One of the things that happens to your body in space is your body gets weak. Your body gets weak because space flight leads to loss in strength and skeletal muscle mass.
What is happening to my bones???
The second thing that happens to your body in space is your heart gets weaker. While in space, the blood pumped out of your heart decreases each minute.
I'M so SICK!! :(
The third thing that happens to your body while in space is, your fitness suffers. Your fitness suffers while in space because the reduced blood flow to the muscles, combined with the loss of muscle mass,impacts aerobic capacity.
The fourth thing that happens to your body when your in space is, you lose bone. While in space you lose bone because the bone materials balance changes causing reduced bone material.
The fifth thing that happens to your body in space is, your immune system suffers. While in space, your immune system suffers because radiation, microgravity, stress, etc, change in the circadian rhythm.