 |
|
 |
|
| Partition Coefficient |
| | see Octanol/water partition coefficient. |
|
| Passive Transfer |
| | The movement across a membrane by simple diffusion. This is the most common way lipophilic xenobiotics pass through cell membranes. |
|
| Percutaneous absorption |
| | The transfer of a substance from the outer surface of the skin through the corneum and outer layers and into the systemic circulation. |
|
| Phagocytosis |
| | The engulfing of particles by certain cells of the circulatory and lymphatic systems, known as phagocytes. Phagocytosis is a primary cellular defense mechanism against foreign particles or organisms. |
|
| Pharmacokinetics |
| | Quantitation of the time course of chemical absorption, distribution, metabolism, and elimination. |
|
| Phospholipids |
| | Molecules containing phosphates and lipids found in the cell membrane. The phosphate head is hydrophilic, whereas the lipid tail is hydrophobic. |
|
| Pinocytosis |
| | The process whereby a liquid is engulfed and taken into a cell by an inward folding of the cell membrane, which detaches and moves into the cytoplasm. |
|
| Plasma |
| | The non-cellular, fluid portion of whole blood. |
|
| Plasma membrane |
| | The membrane composed of phospholipids, proteins, and cholesterol that forms the outer boundary of a cell and regulates the movement of substances into and out of the cell. Same as "cell membrane." |
|
| Polar |
| | A term used to describe a molecule which is charged or ionized. Polar substances are usually the easiest for the body to excrete. |
|
| Portal circulation |
| | The term applied to the venous circulation draining the tissues of the gastrointestinal tract into the liver. |
|
| PPM |
| | Parts per million - the number of units of a substance in a million units. PPM is a common concentration unit for dilute samples of dissolved substances or airborne substances. |
|
| Protein |
| | A complex nitrogenous substance which constitutes the main building material in cells. |
|
 |
