Physiology Behind Signs and Symptoms of Snakebite (2)
[Bite assumed to be inflicted by common tiger snake, therefore not all physiological explanations will apply to other species of snakes]
Paired fang marks or a single mark or scratch may be seen
– Entry site; redness (also other cardinal signs) caused by localised affects of immune system, e.g. mobilisation of WBC’s
Headache; nausea and vomiting; confusion and collapse
– Can sometimes be attributed to fear, i.e. psychologically induced
– Interruption of post-synaptic neurotoxins (as characterised by the rapid onset of this symptom, <1hr)
Dizziness and blurred vision
– Can sometimes be attributed to fear
Abdominal cramps and pain
– Procoagulant activity – leading to widespread clot formation/debrinogenation
Difficulty in speaking, swallowing or breathing; facial or limb weakness and paralysis; fitting, and loss of consciousness
– Potent pre-synaptic neurotoxins (have negative effect on membrane proteins, such as ion channels)
– Myotoxins, affect skeletal muscle causing loss of control (i.e. the muscles usually under conscious control)
Respiratory and/or cardiac arrest
– Procoagulant activity – leading to widespread clot formation/defibrination
– Potent pre-synaptic neurotoxins (have negative effect on membrane proteins, such as ion channels)
– Myotoxins, affect skeletal muscle causing loss of control (i.e. the muscles usually under conscious control)
References
http://www.avru.org/compendium/biogs/A000084b.htm
http://gorp.away.com/gorp/health/snakefaq15.htm
http://en.wikipedia.org/wiki/Neurotoxin
http://www.usyd.edu.au/anaes/venom/snakebite.html
Lecture 15: Envenomation and the neuromuscular junction (W. Hodgson)
