The Skeletal System

The Skeletal System

Pablo de EstebanCamila Rodriguez

The Skeleton

• Supports the body• Protects internal organs• Provides for movement• Stores mineral reserves• Allows an area for blood cell formation

Bones

A solid network of living cells and protein fiber that are surrounded by deposits of calcium cells.

• Infants: 350 bones• Adult: 206 bones

Structure of Bones –

Periosteum: tough layer of connective tissue that surrounds the bone through which Blood vessels pass caring oxygen and nutrients to the bones. • Haversian canal: runs through compact bone, beneath

peritoneum, contains blood vessels and nerves.• Spongy bone: adds strength to the bone. Bone marrows: cavity that contains soft tissue• Yellow marrow: made up of fat cells• Red marrow: produces red blood cells, some white cells, cell

fragments (platelets)

Development of bones

Cartilage: connective tissue scattered into a network of protein fibers.

• Strong and flexible

Development of Bones

• Ossification: process in which cartilage is replaced by bone. Cells involved:

1. Osteoblasts: secrete mineral diposits that produces new bone tissue to replace the cartilage into bone.

2. Osteocytes: the mature form of Osteoblasts surrounded by bone tissue, mantains cellular activities of the bone.

3 .Osteoclasts: breaks down bone removing damaged bone tissue.

Ossification

Joints

Are the place where one bone attaches to another.

Types of joints

• Immovable joints• Slightly movable joint• Freely movable joint

Immovable Joints

• Allows no movement because the bones are interlocked and held together by connective tissue

ex: where the bones in the skull meet

Slightly Movable Joints

• Permit a small amount of restricted movement. The bones in these areas are separated from each other.

Freely Movable Joints

http://www.jeffsims.net/flash/skeleton.html

• Permit movement in one or more direction• Grouped according to the shapes of the

surfaces of the adjacent bones

Structure of Joints

• Joint Capsule: surrounds the joints and helps hold the bones together while still allowing them to move.

• Layers: 1. Ligaments: surrounds bones and holds them

together.2. Cells in the other layer produce a substance called

synovial fluid => lubricating film which enables the ends of the bones to slip past each other smoothly.