Cool tech 62: Cyborgs on a nanotech level
A transhumanist a while ago came up with rough plans for respirocytes, nanomachines that drift in the bloodsteam and collect oxygen and carbon dioxide under pressure. Someone with respirocytes in them could hypothetically hold their breath for over an hour, which would among other things reduce the need for scuba tanks among divers.
But why not go further, like replacing the entire function of the blood with nanotechnology? Hunter-killer nanotech could attack invasive pathogens and parasites, antihistimine-like machines could compare molecules they come across against a library of allergens and toxins for either destruction or sequestration, platelet-mimics could deliver coagulants to an injury site or even seal it themselves with biodegradable polymers.
The periosteum, the sheathes covering our bones, could be reinforced with fullerenes or other carbon composites, or sufficiently small and robust nanotech could reinforce the entire bone structure the same way. The chain proteins that actually hold our cells one to another and prevent us from falling apart into living slime would be a bit harder to reinforce, since our soft tissues need to stay soft, but very durable structures could be introduced to make those soft tissues less likely to be cut or torn.
If nanomachines could be given any sort of ability to rapidly communicate with one another, a network could be established within our bodies, where, for one, hormonal levels could be regulated; an athlete could get adrenaline on demand, a bomb disposal team member could have it suppressed, and a diabetic would never need to monitor his or her insulin again. This network could also monitor and direct our cardiopulmonary system when needed; nearly all heart attacks would be prevented, and a person who suffers a high-level spinal injury wouldn't have to worry about suffocating because they can't control their diaphragm or the muscles lining their ribs. A sufficiently advanced network might even help them bypass the injury site.