Can prolonged bed rest cause body to shut down eventually?

No, but major things: Prolonged bed rest can result in atrophy of muscles and in contractures where joints can be moved only with difficulty. This can occur in people with strokes who are not moved and exercised. Bedsores can also occur. If that person is fed the whole body will not shut down, but prolonged bed rest requires much support to keep muscles, bones, skin and lungs working well.