BIOSCI 107 - Introduction to Neurons: The Resting Membrane Potential

Comprehensive vocabulary flashcards covering the structural features of neurons, resting membrane potential, ion concentrations, and mathematical equations (Nernst and Goldman) and their applications in neuroscience.

Neuroscience

A scientific discipline concerned with the function and structure of the nervous system.

Nervous System Components

Composed of the Central Nervous System (CNS) and the Peripheral Nervous System (PNS).

Nervous System Cells

Consists of neurons and glia.

Neurons (Nerve cells)

The principal building blocks and instruments of communication in the brain, utilizing electrical signals (dendrites, cell body, axon) and chemical signals (synapses).

Resting Membrane Potential (RMP)

The electrical potential difference across a cell membrane, typically $50$ to $70\,mV$ lower (more negative) in the cytosol than in the extracellular fluid.

Excitable Tissues

Tissues, specifically neurons and muscle fibres, that can suddenly respond with a transient change of potential (an action potential) in response to a stimulus.

Microelectrode recording technique

A method to measure intracellular potentials using a pipette and a ground to record from a neuron.

Patch-clamp technique

A method to measure intracellular potentials that involves creating a gigaohm seal at the pipette tip.

Intracellular Potential Convention

The potential outside the cell is defined as $0$, meaning intracellular potential is normally below zero, such as $-65\,mV$.

Extracellular Concentration of $K^+$

$$5\,mM$$

Intracellular Concentration of $K^+$

$$100\,mM$$

Extracellular Concentration of $Na^+$

$$150\,mM$$

Intracellular Concentration of $Na^+$

$$15\,mM$$

$Na^+/K^+$ Pump Ratio

Maintains concentration gradients by moving $3\,Na^+$ out and $2\,K^+$ in.

Non-gated ('leak') channels

Ion channels that are open at rest (on-off state) and allow for the diffusion of ions.

Gated channels

Ion channels that are closed at rest and can be voltage-gated, ligand-gated, or mechanically gated.

Relative Permeability ($P_K / P_{Na}$) in Neurons

At rest, the ratio is approximately $40/1$ because neurons have many leak $K^+$ channels but very few leak $Na^+$ channels.

Equilibrium Potential ($E_{ion}$)

An intracellular potential at which the net flow of ions is zero according to its electrochemical gradient.

Nernst Equation

$$E_{ion} = 61.5\,mV \times \log \frac{[ion]_o}{[ion]_i}$$

Equilibrium potential for $K^+$ ($E_K$)

Approximately $-80\,mV$.

Equilibrium potential for $Na^+$ ($E_{Na}$)

$+60\,mV$.

Glial Cell RMP

In glia cells, the RMP is equal to $E_K$ ($-80\,mV$) because they have leak channels only for $K^+$.

Goldman Equation

A formula for calculating RMP that accounts for both concentration gradients and the relative permeability ($P$) of the membrane to $K^+$ and $Na^+$: $V_m = 61.5\,mV \log \frac{P_K[K^+]_o + P_{Na}[Na^+]_o}{P_K[K^+]_i + P_{Na}[Na^+]_i}$

A. Hodgkin and A. Huxley

Winners of the 1963 Nobel prize in Physiology and Medicine for their 1938 experiment on the squid giant axon regarding the resting membrane potential.