Photograph by Rich Reid. Tundras are among Earth's coldest, harshest biomes. Tundra ecosystems are treeless regions found in the Arctic and on the tops of mountains, where the climate is cold and windy and rainfall is scant. Tundra lands are snow-covered for much of the year, until summer brings a burst of wildflowers.
Muscle is a soft tissue found in most animals. Muscle cells contain protein filaments of actin and myosin that slide past one another, producing a contraction that changes both the length and the shape of the cell. The statement that the tongue is the strongest muscle in the body appears frequently in lists of surprising facts, but it is difficult to find any definition of strength that would make this statement true. 2  Note that the tongue consists of eight muscles, not one.
Muscles (smooth, skeletal and cardiac muscles). 1  Receptors in muscles provide the brain with information about body position and movement. 2  The brain controls the contraction of skeletal muscle. 3  The nervous system regulates the speed at which food moves through the digestive tract.uscles (smooth, skeletal and cardiac muscles). 1  Receptors in muscles provide the brain with information about body position and movement. 2  The brain controls the contraction of skeletal muscle. 3  The nervous system regulates the speed at which food moves through the digestive tract.