The Skeletal System

The Skeletal System

Major Functions of the Skeletal System

Shape and support for the bodyProtects inner organs

Skull – brainRibs – heart and lungs

Muscles attach to bonesCreates red blood cells, white blood

cells, and platelets in the marrowStores calcium and phosphorus

Bone Structure Not completely smooth

Bumps, rough edges, pits, holesCovered by periosteum

Tough, tight fitting membraneContains blood vessels, allows oxygen to reach inner bone, allows for wastes to leave

Bone MarrowFatty tissue found within bonesProduces red blood cells

2,000,000/secProduces white blood cells

Not as fast as redProduces platelets

CartilageThick, smooth layer of tissueCovers ends of bonesDoes not contain blood vessels or

mineralsAbsorbs shock, reduces frictionPainful when it wears away

Bones rub togetherArthritis develops

Bone DevelopmentOsteoblasts

Bone forming cellsDeposit calcium and phosphorus (hardness)

OsteoclastsCells that break down bone (normal)

Bones are always being broken down and reformed

JointsWhere two or more bones meetHeld together by ligaments

Tough bands of tissueMany joints held together by more

than one ligamentEx. knee

Types of JointsImmovable joints

Allow little or no movementMovable joints

Allow wide range of movements

Immovable JointsIncludes joints in

skull and pelvis

Movable JointsPivot

One bone rotates in the ring of another

Ex. Turning your head http://www.dkimages.com/discover/previews/940/672504.JPG

Ball and socketOne bone has a cup like cavity

Another bone has a rounded end that fits inside

Ex. Hips, shoulders http://archive.ncsa.uiuc.edu/Cyberia/VideoTestbed/

Projects/NewAnatomy/images/bshoulder.JPG

HingeBack and forth movement (like hinges on a door)

Less flexible, more stable

Ex. Elbows, knees, fingers http://www.dkimages.com/discover/previews/940/672450.JPG

GlidingOne bone slides

over anotherBack and forth

motionMost frequently

usedEx. Wrists, ankles,

vertebraehttp://www.teachpe.com/images/anatomy/gliding_joint.jpg

Bone ShapesShort –toes

(phalanges)Small precise

movementsSupport weight

Long – legs & arms, length of fingersStrongSupport weightAllow movement

Bone ShapesFlat – ribs, sternum

& shoulderProtect organs

Irregular – vertebrae & inner earSupport - vertebraeHearing – inner ear

Bone Shapes