Marvel is known for its attempts to quantify its characters and make them as scientific as possible, but how does that work with a magical being like Thor? As a fantastical god who hurls lightning and tosses mountains, Thor is far from having a typical person's anatomy, but the small details of how his biology works aren't just awesome, they're downright mythical.
The first thing to understand about Thor's anatomy is that, despite appearances, it's truly nothing like a typical human's. While Thor has worn the form of a Dr. Donald Blake, his true form is that of an Asgardian. Marvel guidebooks make it very clear that all Asgardians are far above humans when it comes to their physicality, with denser flesh and bones and multi-ton strength. On top of that, Thor is one of the strongest Asgardians of all.
Thor Is Stronger Than Other Asgardians
Either due to his special heritage as the son of Odin or just through his own lifetime of adventures and training, Thor has managed to become several orders of magnitude stronger than other Asgardians. Whereas most Asgardians can lift or press 25-30 tons, Thor can lift 100+, and the way he can shatter mountains and threaten entire planets with his blows indicates that there may be no upper limit to how strong his particular brand of Asgardian can grow.
Thor's Immune System Can Survive Almost Anything, Even the Black Death
It would seem that Thor is just as hardy on the inside as the outside, as his magical nature grants him immunity to almost all forms of disease or virus. He has even walked through European villages suffering from the Black Death, seeing villagers sick at their bedside without becoming infected with the plague, but this does not mean that no disease has ever managed to hurt Thor.
When Ragnarok once threatened the Nine Realms, Thor came under the influence of a magical disease that blew through his body's defenses. He noted that he had never been sick before, and he grew increasingly weak over time. Even then, Thor managed to recover, and this might just be one of his most underrated abilities in his repertoire considering the times that Thor was moonlighting as a doctor.
Thor, The God of Thunder, Is Resilient Against More Than Just Electricity
As scientific as Marvel can get about Thor's biology, at the end of the day, magic is magic, and that grants Thor an incredible level of durability, even to esoteric forms of damage. Being the God of Thunder naturally grants him a resistance to electricity, but even conventional forms of thermal damage, like ice and fire, show little effect on the golden-haired Avenger.
Even weirder forms of attacks, like reality-warping or telepathic assault, have been shown to struggle immensely against Thor's natural magical resistances. In an early adventure when a being called the Space Phantom was teleporting Avengers to Limbo and assuming their powers, the Space Phantom tried the trick on Thor and the teleportation beam bounced off and sent the Space Phantom to Limbo instead.
Thor's Godly Senses Are Unlike Any Earthly Avenger's
On top of the all-around physical and magical superiority that Thor demonstrates, even his sensory input greatly exceeds the average human. Whole new colors and sounds are available to the senses of the God of Thunder, and there's a magical sixth sense that can't even be described. In the Ultimate Universe, Thor was able to sense when others were wielding lightning powers, and his status as a god allowed him to hear the prayers of people around the world.
The Destroyer Is Part of Thor
By the miraculous circumstance that Thor is able to be injured, his body tends to regenerate at a superhuman degree and to a superhuman extent. Throughout his long life, Thor has had his teeth and eyes removed, his flesh seared off and been impaled, yet he always bounces back, fully regenerating if granted enough time.
Of course, that's not to say that he's never been dealt lasting damage. Most famously, Thor's arm was ripped off and eventually replaced with the arm of the Destroyer armor, and movie audiences know his Marvel Cinematic Universe incarnation lost an eye. Rocket was luckily able to provide Thor a bionic replacement, but given just how hardy his comic book counterpart is, don't be surprised if the original grows right back when the character next appears on the big screen.