excretion — excretion1 /ik skree sheuhn/, n. 1. the act of excreting. 2. the substance excreted, as urine or sweat, or certain plant products. [1595 1605; < LL excretion (s. of excretio) that which is sifted out. See EXCRETE, ION] excretion2 /ik skree… … Universalium
nervous system, human — ▪ anatomy Introduction system that conducts stimuli from sensory receptors to the brain and spinal cord and that conducts impulses back to other parts of the body. As with other higher vertebrates, the human nervous system has two main… … Universalium
human aging — ▪ physiology and sociology Introduction physiological changes that take place in the human body leading to senescence, the decline of biological functions and of the ability to adapt to metabolic stress. In humans the physiological… … Universalium
maxillary gland — Excretory organ in maxillary somite with duct opening on maxilla. (Syn. shell gland) [McLaughlin, 1980]. Excretory organ located in maxillary segment, having its duct opening on maxilla. (Syn. shell gland) [Moore and McCormick, 1969]. Nephridial… … Crustacea glossary
animal development — Introduction the processes that lead eventually to the formation of a new animal starting from cells derived from one or more parent individuals. Development thus occurs following the process by which a new generation of organisms is produced by … Universalium
gastropod — /gas treuh pod /, n. 1. any mollusk of the class Gastropoda, comprising the snails, whelks, slugs, etc. adj. 2. Also, gastropodous /ga strop euh deuhs/. belonging or pertaining to the gastropods. [1820 30; < NL Gast(e)ropoda a class of mollusks.… … Universalium
annelid — /an l id/, n. 1. any segmented worm of the phylum Annelida, including the earthworms, leeches, and various marine forms. adj. 2. belonging or pertaining to the Annelida. Also, annelidan /euh nel i dn/. [1825 35; see ANNELIDA] * * * Any member of… … Universalium
circulation — circulable /serr kyeuh leuh beuhl/, adj. /serr kyeuh lay sheuhn/, n. 1. an act or instance of circulating, moving in a circle or circuit, or flowing. 2. the continuous movement of blood through the heart and blood vessels, which is maintained… … Universalium
renal system — ▪ anatomy Introduction in humans (human body), organ system that includes the kidneys, where urine is produced, and the ureters, bladder, and urethra for the passage, storage, and voiding of urine. In many respects the human excretory, or… … Universalium
flatworm — /flat werrm /, n. any worm of the phylum Platyhelminthes, having bilateral symmetry and a soft, solid, usually flattened body, including the planarians, tapeworms, and trematodes; platyhelminth. [1895 1900; FLAT1 + WORM] * * * or platyhelminth… … Universalium
fish — fishless, adj. /fish/, n., pl. (esp. collectively) fish, (esp. referring to two or more kinds or species) fishes, v. n. 1. any of various cold blooded, aquatic vertebrates, having gills, commonly fins, and typically an elongated body covered with … Universalium