Ball and socket joints are multiaxial, synovial joints. They are lubricated by a clear, sticky fluid called synovia. Description Also called spheroidal joints, the ball and socket joints are formed by the rounded or "ball-shaped" head of one bone fitting into the cup-like cavity of another bone. The articulating bone fits into the cavity and allows the distal bone to move around. The hip and shoulder joints are examples of the ball and socket joint.

Electrolytes are positively or negatively charged particles that readily dissolve in water. The predominant positively charged electrolytes in the body are sodium, potassium, calcium, and magnesium, while negatively charged electrolytes include chloride, phosphates, and bicarbonate.

When water intake equals water loss, the body is in fluid balance. When water loss is greater than intake, or vice versa, a fluid imbalance may result.

A gliding joint is a synovial joint in which the bony surfaces that the joint holds together are flat, or only slightly rounded. (A synovial joint is the living material that holds two or more bones together but also permits these bones to move relative to each other.) A more precise interpretation of the international Latin anatomical term for the gliding joint would be "joint that joins flat bony surfaces." The wrists have good examples of gliding joints (as well as joints of other types).

Hinge joints are places in the human skeleton where the ends of bones meet and rotate uniaxially (in a single plane, like a knuckle or elbow). They are lubricated with synovial fluids, secreted by the synovial membrane, to ensure easy, pain-free movement.

Human anatomy is the study of the structure of the human body and the relationship between its parts.

In the context of the physical development of children, growth refers to the increase in the size of a child, and development refers to the process by which the child develops his or her psychomotor skills.

An immovable joint is an articulation between bones in which no movement occurs. It is also referred to as synarthrotic (meaning immovable).

Infection is the invasion and replication of microorganisms—viruses, bacteria, protozoa, or fungi—in body tissues.

Joints serve as links between structures; in this case, bones in the human body. There are numerous joints in the body that act to stabilize and control bony segments. One example is the knee joint, which joins the femur and tibia. This joint allows the lower leg to swing freely, but also to be stable during the stance phase of gait. Some joints provide the body with stability, while others provide it with mobility. However, most joints provide both stability and mobility.

Metabolism refers to the highly integrated network of chemical reactions by which living cells grow and sustain themselves.

Muscle contraction is the response a muscle has to any kind of stimuli where the result is shortening in length and development of force.

The muscular system is the body's network of tissues for both voluntary and involuntary movements. Muscle cells are specialized for contraction.

Obesity is an abnormal accumulation of body fat, usually 20% or more over an individual's ideal body weight. Obesity is associated with increased risk of illness, disability, and death.

Pain, medically termed "nociception," is a response to noxious stimuli that is conveyed to the brain by sensory neurons. The discomfort signals actual or impending injury to the body. However, pain is more than a sensation, or the physical awareness of pain; it also includes perception, the subjective interpretation of the discomfort. Perception gives information on the pain's location, intensity, and something about its nature. The various conscious and unconscious responses to both sensation and perception, including the emotional response, add further definition to the overall concept of pain.