Cellular Transport and Resting Membrane Potential

Vocabulary flashcards covering resting membrane potential, ion concentrations, passive and active transport mechanisms, membrane proteins, and vesicular transport based on lecture notes.

Resting Membrane Potential (RMP)

An electrical potential across the cell membrane that is always negative, specifically measured at $-70\,mV$ in neurons.

Intracellular Ion Distribution

The relative ion concentrations inside the cell at rest, characterized by low $[Na^+]$ and high $[K^+]$.

Extracellular Ion Distribution

The relative ion concentrations outside the cell at rest, characterized by high $[Na^+]$ and low $[K^+]$.

RMP Maintenance Factors

The three factors that maintain resting membrane potential: 1) $Na^+/K^+$ pump, 2) negatively charged proteins inside the cell, and 3) leaky $[K^+]$ channels allowing $K^+$ to diffuse out of the cell.

Phospholipids

Amphipathic lipid molecules with one polar head and two non-polar tails that form the cell membrane bilayer.

Peripheral Membrane Proteins

Membrane proteins attached to the outer or inner surface of the cell membrane.

Integral Membrane Proteins

Membrane proteins embedded within the cell membrane having both hydrophobic and hydrophilic regions, which can function in transport or as cell surface receptors.

Passive Transport

Cellular transport that does not require energy, where molecules move down their concentration gradient via diffusion.

Facilitated Diffusion

A form of passive transport where molecules diffuse across the cell membrane using a channel (for ions) or a carrier (for small polar molecules like glucose).

Active Transport

Cellular transport that requires energy, most often provided as ATP, to move molecules against their concentration gradient.

Primary Active Transport

Active transport that directly involves or uses ATP to pump molecules against their concentration gradient.

Sodium-Potassium Pump (Na+/K+ ATPase)

A primary active transport mechanism that pumps $3\,Na^+$ out of the cell and $2\,K^+$ into the cell against their concentration gradients.

Secondary Active Transport

Active transport that does not directly use ATP, but instead relies on energy provided by another molecule moving down its concentration gradient.

Symport (Cotransporter)

A type of secondary active transport where $Na^+$ moves into the cell down its concentration gradient, providing energy for another molecule (such as glucose) to move into the cell against its concentration gradient.

Antiport (Exchanger)

A type of secondary active transport where $Na^+$ moves into the cell down its concentration gradient, providing energy for another ion (such as $H^+$) to move out of the cell against its concentration gradient.

H+ Ions

Ions that determine acidity in solutions, where a higher concentration corresponds to a more acidic state and a lower concentration corresponds to a less acidic (more basic) state.

Vesicular Transport

An active transport process where large molecules are transported across the membrane enclosed within vesicles.

Exocytosis

Vesicular transport in which vesicles containing large molecules fuse with the plasma membrane to release contents into extracellular space, such as neurons releasing neurotransmitters.

Endocytosis

Vesicular transport in which large extracellular molecules are surrounded by cell membrane extensions, which then pinch off to enclose the molecules in a vesicle.

Phagocytosis

A specific form of endocytosis referred to as cellular eating.

LDL

Low density lipoproteins, commonly known as bad cholesterol.