loss of amplitude, as it triggers adjacent sections of the membrane to undergo similar changes. This phenomenon is crucial for the transmission of signals over long distances in the nervous system, enabling communication between neurons and from neurons to other types of cells, such as muscle cells or gland cells.

The other choices do not adequately define an impulse. A fleeting electrical discharge can refer to transient changes in membrane potential but does not capture the concept of propagation inherent to an impulse. Neurotransmitter release is involved in communication between neurons but occurs at the synapse after an action potential, rather than defining the impulse itself. A cellular resting state describes the neuron when it is not actively transmitting an impulse, highlighting the importance of learning about