As we all know, a few species of snakes swallow rodents as a whole. My question is what happens to the teeth and bones of these animals? Won't they cut into the flesh of the snake and hurt it? Are the digestive acids strong enough to dissolve bones and teeth? Even so, I'm sure the process takes time, and during this period won't the snake get injured?
Almost everything the snake eats is completely digested. They have a very efficient digestive system. Things that wouldn't be digested would be the rodent's claws and hair and feathers of birds. And during digestion, the snake's intestines go into overdrive mode and expand when necessary. When the snake isn't eating, the intestines are usually dormant.
If something goes wrong though, or if the snake is threatened, the snake regurgitates everything in order to increase its mobility.
Owing to their narrow structure, no chewing mechanism nor limbs, a snake has to swallow its prey as a whole. In fact, their success and diversity is partly due to their ability to swallow prey relatively larger than their own body size. So inevitably, they need to process the parts like teeth, bones, exoskeleton and things of such nature.
Snake saliva not only eases swallowing by lubrication, but also contains powerful enzymes to break down tissues and even egg shells. But snakes generally cannot digest keratin (claws, hair) or chitin (arthropod exoskeleton). Many prey are covered with tough hide and if a snake relied solely on its digestive juices, it would take a long to time to get through to the nutrients. So this is speeded up by snake venom. Venom not only immobilises prey but also starts digesting the prey from the inside. A study showed that when a fer-de-lance (Bothrops asper) is deprived of its venom it took 12 days to digest a rat instead of the usual 2-3 days.
However, there is no consensus among different theories arguing the utility of a snake's venom. The above mentioned opinion is based on digestion hypothesis of venom utility.