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The Effects of Gravity on the Human Body
Transcript of The Effects of Gravity on the Human Body
What would stronger/extra gravity do to the human body?
What would zero gravity do to the body?
What does normal gravity do to the human body?
The vestibular system helps the brain orient itself relative to the floor and the ceiling; it is what creates our sense of balance.
The proprioceptive system is what helps the brain determine where arms and legs are in relation to each other. This is compromised when initially in space.
"The first night in space when I was drifting off to sleep, "I suddenly realized that I had lost track of ... my arms and legs. For all my mind could tell, my limbs were not there." - one Apollo astronaut said in a NASA interview
What is gravity?
Gravity is the force that attracts a body toward the center of the Earth, or toward any other physical body having mass.
Gravity on Earth equals 9.81 m/s^2.
Gravity compresses the spine throughout the day; this results in discs losing moisture. As discs lose moisture, a person becomes shorter. Over a lifetime, one may lose anywhere from (1/2)'' to 2'' of height. Don't worry though, this moisture is replaced at nighttime, restoring the discs almost to their former glory.
Waist and Internal Organs?
Because gravity pulls organs down, organs become compressed. As a result in the shift of matter, your waist increases. Since your waist increases, your flexibility and range of movement decrease. As your organs become slightly displaced, their efficiency is compromised to a degree.
Because gravity pulls things down, blood has difficulty working its way up through veins when you get older. This eventually leads to varicose veins, decreased scalp circulation, and swollen limbs. This decrease in blood flow results in deterioration to valuable organs such as eyes, skin, and the brain.
How do people combat these effects of gravity?
Yogis would practice yoga poses upside down so that they could fix the placement of organs that gravity pulls down.
Babies sleep bottom up, keeping their heads below their hearts, encouraging a proper supply of blood to the brain.
Short Term Effects
What's wrong with a little disorientation?
This disorientation of astronauts makes them sick. When they're sick they cannot complete their jobs well or on time.
One famous example took place during Apollo 9 in 1969. Rusty Schweickart had to change a planned spacewalk because he was feeling ill.
Long Term Effects
Due to being used less, muscles lose mass. When astronauts return to Earth, their muscles may not be strong enough to allow them to move themselves.
Calcium from bones secretes out through urine. This makes astronauts more susceptible to breaking bones, like a person with osteoporosis.
This deterioration of the bones and release of calcium may lead to kidney stones.
The heart performs well in space since the heart has to work less because there is no gravity making pumping blood all the way through difficult. This may result in the heart becoming weaker and/or smaller.
There is also a concern that space radiation may affect endothelial cells, the lining of blood vessels, which might initiate or accelerate coronary heart disease.
How do they combat this?
Astronauts exercise for two hours daily to try and maintain some muscle mass; however, months of rehabilitation is required after a typical 6 month mission.
Due to a lack of compression upon the spine, the discs between vertebrae soak up more fluid than they would on Earth. This results in astronauts becoming taller. This lengthening of the spine may also cause back pain.
Bodily fluids (such as blood) are redistributed to the upper part of the body and away from the lower limbs. While in space, astronauts often have a puffy face due to this fluid shift and legs that are smaller in circumference. The fluid shift to the head can also lead to a feeling of congestion.
The international standard unit of force is called a Newton (N). On Earth’s surface, roughly 0.98N equals the downward force of gravity on 100 grams of mass. To calculate the force of gravity, physicists use the formula f = ma (force = mass x acceleration).
The excess gravity on the body will pull fluids down into limbs and causes the heart to work harder to get blood around the body. Since the heart is working harder, it gets stronger.
The shift in fluid causes a change in intercranial pressure. This leads eye shape to morph, which changes eye functuionality.
The force of gravity would pull your organs down more than 1G would. This would increase the rate at which your organs loose optimal functionality. Your waist also increases because the matter sits around there.
Waist and Internal Organs
Since it would take more strength just to complete daily activities, our muscle mass would increase due to more usage.
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The impact of gravity on life. Retrieved May 28, 2015, from http://www.dsls.usra.edu/biologycourse/workbook/Unit7-1.2 Suppl.pdf
The Pull of HyperGravity. (2003,
February 7). Retrieved May 29, 2015.
Thompson, H., & Havern, S. (n.d.). Gravity.
Retrieved May 30, 2015, from http://web.stanford.edu/~buzzt/gravity.html