Skeletal System Notes

Your body has two organ systems that work together to provide support & help you move– the skeletal system & the muscular system.

The skeletal system is made up of bones & cartilage that form the framework of your body.

The muscular system includes the muscles that help you move & help things inside your body move.

All humans have a stiff internal skeleton made of bone.

The bones of your body have five main jobs–

-to support the body & give it shape

-to protect internal organs -to work with the muscles to move -to protect internal organs

-to store fat & other minerals (calcium & phosphorus)

-to make blood cells (bone marrow)

A human baby is born with 350 bones, but an adult human has 206 bones.

Bones are made up of mostly calcium & phosphorus.

Bones are very much alive & contain blood vessels & nerve tissue.

Cartilage is a strong flexible connective tissue found at end of bones where it acts as a cushion.

Cartilage has no blood cells so it must absorb nutrients from body fluids. (diffusion)

Bones are attached to other bones by connective tissues called ligaments.

A joint is the place where two bones come together & are joined by ligaments to allow bones to move in different ways.

Two types of joints in the body…

Immovable joints allow little or no movement (skull & ribs)

Movable joints that allow a wide range of movement.

Bones rotate around each other (allows side-to-side motion) Pivot joint Bones rotate around each other (allows side-to-side motion)

Examples… Neck

Bones slide over each other (allows you to bend & flex) Gliding joint Bones slide over each other (allows you to bend & flex)

Examples… Wrist, ankle, vertebrae (back)

Back-and-forth motion (can only move one direction… unable to twist) Hinge joint Back-and-forth motion (can only move one direction… unable to twist)

Examples… Knee, elbow, fingers, toes, jaw

Rotational or circular motion… greatest range of motion Ball & socket joint Rotational or circular motion… greatest range of motion

Examples… Shoulder, hip

The best ways to keep your bones healthy are regular exercise & to eat a balanced diet with meats, beans, green leafy vegetables & dairy products.

Osteoporosis is the condition where mineral loss can cause bones to become weak & break easily.