bones, cartilage, and the special structures that connect them make up your skeletal system
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Bones, cartilage, and the special structures that connect them make up your skeletal system
Major Organs of the Major Organs of the Skeletal SystemSkeletal System
Skull Clavicle Ribs
Humerus RadiusUlna
Patella Femur Tibia Fibula Pelvic Vertebral girdle column
When you were born, your skeleton had around 350 bones.
By the time you become an adult, you will only have around 206 bones.
This is because, as you grow, some of the bones join together to form one bone.
•Protection•Storage•Movement•Blood Cell Formation
Protection•Your heart and lungs are shielded by your ribs
•Your spinal cord is protected by your vertebrae
Your brain is protected by your skull
Storage
•Bones store minerals that help the nerves and muscles function properly
•Your arm and leg bones also store fat that can be used for energy
Movement•Skeletal muscles pull on the bones to produce movement
•Without bones, you would not be able to sit, stand, walk, or run
Blood Cell Formation
•Some of your bones are filled with a special material that makes blood cells
•A bone may seem lifeless, but it is a living organ made of several different tissues.
•Bone is composed of connective tissue and minerals that are deposited by living cells called
osteoblasts.
Different Kinds Different Kinds of Bone Tissueof Bone Tissue
Compact BoneBone tissue that does not have any visible
open spacesSpongy Bone
Bone tissue that has many open spacesSpongy bone provides most of the strength
and support for a bone. It acts like the trusses of a bridge.
Bone MarrowRed marrow, found in spongy bone, produces
red blood cellsYellow marrow, found in the central cavity of
long bones, stores fat
•The place where two or more bones connect is called a joint
•Some joints allow a lot of movement, while other joints are fixed.
• Joints that have a wide range of movement tend to be more susceptible to injury that those that are less flexible.
Three Types of Three Types of JointsJoints
• Sliding Joint– Sliding joints allow bones in the hand to
glide over one another, giving some flexibility to the area.
• Ball-and-Socket Joint– Like a joystick on a computer game, the
shoulder enables your arm to move freely in all directions.
• Hinge Joint– Like a hinge on a door, the knee enables
you to flex and extend your lower leg.
SlidinSliding g
JointJoint
Ball-and-Ball-and-Socket JointSocket Joint
Hinge JointHinge Joint
• Joints are kept together with strong elastic bands of connective tissue called ligaments.
• A strained ligament will usually heal with time, but a torn ligament will not.
• A torn ligament must be repaired surgically• Cartilage helps cushion the area where two
bones meet• If cartilage wears away, the joint becomes
arthritic.