Download Ch. 14 Sec. 2 Notes

Ch. 14 Sec. 2 Notes
The Skeletal System
*Your framework, or skeleton, is made up of all the bones in your body
-The # of bones in your skeleton, depends on your age
Ex: Babies have 275 bones and adults have 206 bones
-When you grow, bones fuse together
What the Skeletal System Does
Skeleton has 5 major functions:
1. Shape and Support
2. Enables you to move
3. Protects your organs
4. Produces blood cells
5. Stores minerals and other materials until your body needs them
Shape and Support
-Skeleton determines the shape of body
-Backbone is the center of your skeleton
-Smaller bones called vertebrae support your backbone
-Vertebra bones are the reason your back can bend
Movement and Protection
-Your muscles allow your skeleton to move
-Skeletons protect organs
Ex: Skull protects brain
Production and Storage of Substances
*Bones produce certain blood cells needed in body
*Bones store minerals such as calcium and phosphorus
-When your body needs these minerals, the bones release small amounts of
them into blood
Joints of the Skeleton
*A joint is a place in the body where 2 bones come together
*Joints allow bones to move in different ways
*There are 2 types of joints:
1. Immovable joints
2. Movable joints
Immovable Joints
*Skull is the only part with immovable joints
Movable Joints
*Allow body to make a wide range of movements
*Movable joints are held together by strong connective tissues called ligaments
*Most joints are also connected by cartilage
-More flexible than bone
-Cartilage covers the ends of bones and keeps them from rubbing against
each other
Bones - Strong and Living
*Bones are complex living structures that undergo growth and development
Bone Structure
*Thin, tough membrane covers all the bone except the ends
*Blood vessels and nerves enter and leave the bone through the membrane
*Beneath the bone's outer membrane is a layer of compact bone, which is hard and
dense, but not solid
*Inside the compact bone is a layer of spongy bone
-Many small spaces within it
*These spaces are filled with connective tissue called marrow
-There are 2 types of marrow: red and yellow
-Red marrow produces blood cells
-Yellow marrow stores fat that can be used for energy
Bone Strength
*Bones can absorb more force than concrete without breaking and are much lighter
*Bones make up 20% of your body weight
*Bones contain phosphorus and calcium, which make them strong
Bone Growth
*Bones are alive!
-Contain cells and tissues
*Form new bone tissue as you grow
*Continue to produce bone tissue after you've stopped growing
-If you break a bone, new tissue will grow to repair it
Bone Development
*As an infant, much of your skeleton was cartilage
*As you grow, the cartilage is replaced with hard bone tissue
Taking Care of Your Bones
*A combination of a balanced diet and regular exercise are important for a lifetime
of healthy bones
Diet
*A well-balanced diet includes enough calcium and phosphorus to keep bones strong
*Meats, whole grains, leafy green vegetables, and dairy are good sources of these
minerals
Exercise
*Weight-bearing activities help your bones grow stronger and denser
Ex: running, skating, dancing
Osteoporosis
*Mineral loss can lead to osteoporosis
-Condition in which the body's bones become weak and break easily