| A | B |
|---|
| skeletal system | body system that includes bones and the connective tissues that hold the bones together in the body |
| appendicular skeleton | part of the skeletal system that allows for most of the body's movements; includes bones of the arms, shoulders, legs, and pelvis |
| axial skeleton | part of the skeletal system that supports the body's weight and protects the body's internal tissues; includes the bones of the skull, spinal column, and rib cage |
| vertebrae | bones that make up the spinal column (singular: vertebra) |
| cartilage | tough, elastic, and fibrous connective tissue found between bones |
| joint | location in the body where two bones meet |
| ligament | long, flexible band of connective tissue that joins two bones across a joint |
| calcification | process that hardens bones by adding calcium phosphate and collagen |
| muscular system | body system that moves bones within and substances throughout the body |
| muscle fiber | cell of the muscular system that shortens when it is stimulated by the nervous system |
| skeletal muscle | muscle tissue that is attached to the skeletal system and, when contracted, moves bones |
| tendon | band of connective tissue that joins a muscle to the bone that it moves |
| smooth muscle | muscle tissue that moves substances, such as food and blood, through organs and tissues, such as the digestive system organs and blood vessels |
| cardiac muscle | muscle tissue that is only found in the heart |
| myofibril | long strand of protein within a muscle fiber |
| sarcomere | section of a muscle fiber that contains all of the filaments necessary to cause muscle contraction |
| actin | filament that is pulled by myosin filaments to cause muscle contraction |
| myosin | filament that pulls actin filaments to cause muscle contraction |
| integumentary system | body system that separates the other body systems from the external environment; includes the skin and the tissues found within it |
| keratin | protein the binds to lipids inside a skin cell, forming a waterproof layer within the skin |
| epidermis | outermost layer of skin that consists mainly of dead skin cells, and provides a barrier to pathogens |
| dermis | second layer of skin that includes structural proteins, blood vessels, glands, and hair follicles |
| hair follicle | pit in the dermis of the skin that contains cells that produce hair |
