Smooth muscle, such as in the digestive system, is also controlled by the autonomic nervous system. Like heart muscle, it is not under our conscious control. The SNS is responsible for controlling voluntary body movements, such as movement of the arms and legs.
The oceans cover 71 percent of the Earth's surface and contain 97 percent of the Earth's water. Less than 1 percent of the Earth's water is fresh water, and 2-3 percent is contained in glaciers and ice caps. The oceans contain 99 percent of the living space on the planet. If the ocean's total salt content were dried, it would cover the continents to a depth of 5 feet.
Distribution of water. The world's oceans contain 97% of the water in the hydrosphere, most of which is salt water. Ice caps, like that found covering Antarctica, and glaciers that occupy high alpine locations, compose a little more than 2% of all water found on earth.