San Diego has on average 146 sunny days and 117 partly cloudy days a year. The average annual precipitation is less than 12 inches (300 mm), resulting in a borderline arid climate.
Skeletal muscle makes up the bulk of muscles in the body. See also skeletal muscle groups. A whole skeletal muscle is considered an organ of the muscular system. Each organ or muscle consists of skeletal muscle tissue, connective tissue, nerve tissue, and blood or vascular tissue. Skeletal muscles vary considerably in size, shape, and arrangement of fibers.
Your skin is an organ-it's made of multiple layers of epithelial tissue. Your heart is an organ-made up of epithelial, muscle, nervous, and connective tissues. Organs working together to perform a function are called an organ system. There are 10 major organ systems in your body. One is the digestive system.