THE THE SKELETAL SKELETAL SYSTEMSYSTEM

I. BONE STRUCTURE & FUNCTION

A.A.FUNCTIONFUNCTION1.Support2.Protection3.Movement4.Blood formation5.Electrolyte Balance6.Acid Base Balance

I. BONE STRUCTURE & FUNCTION

B.B.StructureStructure

1.1.ShapeShape– Long bones– Short bones– Flat bones– Irregular

bones

Long bones Short bones

Flat bones

Irregular bones

Classify the bone types to the left

B. StructureB. Structure2. 2. Parts of BoneParts of Bone

– EpiphysesEpiphyses• Contains

red bone marrow

• Spongy bone and compact bone

B.B. StructureStructure2.2.Parts of BoneParts of Bone

– DiaphysisDiaphysis• Shaft of

bone• Contains

yellow bone marrow (stores fat)

• Spongy and compact bone

B.B. StructureStructure2.2.Parts of BoneParts of Bone

– PeriosteumPeriosteum– Epiphyseal Epiphyseal

plateplate Allows for Allows for

growth in growth in bone bone

Found only Found only in childrenin children

3.3.Mature BoneMature Bone

Osseous Osseous TissueTissue

B. StructureB. Structure

• Called Lamellar Lamellar bonebone•Two kinds

CompactCompact Spongy Spongy (cancellous)(cancellous)

3. Mature 3. Mature BoneBone

• Spongy Spongy (cancellous)(cancellous)

• contains contains trabeculaetrabeculae

• contains spacescontains spaces

3. Mature 3. Mature BoneBone

• Dense, few Dense, few spacesspaces• Haversian canalsHaversian canals• Concentric Concentric LamellaeLamellae

Compact Compact BoneBone

3. Mature 3. Mature BoneBone

I. BONE STRUCTURE & FUNCTION

Background minerals C.C.HistologyHistology1.1. MatrixMatrix

C. HistologyC. Histology2.2. Bone cellsBone cells

Osteoblasts

Osteocytes

Osteoclasts

OsteoblastsOsteoclasts

Osteocytes

Name C, D & EName C, D & E

D = OsteoblastE = Osteocytes

C = Osteoclast

D. MembranesD. Membranes1.1. PeriosteumPeriosteum:

a.The external covering of bone

D. MembranesD. Membranes2. endosteum:

a. Found on internal bone surfaceb. covers trabeculae of spongy bone c. in marrow cavities

II. BONE GROWTH & DEVELOPMENTA.A.Two Patterns of Bone Two Patterns of Bone

FormationFormation1.1. Intramembranous Intramembranous bones bones

– originate between originate between sheet-like sheet-like layers of layers of connective connective tissues tissues

II. BONE GROWTH & DEVELOPMENTA.A.Two Patterns of Bone Two Patterns of Bone

FormationFormation 2.2. Endochondral Endochondral bones bones

– begin as masses begin as masses of hyaline of hyaline cartilage that cartilage that bone tissue later bone tissue later replaces. replaces.

II. BONE GROWTH & DEVELOPMENTB.B.Growth in Long BonesGrowth in Long Bones

1.1. grow by interstitial growth at grow by interstitial growth at epiphyseal platesepiphyseal plates

a.a. rate of cartilage growth is rate of cartilage growth is balanced by replacement with balanced by replacement with bone bone

b.b. end of growth as cartilage end of growth as cartilage cells slow down division cells slow down division

II. BONE GROWTH & DEVELOPMENTB.B.Growth in Long BonesGrowth in Long Bones

2. bones grow in width by 2. bones grow in width by appositional growthappositional growth

a.a. Osteoblasts in periosteum: Osteoblasts in periosteum: secretes bone matrix secretes bone matrix

b.b. Osteoclasts in endosteum: Osteoclasts in endosteum: removes bone matrix (a little removes bone matrix (a little slower) slower)

Appositional Growth Appositional Growth

– New bone forms at ridges around New bone forms at ridges around blood vessels blood vessels

– Periosteum becomes endosteumPeriosteum becomes endosteum

– New lamella formedNew lamella formed

– More bone added forming osteonMore bone added forming osteon

Appositional Growth Appositional Growth

II. BONE GROWTH & DEVELOPMENTC.C.HormonesHormones

1. growth hormone from pituitary: 1. growth hormone from pituitary: stimulates growth in childhood stimulates growth in childhood

a.a. Gigantism:Gigantism: excessive growth excessive growth hormone hormone

b.b. dwarfism:dwarfism: not enough growth not enough growth hormone or thyroid hormones hormone or thyroid hormones

II. BONE GROWTH & DEVELOPMENTC.C.HormonesHormones

2. 2. thyroid:thyroid: regulates activity of regulates activity of growth hormone growth hormone

3. 3. sex hormones:sex hormones: promote growth promote growth spurt, induce epiphyseal plate spurt, induce epiphyseal plate closure closure

estrogenestrogen: maintains bone : maintains bone densitydensity

III. Bone Maintenance & RepairA.Bone remodeling: 1. Life long process

2. Local areas of bone are destroyed and rebuilt

3. Repairs microdamage caused by normal wear and tear

B.Fractures 1. Simple1. Simple

bone breaks cleanly, does not break through skin

B.Fractures 2. Compound2. Compound

broken ends protrude through the skin, risk of bone infection

B.Fractures 3. Greenstick3. Greenstick

Greenstick: Greenstick: (children)

Does not break completely

C. RepairC. Repair1. Hematoma formsHematoma forms 2. Spongy bone forms in area of 2. Spongy bone forms in area of

hematomahematoma

III. Remodeling and Repair

C. RepairC. Repair3. Osteoblasts lay down new bone Osteoblasts lay down new bone

matrix matrix 4. Remodeling4. Remodeling

III. Calcium HomeostasisA.A.Blood CaBlood Ca2+2+ Level Level

1.1. Has a very narrow range Has a very narrow range

2.2. CaCa2+2+ Required forRequired for

– For normal muscle contractionFor normal muscle contraction

– Nerve impulsesNerve impulses

III. Calcium HomeostasisA.A.Blood CaBlood Ca2+2+ Level Level

3.3. Abnormal levelsAbnormal levels

– HypocalcemiaHypocalcemia

causes marked jitteriness and causes marked jitteriness and convulsive seizures convulsive seizures

III. Calcium HomeostasisA.A.Blood CaBlood Ca2+2+ Level Level

3.3. Abnormal levelsAbnormal levels

– HypercalcemiaHypercalcemia

the most common life-the most common life-threatening metabolic disorder threatening metabolic disorder associated with cancerassociated with cancer

III. Calcium HomeostasisB.B.Bone’s Role Bone’s Role

1.1. Major storage site for calcium Major storage site for calcium

2.2. Calcium movesCalcium moves

– Into bone as osteoblasts build Into bone as osteoblasts build new bone new bone

– Out of bone as osteoclasts Out of bone as osteoclasts break down bone break down bone

III. Calcium HomeostasisC.C.Bone, Calcium and Bone, Calcium and

Hormones Hormones 1.1.Parathyroid Hormone –Parathyroid Hormone – Increases blood CaIncreases blood Ca2+2+ levels levels

2.2. CalcitoninCalcitonin

Decreases blood CaDecreases blood Ca2+2+ levels levels

D. Homeostatic Imbalances

• Osteopenia Osteopenia – Inadequate ossification

• Osteoporosis Osteoporosis – Bone absorption outpaces deposition – Fractures common – More common in elderly women

III. Calcium Homeostasis

• RicketsRickets – Lack of vitamin D or

calcium during growth – Bowed legs – Deformed pelvis

D. Homeostatic Imbalances

Rickets

•Osteosarcoma  – Bone cancer – Usually between ages 10-25 – Survival rate is about 50% with amputation

D. Homeostatic ImbalancesD. Homeostatic Imbalances

•Bone spurBone spur – Abnormal projection at one site of bone due to

overgrowth – Common in aging bones

D. Homeostatic Imbalances

IV. The Skeleton

There are 206 boneThere are 206 bone

IV. The SkeletonA.A.OrganizationOrganization

1.1. Axial SkeletonAxial Skeleton

– SkullSkull

– Vertebral Column Vertebral Column

– VertebraeVertebrae

– RibsRibs

2.2. Appendicular SkeletonAppendicular Skeleton

– limbslimbs

– girdlesgirdles

B. Male vs. Female Skeleton - B. Male vs. Female Skeleton - PelvisPelvis

a. spines farther apart in male

b. hole in ischium: smaller and triangular in female

c. angle across pubic symphysis = pubic arch: less than 90° and more sharply angled in male

d. distance between ischia larger in female

C.C.Bone Markings –Bone Markings –

1. Kinds

For muscle attachment

For formation of a joint

To allow blood vessels or nerves to pass through

• Articulating Surfaces

•Openings

• Depressions & Enlargements 1. Kinds

C.C.Bone Markings –Bone Markings –

2. Articulating surfaces

A rounded projection set off from the body of a bone by a constriction (the neck) ex. head of femur

Head

C.C.Bone Markings –Bone Markings –

2. Articulating surfaces

Condyle

Any large articulating surface, may be concave or convex

C.C.Bone Markings –Bone Markings –

2. Articulating surfaces

A smooth, flat surface, generally small

Facet

C.C.Bone Markings –Bone Markings –

2. Articulating surfaces

A shallow depression

Fossa

C.C.Bone Markings –Bone Markings –

3. Enlargements & Processes

generic term for bone projection that serves as a point for attachment of other structures

Process

C.C.Bone Markings –Bone Markings –

3. Enlargements

projection or swelling to the side of or above a condyle

Epicondyle

C.C.Bone Markings –Bone Markings –

Spine

a sharp, slender projecting process

3. Enlargements

C.C.Bone Markings –Bone Markings –

a small rounded projection

Tubercle

3. Enlargements

C.C.Bone Markings –Bone Markings –

a large rounded roughened projection

3. Enlargements

Turberosity

C.C.Bone Markings –Bone Markings –

3. Enlargements

Trochantera large blunt projection

C.C.Bone Markings –Bone Markings –

3. Enlargements

a prominent border or ridge

Crest

C.C.Bone Markings –Bone Markings –

3. Enlargements A major branch or division off of the main body of a bone

Ramus

C.C.Bone Markings –Bone Markings –

4. Openings

C.C.Bone Markings –Bone Markings –

4. Openings

Canal like opening

Meatus

C.C.Bone Markings –Bone Markings –

5. Depressions

A shallow groove

Sulcus

C.C.Bone Markings –Bone Markings –

5. Depressions

A very shallow groove

Fovea

C.C.Bone Markings –Bone Markings –

5. Depressions

A deep groove

Fissure

That’s All Folks!