What does it mean when a membrane is depolarized?

As a neuroscientist with a focus on cellular and molecular neuroscience, I can explain the concept of membrane depolarization. When a cell, particularly a neuron, is at rest, it has a certain electrical charge across its cell membrane known as the resting membrane potential. This is typically around -70 millivolts (mV) in neurons, where the inside of the cell is more negatively charged compared to the outside. Depolarization occurs when there is a decrease in this negative charge, causing the inside of the cell to become less negatively charged or even positively charged relative to the outside. This shift in electrical potential is often due to the opening of ion channels in the membrane that allow positively charged ions, such as sodium (Na+), to flow into the cell. The significance of depolarization is that it can lead to the generation of an action potential, which is the electrical signal that travels down the neuron and is essential for communication between neurons and for the neuron to interact with other cells, such as muscles or glands. Here's the translation in Chinese: 作为一名专注于细胞和分子神经科学的神经科学家，我可以解释膜去极化的概念。 当一个细胞，特别是一个神经元，在休息状态下，它的细胞膜上有一种称为静息膜电位的电荷。在神经元中，这通常是大约-70毫伏特（mV），其中细胞内部比外部带有更多的负电荷。 去极化发生在这种负电荷减少时，导致细胞内部相对于外部变得不那么负电荷，甚至可能变成正电荷。这种电位的转变通常是由于膜上离子通道的打开，允许带正电荷的离子，如钠（Na+），流入细胞。 去极化的重要性在于它可以导致动作电位的产生，这是沿着神经元传播的电信号，对于神经元之间的通信以及神经元与其他细胞（如肌肉或腺体）的相互作用至关重要。

the process of reversing the charge across a cell membrane (usually a NEURON), so causing an ACTION POTENTIAL. In depolarization, the inside of the membrane, which is normally negatively charged, becomes positive and the outside negative. This is brought about by positive sodium ions rapidly passing into the axon.