- Slides: 16
Poison apparatus, biting mechanism, snake venom and its importance q All the poisonous snakes have in their heads a poison apparatus. This apparatus includes a pair of poison glands, their ducts and a pair of fangs. q POISON GLANDS: § The poison glands are situated one on either side of the upper jaw. § The poison glands are possibly the superior labial glands or parotid glands. § The glands are enclosed in thick fibrous connective tissue and are covered by a fan-shaped constriction muscles.
q POISON DUCTS: A narrow poison duct leads anteriorly from each poison gland to the base of a poison fang to enter its groove or canal. q POISON FANGS: One or more pairs of poison teeth are always attached in the upper jaw to the poison duct & open below at the tip. On the basis of structure and position, three types of fangs occur in poisonous snakes. 1. Proteroglyphous: These fangs are small, in front of maxillae and permanently erect. These fangs are found in cobras, Kraits, coral snakes & sea snake.
2. Solenoglyphous: In Vipers and rattle snakes, a large functional fang occurs on front of each maxilla containing a few developing fangs. The fangs are movable and turned inside to the roof of mouth when closed. A hollow poison canal runs through the fang opening at the tip. 3. Ophisthoglyphous: these fangs are small and lie at the back of maxillae. § Found in vine snake, cat snake, Indian flying snake, pit vipers. § This fangs are movable fangs can penetrate deep into the tissues of the victims.
BITING MECHANISM IN SNAKE The mechanism of biting is a complicated process and the sequences of biting may be discussed in three observable steps. These are… 1. Opening of mouth: just before biting the digastric muscle contracts and as a result mouth opens. 2. Rotation of maxilla: As the mouth opens, the lower jaw moves forward and a rotation of squamosal, quadrate and mandible in relation to each other occurs. § Now the sphenopterygoid muscles contract. § This contraction results in forward movement of pterygoid and up-pushing of ectopterygoid. § This movemnt brings about a rotation of maxilla on its own axis, and the end result the fang is raised & comes to its striking position. The fangs assumes almost vertical
3. Closing of mouth: This brought about by the contraction of the temporalis muscles and sphenopterygoid muscles. § The point of fang is directed backward while the mouth is closed. § It takes longer time to open the mouth than to close it. § The poison is transferred to the prey by squeezing of poison gland. § Pressure of the prey inside the mouth and the contraction of mandibular muscles. § During the contraction of muscles the posterior ligaments is relaxed and during the rotation of the squamosal bone the fan-shaped ligaments are stretched to sqeeze the walls of the gland.
SNAKE VENOM AND ITS IMPORTANCE NATURE & PROPERTIES OF SNAKE VENOM Ø Snake venom is a clear, transparent, pale yellow colored fluid having specific gravity of 1. 03 -1. 07. Ø The p. H of the venom varies in different species e. g. , Russell’s Viper, s p. H is 5. 8 and cobra venom is 6. 6. Ø It is protein in nature containing many enzymes, viz. , Proteinase, Hyaluronidase, L-Arginine hydrolase, Transaminase, L- amino acid oxidase, Phospholipase- A, B & C. Phosphodiesterase, Acid phosphatase, Exopeptidases, Cholinesterase, Alkaline phosphatase, Ribo & Deoxyribonucleases. The composition of venom varies species to species. Ø Most snake venoms are tasteless but cobras venom is slightly bitter. Ø It is acidic in reaction and soluble in water & glycerine. Ø It is destroyed by coagulating agents like Kmno 4, Ag. No 3, alcohol, Na. OH & KOH.
Ø The Venom contains metals like Zink (Zn), Sulphur (S) and Copper (Cu) etc. Ø The venom is thermo labile. Ø It can be dried and the dried venom is thermostable.
Types of Snake Venom Snake venom is classified into 3 groups according to the nature of action on human beings. 1. NEUROTOXIC: The venom effects mainly on Nervous system. Ultimately the respiration ceases due to failure of CNS. This type of venom occurs in Cobras, Mambas & Coral snakes. 2. HAEMOTOXIC: The venom acts on Blood Vascular system. Causing haemorrages, RBC is destroyed, distrubs the clotting mechanism. Occurs among Vipers & rattle snakes. 3. MYOTOXIC: The venom effects on muscles. This type of venom is seen in sea snakes.
Importance of Snake Venom ü Snake venoms are used for the treatment of diseases like epilepsy, asthma, arthritis, chronic nervous and muscular pain, migraine and cancer. ü Russell’s vipers venom can be used as hemostatic agents. ü To stop the internal bleeding venom’s dilution can be used. ü In homeopathy rattle snake’s venom is used to cure various diseases like sciatica, laryngitis.