Effects of space flight on human body

By Azka Amjad 

Effects of space flight on human body:

Space anemia:

There are many space companies currently working on Mars mission like blue origin, space company owned by Jeff Bezos and space X owned by Elon musk. But especially Elon musk and SpaceX are the most prominent names in this regard. 

Elon musk, the CEO of spaceX wishes to make humans a multi planetary species. He wants to set up a colony on Mars so that humans can tackle future problems. SpaceX has been working on this Mars mission for a long time. But how will it affect human life? 

Will humans be able to survive on a planet other than their mother planet? 

Elon musk said that we can land humans on Mars within 10 years but a major problem has come across on the way of this mission. A major concern regarding the health of astronauts has come forward i.e Space Anemia

You must have heard about anemia and its different types like

1. Blood loss anemia( can be acute like in case of hemorrhage or can be chronic) 

2. Iron deficiency anemia

3. Aplastic anemia(due bone marrow dysfunction as bone produces RBCs) 

4. Megaloblastic anemia( due to deficiency of Vitamin B12, folic acid or intrinsic factor as they are required for maturation of red blood cells) 

5. Hemolytic  anemia ( it can be intrinsic or extrinsic) 

• Intrinsic like membrane defects as in case of hereditary spherocytosis in which cell membranes of RBCs become fragile so they can't withstand  compression or enzymes defects etc

• Extrinsic hemolytic anemia can be due to problem outside the cell like

           Autoimmune disorders

          Microangiopathic ( due to              small vessels) 

But today we're gonna discuss space anemia faced by astronauts during space flight. 

It has been observed that Hemolysis of red blood cells i.e destruction of RBCs is the primary effect of shifting from Earth's gravity to microgravity in space. 

But the real cause behind the increased rate of hemolysis during space flight is still unclear and researchers are working on it. 

A normal human body creates and destroys about 2 million red blood cells each second here on Earth's surface but in space it destroys 54% more red blood cells. And it leads to a severe anemia known as Space Anemia. In space anemia, the body of astronauts destroys approximately 3 million red blood cells.As red blood cells have hemoglobin which transports oxygen to tissues from lungs ,so, severe anemia in astronauts can be a big obstacle on their way to colonize Mars. 

There is also a high degree of radiation risk in space . It can also lead to cancer and megaloblastic anemia as high doses of radiation can affect bone marrow,  ISS orbits in low earth orbit and is protected by earth's magnetosphere from solar particles and high energy cosmic rays. Also space suits are designed in such a way to protect astronauts from hostile environmental conditions in space. 

There are different space suit designs to provide protection to astronauts from radiation like

AstroRad designed by Israelian company StemRad and israelian space agency.

PERSEO PErsonal Radiation Shielding for interplanEtary missiOn by Italian space agency and NASA. 

Although this space anemia has already been known to researchers, it was thought it will be resolved once astronaut's bodies adapt to that environment. But now, a new study shows that's not the case. In space an astronaut's body will show this negative impact and these effects will persist even after astronauts return to Earth. 

Researchers from the Canadian space agency and University of Ottawa tested the blood samples of 14 astronauts before, during and after their space flight and found that 5 out of 14 astronauts were severely anemic. 

This space anemia produces effects like fatigue, dizziness and physical weakness. But long term exposure to such an environment may even lead to heart failure. 

So it will make it quite difficult for astronauts to conduct challenging tasks in space, which require physical strength and concentration. And with the present technology, it will take about 2 years for astronauts to take a mars trip and return to Earth. Though their RBC level return to normal  3-4 months after their return to Earth but still it will destroy 30% more red blood cells than normal

So space anemia is currently a big hindrance in the way of SpaceX to occupy Mars. 

Working of heart in space:

As our human body is adapted to work in gravity, what will happen to it in microgravity? 

Lets us have a look on working of cardiovascular system in space

As you know normally gravity pulls blood with a greater force down to our legs but in space in microgravity blood will start to move in opposite direction i.e from legs towards head so it will lead to "puffy face and birds legs syndrome"

In this case the face and neck will swell due to greater fluid concentration and legs will become thin. 

Volume of body fluids in the body also decreases due to frequent urination as a result of feedback by kidneys to maintain blood pressure. 

So Cardiac output is also gonna decrease. As cardiac muscles don't need to work that hard, they'll regress as its the law of nature that the structures we don't use tend to regress with time.  (Use it or loose it)

"Disuse cardiac atrophy" refers to loss of cardiac muscle mass due to reduced heart functioning. As a result of disuse atrophy shape of the heart changes from oval to round during space flight. 

Musculoskeletal system:

As on Earth our muscles are being used everytime against gravity and so they increase in mass and size. But in space, in zero gravity, astronauts don't have to use their muscles against gravity so muscles are not used effectively in microgravity on ISS which causes muscle mass and size to decrease i.e muscular atrophy. This is one of the reasons that when astronauts return to earth from ISS, they face trouble while walking.

Post(after) flight Orthostatic intolerance:

Post flight Orthostatic intolerance is a condition in which astronauts can't maintain upright posture after returning from a space flight.

It is very commonly seen in astronauts involved in long term space flight as compared to those in short term space flight.