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Parasite

/ˈparəˌsīt/ Noun, pl. parasites (Biology) 1. A (generally undesirable) living organism that exists by stealing the resources produced/collected by another living organism. (wiktionary.org) 2. An organism living in, with, or on another organism in parasitism. (merriam-webster.com) 3.Something that resembles a biological parasite in dependence on something else for existence or support without making a useful or adequate return. (merriam-webster.com) 4. An animal or plant that lives in or on a host (another animal or plant); it obtains nourishment from the host without benefiting or killing the host. (wordnetweb.princeton.edu) Other definitions: (Pejorative) 1. A person who lives on other people’s efforts or expense and gives little back. (wiktionary.org) 2. A person who exploits the hospitality of the rich and earns welcome by flattery. (merriam-webster.com) (Literary, poetic) 1. A climbing plant which is supported by a wall, trellis etc. (wiktionary.org) Word origin: From Latin parasitus “toady, sponger,” and directly from Greek parasitos “one who lives at another’s expense, person who eats at the table of another,” from noun use of an adjective meaning “feeding beside,” from para- “beside” + sitos “food,” of unknown...

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Parasitism

Noun 1. A non-mutual relationship between organisms of different species where one organism, the parasite, benefits at the expense of the other, the host. Traditionally parasite referred to organisms with lifestages that needed more than one host (e.g. Taenia solium). These are now called macroparasites (typically protozoa and helminths). Parasite now also refers to microparasites, which are typically smaller, such as viruses and bacteria, and can be directly transmitted between hosts of the same species. (wikipedia.org) 2. Interaction between two organisms, in which one organism (the parasite) benefits and the other (the host) is harmed. (wiktionary.org) 3. A form of symbiosis in which one organism (called parasite) benefits at the expense of another organism usually of different species (called host). The association may also lead to the injury of the host. (biology-online.org) 4. The relation between two different kinds of organisms in which one receives benefits from the other by causing damage to it (usually not fatal damage). (wordnetweb.princeton.edu) Word origin: From Latin parasitus “toady, sponger,” and directly from Greek parasitos “one who lives at another’s expense, person who eats at the table of another,” from noun use of an adjective meaning “feeding beside,” from para- “beside” + sitos “food,” of unknown...

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Parasympathetic Nervous System

/ˌparəˌsimpəˈTHetik/ Noun 1. Primarily modulates visceral organs such as glands. Responses are never activated en masse as in the fight-or-flight sympathetic response. While providing important control of many tissues, the parasympathetic system, unlike the sympathetic system, is not crucial for the maintenance of life. (global.britannica.com) 2. Of or relating to the part of the automatic nervous system that counterbalances the action of the sympathetic nerves. It consists of nerves arising from the brain and the lower end of the spinal cord and supplying the internal organs, blood vessels, and glands. (Google Dictionary) 3. The part of the autonomic nervous system that contains chiefly cholinergic fibers, that tends to induce secretion, to increase the tone and contractility of smooth muscle, and to slow heart rate, and that consists of a cranial and a sacral part. (merriam-webster.com) 4. Originates in the brain stem and lower part of the spinal cord; opposes physiological effects of the sympathetic nervous system: stimulates digestive secretions; slows the heart; constricts the pupils; dilates blood vessels. (wordnetweb.princeton.edu) Also written as: PSNS, PNS Word origin: From para- “beside” + from Modern Latin sympatheticus, from Greek sympathetikos, from sympathein, from sympathes “having a fellow feeling, affected by like...

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Parathormone

/ˌparəˈθɔːməʊn/ Noun 1. Also called parathyroid hormone. 2. Substance produced and secreted by the parathyroid glands that regulates serum calcium concentration....

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Parathyroid

/parəˈθʌɪrɔɪd/ Noun 1. A parathyroid hormone. (wiktionary.org) 2. Endocrine gland occurring in all vertebrate species from amphibia upward, usually located close to and behind the thyroid gland. Humans usually have four parathyroid glands, each composed of closely packed epithelial cells separated by thin fibrous bands and some fat cells. The parathyroid glands secrete parathormone (also called parathyroid hormone), which functions to maintain normal serum calcium and phosphate concentrations. 3. A gland next to the thyroid which secretes a hormone ( parathyroid hormone ) that regulates calcium levels in a person’s body. (Google Dictionary) 4. A sterile preparation of the water soluble principle of the parathyroid glands, administered parenterally as an antihypocalcaemic, especially in the treatment of acute hypoparathyroidism with tetany. (biology-online.org) Adjective 1. Situated near the thyroid gland. (wiktionary.org) 2. Pertaining to the parathyroid glands or their extracts....

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