Dr. J AGDISH KAUR P.G.G.C.,Sector 11 Chandigarh Poison apparatus Dr. J AGDISH KAUR P.G.G.C.,Sector 11 Chandigarh

Components of poison apparatus poison glands (secretion of poison) poison ducts (conduction of poison), Fangs ( injection of poison) muscles (squeezing the poison)

Poison glands: Saclike glands situated one on either side of the upper jaw. Modified superior labial, or parotid glands. Each gland is covered by a constrictor muscle The contraction of the muscle, during the bite, squeezes the poison from the gland. 2. Poison duct: From each poison gland a narrow poison duct leads to the base of the poison fang. 3. Fangs: These are modified teeth attached to maxillary bones. They are grooved and help in injecting the poison into the body of the victim. Fangs serve as hypodermic needles. The poison is faint yellow, tasteless and odour less fluid acidic in reaction. It is fatal only when mixed in blood.

Snake venom Highly modified saliva that is produced by special glands of certain species of snakes. a combination of many different proteins and enzymes. Many of these proteins are harmless to humans, but some are toxins. Snake venoms are generally not dangerous when ingested, and are therefore not technically poisons. Consists of proteins, enzymes, substances with a cytotoxic effect, neurotoxins and coagulants.

* Phosphodiesterases are used to interfere with the prey's cardiac system, mainly to lower the blood pressure. * Phospholipase A2 causes hemolysis by lysing the phospholipid cell membranes of red blood cells. * Snake venom inhibits cholinesterase to make the prey lose muscle control. * Hyaluronidase increases tissue permeability to increase the rate that other enzymes are absorbed into the prey's tissues. * Amino acid oxidases and proteases are used for digestion. Amino acid oxidase also triggers some other enzymes and is responsible for the yellow color of the venom of some species. * Snake venom often contains ATPase, an enzyme which catalyzes the hydrolysis of ATP to ADP and a free phosphate ion, or to AMP and diphosphate.

1. Fasciculins 2. Dendrotoxins 3. α-neurotoxins 2. Cytotoxins 1. Phospholipases 2. Cardiotoxins 3. Haemotoxins

Snake example: Black Mamba 1) Fasciculins: These toxins attack cholinergic neurons (those that use ACh as a transmitter) by destroying acetylcholinesterase (AChE). ACh therefore cannot be broken down and stays in the receptor. This causes tetany, which can lead to death. Snake example: Black Mamba 2) Dendrotoxins: Dendrotoxins inhibit neurotransmissions by blocking the exchange of + and – ions across the neuronal membrane ==> no nerve impulse. So it paralyses the nerves. Snake example: Mambas

3) α-neurotoxins: α-neurotoxins also attack cholinergic neurons. They mimic the shape of the acetylcholine molecule and therefore fit into the receptors → they block the ACh flow → feeling of numbness and paralysis. Snake examples: - Kraits use erabutoxin (the Many-banded krait uses Bungarotoxin) Cobras use cobratoxin,

Snake example: King Cobra and some other cobras 1) Phospholipases: Phospholipase is an enzyme that transforms the phospholipid molecule into a lysophospholipid (soap) ==> the new molecule attracts and binds fat and rips a hole in the cell membrane. Consequently water flows into the cell and destroys the molecules in it. That is called necrosis. Snake example: The Japanese Habu snakes (low toxicity) 2) Cardiotoxins: Actually cardiotoxins are muscle venoms. They bind to particular sites on the surface of muscle cells causing depolarisation ==> the toxin prevents muscle contraction. For example the heart muscle: the heart will beat irregularly and stop beating, which will cause death. Snake example: King Cobra and some other cobras

3) Haemotoxins: The toxin destroys red blood cells (erythrocytes). This symptom is called haemolysis. As it is a very slowly progressing venom it would probably not kill a human - another toxin in the snake’s venom would most certainly have caused death by then. Snake example: most Vipers and the members of Naja genus

Antivenin An antivenin is prepared by injecting increased doses of snake venom into the horse until the horse becomes fully immunised. Then blood serum of the horse is collected and preserved. In India Antivenin is produced at the Haffkin's Institute at Bombay and Central Research Institute in Himachal Pradesh.