Physio Module 4: Membrane Dynamics

Plasma membrane

The structure that partitions fluids inside cells and allows for selective exchange of substances.

Cytosol

The fluid inside cells that contains organelles, proteins, and various substances.

Interstitial fluid

Fluid that surrounds and bathes the cells, containing thousands of substances.

Homeostasis

The condition of maintaining a stable internal environment in the cells despite external changes.

Passive process

A type of transport where substances move down a concentration gradient without the need for cellular energy.

Active process

A type of transport that requires energy to move substances against their concentration gradient.

Diffusion

A passive process where materials move from an area of high concentration to low concentration until equilibrated.

Osmosis

The special diffusion of water across a selectively permeable membrane, from an area of low solute concentration to high.

Osmolarity

A measure of solute concentration in a solution, indicating the total number of solute particles.

Tonicity

Describes the effect of a solution on the volume of a cell, based on the concentration of non-penetrating solutes.

Hyperosmotic solution

A solution that has a higher concentration of solutes compared to another.

Hypoosmotic solution

A solution that has a lower concentration of solutes compared to another.

Isotonic solution

A solution where the concentration of solutes is equal to that of another solution, resulting in no net movement of water.

Vesicular transport

The process used to transport large molecules in and out of cells via membrane-bound vesicles.

Exocytosis

The active process of exporting bulky molecules, such as proteins or polysaccharides, from the cell.

Endocytosis

The process of importing substances useful to the cell, involving engulfing the material.

Phagocytosis

The engulfment of particles by wrapping the membrane around them to form a vacuole.

Pinocytosis

A type of endocytosis that involves the ingestion of liquid into small vesicles.

Membrane potential

The difference in electric charge across a cell's membrane, influenced by the concentration gradients of ions.

Resting membrane potential

The electrical potential difference across the plasma membrane of a resting cell, influenced by ion distribution.

Carrier proteins

Proteins that facilitate movement of substances across the cell membrane; can be involved in both active and facilitated transport.

Gated channels

Channels in the membrane that open or close in response to signals, regulating the flow of substances.