Osmosis, Tonicity, and Pressures

Vocabulary flashcards covering the principles of osmosis, pressure types, osmolar concentrations, and tonicity as described in the lecture notes.

Osmosis

The movement of water across a semipermeable membrane from lower solute concentration toward higher solute concentration.

Osmotic pressure

A pulling pressure or force created by non-permeable solutes that is driven by the difference in solute concentration across a semipermeable membrane.

Hydrostatic pressure

A pushing pressure exerted by a stationary fluid at equilibrium that causes water or fluid to move or be pushed.

Oncotic pressure

Also called colloid osmotic pressure, it is the osmotic pressure generated primarily by plasma proteins, such as albumin, which tends to pull water into blood vessels.

Osmolarity

The concentration of osmotically active particles per liter of solution, expressed in units such as $\text{osm/L}$ or $\text{mOsm/L}$.

Osmolality

The concentration of osmotically active particles expressed as osmoles per kilogram ($\text{osm/kg}$) of water.

Isosmotic solutions

Solutions that have equal osmolarity and equal osmotic pressure.

Hyperosmotic

A solution with a higher osmolarity and greater osmotic pressure than a comparison solution, toward which water tends to move.

Hypo-osmotic

A solution with a lower osmolarity and lower osmotic pressure than a comparison solution, which water tends to leave.

Tonicity

A property that describes how a solution affects cell volume, depending only on solutes that cannot easily cross the cell membrane.

Isotonic

A solution in which cells neither swell nor shrink because there is no osmotic pressure difference between the cell interior and the extracellular solution.

Hypotonic

A solution that causes cells to swell because the extracellular fluid has a lower effective solute concentration, causing water to enter the cells.

Hypertonic

A solution that causes cells to shrink because the extracellular fluid has a higher effective solute concentration, causing water to leave the cells.

Albumin

The primary plasma protein responsible for generating oncotic pressure to maintain intravascular fluid volume.

Edema

A clinical condition where fluid moves into tissue spaces, which can be caused by a decrease in blood oncotic pressure or an imbalance in hydrostatic pressure.