Bio Unit 2 Concept 2: P.L.

A set of vocabulary flashcards covering key topics in homeostasis, feedback mechanisms, cell membrane transport, and solution tonicity.

Static Equilibrium

A state in which there is absolutely no change happening within a system, and everything is at a complete standstill.

Dynamic Equilibrium

A state in which changes are constantly occurring, but the overall system stays within a balanced, stable range.

Homeostasis

A state of dynamic equilibrium in which an organism constantly adjusts internal conditions to keep them within a narrow, healthy target range.

Stimulus

Any change in the internal or external environment (such as a drop in outside temperature) that is detected by receptors to trigger a response.

Negative Feedback Loop

A control mechanism where the body responds to a stimulus by reversing or counteracting the change to bring conditions back to a normal set point (e.g., thermoregulation, blood sugar regulation).

Positive Feedback Loop

A control mechanism where the body responds to a stimulus by amplifying or increasing the change, pushing the system further away from its starting state until a specific biological event is completed (e.g., childbirth, blood clotting).

Cell Membrane

A selectively permeable structure that acts as a gatekeeper, tightly controlling which molecules enter and leave the cell to maintain homeostasis.

Passive Transport

A category of cellular transport that does not require cellular energy (ATP) and moves substances 'down' their concentration gradient from high to low concentration.

Active Transport

A category of cellular transport that requires cellular energy (ATP) to push substances 'against' their concentration gradient from low to high concentration.

Simple Diffusion

A type of passive transport in which small, nonpolar molecules slip directly through the lipid bilayer (e.g., Oxygen, Carbon dioxide).

Facilitated Diffusion

A type of passive transport in which larger or charged molecules pass through specific protein channels (e.g., Glucose, Sodium ions).

Osmosis

A type of passive transport defined as the specific diffusion of water molecules across the cell membrane through aquaporins.

Protein Pumps

A type of active transport in which transport proteins use ATP to actively pump specific molecules across the membrane (e.g., Sodium-Potassium pump).

Endocytosis

A type of active transport where the cell membrane folds inward to engulf large materials via a vesicle (e.g., White blood cells engulfing bacteria).

Exocytosis

A type of active transport where a vesicle fuses with the cell membrane to force large materials out of the cell (e.g., Releasing hormones).

Hypotonic Solution

A solution with a lower solute concentration outside the cell, causing water to rush into the cell so that it swells and bursts (lyse).

Isotonic Solution

A solution with an equal solute concentration relative to the inside of the cell, where water moves in and out at an equal rate and cell size remains normal.

Hypertonic Solution

A solution with a higher solute concentration outside the cell, causing water to rush out of the cell so that it shrinks and shrivels (crenate).