notes 13-2 the skeletal system. bones a newborn has about 275 bones, but an adult has about 206...

Notes 13-2

The Skeletal System

Bones

• A Newborn has about 275 bones, but an adult has about 206 bones

• Some bones fuse together as you grow• Bones are hard but spongy inside

Functions• Your skeleton has five major

functions. It provides shape and support, enables you to move, protects your organs, produces blood cells, and stores minerals and other materials until your body needs them.

Shape and support

• Your skeleton is the framework of your body and it determines your shape

• The vertebral column is the center of the skeleton, it is made up of 26 small bones (Why is that important???)

Movement and protection

• Most bones are attached to muscles. Muscle pull on bones to allow movement.

• Bones protect your vital organs

Production and storage of substances

• Bones help your body make and store minerals such as Calcium and Phosphorous

• When your body needs these minerals, your bones release small amounts of them into the blood stream

Joints of the Skeleton

• A joint is a place in the body where two bones come together. Joints allow bones to move in different ways. There are movable joints and immovable joints.

Connective tissue (CT)

• Ligaments: CT that hold movable joints together

• Cartilage: CT that is more flexible than bone. Covers ends of bones to keep them from rubbing together

• Tendon: CT that connects muscles to bones• Marrow: CT found inside the bones. Red

marrow makes blood cells, yellow marrow stores fats.

Bones—Strong and Living• Bones are complex living structures that undergo growth and

development.

Strength and Growth

• “Hard as a Rock!”• Rocks are hard because they are made of

compacted minerals. Bones are similar.• Bones are alive. They are made up of cells and

tissues.• Bones grow and make repairs.• As an infant, much of your skeleton was

cartilage. Some of it was later replaced with hard bone tissue.

Keep healthy bones

• Balance diet• Exercise regularly

• Osteoporosis: With age, your bones may lose some of their minerals, which weakens your bones.

Osteoporosis