Body Fluids, Cell Membrane Transport, and Chemical Messengers

These flashcards cover key concepts related to body fluids, transport mechanisms, and chemical signaling in cells.

Total Body Water (TBW)

Refers to the total amount of water in the body, which consists of water and dissolved materials.

Intracellular Fluid (ICF)

Fluid found inside cells, accounting for 28 liters in a 70-kg male.

Extracellular Fluid (ECF)

Fluid found outside cells, comprising plasma and interstitial fluid.

Passive Transport

Movement of substances across membranes without the use of cellular energy.

Active Transport

Movement of substances against their concentration gradient, requiring cellular energy.

Chemical Driving Force

Movement of particles from areas of higher to lower concentration due to concentration gradients.

Electrical Driving Force

Force resulting from the unequal distribution of charged ions across a membrane.

Equilibrium Potential (Ex)

The membrane potential at which the electrical force is equal and opposite to the chemical force.

Osmolarity

Total solute concentration of a solution, affecting water movement across membranes.

Tonicity

The effect of a solution's osmolarity on cell volume, classified as isotonic, hypertonic, or hypotonic.

Endocytosis

The process of taking substances into the cell by engulfing them in a vesicle.

Exocytosis

The process of releasing substances from a cell by vesicular transport.

Signal Transduction

The process through which a chemical messenger binds to a receptor and elicits a response in a target cell.

Lipophobic Ligand

Water-soluble chemical messengers that do not cross the cell membrane easily.

Lipophilic Ligand

Lipid-soluble chemical messengers that can easily cross the cell membrane.

G Protein-Coupled Receptors

Receptors that interact with G proteins to mediate cellular responses initiated by chemical messengers.

Second Messenger

Intracellular signaling molecules released by the binding of a messenger to a receptor on the cell surface.