Stretchingafteractivitymayhelppreventinjuries. Regularstretchingimprovestheflexibility
of muscles and tendons. It also improves the range of mobility of your joints. Stretching
can also improve your posture, and may help prevent some aches and pains caused by tight
muscles.
Lesson Summary
- Bones, cartilage, and ligaments make up the skeletal system. The skeleton supports
the body against the pull of gravity. The skeleton provides a framework that supports
and protects the soft organs of the body. Bones work together with muscles as simple
mechanical lever systems to move the body. Blood cells are made mostly inside the
bone marrow. Bones store calcium. - There are three types of joints in the body:fixed, partly movable, andmovable. Fixed
joints do not allow any bone movement. Partly movable joints allow only a little
movement. Movable joints allow movement and provide mechanical support for the
body. Joints are a type of lever, which is a rigid object that is used to increase the
mechanical force that can be applied to another object. Joints reduce the amount of
energy that is spent moving the body around. Calcium and vitamin D are two of the
most important nutrients for a healthy skeletal system. - Bones need calcium to grow properly. Vitamin D deficiency results in problems with
bone growth and hardening. Osteoporosis is a disease in which bones become lighter
and more porous than they should be. Light and porous bones are more likely to break
than dense bones. Osteomalacia is a bone disease in which the bones do not harden
properly and they can break easily. Osteoarthritis is a condition in which the cartilage
at the ends of the bones breaks down. The break down of the cartilage leads to pain
and stiffness in the joint. A sprain is an injury to a ligament. A fracture is a break or
crack in a bone.
Review Questions
- What are the organs of the skeletal system?
- Name one tissue of the skeletal system.
- List four functions of the skeletal system.
- Name three types of movable joints.
- “All joints in the body are movable.” Do you agree with this statement? Explain why
or why not. (Intermediate - How are the joints in your body similar to levers?
- Why is calcium important for a healthy skeletal system?
- The recommended daily amount of calcium for teenagers is 1300 mg. If a person
gets only 1000 mg a day, what percentage of the recommended daily amount are they
getting?