Human Anatomy

"The human skeleton consists of 206 bones. We are actually born with more bones (about 300), but many fuse together as a child grows up. These bones support your body and allow you to move. Bones contain a lot of calcium (an element found in milk, broccoli, and other foods). Bones manufacture blood cells and store important minerals. The longest bone in our bodies is the femur (thigh bone). The smallest bone is the stirrup bone inside the ear. Each hand has 26 bones in it. Your nose and ears are not made of bone; they are made of cartilage, a flexible substance that is not as hard as bone. Joints: Bones are connected to other bones at joints. There are many different types of joints, including: fixed joints (such as in the skull, which consists of many bones), hinged joints (such as in the fingers and toes), and ball-and-socket joints (such as the shoulders and hips). Differences between males and females: Males and females have slightly different skeletons, including a different elbow angle. Males have slightly thicker and longer legs and arms; females have a wider pelvis and a larger space within the pelvis, through which babies travel when they are born. axon - the long extension of a neuron that carries nerve impulses away from the body of the cell. axon terminals - the hair-like ends of the axon cell body - the cell body of the neuron; it contains the nucleus (also called the soma) dendrites - the branching structure of a neuron that receives messages (attached to the cell body) myelin sheath - the fatty substance that surrounds and protects some nerve fibers node of Ranvier - one of the many gaps in the myelin sheath - this is where the action potential occurs during saltatory conduction along the axon nucleus - the organelle in the cell body of the neuron that contains the genetic material of the cell Schwann's cells - cells that produce myelin - they are located within the myelin sheath. "