BIOL 031 Lecture Notes - Lecture 29: Osmotic Concentration, Passive Transport, Aquaporin
13 Aug 2020
School
Department
Course
Professor
Document Summary
Two fluid compartments, the cell and the extracellular fluid (ecf) The body is 60% icf and 30% ecf (30% ecf = 25% plasma and 75% interstitial fluid) The body is mostly water: greater variation of water content according to age and sex, lesser variation of water among compartments. Movement of water across a membrane in response to a solute concentration gradient: movement through aquaporins, special protein channels in the membrane. The movement of water from an area of low water concentration to high water concentration; movement from high solute concentration to low solute concentration. Molarity versus osmolarity: molarity expresses concentration, osmolarity expresses number of particles, osmolarity is more relevant. Osmolarity versus osmolality: although different definitions, practically interchangeable in physiology. Isosmotic: water concentration is the same on both sides. Hyperosmotic: higher concentration of solutes than its surrounding. Hyposmotic: lower concentration of solutes than its surroundings. Tonicity versus osmolarity: comparative term for change in volume of a cell.
