Ch. 14.2 Notes

The Skeletal System

Skeleton

• The skeleton is made up of all the bones in your body.

• A newborn has about 275 bones.• An adult has only about 206 bones.

What the Skeletal System Does

• Your skeleton has 5 major functions:– Provide shape and support– Enables you to move– Protects your organs– Produces blood cells– Stores minerals and other materials until your

body needs them.

Shape and Support

• Your skeleton determines the shape of your body.

• Your backbone is the center of your skeleton.• It is made up of 26 small bones called the

vertebrae.• If your backbone was just one bone, you

would not be able to bend or twist.

Movement and Protection

• Most of the body’s bones are associated with muscles.

• The muscles pull on the bones to make the body move.

• Bones also protect many of the organs in your body.

• Your skull protects your brain.

Production and Storage of Substance

• The bones of your arms and legs act like factories to produce blood cells.

• The center of the bone is called the marrow. This is where the blood cells are made.

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.

Bone Structure

• Compact bone: is hard and dense, but not solid.

• Spongy bone: has many small spaces within it.• Marrow: two types: red and yellow.– Red makes blood cells– Yellow stores fats that serve as reserved energy

Bone Strength

• The structure of bones makes it both strong and lightweight.

• They actually absorb more force without breaking than concrete or granite rock!

Taking Care of your Bones

• A combination of a balanced diet and regular exercise are important for a lifetime of healthy bones.

• Diet: Eat a well balanced diet! • Meats, whole grains, and leafy green vegetables

are good sources of calcium and phosphorus.• Dairy is also a good source

• Exercise: puts stress on your body, so your body builds stronger bones.

Immovable Joints

• Some joints in the body connect bones in a way that allows little or no movement.

• These joints are called immovable. • The bones of the skull are held together by

immovable joints.

Movable Joints

• Most of the joints in your body are movable.• The bones in movable joints are held together

by strong connective tissues called ligaments.• Most joints have a second type of connective

tissue called cartilage.• Cartilage covers the ends of the bones to keep

them from rubbing together.

Bones – Strong and Living

• Bones are complex living structures that undergo growth and development.

Osteoporosis

• As people become older, their bones begin to lose some of the minerals they contain.

• Osteoporosis is a condition in which your bones become weak and break easily.

• Taking care of your bones while your younger will protect you when you are older.