Neuroscience Grade 2: Excitable Tissues

Specialized tissues (like muscle and nerve) that can respond to stimuli by producing electrical signals.

The ability of all living tissues to respond to stimuli (both internal and external).

The ability of specialized cells to respond to certain stimuli by producing electrical signals (action potentials).

An electrical signal produced and transmitted across the membrane of excitable cells.

Pores in cell membranes that allow specific ions to move across, crucial for electrical signals.

The electrical difference across the membrane of a cell when it's not transmitting a signal.

A protein that actively transports sodium ions (Na⁺) out of and potassium ions (K⁺) into the cell, maintaining the resting membrane potential.

The ability of a cell to transmit an electrical impulse along its membrane.

A device used to visualize electrical activity in nerve membranes. An upward deflection indicates the inside of the membrane is becoming more positive, a downward deflection indicates it's becoming more negative.

A mathematical formula that calculates the equilibrium potential for a specific ion. Essentially, it determines the voltage needed to balance the ion's movement across the membrane due to concentration differences.

Approximately -90 mV, meaning the inside of the nerve cell is more negative than the outside at equilibrium for potassium ions.

Approximately +60 mV, meaning the inside of the nerve cell is more positive than the outside at equilibrium for sodium ions.

The ease with which an ion can pass through the membrane. Nerve membranes are significantly more permeable to potassium ions than to sodium ions (about 100 times more).

The difference in electrical charge across the membrane of a nerve cell. Caused by the uneven distribution of ions (cations and anions) between the intracellular and extracellular fluid.

Approximately -90 millivolts (mV). This means the inside of the cell is 90 mV more negative than the outside.

A cell is polarized when there's a voltage difference across its membrane, like the negative charge inside the cell during resting potential.

K⁺ ions move out of the cell more than Na⁺ ions move in, contributing to the negative charge inside the cell.

A protein that actively pumps 3 Na⁺ ions out of the cell for every 2 K⁺ ions pumped in, maintaining the negative charge inside.

By pushing out more positive charges (Na⁺) than it brings in (K⁺), it reinforces the negative charge inside the cell.

The presence of negatively charged proteins inside the cell also contributes to the overall negative charge within the cell.

A cell with many open ion channels, resulting in a low input resistance and difficulty changing membrane potential.

Chloride channels can influence cell excitability by modifying membrane resistance.

These drugs increase the duration of Cl- channel opening, leading to increased Cl- influx and membrane hyperpolarization, reducing neuronal excitability.

A change in membrane potential that makes it more negative, making it harder for the neuron to fire.

A measure of how difficult it is to change the membrane potential of a cell.

Cells like epithelial cells and adipose cells that do not change their membrane potential over time in response to stimuli.

Cells like neurons and muscle cells that can generate electrical signals in response to stimuli.

Ion channel dysfunction can lead to various diseases like ataxias, paralyses, epilepsies, and deafness, highlighting their importance in brain function.

Conditions caused by mutations in ion channels, affecting the flow of charged particles across cell membranes. These disruptions can lead to problems like epilepsy, migraines, and heart rhythm disorders.

A protein in cell membranes that actively pumps sodium ions out and potassium ions into the cell. This helps maintain the resting membrane potential and is crucial for nerve and muscle function.

The daily 24-hour cycle of biological processes in living organisms, including sleep-wake cycles, hormone release, and body temperature fluctuations.

A hormone produced by the pineal gland, primarily at night. It plays a crucial role in regulating sleep, circadian rhythms, and other biological processes.

The electrical difference across the membrane of a nerve cell when it's not transmitting a signal. This difference is maintained by the sodium-potassium pump and ion channel activity.