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List the steps in the growth of a long bone.

Explain how nutritional factors affect bone development.

What effects do hormones have on bone growth? How does physical exercise affect bone structure?

Bone Function

Bones shape, support, and protect body structures. They also act as levers that aid body movements, house tissues that produce blood cells, and store various inorganic salts.

Support and Protection

Bones give shape to structures such as the head, face, thorax, and limbs. They also provide support and protection. For example, the bones of the lower limbs, pelvis, and vertebral column support the body's weight. The bones of the skull protect the eyes, ears, and brain. Those of the rib cage and shoulder girdle protect the heart and lungs, whereas bones of the pelvic girdle protect the lower abdominal and internal reproductive organs.

Body Movement

Whenever limbs or other body parts move, bones and muscles interact as simple mechanical devices called levers (lev'erz). A lever has four basic components: (1) a rigid bar or rod, (2) a pivot or fulcrum on which the bar turns, (3) an object that is moved against resistance, and (4) a force that supplies energy for the movement of the bar.

A pair of scissors is a lever. The handle and blade form a rigid bar that rocks on a pivot near the center (the screw). The material to be cut by the blades represents the resistance, while the person on the handle end supplies the force needed for cutting the material.

Figure 7.13 shows the three types of levers, which differ in their arrangements. A first-class lever's parts are like those of a pair of scissors. Its pivot is located between

Resistance

Resistance

Force

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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