Effect of space on Human body
1) Effect on cardiovascular system
Human beings living on Earth are affected by gravity because about two-thirds of our daily activities are standing or sitting. Because of this great amounts of body fluids such as blood pool in the lower part of the body. The human body is equipped with various mechanisms to oppose gravity to maintain sufficient blood flow to the brain.
2) Effects on bone
Bones are systems involved in maintaining posture. The adult human body has 1,000 to 1,200 grams of calcium and 400 to 500 grams of phosphorus. However, once gravitational stress is removed, bone calcium and phosphorus are excessively excreted in urine and faeces. It is seen that 3.2% of average bone loss occurred after nearly 10 days of weightlessness. The loss of calcium in urine may produce urinary stone, which might cause severe pain, the decrease of bone density will lead to bone fracture. Therefore, countermeasures are necessary.
3) Effects on muscle
The human body floats within the orbiting spacecraft. Therefore, astronauts can move around in spacecraft just by softly pushing against its wall. In a micro gravity environment, muscles rapidly weaken due to the lack of use.
4) Space motion sickness
A few minutes or a few hours after entering weightlessness, astronauts experience space motion sickness, which is characterized by headaches, malaise, nausea and vomiting. Sixty to seventy percent of the astronauts experience these symptoms.
5) Effect on hematologic and immunologic system
One significant alteration in the hematologic and immunologic system in micro gravity is the transformation of red blood cells, the main component of blood. Ninety percent of our normal red blood cells have a biconcave discoid shape (i.e.) a doughnut without a hole. In weightlessness, some red blood cells transform into "mulberry" or spherical shape. However, they are readily reversed even after long-term space mission.
6) Effects of space radiation
Space radiation exists in the space environment. On the Earth, the atmosphere and magnetic field provide a shield for humans, and prevent space radiation from penetrating to the Earth's surface. Due to the absence of such shielding in the space environment, astronauts are subjected to greater amounts of space radiation than they would receive on the Earth. Therefore, the space radiation may seriously affect the astronauts.