The Skeletal System
Chapter 45.2The Skeletal System
The Human SkeletonHas approximately 206 bones!Functions:Gives
Shape and SupportProtectionMoves MusclesForms Blood CellsStores
Minerals- Ex: Calcium and PhosphorusBones are moist, living tissues
(not dry!)
Parts of the Skeleton2 Parts:Axial- bones of
the:SkullRibsSpineSternumAppendicular- bones of
the:ArmsLegsScapulaClaviclePelvis
Bone StructurePeriosteum-tough membrane that surrounds the bones
surface. Contains blood vessels to supply nutrients.Compact Bone-
hard material found under the periosteum. Makes bones strong and
capable of enduring large amounts of stress
Spongy Bone- network of connective tissue found under the
compact bone. Hard/strong tissue. Makes bones lightMarrow: soft
tissue in spongy boneRed: produces red blood cells, platelets, and
white blood cellsYellow: consists mostly of fat cells and serves as
an energy storage
Bone StructureCompact bone is composed of cylinders of mineral
crystals and protein fibers called lamellaeIn the center of each
cylinder is a narrow channel called a Haversian canalBlood vessels
run through interconnected Haversian canals, which carries
nutrients throughout the boneSurrounding each Haversian canal are
protein fibers and ostecytes (bone cells)
Bone DevelopmentBones develop from cartilageConnective
tissueTough, yet flexibleIn fetal development:Month 2: most of the
skeleton is cartilageMonth 3: Ossification turns most cartilage
into bonesSome cartilage is left for flexible areas between
bonesEx: tip of the nose, outer ear, and inside the tracheaNormal
bone development depends on regular exercise and diet, mainly
calcium and vitamin D intakeLack of this can lead to
osteoporosis
JointsThe place where 2 bones meetTough bands of connective
tissue called ligaments hold the bones of the joint in
placeSynovial fluid- a lubricating substance that helps protect the
ends of the bones from damage by friction
Hinge JointFound in your elbowAllows you to move arm forward and
backwardLike a hinge in a door
Gliding JointAllows bones to glide over one anotherLike small
bones in your feet-allows flexing when walking
Pivot JointTop 2 vertebrae in your neck. Allows you to move your
head side to side.
Ball and Socket JointFound in your shoulder or hipAllows you to
move up/down, forward/backward, or rotate in a circle
Saddle JointAt the base of your thumbAllows you to rotate your
thumb and grasp objects with your hand
Possible injuries and illnessesRheumatoid Arthritis-immune
system attacks body tissues. Joints become inflamed, swollen,
stiff, and deformedOsteoarthritis- degenerative joint disease where
cartilage covering the bones become thin and rough.Sprain
(ligament)- could either overstretch or possibly tearStrain
(tendon)- could either overstretch or possibly tear
