Gravity gives us a reason to have equilibrium, to balance ourselves within gravity’s suction.
The body organs themselves function fine without gravity. They mostly use squeezing and sucking actions to move material around the body.
According to this piece from NASA
http://www.hq.nasa.gov/pao/History/SP-4026/noord28.html
One of the physiological effects of weightlessness is that one has a feeling of falling.
The course of the psychological impressions apparently would more or less be the following: in the beginning at least during a rapid, abrupt occurrence of the absence of gravity anxiety; the brain and senses are functioning extremely intensively, all thoughts are strongly factual and are quickly comprehended with a penetrating logic; time appears to move more slowly; and a unique insensitivity to pains and feelings of displeasure appear. Later, these phenomena subside, and only a certain feeling of elevated vitality and physical fitness remain, perhaps similar to that experienced after taking a stimulant; until finally after a longer period of adaptation, the psychological state possibly becomes entirely normal.
Water has some unusual observable behavior in a micro gravity environment, like outer space. If one tries to put water into a bathtub it would float out of the bath tube and stick to the walls.
The surface tension of the water is a stronger force with out the influence of gravity. If the walls of the room were absorbent the water would stick to and be absorbed by the wall until they were saturated. The rest of the water would float around behaving like soap bubbles in the air, joining together in to larger and large ‘bubbles’.
If water were in a large mayonnaise jar it would stick to the inside of the jar because of surface tension. One could not pore water out of the jar. One could move the jar forward and stop having the water continue in that direction and coming out of the jar.
Creating a blood pressure gradient,
When one is standing there is a blood pressure gradient in the body. Blood pools in the feet and thins out in the head. In the legs and feet blood pressure is about 200 mmHg (millimeters of mercury). In the brain, though, it’s only 60 to 80 mmHg. When a person is in micro gravity environment, like out space, there is equal blood pressure in the lower and upper body. So the body senses there is too much blood, decreases the amount of over all blood in the body. When the person returns to a gravity environment the body senses that there is too much blood volume so it decreases the amount of over all blood.
Bone loss in a micro gravity space environment is more difficult to recover from.
An astronaut can lose up to 40% of her bone mass.
One piece of exercise equipment used in space is a like a vacuum cleaner tube, about 3 feet round and comes up to the waist of an astronaut. The astronaut stands in the device and it sucks down on the exerciser to simulate gravity. So gravity really sucks well.
Heavy yoga is dedicated to research and poetic enthusiasm relating to gravity.