the skeletal system skeletal system includes: skeletal system includes: –bones of the skeleton...
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Functions of the Skeletal System 4. Blood cell production (red marrow) 5. Protection 6. Leverage (force of motion)TRANSCRIPT
The Skeletal SystemThe Skeletal System• Skeletal system includes:Skeletal system includes:
– bones of the skeletonbones of the skeleton– cartilages, ligaments, and connective cartilages, ligaments, and connective
tissuestissues
Functions of the Functions of the Skeletal SystemSkeletal System1.1. SupportSupport2.2. Storage of minerals (calcium)Storage of minerals (calcium)3.3. Storage of lipids (Storage of lipids (yellow marrowyellow marrow))
Functions of the Functions of the Skeletal SystemSkeletal System4.4. Blood cell production (Blood cell production (red marrowred marrow))5.5. ProtectionProtection6.6. Leverage (force of motion)Leverage (force of motion)
Classification of BonesClassification of Bones• Bone are identified by:Bone are identified by:
– shapeshape– internal tissuesinternal tissues– bone markingsbone markings
Bone ShapesBone Shapes1.1. Long bonesLong bones2.2. Flat bonesFlat bones3.3. Sutural bonesSutural bones4.4. Irregular bonesIrregular bones5.5. Short bonesShort bones6.6. Sesamoid bonesSesamoid bones
Long BonesLong Bones
Figure 6–1a
Long BonesLong Bones• Are long and thinAre long and thin• Are found in arms, legs, hands, feet, Are found in arms, legs, hands, feet,
fingers, and toes fingers, and toes
Flat BonesFlat Bones
Figure 6–1b
Flat BonesFlat Bones• Are thin with parallel surfacesAre thin with parallel surfaces• Are found in the skull, sternum, ribs, Are found in the skull, sternum, ribs,
and scapulaand scapula
Sutural BonesSutural Bones
Figure 6–1c
Sutural BonesSutural Bones• Are small, irregular bonesAre small, irregular bones• Are found between the flat bones of Are found between the flat bones of
the skullthe skull
Irregular Bones Irregular Bones
Figure 6–1d
Irregular Bones Irregular Bones • Have complex shapes Have complex shapes • Examples:Examples:
– spinal vertebrae spinal vertebrae – pelvic bones pelvic bones
Short BonesShort Bones
Figure 6–1e
Short BonesShort Bones• Are small and thickAre small and thick• Examples:Examples:
– ankle ankle – wrist boneswrist bones
Sesamoid BonesSesamoid Bones
Figure 6–1f
Sesamoid BonesSesamoid Bones• Are small and flatAre small and flat• Develop inside tendons near joints of Develop inside tendons near joints of
knees, hands, and feetknees, hands, and feet
Bone MarkingsBone Markings• Depressions or grooves:Depressions or grooves:
– along bone surfacealong bone surface• Projections:Projections:
– where tendons and ligaments attachwhere tendons and ligaments attach– at articulations with other bones at articulations with other bones
• Tunnels:Tunnels:– where blood and nerves enter bonewhere blood and nerves enter bone
Bone MarkingsBone Markings
Table 6–1 (2 of 2)
Long BonesLong Bones• The The femurfemur
Figure 6–2a
Long BonesLong Bones• DiaphysisDiaphysis: :
– the shaft the shaft • EpiphysisEpiphysis: :
– wide part at each endwide part at each end– articulation with other bonesarticulation with other bones
• MetaphysisMetaphysis: : – where diaphysis and epiphysis meetwhere diaphysis and epiphysis meet
The DiaphysisThe Diaphysis• A heavy wall of A heavy wall of compact bonecompact bone, or, or
dense bonedense bone• A central space called A central space called marrow cavitymarrow cavity
The Epiphysis The Epiphysis • Mostly Mostly spongyspongy (cancellous)(cancellous) bonebone • Covered with compact bone (Covered with compact bone (cortexcortex))
Flat BonesFlat Bones• The The parietal boneparietal bone of the skull of the skull
Figure 6–2b
Flat BonesFlat Bones• Resembles a sandwich of spongy Resembles a sandwich of spongy
bonebone• Between 2 layers of compact boneBetween 2 layers of compact bone
Bone (Bone (OsseousOsseous) Tissue ) Tissue • Dense, supportive connective tissueDense, supportive connective tissue• Contains specialized cellsContains specialized cells• Produces solid matrix of calcium salt Produces solid matrix of calcium salt
depositsdeposits• Around collagen fibersAround collagen fibers
Characteristics of Bone Characteristics of Bone TissueTissue• Dense Dense matrixmatrix, containing:, containing:
– deposits of calcium saltsdeposits of calcium salts– bone cellsbone cells within within lacunaelacunae organized organized
around blood vesselsaround blood vessels
Characteristics of Bone Characteristics of Bone TissueTissue• CanaliculiCanaliculi: :
– form pathways for blood vesselsform pathways for blood vessels– exchange nutrients and wastesexchange nutrients and wastes
Characteristics of Bone Characteristics of Bone TissueTissue• PeriosteumPeriosteum: :
– covers outer surfaces of bones covers outer surfaces of bones – consist of outer consist of outer fibrousfibrous and inner and inner
cellularcellular layers layers
Matrix MineralsMatrix Minerals• 2/3 of bone matrix is 2/3 of bone matrix is calcium calcium
phosphatephosphate, Ca, Ca33(PO(PO44))22::– reacts with reacts with calcium hydroxidecalcium hydroxide, Ca(OH), Ca(OH)22 – to form crystals of to form crystals of hydroxyapatitehydroxyapatite, ,
CaCa1010(PO(PO44))66(OH)(OH)22
– which incorporates other calcium salts which incorporates other calcium salts and ionsand ions
Matrix ProteinsMatrix Proteins• 1/3 of bone matrix is protein fibers 1/3 of bone matrix is protein fibers
((collagencollagen))
Bone CellsBone Cells• Make up only 2% of bone mass:Make up only 2% of bone mass:
– osteocytesosteocytes– osteoblastsosteoblasts– osteoprogenitor cellsosteoprogenitor cells– osteoclastsosteoclasts
OsteocytesOsteocytes• Mature bone Mature bone
cells that cells that maintain the maintain the bone matrixbone matrix
Figure 6–3 (1 of 4)
OsteocytesOsteocytes• Live in Live in lacunaelacunae • Are between layers (Are between layers (lamellaelamellae) of ) of
matrixmatrix• Connect by cytoplasmic extensions Connect by cytoplasmic extensions
through through canaliculicanaliculi in lamellae in lamellae• Do not divideDo not divide
Osteocyte FunctionsOsteocyte Functions• To maintain protein and mineral To maintain protein and mineral
content of matrixcontent of matrix• To help repair damaged boneTo help repair damaged bone
OsteoblastsOsteoblasts • Immature bone Immature bone
cells that secrete cells that secrete matrix matrix compounds compounds ((osteogenesisosteogenesis))
Figure 6–3 (2 of 4)
OsteoidOsteoid• Matrix produced by osteoblasts, but Matrix produced by osteoblasts, but
not yet calcified to form not yet calcified to form bonebone• Osteoblasts surrounded by bone Osteoblasts surrounded by bone
become become osteocytesosteocytes
Osteoprogenitor CellsOsteoprogenitor Cells • Mesenchymal stem cells that divide Mesenchymal stem cells that divide
to produce osteoblaststo produce osteoblasts
Figure 6–3 (3 of 4)
Osteoprogenitor Cells Osteoprogenitor Cells • Are located in inner, cellular layer of Are located in inner, cellular layer of
periosteum (periosteum (endosteumendosteum))• Assist in fracture repairAssist in fracture repair
OsteoclastsOsteoclasts • Secrete acids and protein-digesting enzymesSecrete acids and protein-digesting enzymes
Figure 6–3 (4 of 4)
Osteoclasts Osteoclasts • Giant, mutlinucleate cellsGiant, mutlinucleate cells• Dissolve bone matrix and release Dissolve bone matrix and release
stored minerals (stored minerals (osteolysisosteolysis))• Are derived from stem cells that Are derived from stem cells that
produce macrophagesproduce macrophages
HomeostasisHomeostasis• Bone building (by osteocytes) and Bone building (by osteocytes) and
bone recycling (by osteoclasts) must bone recycling (by osteoclasts) must balance:balance:– more breakdown than building, bones more breakdown than building, bones
become weakbecome weak– exercise causes osteocytes to build exercise causes osteocytes to build
bonebone
Compact BoneCompact Bone
Figure 6–5
OsteonOsteon• The basic unit of mature compact The basic unit of mature compact
bonebone• Osteocytes are arranged in Osteocytes are arranged in
concentric lamellaeconcentric lamellae• Around a Around a central canalcentral canal containing containing
blood vesselsblood vessels
Perforating CanalsPerforating Canals• Perpendicular to the central canalPerpendicular to the central canal• Carry blood vessels into bone and Carry blood vessels into bone and
marrowmarrow
Circumferential LamellaeCircumferential Lamellae• Lamellae wrapped around the long Lamellae wrapped around the long
bonebone• Binds osteons togetherBinds osteons together
Spongy BoneSpongy Bone
Figure 6–6
Spongy BoneSpongy Bone• Does not have osteonsDoes not have osteons• The matrix forms an open network of The matrix forms an open network of
trabeculaetrabeculae• Trabeculae have no blood vesselsTrabeculae have no blood vessels
Red MarrowRed Marrow• The space between trabeculae is The space between trabeculae is
filled with filled with red bone marrowred bone marrow::– which has blood vesselswhich has blood vessels– forms red blood cellsforms red blood cells– and supplies nutrients to osteocytesand supplies nutrients to osteocytes
Yellow MarrowYellow Marrow• In some bones, spongy bone holds In some bones, spongy bone holds
yellow bone marrowyellow bone marrow::– is yellow because it stores fatis yellow because it stores fat
Weight–Bearing BonesWeight–Bearing Bones
Figure 6–7
Weight–Bearing BonesWeight–Bearing Bones• The femur transfers weight from hip The femur transfers weight from hip
joint to knee joint:joint to knee joint:– causing causing tensiontension on the lateral side of the on the lateral side of the
shaftshaft– and and compressioncompression on the medial side on the medial side
Periosteum and EndosteumPeriosteum and Endosteum• Compact bone is covered with Compact bone is covered with
membrane:membrane:– periosteumperiosteum on the outside on the outside – endosteumendosteum on the inside on the inside
PeriosteumPeriosteum
Figure 6–8a
PeriosteumPeriosteum• Covers all bones:Covers all bones:
– except parts enclosed in joint capsulesexcept parts enclosed in joint capsules• It is made up of:It is made up of:
– an outer, fibrous layeran outer, fibrous layer– and an inner, cellular layerand an inner, cellular layer
Perforating FibersPerforating Fibers• Collagen fibers of the periosteum:Collagen fibers of the periosteum:
– connect with collagen fibers in boneconnect with collagen fibers in bone– and with fibers of joint capsules, and with fibers of joint capsules,
attached tendons, and ligamentsattached tendons, and ligaments
Functions of PeriosteumFunctions of Periosteum1.1. Isolate bone from surrounding Isolate bone from surrounding
tissuestissues2.2. Provide a route for circulatory and Provide a route for circulatory and
nervous supplynervous supply3.3. Participate in bone growth and Participate in bone growth and
repairrepair
EndosteumEndosteum
Figure 6–8b
EndosteumEndosteum• An incomplete cellular layer:An incomplete cellular layer:
– lines the marrow cavitylines the marrow cavity– covers trabeculae of spongy bonecovers trabeculae of spongy bone– lines central canalslines central canals
EndosteumEndosteum• Contains osteoblasts, Contains osteoblasts,
osteoprogenitor cells, and osteoprogenitor cells, and osteoclastsosteoclasts
• Is active in bone growth and repairIs active in bone growth and repair
Bone DevelopmentBone Development• Human bones grow until about age Human bones grow until about age
2525• OsteogenesisOsteogenesis::
– bone formationbone formation• OssificationOssification: :
– the process of replacing other tissues the process of replacing other tissues with bonewith bone
OssificationOssification• The 2 main forms of ossification are:The 2 main forms of ossification are:
– intramembranous ossificationintramembranous ossification– endochondral ossificationendochondral ossification
Endochondral OssificationEndochondral Ossification• Ossifies bones that originate as Ossifies bones that originate as
hyaline cartilagehyaline cartilage• Most bones originate as hyaline Most bones originate as hyaline
cartilagecartilage
Endochondral OssificationEndochondral Ossification• Growth and ossification of long bones Growth and ossification of long bones
occurs in 6 stepsoccurs in 6 steps
Endochondral Endochondral Ossification: Step 1Ossification: Step 1
• Chondrocytes in the center Chondrocytes in the center of hyaline cartilage:of hyaline cartilage:– enlargeenlarge– form struts and calcifyform struts and calcify– die, leaving cavities in die, leaving cavities in
cartilagecartilage
Figure 6–9 (Step 1)
Endochondral Endochondral Ossification: Step 2Ossification: Step 2
Figure 6–9 (Step 2)
Endochondral Endochondral Ossification: Step 2Ossification: Step 2• Blood vessels grow around the edges Blood vessels grow around the edges
of the cartilage of the cartilage • Cells in the perichondrium change to Cells in the perichondrium change to
osteoblasts: osteoblasts: – producing a layer of superficial bone producing a layer of superficial bone
around the shaft which will continue to around the shaft which will continue to grow and become compact bone grow and become compact bone (appositional growth)(appositional growth)
Endochondral Endochondral Ossification: Step 3Ossification: Step 3
• Blood vessels enter the Blood vessels enter the cartilage:cartilage:– bringing fibroblasts that bringing fibroblasts that
become osteoblastsbecome osteoblasts– spongy bone develops at spongy bone develops at
the the primary ossification primary ossification centercenter
Figure 6–9 (Step 3)
Endochondral Endochondral Ossification: Step 4Ossification: Step 4
Figure 6–9 (Step 4)
• Remodeling creates a Remodeling creates a marrow cavitymarrow cavity::– bone replaces cartilage at bone replaces cartilage at
the the metaphysesmetaphyses
Endochondral Endochondral Ossification: Step 5Ossification: Step 5
• Capillaries and Capillaries and osteoblasts enter the osteoblasts enter the epiphyses:epiphyses:– creating creating secondary secondary
ossification centersossification centers
Figure 6–9 (Step 5)
Endochondral Endochondral Ossification: Step 6Ossification: Step 6
Figure 6–9 (Step 6)
Endochondral Endochondral Ossification: Step 6Ossification: Step 6• Epiphyses fill with spongy bone:Epiphyses fill with spongy bone:
– cartilage within the joint cavity is cartilage within the joint cavity is articulation cartilagearticulation cartilage
– cartilage at the metaphysis is cartilage at the metaphysis is epiphyseal cartilageepiphyseal cartilage
• Appositional growthAppositional growth::– compact bone thickens compact bone thickens
and strengthens long bone and strengthens long bone with layers of with layers of circumferential lamellaecircumferential lamellae
Endochondral OssificationPLAYFigure 6–9 (Step 2)
Endochondral OssificationEndochondral Ossification
Epiphyseal LinesEpiphyseal Lines
Figure 6–10
Epiphyseal LinesEpiphyseal Lines• When long bone stops growing, after When long bone stops growing, after
puberty:puberty:– epiphyseal cartilage disappears epiphyseal cartilage disappears – is visible on X-rays as an is visible on X-rays as an epiphyseal lineepiphyseal line
RemodelingRemodeling• The adult skeleton:The adult skeleton:
– maintains itselfmaintains itself– replaces mineral reserves replaces mineral reserves
• RemodelingRemodeling::– recycles and renews bone matrix recycles and renews bone matrix – involves osteocytes, osteoblasts, and involves osteocytes, osteoblasts, and
osteoclasts osteoclasts
Functions of CalciumFunctions of Calcium• Calcium ionsCalcium ions are vital to: are vital to:
– membranesmembranes– neuronsneurons– muscle cells, especially heart cellsmuscle cells, especially heart cells
Calcium RegulationCalcium Regulation• Calcium ions in body fluids:Calcium ions in body fluids:
– must be closely regulatedmust be closely regulated• Homeostasis is maintained:Homeostasis is maintained:
– by by calcitonincalcitonin and and parathyroid hormoneparathyroid hormone– which control storage, absorption, and which control storage, absorption, and
excretionexcretion
Calcitonin and Parathyroid Calcitonin and Parathyroid Hormone ControlHormone Control• Bones:Bones:
– where calcium is storedwhere calcium is stored• Digestive tract:Digestive tract:
– where calcium is absorbedwhere calcium is absorbed• Kidneys:Kidneys:
– where calcium is excretedwhere calcium is excreted
CalcitoninCalcitonin• Secreted by Secreted by C cellsC cells (parafollicular (parafollicular
cells)cells) in in thyroidthyroid•DecreasesDecreases calcium ion levels by: calcium ion levels by:
– inhibiting osteoclast activityinhibiting osteoclast activity– increasing calcium excretion at kidneysincreasing calcium excretion at kidneys
Figure 6–16 (1 of 9)
The Major Types of The Major Types of Fractures Fractures
• Pott’s fracturePott’s fracture
The Major Types of The Major Types of Fractures Fractures
• Comminuted Comminuted fracturesfractures
Figure 6–16 (2 of 9)
The Major Types of The Major Types of Fractures Fractures
• Transverse fracturesTransverse fractures
Figure 6–16 (3 of 9)
The Major Types of The Major Types of Fractures Fractures
• Spiral fracturesSpiral fractures
Figure 6–16 (4 of 9)
Figure 6–16 (5 of 9)
The Major Types of The Major Types of Fractures Fractures
• Displaced fracturesDisplaced fractures
Figure 6–16 (6 of 9)
The Major Types of The Major Types of Fractures Fractures
• Colles’ fractureColles’ fracture
Figure 6–16 (7 of 9)
The Major Types of The Major Types of Fractures Fractures
• Greenstick fractureGreenstick fracture
Figure 6–16 (8 of 9)
The Major Types of The Major Types of Fractures Fractures
• Epiphyseal fracturesEpiphyseal fractures
Figure 6–16 (9 of 9)
The Major Types of The Major Types of Fractures Fractures
• Compression fracturesCompression fractures