system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What are the effects of venoms and antivenoms on blood?

For example I've seen that blood can coagulate. In that case what would be the effect of the antivenom? To de-coagulate?

What are some other effects of venoms and the respective antivenoms?
gpt
It depends on the venom at hand. Let me give two examples:

1) Snakes (particularly Rattlesnakes) – their venom acts as a neurotoxin. In other words, it inhibits neural signals from being completed for voluntary and involuntary muscles. That is why one of the biggest signs that you are undergoing a neurotoxic attack is creeping numbness, difficulty breathing, and paralysis. These all happen because the venomous components (molecules) interfere with signaling molecules in your neural synapses and it causes muscles (limbs, lungs, heart, etc.) to just stop responding to your brain's signals.

2) Brown Recluse spider– Now in these guys, the venom acts differently because instead of blocking muscular function, it flat-out begins killing cells near or associated with the bite region. The flesh decomposes really badly (which can lead to septic shock down the line) in a process known as necrosis. This varies in action from direct lysis of your tissue cells to something like inhibiting gaseous (O2<->CO2) exchange. 

It really depends on the venom you are looking at. Each venomous bite has a different cocktail of chemicals that elicit different reactions from species to species.

As for antivenoms, they can behave just like you said. Their main modes of action is to either reverse the chemical reactions going on or to "out compete" the binding of venom with important molecules. An example with a synthetic "venom" - Sarin Gas. Sarin binds to a signal molecule and it locks the muscle by blocking these signals. Something like Pralidoxime is then used to bind to the signal instead of Sarin and it thus knocks off the blocking agent and allows the signal molecule to be recycled.

Edit: Added the antivenom bit and finished an incomplete thought.