Skeletal System Essential Questions (Key Concepts) 1.What are the functions of the skeletal system? 2.What role do joints play in the body? 3.What are the characteristics of bone, and how can you keep your bones strong and healthy?

KEY TERMS Skeleton Ligament Compact bone Marrow Vertebra Cartilage Spongy bone Joint osteoporosis

A newborn has about 275 bones An adult has 206 bones

What the Skeletal System Does 1. Provides shape and support

2. Allows movement Bones are attached to muscles

3. Protects tissues and organs Ex. Skull protects brain and backbone protects your spinal cord

4. Produces red blood cells In marrow of long bones

5. Stores certain materials Many of them give bone its stiffness –(Ex. Calcium and phosphorus)

A Joint –is any place where 2 bones come together Some joints allow movement, some don’t Joints in the skull are immovable Joints of the Skeleton

Movable Joints Pivot joints – allow for rotation of one bone around another Ex. Vertebrae in neck

Ball-and-socket Joint provide for circular motion of bones. Ex. Shoulder and hip

Hinge joint Allows for movement in a forwards/backwards direction. Ex. elbow

Ligaments Strong connective tissue that hold bones together – Connect bone to bone

Cartilage Connective tissue that is more flexible than bone. Covers the ends of bones and keeps them from rubbing against each other

Cartilage Most cartilage in body is replaced by bone Remains in certain places such as where bone meets bone (knee, ankle, elbow) Cartilage cushions bones against sudden jolts Provides a slippery surface so bones can move without rubbing one another.

Bone Structure Bones are strong and light and made up of tissues – nerve, bone, blood Two types of bone – compact and spongy

Compact Bone Compact bone is hard and dense but not solid - Long bones like the femur have a shaft made of compact bone

Spongy Bone Spongy bone has many small spaces in it, makes it lightweight but strong. Found at the ends of bones

Bone Marrow Marrow – soft connective tissue found in the spaces of bones Two types – red and yellow

Yellow Marrow Yellow marrow (made of blood vessels and fat)

Red Marrow Red marrow makes blood cells and is found in cavities of skull, ribs, breastbone and vertebral column

Bone Strength Structure of bone makes it strong and lightweight Bones can absorb more force without breaking than concrete or granite rock Bone are only 20% of an adult’s weight

Bone Growth Bones form new bone tissue as you grow Throughout your life, you still continue to form bone tissue New bone tissue forms after a break to fill the gap Sometimes healed region of new bone is stronger than original bone

Bone Development Many bones in newborns are cartilage Bone replaces cartilage until you’re done growing Replacing cartilage with bone begins 7 months before birth and ends at about 25 yrs old. Cartilage remains in Joints and the tip of the nose and ears

Taking Care of Your Bones A well balanced diet is important for healthy bones – need good sources of calcium (Ca) and phosphorus (P) –Meat, whole grains and leafy greens – P –Dairy is a good source of Ca Exercise is important to build and maintain strong bones –Especially weight bearing exercise such as running, skating, and dancing

Osteoporosis A condition in which the body’s bones become weak and break easily Women are more prone to osteoporosis than men A balanced diet and exercise during the teenage years are important in preventing osteoporosis later in life

osteoporosis