Chapter 3: Cells and Tissues - Membrane Transport

Vocabulary flashcards covering membrane transport, osmosis, and tissue anatomy concepts from the notes.

Solute

Substances (solid, liquid, or gas) dissolved by solvents in a solution.

Solvent

The substance that dissolves solutes; example: water.

Solution

Mixtures of solutes and solvents (e.g., salt dissolved in water).

Membrane Transport

Movement of substances into or out of the cell across the cell membrane.

Passive Transport

Movement across the membrane that does not require ATP energy.

Active Transport

Movement across the membrane that requires ATP energy.

Diffusion

Movement of solutes from high to low concentration toward equilibrium; no ATP required.

Simple Diffusion

Diffusion of small, lipid-soluble substances directly through the phospholipid bilayer down their concentration gradient.

Facilitated Diffusion

Diffusion across the membrane via transport proteins (channels or carriers) down the concentration gradient; no ATP.

Osmosis

Diffusion of water across a semipermeable membrane toward higher solute concentration.

Concentration Gradient

Unequal distribution of solutes across space, from high to low.

Equilibrium

State in which solute concentrations are equal on both sides and net movement stops.

Lipid Bilayer

The phospholipid bilayer that forms the cell membrane through which many substances can diffuse.

Lipid-Soluble Substances

Substances that easily cross membranes due to their nonpolar, lipid-soluble nature.

Gases (O2 and CO2)

Small, nonpolar gas molecules that diffuse easily through membranes.

Small Ions (e.g., Chloride)

Tiny charged particles that may require channels for diffusion.

Isotonic Solution

Solution with the same solute concentration as the cell; no net water movement.

Hypotonic Solution

Solution with lower solute concentration than the cell; water enters; cells swell.

Hypertonic Solution

Solution with higher solute concentration than the cell; water leaves; cells shrink.

Edema

Swelling in the interstitial space due to water accumulation.

Dehydration

Loss of water from cells, often when exposed to hypertonic conditions.

Endocytosis

Active transport process where materials are brought into the cell via vesicles.

Exocytosis

Active transport process where materials are released from the cell via vesicles.

ATP

Adenosine triphosphate; energy molecule used to drive active transport.

Semipermeable Membrane

A membrane that allows some substances to pass while restricting others.

Epithelial Tissue

Tissue that forms sheets; covers/lines surfaces and participates in secretion, absorption, diffusion, and protection.

Basement Membrane

Deeper surface of epithelial tissue; anchors tissue beneath and is avascular.

Apical Surface

The upper free surface of epithelial tissue.

Avascular

Lacks blood vessels; nutrients reach epithelial cells by diffusion.

Innervated

Nerve supply runs through a tissue.

Cutaneous Membrane

Dry outer covering of the body; example: skin.

Simple Epithelium

Epithelium with a single cell layer.

Stratified Epithelium

Epithelium with two or more cell layers.

Squamous

Flat, scale-like epithelial cells with a flattened nucleus.

Cuboidal

Cube-shaped epithelial cells with a round nucleus.

Columnar

Tall, column-shaped epithelial cells with a column-shaped nucleus.

Tissue

Two or more different types of cells working together to perform a specific function.

Histology

The study of tissues.