Neurons Are Excitable Cells

Neurons are specialized to sense, transduce, process, store, and transmit information. Information is carried both within and between neurons in the form of electrical and chemical signals. Neurons are known as excitable cells, in that they are capable of altering their membrane potential to serve as a signaling mechanism. The membrane potential arises because the plasma membrane is not freely permeable to ions present in the intracellular and extracellular environment. The major ions used by nerve cells to carry signals are Na + , K + , Ca2+ and Cl_. Ion channels specific for these ions are present in the plasma membrane. When they open, ions may pass into or out of the cell depending upon their concentration gradients, changing the membrane potential and also initiating second messenger cascades, activating enzymes, modifying the cytoskeleton, and regulating gene transcription. Ionic gradients are maintained by the action ofelectrogenic pumps, which actively pump ions into and out of the cell against their concentration gradients. These pumps are energy-dependent, that is, they require the hydrolysis of adenosine triphosphate (ATP) and are thus referred to as ATPases.

Breaking Bulimia

Breaking Bulimia

We have all been there: turning to the refrigerator if feeling lonely or bored or indulging in seconds or thirds if strained. But if you suffer from bulimia, the from time to time urge to overeat is more like an obsession.

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