Venom

Venom is any of diverse toxins produced by certain animals, such as snakes, stingrays, spiders, and scorpions, and capable of bieng delivered, usually by a bite, sting, spine, or bristle, to another organism, causing injury, illness, or death. Venom typically is used for the purpose of defense and hunting, although some venoms also have a digestive function as well. Venom contrasts with poison in that poison is absorbed by ingestion or through the skin, while venom is delivered or injected, typically subcutaneously to cause its effect. the spitting cobra can *****; catepillars use bristles; nemacysts...

key is mechanism to deliver the toxin, as opposed to be absorbed by the organism via consumption or simple diffusion after contact

or, better still, poison more general term and venom is a specific type of poison.. This seems most common that it is aposion with an active component. Poison is either seen as a more general term, of which venom is a subcategory, or is itself viewed as.. In this sense, plants are poisionous, snakes generally venomous, though some are poisonous as well.

Among animals widely known to use venom are snakes (such as elapids and vipers), lizards (such as Gila monster), spiders, centipedes, scorpions, stinging insects (such as beeds adn wasps), fishes (stingrays, scorpionfish, along with many others), and jellyfish, and male platypus.

snake venoms are generally not dangerous when ingested, and are therefore not technically poisons.

Mechanics of spitting Venom can be ejected otherwise than by a bite, as in the so-called spitting cobras of the genera Naja and Hemachatus. Some of these deadly snakes, when irritated, are capable of shooting venom from the mouth, at a distance of 4 to 8 feet. These snakes' fangs have been modified for the purposes of spitting: inside the fangs of a spitting cobra is a channel which makes a ninety degree bend to the lower front of the fang. When the snake is threatened the muscles of the venom gland squeeze the venom sack and as a result venom is projected forward. Spitters may spit thirty or forty times in succession, and even then the snake is still able to deliver a fatal bite.

Spitting is a defensive reaction only. The snake tends to aim for the eyes of a perceived threat; a direct hit can cause temporary shock and blindness through severe inflammation of the cornea and conjunctiva.

Wasp sting, with droplet of venom

Terminology: Toxin, poison, venom

A toxin is a chemical substance that is capable of causing injury, illness, or death to an organism (poison) and that is produced by living cells or another organism. Toxins are nearly always proteins that are capable of causing harm on contact or absorption with body tissues by interacting with biological macromolecules such as enzymes or cellular receptors. Toxins vary greatly in their severity, ranging from usually minor and acute (as in a bee sting) to almost immediately deadly (as in botulinum toxin).

Biotoxins vary greatly in purpose and mechanism, and they can be highly complex (the venom of the cone snail contains dozens of small proteins, each targeting a specific nerve channel or receptor), or a single, relatively small protein.

The term toxin comes from the Greek τοξικόν toxikon, meaning "(poison) for use on arrows." In the context of biology, poisons are substances that can cause damage, illness, or death to organisms, usually by chemical reaction or other activity on the molecular scale, when a sufficient quantity is absorbed by an organism.

Toxin is a subcategory of poison, referring to a substance produced by a living organism. However, when used non-technically, the term "toxin" is often applied to any poisonous substance. Many non-technical and lifestyle journalists also follow this usage to refer to toxic substances in general, though some specialist journalists maintain the distinction that toxins are only those produced by living organisms. In the context of alternative medicine the term toxin often is used nonspecifically as well to refer to any substance claimed to cause ill health, ranging anywhere from trace amounts of pesticides to common food items like refined sugar or additives like artificial sweeteners and MSG.

In pop psychology, the term toxin sometimes is used to describe things that have an adverse effect on psychological health, such as a "toxic relationship," "toxic work environment," or "toxic shame."

Venoms usually are defined as biologic toxins that are delivered subcutaneously, such as injected by a bite or sting, to cause their effect. In normal usage, a poisonous organism is one that is harmful to consume, but a venomous organism uses poison to defend itself while still alive. A single organism can be both venomous and poisonous.

The derivative forms "toxic" and "poisonous" are synonymous.

Venomous vs. poisonous

There is a difference between organisms that are "venomous" and those that are "poisonous", two commonly confused terms applied to plant and animal life. Venomous, as stated above, refers to animals that deliver (often, inject) venom into their prey when hunting or as a defense mechanism. Poisonous, on the other hand, describes plants or animals that are harmful when consumed or touched. A poison tends to be distributed over a large part of the body of the organism producing it, while venom is typically produced in organs specialized for the purpose. One species of bird, the hooded pitohui, although not venomous, is poisonous, secreting a neurotoxin onto its skin and feathers. The slow loris, a primate, blurs the boundary between poisonous and venomous; it has poison-secreting patches on the inside of its elbows which it is believed to smear on its young to prevent them from being eaten. However, it will also lick these patches, giving it a venomous bite.

Examples

The animals most widely known to use venom are snakes, some species of which inject venom into their prey through hollow fangs; spiders and centipedes, which also inject venom through fangs; scorpions and stinging insects, which inject venom with a sting (which, in insects such as bees and wasps, is a modified egg-laying device – the ovipositor). Many caterpillars have defensive venom glands associated with specialized bristles on the body, known as urticating hairs, and can be lethal to humans (e.g., that of the Lonomia moth). Venom is also found in a few reptiles besides snakes, such as the gila monster and Mexican beaded lizard. Other insects, such as true bugs [1] and many ants, also produce venom. Venom can also be found in some fish, such as the cartilaginous fishes – stingrays, sharks, and chimaeras – and the teleost fishes including monognathus eels, catfishes, stonefishes and waspfishes, scorpionfishes and lionfishes, gurnard perches, rabbitfishes, surgeonfishes, scats, stargazers, weevers, carangids, saber-toothed blenny, and toadfish. In fact, recent studies have shown that there are more venomous ray-finned fishes than all other venomous vertebrates combined. There are many other venomous invertebrates, including jellyfish and cone snails. The box jellyfish is widely considered the most venomous creature in the world.[2] Some mammals are also venomous, including solenodons, shrews, the slow loris, and the male platypus.

Because they are tasked to defend their hives and food stores, bees synthesize and employ an acidic venom (apitoxin) to cause pain in those that they sting, whereas wasps use a chemically different venom designed to paralyze prey, so it can be stored alive in the food chambers of their young. The use of venom is much more widespread than just these examples, of course.

Mechanics of spitting Venom can be ejected otherwise than by a bite, as in the so-called spitting cobras of the genera Naja and Hemachatus. Some of these deadly snakes, when irritated, are capable of shooting venom from the mouth, at a distance of 4 to 8 feet. These snakes' fangs have been modified for the purposes of spitting: inside the fangs of a spitting cobra is a channel which makes a ninety degree bend to the lower front of the fang. When the snake is threatened the muscles of the venom gland squeeze the venom sack and as a result venom is projected forward. Spitters may spit thirty or forty times in succession, and even then the snake is still able to deliver a fatal bite.

Spitting is a defensive reaction only. The snake tends to aim for the eyes of a perceived threat; a direct hit can cause temporary shock and blindness through severe inflammation of the cornea and conjunctiva. While there are no serious results if the venom is washed away at once with plenty of water, the blindness caused by a successful spit can become permanent if left untreated. Contact with the skin is not in itself dangerous, but open wounds may become envenomed.

Snake venom

Snake venom is produced by glands below the eye and delivered to the victim through tubular or channeled fangs. Snake poisons contain a variety of peptide toxins. Snakes use their venom principally for hunting, though the threat of being bitten serves also as a defense. Snake bites cause a variety of symptoms including pain, swelling, tissue damage, low blood pressure, convulsions, and hemorrhaging (varying by species of snake).

Doctors treat victims of a venomous bite with antivenin, which is created by dosing an animal such as a sheep, horse, goat, or rabbit with a small amount of the targeted venom. The immune system of the subject animal responds to the dose, producing antibodies to the venom's active molecule; the antibodies can then be harvested from the animal's blood and applied to treat envenomation in others. This treatment can be used effectively only a limited number of times for a given person, however, as that person will ultimately develop antibodies to neutralize the foreign animal antibodies injected into him (anti-antibody antibodies). Even if that person does not suffer a serious allergic reaction to the antivenom, his own immune system can destroy the antivenin before the antivenin can destroy the venom. Though most people never require even one treatment of antivenin in their lifetime, let alone several, people who work with snakes or other venomous animals may. Fortunately, these people often develop antibodies of their own against the venom of whatever animals they handle, and thereby are protected without the assistance of exogenous antibodies.

Aristolochia rugosa and Aristolochia trilobata, or "Dutchman's Pipe," are recorded in a list of plants used worldwide and in the West Indies, South and Central America against snakebites and scorpion stings. Aristolochic acid inhibits inflammation induced by immune complexes, and nonimmunological agents (carrageenan or croton oil).^{[citation needed]} Aristolochic acid inhibits the activity of snake venom phospholipase (PLA2) by forming a 1:1 complex with the enzyme. Since phospholipase enzymes play a significant part in the cascade leading to the inflammatory and pain response, their inhibition could lead to relief of problems from scorpion envenomation.

See also

• Toxin
• Poison
• Toxinology
• Schmidt Sting Pain Index
• Venomous mammals
• Venomous fish
• Big Four (Indian snakes)
• Envenomation
• Venomous animals (category)

Bibliography

• Leo Smith and Ward C. Wheeler. 2006. Venom evolution widespread in fishes: A phylogenetic road map for the bioprospecting of piscine venoms. Journal of Heredity 97(3): 206-217.
• Lans C, Harper T, Georges K, Bridgewater E. 2001. Medicinal and ethnoveterinary remedies of hunters in Trinidad. BMC Complement Altern Med. 2001;1:10. Epub 2001 Nov 30. http://www.biomedcentral.com/1472-6882/1/10

http://www.bartleby.com/68/33/6333.html Bartleby

Template:Poisoning and toxicity

Credits

New World Encyclopedia writers and editors rewrote and completed the Wikipedia article in accordance with New World Encyclopedia standards. This article abides by terms of the Creative Commons CC-by-sa 3.0 License (CC-by-sa), which may be used and disseminated with proper attribution. Credit is due under the terms of this license that can reference both the New World Encyclopedia contributors and the selfless volunteer contributors of the Wikimedia Foundation. To cite this article click here for a list of acceptable citing formats.The history of earlier contributions by wikipedians is accessible to researchers here:

• Venom  ^history

The history of this article since it was imported to New World Encyclopedia:

• History of "Venom"

Note: Some restrictions may apply to use of individual images which are separately licensed.