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How does snake venom work?

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Quick answer

Snake venom is a cocktail of proteins injected through fangs. Neurotoxins, found in cobras and kraits, block nerve signals to muscles and can paralyse breathing. Haemotoxins, typical of many vipers, disrupt blood clotting and damage vessels, causing bleeding. Cytotoxins destroy tissue around the bite. Antivenom contains antibodies that bind and neutralise these toxins.

Snake venom works as a mixture of proteins and enzymes, produced in modified salivary glands and injected through fangs, that attacks specific systems in the victim's body. Depending on the species, its toxins can paralyse nerves and muscles, disrupt blood clotting, or destroy tissue around the bite.

Step by step

  1. The snake strikes, and muscles squeeze venom from glands in its head down ducts into the fangs.
  2. Hollow or grooved fangs inject the venom under the skin or into muscle of the prey.
  3. The venom's proteins spread through tissue fluid and the lymphatic system toward blood and nerves.
  4. Specific toxins latch onto targets such as nerve receptors, clotting proteins or cell membranes and disable them.
  5. The prey becomes paralysed, bleeds internally or suffers tissue damage, letting the snake swallow it safely.

Key things to understand

  1. Venom is made in modified salivary glands behind each eye and stored there until the snake bites.
  2. Muscles around the glands squeeze venom through ducts into hollow or grooved fangs that inject it into prey.
  3. Neurotoxins, common in cobras and kraits, block signals between nerves and muscles, causing paralysis that can stop breathing.
  4. Many viper venoms contain enzymes that break down blood vessel walls and use up clotting factors, causing bleeding and swelling.
  5. Cytotoxic components destroy cells near the bite, while digestive enzymes help the snake begin breaking down its prey.

Labelled diagram

  1. Venom gland

    A modified salivary gland behind the eye makes and stores venom.

  2. Fang

    Hollow or grooved teeth deliver venom deep into tissue during the bite.

  3. Neurotoxins

    Block nerve-to-muscle signals, causing weakness and paralysis.

  4. Haemotoxins

    Damage blood vessels and disrupt clotting, leading to bleeding.

  5. Antivenom

    Antibodies that bind circulating toxins before they reach more targets.

From venom gland to target in the body

Real-world examples

  • India's 'big four' snakes, the spectacled cobra, common krait, Russell's viper and saw-scaled viper, cause most of the country's serious bites.
  • The common krait's neurotoxic venom can cause paralysis after a nearly painless night-time bite.
  • Russell's viper venom disrupts blood clotting, and its effects have long been studied in Indian hospitals.
  • Spitting cobras in Africa spray venom toward the eyes of threats as a defence.

Common mistake

✗ Myth: All snakes are venomous, so every snake bite is deadly.

✓ Fact: Most snake species are not dangerously venomous, and even venomous ones sometimes give dry bites. Still, any bite of uncertain origin should be treated as an emergency and checked by a doctor at a hospital.

People also ask

How does snake venom kill you?
It depends on the venom. Neurotoxic venom from cobras and kraits blocks signals from nerves to muscles, which can paralyse the breathing muscles. Haemotoxic venom from many vipers prevents blood from clotting and damages vessels, causing dangerous internal bleeding. Some venoms also harm the kidneys. Prompt hospital care with antivenom greatly improves survival.
What is snake venom made of?
Snake venom is mostly proteins and peptides, many of them enzymes. Common ingredients include three-finger toxins that target nerves, phospholipases that damage cell membranes, metalloproteinases that break down blood vessel walls, and serine proteases that interfere with clotting. Each species has its own mix, which is why antivenoms are made for specific snakes.
Is snake venom harmful if swallowed?
Venom is generally much less dangerous when swallowed than when injected, because stomach acid and digestive enzymes break down many of its proteins before they are absorbed. However, venom entering the body through cuts, ulcers or the eyes can still cause harm, so it should never be handled or tasted.
How does antivenom work?
Antivenom is made by exposing animals, usually horses, to small, safe amounts of venom so they produce antibodies. Those purified antibodies bind and neutralise venom toxins in a bitten person, though they cannot undo damage already done.
What is the difference between venom and poison?
Venom is injected through a bite or sting, while poison harms when swallowed, inhaled or touched. Snakes are venomous, whereas animals such as poison dart frogs are poisonous.
Do all venomous snake bites inject venom?
No. Some bites are 'dry', delivering little or no venom, because snakes can control how much they release. Any bite from a venomous species still needs urgent hospital assessment, since symptoms can appear hours later.
Why are snakes not harmed by their own venom?
Many venomous snakes have altered target proteins, such as nerve receptors, that their toxins cannot bind well. They also keep venom sealed in glands and ducts, away from their own bloodstream.

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