Many living organisms or cells produce toxins either as a by-product of their metabolism or for self-defence purposes. Some organisms such as snakes have evolved toxins (more technically: venom) to incapacitate prey almost immediately.
Some toxins have relatively minor consequences on humans, while others are immediately life-threatening. For instance, bee venom contains a toxin called melittin that can cause localised pain and swelling, but the effect will dissipate after a while. Other organisms, such as black widow spiders contain latrotoxins in their venom, which almost always causes death, if left untreated.
From an anatomical perspective, toxins are molecules that can cause diseases on contact or absorption into the body. These molecules are typically proteins or peptides that bind with specific receptors in the cells.
Cytotoxins are toxins that work at the cellular level. Cytotoxins can induce a variety of ill effects in cells, ranging from necrosis to inhibition of cell division to apoptosis (programmed cell death). Necrosis (or cell death) occurs in a variety of ways: the cell membrane loses integrity, nucleus structure is compromised, or the cell metabolism shuts down. Castor beans produce ricin, a lethal cytotoxin that has infamously been used in many assassination attempts. Honey bees venom contain a toxin called apitoxin – it is a colourless and bitter liquid that can produce localised inflammation when injected via a bee’s sting.
Necrotoxins are toxins that cause the death (necrosis) of the cells. Examples of organisms that possess necrotoxins include the brown recluse spider, puff adder viper. Once the toxin enters the tissue, it causes the premature death of living cells. When a large number of cells die, the corresponding tissue dies as well. This condition is often irreversible and can cause death if untreated.
Neurotoxins are a class of toxins that primarily affect the nervous system of organisms. The toxin works by disrupting the ion channels and hampering the flow of electrons. The black widow spider, box jellyfish, king cobras, blue-ringed octopus all produce neurotoxins. If the toxin enters the human body, it can lead to paralysis. Therefore, a bite from a snake, such as a cobra can paralyse the individual, rendering them incapable of using their muscles. If left untreated, the venom can essentially “cut off” communication between the brain and other vital organs. This is how death is caused when an organism with neurotoxic venom bites/stings an individual.
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