Another name for these organs is otolithic or macular organs. Note that a single brain stem neuron could in theory receive 5 different inputs. There are five end organs in the inner ear of vertebrates, and an additional organ in the inner ear of birds. The added mass of the crystals facilitates deformation and stimulation of hair cell plasma membranes. Figure 4 illustrates a mechanism by which the sophisticated sensors of the inner ear picks up information, translates it, and conveys the information to the brain.
Every organism has devices to detect gravity.
The eye also provides very important information, that together with information from the trunk and limbs is processed in the brain for maintaining a stable posture. We know that modified gravity alters not only the way in which vertebrates sense the environment, but also the way in which the body functions. It should become obvious why scientists bother to study the effect of gravity on living organisms, and why NASA supports investigation of this type. It is assumed that organisms which have developed for millions of years under the ever present influence of gravity will be affected when conceived and reared under the altered gravity of space. In space, electrolyte imbalance is significant and it is assumed that such an imbalance also con-tributes to malfunctioning of hair cells.