Aqueous humor: In medicine, humor refers to a fluid (or semifluid) substance. Thus, the aqueous humor is the fluid normally present in the front and rear chambers of the eye. It is a clear, watery fluid that flows between and nourishes the lens and the cornea; it is secreted by the ciliary processes.
The humors were part of an ancient theory that health came from balance between the bodily liquids. These liquids were termed humors. Disease arose when imbalance occurred between the humors. The humors were:
Gall (black bile thought to be secreted by the kidneys and spleen)
Choler (yellow bile secreted by the liver)
This theory (which was variously called the humoral theory, humoralism, and humorism) was devised well before Hippocrates (c.460-c.375 BC). It was not definitively demolished until Rudolf Virchow published his formative book, Cellularpathologie, in 1858 that laid out the cellular basis of pathology. Present day pathology rests on a cellular and molecular foundation. The humors have been dispelled, except for the aqueous humor.
- Arabidopsis thaliana
Arabidopsis thaliana: A plant belonging to the mustard family. Arabidopsis was the first plant genome to be sequenced, and is a popular tool for understanding the molecular biology of many plant traits, including flower development and light sensing. See also: Arabidopsis thaliana genome.
- Arabidopsis thaliana genome
Arabidopsis thaliana genome: All of the genetic information contained in Arabidopsis thaliana, a plant belonging to the mustard family. The genomes of particular nonhuman organisms such as Arabidopsis have been studied for a number of reasons including the need to improve sequencing and analysis techniques. These nonhuman genomes also provide powerful sets of data against […]
Arachnodactyly: Long spider-like fingers and toes, a frequent finding in Marfan syndrome, a heritable disorder of connective tissue. “Arachnodactyly” is derived from the Greek “arachne” (spider) and “daktylos” (finger). The Greek word was derived from the name “Arachne,” a maiden in Greek mythology whom the goddess Athena turned into a spider after the girl, a […]
Inflammation of the middle layer of membranes covering the brain and spinal cord. Arachnoiditis can occur as a complication of procedures such as myelograms, spinal operations, epidural steroid injections, and injury to the spine.
Arachnophobia: An abnormal and persistent fear of spiders. Sufferers from arachnophobia experience undue anxiety, even though they realize that the risk of encountering a spider and being harmed by it is small or nonexistent. They may avoid going barefoot and may be especially alert when taking showers or getting into and out of bed.