Human Biology Ch.1.2

Made up of a strong connective tissue called bone, the skeletal system
serves as the anchor for all of the body’s movement, provides
support, and protects soft organs inside the body.


Long bones: found in the arms and legs.
Short bones: found in the feet and hands.
Irregular bones: found in the spine.
Flat bones: found in the ribs and skull.

* Compact Bone
Surrounding the spongy, inner layer of the bone.
It covers the outside of most bones and functions as the basic supportive tissue of the body, the part of the body you call the skeleton.
* Spongy Bone
Inside the bone, the calcium network is less dense. It is strong, and lightweight. Spongy bone makes up most of the short, flat, irregular bones, and the ends of long bones.

The Axial Skeleton is the part of the skeleton that forms the axis. (including head, spine, and ribs)
* The skull, the cranium, protects the brain and they do not move.
* The skull connects to the spinal column which makes up the main portion of the axial skeleton. Many bones in spinal column, vertebrae, allows the flexibility.
* The rib bones function to protect the soft internal organs.

The Appendicular Skeleton function mainly to allow movement. (includes arms, shoulders, hips and legs)

•The upper arm bone connects to the shoulder and it connects with the two bones of the lower arm.
•The lower part of the body, the legs and the hip bones, bears all of the body’s weight when you are standing.

Infancy: A newborn’s skull has spaces between them. During the growth of the skull, the spaces between the bones close.

Childhood: Bone growth occurs at growth plates which are made out of cartilage.
Adolescence: At the end of adolescence, the growth plate become hard and bones stop growing.

Adulthood: As people age, more bone is broken down than is formed. (Decrease in bone mass and density.)

Three types of joints are:
•Immovable- locks bones together like puzzle pieces.
•Slightly movable- able to flex slightly. (ribs are connected to your sternum by slightly movable joints)
•Freely movable – allow your body to bend and to move. The entire joint is surrounded by connective tissue.
Movable joints can be classified by the type of movement they produce. (Angular movement: a hinge joint, Rotational movement: a ball and socket joint)