Transportation of Molecules Across the Cell Membrane

These flashcards cover key concepts related to the transport of molecules across cell membranes, cell junctions, and mechanisms of homeostasis.

Passive Diffusion

The movement of molecules across a cell membrane without the use of energy, following their concentration gradient.

Active Transport

The movement of molecules across a cell membrane against their concentration gradient, requiring energy.

Facilitated Transport

The process of transporting molecules across a cell membrane via a membrane protein, without the use of energy.

Endocytosis

A process in which a cell engulfs material from its environment to bring substances into the cell.

Exocytosis

A process through which a cell expels materials by enclosing them in a vesicle that fuses with the plasma membrane.

Diffusion

The process of molecules moving from an area of higher concentration to an area of lower concentration.

Osmosis

The movement of water molecules through a semipermeable membrane from a region of lower solute concentration to a region of higher solute concentration.

Hypotonic Solution

A solution with a lower concentration of solutes compared to the inside of a cell, causing water to flow into the cell.

Hypertonic Solution

A solution with a higher concentration of solutes compared to the inside of a cell, causing water to flow out of the cell.

Isotonic Solution

A solution with an equal concentration of solutes compared to the inside of a cell, resulting in no net movement of water.

Cell Junctions

Structures that connect cells to each other or to the extracellular matrix, facilitating communication and stability.

Occluding Junctions

Cell junctions that form an impermeable barrier by sealing cells together.

Anchoring Junctions

Cell junctions that attach cells and their cytoskeletons to other cells or the extracellular matrix.

Communicating Junctions

Junctions that allow the exchange of chemical or electrical signals between adjacent cells.

Cadherins

A type of membrane protein involved in cell-cell adhesion, important for forming adherens junctions and desmosomes.

Negative Feedback

A regulatory mechanism in biological systems where the output of a process inhibits or reverses the initial stimulus.

Positive Feedback

A regulatory mechanism in biological systems where the output of a process intensifies the initial stimulus, pushing the system further from equilibrium.

Sensor

A component of a homeostasis control system that detects changes in the internal or external environment.

Effector

The part of a homeostasis control system that acts to bring about changes in response to a stimulus.