Download Skeletal System The human skeleton consists of bones

Skeletal System
The human skeleton consists of bones, cartilage, ligaments, and tendons. It accounts for ~20% of
human body weight.
Bones provide a rigid framework that support and protect the soft organs of the body. The skeleton
supports the body against the pull of gravity. It also protects the soft body parts. The fused bones of
the cranium surround the brain to make it less vulnerable to injury. Vertebrae surround and protect
the spinal cord, and the bones of the rib cage help protect the heart and lungs.
Bones contain more calcium than any other organ. The intercellular matrix of bones contains large
amounts of calcium salts. When blood calcium levels decrease below normal, calcium is released
from the bones. When blood calcium levels increase, the excess calcium is stored in the bone
matrix.
Hematopoiesis is the formation of blood cells and takes place mainly in the red marrow of the
bones.
There are two types of bone tissue: compact and spongy. Compact bone consists of closely- packed
osteons, or canal systems. Spongy bone consists of plates of bone.
An adult skeleton consists of 206 bones. A newborn baby has 300 bones.
A joint is an interconnection of two bones. Each joint has a range of movement and stability.
Tendons- attach muscle to bone.
Ligaments- attach bone to bone
Cartilage- a type of connective tissue. It is a firm, gel-like substance. The body contains three main
types of cartilage: hyaline, elastic, and fibro cartilage.