Anatomy is the study of the body. Physiology is the study of the function of the body. It is important to understand the differences between adult and child/teen anatomy and physiology. There are four components in the body that restrict or allow movement:

• The tissues
• The skeletal system
• The muscular system
• The nervous system

Let's look at each of these separately.

Tissues 

Cells organize themselves into groups with similar structures in order to perform certain functions. Those groups are called tissues. There are four major classifications of tissues: epithelial, connective, muscle, and nervous.

Skeletal System

Our bones are constantly changing, especially for students. We are born with approximately 270 bones, which fuse together (ossify) throughout childhood.

The main difference between the bones of a child and those of an adult is that children’s bones are growing, are more elastic and heal faster. Because they are not calcified and tend to be flexible, a child's ligaments also are more elastic.

For a child, growth is not uniform: It happens in spurts. From childhood until puberty, the extremities of the body grow faster.

The Muscular System

The main functions of the muscular system are to maintain posture and tone, stabilize joints and promote movement.

The Nervous System

The nervous system plays important roles, including assimilating information from the environment and orientating us to possible danger.

The Sympathetic Nervous System is activated in situations that require alertness and energy such as when we are doing physical activities or in moments of stress or danger.

On the other hand, the Parasympathetic Nervous System is responsible for conserving and restoring the body and can be called the "rest and digest" state.