Cells 1

What is osmosis?

The diffusion of a solvent, such as water, through a selectively permeable membrane.

Why is osmosis important in the body?

It determines the distribution of water in various fluid-containing compartments of the body.

What is edema?

Swelling due to the abnormal accumulation of fluid in tissues.

How does water cross the plasma membrane if it is polar?

A small amount can 'sneak through' because of its small size.

What are aquaporins?

Water-specific channels constructed by transmembrane proteins that allow single-file diffusion of water molecules.

Where are aquaporin channels abundant?

In red blood cells and cells involved in water balance, such as kidney tubule cells.

When does osmosis occur?

Whenever the water concentration differs on the two sides of a membrane.

What happens when distilled water is present on both sides of a selectively permeable membrane?

No net osmosis occurs, even though water molecules are moving in both directions.

What is osmolarity?

The total concentration of all solute particles in a solution.

How does an impermeable membrane affect water movement?

Water moves and the volume changes, mimicking osmosis across plasma membranes.

What happens to plant cells when water diffuses into them?

Hydrostatic pressure within the cell equals osmotic pressure, stopping net water entry.

What is osmotic pressure?

The tendency of water to move into the cell by osmosis.

What challenges do living animal cells face compared to plant cells regarding pressure changes?

They lack rigid cell walls, so major changes in hydrostatic or osmotic pressures cannot occur.

What is tonicity?

The ability of a solution to change the shape or plasma membrane tension of cells by altering the cells' internal water volume.

How do intracellular proteins and ions affect water concentration?

Changes in their concentration alter water concentration across the membrane, resulting in net water gain or loss.

What occurs when there is a difference in solute concentration across a membrane?

Water concentration differs, as increasing solute concentration decreases water concentration.

What is the significance of hydrostatic pressure in plant cells?

It pushes water out, while osmotic pressure pulls water in, balancing the two pressures.

What occurs to animal cells when osmotic imbalances happen?

They swell or shrink due to net water gain or loss.

In terms of water movement, what do living systems mimic?

The dynamics of osmosis across plasma membranes.

What defines the shape and tension of a cell's plasma membrane?

The tonicity of the solution surrounding the cell.