Chapter 4: Cellular Transport and Driving Forces

Vocabulary flashcards covering cellular membrane transport, chemical and electrical driving forces, ion concentrations, and transport mechanics based on Chapter 4 lecture notes.

Semi-permeable membrane

The barrier between the inside and outside of the cell that allows the exchange of materials by letting certain things in and keeping other things out.

Phospholipid bilayer

The structural foundation of the cellular membrane consisting of hydrophilic heads and hydrophobic tails.

Permeable

The characteristic of a membrane that allows molecules to pass directly through the phospholipid bilayer.

Selective permeability

The restrictive property of a membrane that regulates which specific substances can enter or leave the cell.

Nonpolar molecules

Molecules such as oxygen, carbon dioxide, and fatty acids that can easily move across the cell membrane.

Intracellular potassium concentration

The condition where potassium is naturally present in high concentration inside the cell and low concentration outside the cell.

Intracellular sodium concentration

The condition where sodium is naturally present in low concentration inside the cell and high concentration outside the cell.

Passive transport

Spontaneous, downhill movement of particles down a concentration gradient from high to low concentration without requiring energy.

Diffusion

The net movement of specific ions or particles down a concentration gradient from an area of higher concentration to lower concentration.

Osmosis

The movement of water strictly from a high water concentration to a low water concentration, which is equivalent to moving from a low solute concentration to a high solute concentration.

Active transport

Non-spontaneous, uphill movement of particles against a force or gradient requiring energy in the form of $ATP$.

Cation

A positively charged ion, such as potassium or sodium.

Anion

A negatively charged ion, such as chloride or bicarbonate.

Chemical driving force

The physical force that pushes particles down their chemical concentration gradient from higher concentration areas to lower concentration areas.

Membrane potential ($V_m$)

The charge separation across a cell membrane caused by an unequal distribution of cations and anions, measured in millivolts ($mV$).

Resting membrane potential

The electrical state of a cell at rest, characterized by an inside environment that is more negative than the outside environment.

Electrical driving force

The force created by differences in electrical charge across a membrane that pulls cations into a negatively charged cell or anions into a positively charged environment.

Electrochemical driving force

The combined total force acting on an ion, representing the sum of both its chemical driving force and its electrical driving force.

Equilibrium potential

The state where the electrical driving force on an ion is equal in magnitude but opposite in direction to its chemical driving force, resulting in no net particle movement across the membrane.

Nernst equation

A mathematical equation used to calculate ion equilibrium values, where variables represent specific properties on exams and full calculations are solved for problem sets.