Anatomy and Physiology: Cell Membrane Structure and Transport Mechanisms

Vocabulary flashcards covering cell membrane components, passive and active transport processes, tonicity, and vesicular transport based on lecture materials.

Cell Membrane

A flexible, dynamic structure composed of phospholipids, cholesterol, carbohydrates, and proteins that separates the cell's internal environment from the external environment and regulates material movement.

Phospholipid

An amphipathic molecule featuring a hydrophilic phosphate head and hydrophobic fatty acid tails, serving as the major structural component of the cell membrane bilayer.

Amphipathic

Refers to a molecule that possesses both hydrophilic ('water-loving') and hydrophobic ('water-fearing') properties.

Intracellular Fluid (ICF)

The fluid located inside the cell, also referred to as cytosol.

Extracellular Fluid (ECF)

The fluid located outside the cell, which encompasses interstitial fluid and intravascular fluid such as blood.

Integral Proteins

Transmembrane proteins that span the entire width of the cell membrane.

Peripheral Proteins

Membrane proteins that do not span the membrane and are attached to either the interior or exterior surface of the cell membrane.

Glycoproteins

Proteins with carbohydrate molecules attached that aid in cell recognition.

Glycocalyx

A structure formed by numerous glycoproteins on the surface of some cells that can serve as hormone receptors, bind to other cells, and help break down nutrients.

Passive Transport

The movement of molecules across a cell membrane along a concentration gradient that does not require cellular energy.

Simple Diffusion

A form of passive transport where small, nonpolar molecules move directly through the cell membrane from higher to lower concentration without using membrane proteins.

Facilitated Diffusion

A form of passive transport where polar or ionic molecules move down their concentration gradient through transmembrane proteins.

Osmosis

The movement of water across a semipermeable membrane from an area of lower solute concentration to an area of higher solute concentration.

Isosmotic Solution

A solution that has an equal concentration of solute compared to another solution.

Hyperosmotic Solution

A solution containing a higher solute concentration when compared to another solution.

Hypoosmotic Solution

A solution containing a lower solute concentration when compared to another solution.

Tonicity

A property describing the osmolarity of the extracellular fluid (ECF) relative to the cytosol of the cell.

Isotonic Solution

A solution with equal water concentration across the cell membrane, allowing the cell to function normally.

Hypertonic Solution

A solution containing more solutes in the external environment than the cytosol, causing the cell to shrink.

Hypotonic Solution

A solution containing fewer solutes in the external environment than the cytosol, causing water to enter the cell so it swells and may burst.

Active Transport

The energy-requiring movement of molecules across a membrane against their concentration gradient, from lower to higher concentration.

Primary Active Transport

A type of active transport that directly utilizes ATP as its energy source.

Secondary Active Transport

A type of active transport that utilizes an electrochemical gradient as its energy source.

Symporters

Transport proteins that move two different molecules in the same direction across the cell membrane.

Antiporters

Transport proteins that move two different molecules in opposite directions across the cell membrane.

Sodium-Potassium Pump

A primary active transport mechanism that uses ATP to move $3$ sodium ions out of the cell and $2$ potassium ions into the cell.

Endocytosis

A form of active transport in which the cell membrane engulfs materials and pinches off to form an intracellular vesicle.

Phagocytosis

A form of endocytosis where the cell membrane extends outward to bring large molecules or particles into the cell.

Pinocytosis

A form of endocytosis where membrane invagination brings in small amounts of extracellular fluid containing dissolved substances.

Receptor-Mediated Endocytosis

A selective form of endocytosis where a specific ligand binds to a membrane receptor to initiate cellular entry via vesicle formation.

Exocytosis

An active transport process of cell secretion where a vesicle fuses with the cell membrane to release its contents, such as hormones or digestive enzymes, outside the cell.