Pharmacology Notes

1. the act of taking up or in by specific chemical or molecular action; especially the passage of liquids or other substances through a surface of the body into body fluids and tissues, as in the absorption of the end products of digestion into the villi that line the intestine.

 

2. in psychology, devotion of thought to one object or activity only.

 

3. in radiology, uptake of energy by matter with which the radiation interacts. It can vary with the mass (density) subjected to x-radiation and the penetrability of the x-rays. A thin lead plate might absorb 100 per cent of an x-ray beam, while several centimeters of tissue might attenuate it only slightly, even at low voltages.

 

4. in chemistry, the penetration of a substance within the inner structure of another;

chemical absorption any process by which one substance in liquid or solid form penetrates the surface of another substance.

digestive absorption the passage of the end products of digestion from the gastrointestinal tract into the blood and lymphatic vessels and the cells of tissues. Absorption of this kind can take place either by diffusion or by active transport.

radiation absorption the dissipation of radiant energy as it passes through matter. This phenomenon is of particular importance in diagnostic and therapeutic radiology, which depends on the interaction between ionizing radiations and matter. As radiation passes through matter, it is absorbed by an amount dependent on the atomic and molecular structure and thickness of the substance, and the energy of the primary photons. If radiations pass through a medium of living or nonliving material without absorption (loss of energy), no biologic or photographic effects can occur. In true absorption the photons of radiation waves give up or transfer all of their energy to electrons within the atoms of the matter through which they are passing.