RMP of the neuron is:
## **Core Concept**
The resting membrane potential (RMP) of a neuron is primarily determined by the differential distribution of ions (mainly sodium [Na+] and potassium [K+]) across the cell membrane and the selective permeability of the membrane to these ions. This concept is fundamental to understanding neuronal physiology.
## **Why the Correct Answer is Right**
The RMP of a typical neuron is approximately -70 millivolts (mV), which is closest to option **C. -70 mV**. This negative potential is largely due to the high permeability of the neuronal membrane to K+ ions and the action of the sodium-potassium pump, which maintains a high concentration of K+ inside the cell and a high concentration of Na+ outside the cell. The movement of K+ ions out of the cell down their concentration gradient results in a net positive charge outside the cell and a net negative charge inside, generating the RMP.
## **Why Each Wrong Option is Incorrect**
- **Option A:** -50 mV is more positive than the typical RMP of a neuron, which does not accurately reflect the resting state.
- **Option B:** -90 mV is more negative than the typical RMP; while some neurons may have RMPs in this range, -70 mV is more universally accepted.
- **Option D:** -100 mV is significantly more negative than the accepted RMP for most neurons, which does not align with standard physiological values.
## **Clinical Pearl / High-Yield Fact**
A key point to remember is that the RMP is not static and can be influenced by various factors, including changes in ion channel expression or function, synaptic inputs, and the presence of certain neurotransmitters or drugs. Understanding the RMP is crucial for comprehending how neurons integrate and transmit information.
## **Correct Answer:** C. -70 mV.