The Skeletal System

Parts and functions of bones.

The skeletal system• Your skeletal system has five functions:

– Support- the bones support organs and hold us upright– Protection- the bones protect the soft organs, example the

skull protects the brain, & the ribs protect the lungs, heart, and other organs.

– Blood cells- inside of bones a substance called bone marrow creates new blood cells.

– Storage of calcium and phosphate- the bones are storage places for calcium and phosphate that allow the bones to be repaired

– Movement- the skeleton works with the muscles to allow the body to be flexible and able to move

Bone tissues• Bones are organs that are made of several types of tissue.

– Compact bone: hard bone, very dense provides the structure and strength of bones.

– Spongy bone: has small holes, or pores that allow spongy bone to be lighter but still strong, this is where red bone marrow is located.

– Cartilage: is not as strong as bone, but is more flexible, it is used to pad bone, and makes up the outer ear, the end of the nose and the wind pipe.

– Bone marrow; is located inside of bones, red bone marrow produces blood cells, and is located in the spongy bone, yellow bone marrow is located in the inner cavity of bones.

Structure of Bone

Cross Section of Bone

Types of Bones

• There are 5 types of bones– Round bones: rounded in shape, the patella (kneecap)– Flat bones: broad w/ flat surfaces, the scapula

(shoulder blade)– Short bones: cube shaped bones, the carpals (wrist

bones)– Long bones: longer than they are wide, the femur (thigh

bone)– Irregularly shaped bones; oddly shaped bones, the

vertebrae (neck bone)

Connective Tissues

• There are 3 basic types of connective tissues, tendons, ligaments, and cartilage.

• Tendons connect muscles to the bones, they help muscles move bones.

• Ligaments connect bones to bones, these are what holds joints together.

• Cartilage, see earlier notes.

Types of Joints

• A joint is any where two bones come together• Hinge joints, move only backwards and forwards, like a door

hinge. Knee, elbow, fingers and toes.• Ball and socket joints, allow for most movement of any joint,

located at the shoulder and hip, allows almost 360 degrees of movement.

• Pivot, allow side to side movement, located in the forearms and the calves.

• Gliding joints, located in the spine, the wrists and ankles, they allow for four way movement back and forth and side to side.

• Immovable, joints where two or more bones come together but they lock and don’t allow movement

General bone information

• Special places called processes and protuberances are where ligaments and tendons attach to bones.

• When we are born we have over 300 bones and adult has 206 bones

• Bones grow at the ends, special areas of cells call growth plates are where bones grow.

• We can tell the sex and age of a skeleton by looking at the bones.

Ageing and telling the sex of a skeleton

• The way that we can tell the sex of a skeleton, the angle of the hips, females are at a flatter wider angle than a males

• The brow ridges over the eyes on a male stand out where a females is smooth.

• The occipital protuberance of a male sticks out and a females doesn’t.

• The jaw line of a male is square, at or almost at 90 degrees

Bone cells

• Osteoblast and osteoclast are two types of bone cells

• Osteoblast are known as bone builders, when an injury occurs to a bone osteoblasts use calcium and phosphate to repair the damage.

• Osteoclasts are known as bone clearers, when an injury occurs osteoclasts dissolve calcium and phosphate from other areas to provide material for osteoblasts to build with, they then come through and clean up any extra from the repair site.