The Skeletal The Skeletal SystemsSystemsThe 206 Bones The 206 Bones In Your Body In Your Body

Functions of Skeletal Functions of Skeletal System System

• Supports bodySupports body• Protects internal organsProtects internal organs

– i.e. skull protects braini.e. skull protects brain• Provides for movementProvides for movement

– Bones=Levers Bones=Levers • Stores Mineral reservesStores Mineral reserves

– Important to body reservesImportant to body reserves• Provide site for blood cell formation Provide site for blood cell formation

– Produced in soft marrow tissue that fills Produced in soft marrow tissue that fills internal cavitiesinternal cavities

Different Parts of Different Parts of Skeletal SystemSkeletal System

• Axial SkeletonAxial Skeleton– Supports central axis of bodySupports central axis of body– i.e. skull, vertebrae column, rib cagei.e. skull, vertebrae column, rib cage

SkullVertebra

e

Column

Rib Cage

Different Parts (cont.) Different Parts (cont.) • Appendicular SkeletonAppendicular Skeleton

– ArmsArms– LegsLegs– Pelvis Pelvis – ShoulderShoulder

Lower Extremities

(Thigh, Leg, Foot, Patella)

Upper Extremities

(Arm, Forearm,

Hand)

Shoulder Girdle

(Clavicle, Scapula)

Pelvic Girdle

(Coxal—Hip bones)

Structure of BonesStructure of Bones• Solid network of living cells Solid network of living cells

and protein fibers that are and protein fibers that are surrounded by deposits of surrounded by deposits of calcium saltscalcium salts

• Surrounded by Surrounded by periosteumperiosteum – Blood vessels that pass Blood vessels that pass

through carry oxygen and through carry oxygen and nutrientsnutrients

• Beneath is Beneath is Haversain Haversain canalcanal – Contains blood vessels and Contains blood vessels and

nerves nerves – Runs through compact boneRuns through compact bone

• Less dense tissue is spongy Less dense tissue is spongy bonebone– Outside of compact boneOutside of compact bone

Bone CellsBone Cells• OsteocytesOsteocytes

– Mature bone cellsMature bone cells– Embedded in bone Embedded in bone

matrixmatrix• OsteoclastsOsteoclasts

– Break down boneBreak down bone• Osteoblasts Osteoblasts

– Produce BoneProduce Bone

Bone MarrowBone Marrow• Within bones are a Within bones are a

soft tissue calledsoft tissue called bone marrowbone marrow..– Yellow marrow: Yellow marrow:

made up of fat cells made up of fat cells – Red marrow: Red marrow:

Produce red blood Produce red blood cells, some kinds of cells, some kinds of white blood cells, white blood cells, and cell fragments and cell fragments called platelets called platelets

Development of BonesDevelopment of Bones• CartilageCartilage

– Skeleton of an embryo and composed Skeleton of an embryo and composed almost entirely of a connective tissue almost entirely of a connective tissue

– Must rely on diffusion of nutrients from Must rely on diffusion of nutrients from tiny blood vessels in surrounding tiny blood vessels in surrounding tissues tissues

• Cartilage is replaced by bone during Cartilage is replaced by bone during the process of bone formation called the process of bone formation called ossification ossification

JointsJoints• A place where one A place where one

bone attaches to bone attaches to another bone another bone

• Immovable Joints Immovable Joints – No movementNo movement– Interlocked and held by Interlocked and held by

connective tissue or connective tissue or fused fused

• Slightly Movable JointsSlightly Movable Joints– Permit a small amount Permit a small amount

of restricted movement of restricted movement – Separated from each Separated from each

otherother

Fixed Joint

Slightly Movable

(Joints between adjacent

vertebrae)

Movable JointsMovable Joints• Freely Movable Joints Freely Movable Joints

– Permit movement in Permit movement in one or more directions one or more directions

• Most common typeMost common type– Ball-and-Socket Joint Ball-and-Socket Joint

permit movement in permit movement in many directionsmany directions

– Hinge joints permit Hinge joints permit back-and-forth motionback-and-forth motion

– Pivot joints rotate Pivot joints rotate around anotheraround another

– Saddle joints one bone Saddle joints one bone to slide in two to slide in two directionsdirections

Structure of Joints Structure of Joints Surrounded by a fibrous Surrounded by a fibrous

joint capsule—helps hold joint capsule—helps hold the bones together while the bones together while still allowing to movestill allowing to move

• One layer forms strips of One layer forms strips of tough connective tissue tough connective tissue called called ligamentsligaments– Attached to the membranes Attached to the membranes

that surround bonesthat surround bones• Cells in other layer of Cells in other layer of

joint capsule produce joint capsule produce substance called synovial substance called synovial fluidfluid– Forms a thin film on Forms a thin film on

cartilage that covers bony cartilage that covers bony surfaces that form the jointsurfaces that form the joint

OsteoporosisOsteoporosis• Bones lose densityBones lose density

– Density = StrengthDensity = Strength• Bones become fragileBones become fragile

– Can cause breaks in hips, wrist, and spine.Can cause breaks in hips, wrist, and spine.

How Osteoporosis OccursHow Osteoporosis Occurs• Bones become Bones become

fragile due tofragile due to– AgingAging– Low intake of Low intake of

calciumcalcium– Family HistoryFamily History– Cigarette smokingCigarette smoking– Low estrogen levelsLow estrogen levels– Vitamin D Vitamin D

deficiency.deficiency.

Osteoporosis Osteoporosis ConsequencesConsequences

• Can cause bones to Can cause bones to break.break.– Leads to major Leads to major

disabilitydisability– Many breaks in the Many breaks in the

spine can occur spine can occur more than once.more than once.

• Decreased quality Decreased quality of life and of life and disability.disability.

Osteoporosis SymptomsOsteoporosis Symptoms• Osteoporosis is especially Osteoporosis is especially

hard to diagnose because hard to diagnose because there are few symptoms.there are few symptoms.

• The only way to tell is if The only way to tell is if there is chronic back there is chronic back pain, which could pain, which could suggest a fracture of the suggest a fracture of the spine. spine.

• If a fracture occurs If a fracture occurs during normal activity, during normal activity, you may want to check if you may want to check if you have osteporosis.you have osteporosis.

Prevention of Prevention of OsteoporosisOsteoporosis

• Drink more milk with vitamin D.Drink more milk with vitamin D.• Certain medications can help fortify Certain medications can help fortify

bones.bones.• Exercise, although not strenuous. Exercise, although not strenuous. • Not smoking.Not smoking.• Also, there are vitamins that can Also, there are vitamins that can

help provide calcium and vitamin D.help provide calcium and vitamin D.