l8-Neurons and Neuronal Communication Flashcards

This set of vocabulary flashcards covers the fundamental principles of neuronal communication, electrical potential measurement, chemical gradients, and the mechanics of the action potential.

Patch Clamping

A technique for measuring electrical potentials where an electrode is sealed to the cell surface.

Intracellular Recording

A measurement of electrical potential where the electrode is placed inside the cell, typically yielding a peak of about $100\,mV$.

Extracellular Recording

A measurement of electrical potential where the electrode is placed outside the cell, typically yielding a measurement of about $0.1\,mV$.

Hyperpolarised

A state where the inside of the cell membrane is more negatively charged than the outside, typical of a cell at rest.

Depolarised

A state where the inside of the cell membrane becomes more positively charged relative to the outside, occurring when cells become activated.

Electrochemical Gradient

The combined influence of energy-dependent specialized pumps, membrane impermeability, and the separation of ionic charge differentials across the membrane.

$Na^+/K^+\text{-ATPase}$ pump

An energy-dependent ($ATP$) pump that maintains a depolarised internal environment by move three sodium ($Na^+$) ions out and two potassium ($K^+$) ions into the cell.

Resting Membrane Potential ($V_m$)

The electrical charge across a neuron's membrane at rest, which is typically around $-70\,mV$, determined principally by $Na^+$ and $K^+$ ions.

Equilibrium Potential

The specific membrane voltage required to prevent the movement of a particular ion down its concentration gradient.

Nernst Equation

A formula used to calculate membrane potential for a specific ion: $E = 58\,(mV) \times \log \frac{[C]<em>{out}}{[C]</em>{in}}$.

$$E_K$$

The equilibrium potential for potassium, which at physiological concentrations is $-90\,mV$.

$$E_{Na}$$

The equilibrium potential for sodium, which at physiological concentrations is $+50\,mV$. (Note: One section in the text also refers to peak $V_m$ approaching $ENa$ quoted at $+60\,mV$ for stopping entry).

Electrostatic Force

One of two specific forces acting on ions across the membrane that is dependent on the electrical charge.

Force of Diffusion

One of two specific forces acting on ions across the membrane that is dependent on the concentration of the ions.

Goldman Hodgkin Katz Equation

An equation used to calculate $V_m$ by accounting for the different permeabilities ($P$) and concentrations of multiple ions, such as $K^+$, $Na^+$, and $Cl^-$.

Optogenetics (Blue Light)

A technique that uses blue light to open cation channels, allowing them to flow into the neuron and cause depolarisation.

Optogenetics (Yellow Light)

A technique that uses yellow light to open $Cl^-$ channels, allowing them to flow into the neuron and cause hyperpolarisation.

Threshold

The specific level of depolarisation required to trigger an all-or-nothing action potential.

Absolute Refractory Period

A period following an action potential caused by the inactivation of $Na^+$ channels, during which the membrane is completely inexcitable.

Relative Refractory Period

A period during the hyperpolarisation phase where a stimuli greater than normal is required to reach the threshold for a new action potential.

Voltage-gated Sodium Channels ($Na_V$)

Channels that open when threshold is reached to allow rapid sodium entry; they possess three functional states: closed (resting), open (active), and inactive (refractory).

Voltage-gated Potassium Channels ($K_V$)

Slower channels (approx. $0.5\,mS$) that open to allow $K^+$ efflux to repolarize/hyperpolarize the neuron; these channels do not have an inactivation state.

After-hyperpolarisation

The phase of the action potential where membrane potential reaches approximately $-90\,mV$ because $K_V$ channels remain open.