Introduction to Physiology Lecture 2

The difference in concentrations of ions (like potassium and sodium) across the cell membrane. This imbalance is essential for generating the Resting Membrane Potential (RMP).

The electrical potential difference across the cell membrane when the cell is at rest. It's a negative charge inside the cell compared to outside.

The cell membrane has different levels of permeability for different ions. It allows some ions to pass more easily than others.

Channels in the cell membrane that allow potassium ions to leak out of the cell, contributing to the RMP.

The state where the forces driving the movement of ions across the membrane are balanced. The concentration gradient pushing ions across the membrane is equal to the electrical force pulling them back.

The electrical activity that occurs within living organisms, primarily in nerve and muscle cells.

The voltage difference across the cell membrane caused by the uneven distribution of ions.

The main factors responsible for creating the RMP are: 1. Unequal ion distribution across the cell membrane, 2. Greater membrane permeability to potassium (K+) than sodium (Na+), 3. Large negatively charged molecules inside the cell, and 4. The Na+/K+ pump.

The RMP of a nerve cell is typically around -70mV because the cell membrane is much more permeable to potassium than sodium. Potassium ions move out of the cell, creating a negative charge inside.

High levels of potassium in the blood (hyperkalemia) can disrupt the RMP of heart cells, leading to irregular heartbeats and even cardiac arrest.

A protein pump in the cell membrane that actively pumps three sodium ions out for every two potassium ions pumped in, contributing to the negative charge inside the cell.

Large negatively charged molecules, like proteins, trapped inside the cell, contribute to the negative charge inside the cell. They can't easily cross the membrane.

A mathematical equation that calculates the equilibrium potential for a specific ion across a membrane. It considers the concentration gradient and the ion's charge.

The electrical potential difference across a membrane when the net movement of a specific ion is zero. The ion is at equilibrium, with no further driving force.

The equilibrium potential for potassium is the electrical potential difference across a membrane when potassium ions are in equilibrium. It is calculated using the Nernst Equation, taking into account the potassium concentration gradient and charge.

The RMP is closer to EK+ because the cell membrane is much more permeable to potassium ions (K+) than sodium ions (Na+). Potassium can move across the membrane more easily, so it has a greater influence on the overall RMP.

A protein pump that actively transports three sodium ions out of the cell and two potassium ions into the cell, using energy from ATP hydrolysis. It maintains the concentration gradients of these ions across the membrane.

While contributing only a small amount (6-8 mV) to the RMP, the sodium-potassium pump is crucial for maintaining the ionic gradients across the membrane. This gradient is essential for the diffusion potential, which is the primary factor determining RMP.

A more accurate equation for predicting the resting membrane potential (RMP), taking into account the permeability (P) of the membrane to different ions and their movement.