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Chapter 7. Skeleton & Skeletal Structure. Function. Support – provide surfaces for anchoring soft organs. Protection – skull, ribs, vertebrae Movement – anchor muscles; joints are pivot places, bones are levers. Storage – fat, minerals (Ca, P, K, Na, S, Mg, Cu,); 2/3 of bone weight. - PowerPoint PPT Presentation
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Chapter 7Chapter 7
Skeleton & Skeletal Skeleton & Skeletal StructureStructure
FunctionFunctionSupport – provide surfaces for
anchoring soft organs.Protection – skull, ribs,
vertebraeMovement – anchor muscles;
joints are pivot places, bones are levers
Storage – fat, minerals (Ca, P, K, Na, S, Mg, Cu,); 2/3 of bone weight
Hematopoiesis – red marrow makes RBC’s, WBC’s, platelets in adults; liver & spleen in infants
CLASSIFICATIONCLASSIFICATIONType of bone
tissue:
–Compact – dense & smooth
–Spongy (cancellous) – open spaces with “girders”
Compact
Spongy
Trabeculae – Trabeculae – “girders”“girders”
ShapeShape–Long bonesLong bones – (femur, humerus,
phalanges, etc.); compact; shaft w/2 ends; act as levers
–Short bonesShort bones – (carpals, tarsals); cube-like
»often embedded in joints to articulate tendons
»spongy w/compact on surface
»bones glide across one another in multiple directions
–Flat bonesFlat bones (cranium, ribs, shoulder)
» protect soft organs
»provide for large muscle attachment
»2 compact bone surfaces w/spongy in between
Structure of a Flat BoneStructure of a Flat Bone External and External and
internal surfaces internal surfaces composed of composed of compact bonecompact bone
Middle layer is Middle layer is spongy bone and spongy bone and bone marrowbone marrow
Skull fracture may Skull fracture may leave inner layer of leave inner layer of compact bone compact bone unharmedunharmed
–IrregularIrregular (bones of the inner skull, vertebrae, hip)
»varied for articulation with muscles, tendons, and ligaments
STRUCTURE (Gross)STRUCTURE (Gross)DiaphysisDiaphysis – – shaft
–cylinder of compact bone
–Covered with periosteum
Medullary cavityMedullary cavity – – center of bone–yellow marrow found
here (fat)–Lined with endosteum
Epiphysis – ends of long bones– spongy with red
marrow– covered by
compact bone and hyaline cartilage
– Epiphyseal disk (plate) – ends of long bones; covered in hyaline cartilage, points of growth; replaced by bone at time of growth = epiphyseal line
– Predictable growth rates
Endosteum – membrane lining the inside of shaft; contains:–Osteoblasts –
bone forming cells on the outside
–Osteoclasts – bone resorption cells on the inside
Periosteum – outer membrane on the diaphysis
Articular Cartilage – ends of articulating long bones; cushions and absorbs stress
Nutrient Formina – holes for blood vessels and nerves
Structure of a Structure of a Long BoneLong Bone
Compact and Compact and spongy bonespongy bone
Marrow cavityMarrow cavity Articular Articular
cartilagecartilage PeriosteumPeriosteum
STRUCTURE (Microscopic)STRUCTURE (Microscopic)Haversian system
(osteon) – structural unit of bone; consists of:–Hard bone matrix
arranged in rings (lamellae)
–Central canal (Haversian canal) through which vessels run
– Volkmann’s canals – perpendicular to Haversian canals; connects nerves and blood vessels to periosteum
– Osteocytes – spider-shaped; lie in lacunae
– Canaliculi – canals that link lacunae to each other and to Haversian canals
Blood Vessels of BoneBlood Vessels of Bone
Spongy – consists of trabeculae (fibers)–Irregularly arranged lamellae
and osteocytes–No osteon present
Spongy Bone Structure and StressSpongy Bone Structure and Stress
CHEMICAL COMPOSITIONCHEMICAL COMPOSITIONOrganic
–contributes to bone structure
–helps resist stretch and twist forces (tensile strength)
–1/3 of bone matrix is organic
–consists of: proteoglycans, glycoproteins, and collagen. Material is secreted by osteoblasts
Inorganic– 2/3 of bone weight
– contributes to bone hardness (compression strength)
– Mineral salts (Ca3PO4, CaOH2, CaCO3)
– Can resist 25,000 lb/in2 of compression and 15,000 lb/in2 of tension
– Lasts well past death
Low calcium = porous bones
Bone GrowthBone Growth Pts of skeleton begin to form within first Pts of skeleton begin to form within first
few weeks of prenatal developmentfew weeks of prenatal development
BONE GROWTHBONE GROWTHLongitudinal Growth (length)
–Chondroblasts slow their growth at the distal end of the epiphysis
–The chondroblasts are replaced by osteocytes
–Growth stops when the epiphyseal plates fuse with the bone; occurs in late adolescence
Appositional growth (diameter)– Thickness can continue with stress
from excessive muscle activity and/or body weight;
– accomplished through the antagonistic actions of osteoclasts and osteoblasts
Animation:Animation:Bone Growth in WidthBone Growth in Width
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Hormonal Regulation
–Human Growth Hormone – stimulates mitosis at epiphyseal plates
–Sex hormones – causes growth spurts; molds male and female skeletons»Girls grow faster than boys and reach full height earlier (estrogen stronger effect)
»Boys grow longer and taller
»Use of anabolic steroids causes growth plate to close prematurely
–Hypo- or hypersecretions – can cause “gigantism” or “dwarfism”
DwarfismDwarfism AchondroplasiaAchondroplasia
– long bones stop growing long bones stop growing in childhoodin childhood
» normal torso, short normal torso, short limbslimbs
– spontaneous mutation spontaneous mutation during DNA replicationduring DNA replication
– failure of cartilage failure of cartilage growthgrowth
Pituitary Pituitary
– lack of growth hormonelack of growth hormone
– normal proportions with normal proportions with short statureshort stature
REMODELINGREMODELING Occurs at the tissue level, not at the
cellular level as in other systems Deposition and Resorption results in
remodeling Unequal by area – for example the
femur is replaced every 5-6 months
Deposition –occurs at an area of
stress or breakage–Osteoblasts put bone
material down on the outside surface of the bone
–Dental braces reposition teeth and remodel bone through pressure variances
–Abnormal calcification Abnormal calcification (ectopic) may occur in (ectopic) may occur in lungs, brain, eyes, muscles, lungs, brain, eyes, muscles, tendons or arteries tendons or arteries (arteriosclerosis)(arteriosclerosis)
Resorption – Osteoclasts absorb bone material from the inside of the bone
Control
–Hormonal through a negative feedback mechanism
–PTH (parathyroid hormone) is released when calcium levels in the blood are low
–This causes osteoclast activity to increase
–When Ca+ levels rise, osteoclast activity ceases
–Calcitonin is released when Ca+ levels are high; this inhibits bone resorption and stimulates osteoblasts to put bone material down on the outside of the bone.
–When Ca+ levels fall, calcitonin release is stopped
–This mechanism balances Ca+ levels in the blood.
–Calcium needed in neurons, Calcium needed in neurons, muscle contraction, blood clotting muscle contraction, blood clotting and exocytosisand exocytosis» ~1100g in adult skeleton~1100g in adult skeleton»plasma concentration is ~ 10 plasma concentration is ~ 10 mg/dL mg/dL
Hormonal Control of Calcium BalanceHormonal Control of Calcium Balance
PTH and calcitonin maintain normal PTH and calcitonin maintain normal blood calcium concentration.blood calcium concentration.
Ca+ is absorbed from food in the intestines in the presence of activated Vitamin D.
Abnormal softness Abnormal softness (rickets) in children (rickets) in children and (osteomalacia) in and (osteomalacia) in adults without adults without vitamin Dvitamin D
Mechanical/gravity/stress causes remodeling
–Wolff’s law »bone grows or remodels in response to forces or stress
»stress causes minute electrical currents to be produced in the bone
»currents accelerate osteoblast activity
»thus the use of exercise for those with osteoporosis.
–Hormones determine whether or when remodeling occurs
–Mechanical stress determines where remodeling occurs.
REPAIRREPAIRRequired when trauma, pathology has
occurredFracture – treated by “reduction”
–Closed reduction – manipulation of ends of bones outside the skin to align ends
–Open reduction – requires surgery and wires/pins
–Traction – risks long-term confinement
Types of Bone FracturesTypes of Bone Fractures
FracturesFractures
Phases of Repair1. Hematoma formation – blood clot; cells die (hours)
2. Callus formation – forms soft tissue then a callus; capillaries grow, phagocytes eat up callus (days)
3. Bony Callus formation – from the migration of osteoblast and osteoclasts to site of injury (6-8 weeks)
4. Remodeling – callus completely removed – (months)
Healing of Fractures Healing of Fractures
Fractures and Their RepairsFractures and Their Repairs
PATHOLOGYPATHOLOGY OsteoporosisOsteoporosis
– disease in which resorption outpaces disease in which resorption outpaces deposition deposition
– Results in porous, light bonesResults in porous, light bones– Risk of hip, wrist, vertebral fracturesRisk of hip, wrist, vertebral fractures– Complications with pneumonia and Complications with pneumonia and
blood clotsblood clots
–Postmenopausal white women Postmenopausal white women at greater risk (30% loss by at greater risk (30% loss by age 70)age 70)
–Black women rarely suffer Black women rarely suffer symptomssymptoms
–caused by a number of factorscaused by a number of factors» decrease in estrogen levels decrease in estrogen levels (estrogen inhibits resorption)(estrogen inhibits resorption)
»low bone stress (lack of exercise)low bone stress (lack of exercise)»inadequate Ca+ and protein inadequate Ca+ and protein consumptionconsumption
»abnormal Vit. D synthesis, abnormal Vit. D synthesis, malabsorption of Ca+malabsorption of Ca+
–TreatmentTreatment
»EEstrogenstrogen R Replacementeplacement T Therapyherapy – slows – slows resorption, but may increase resorption, but may increase cancer risks, stroke, heart cancer risks, stroke, heart diseasedisease
»PTH (Fosamax, Boniva)PTH (Fosamax, Boniva)
»Prevention – exercise, Prevention – exercise, calcium intakecalcium intake
Animation: OsteoporosisAnimation: Osteoporosis
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Osteomalacia–Soft bones–Inadequate
mineralization–Little Ca+
absorption–Called “Ricketts” in
children – usually due to malnutrition
Paget’s Disease
–Excessive absorption and deposition in inappropriate places
–Causes deformities due to the high rate of spongy/compact bone
–Skull, spine, femur and pelvis are common sites
–May be an autoimmune disease with viral triggers
Paget’s Paget’s DiseaseDisease
Chapter 9Chapter 9JointsJoints
Joints are Joints are designed to designed to
secure bones secure bones and, in many and, in many cases, provide cases, provide
movementmovement
ClassificationClassificationStructural:Structural:
–Fibrous Fibrous – – »bones joined by bones joined by fibrous tissue (ligament)fibrous tissue (ligament)
»having no joint cavityhaving no joint cavity»most provide no movementmost provide no movement»Ex: bones of skull, tibia with Ex: bones of skull, tibia with fibula.fibula.
–CartilaginousCartilaginous – – »joints united by joints united by cartilage;cartilage;
»having no joint cavity;having no joint cavity;»provides provides minimal minimal movement;movement;
»Ex: ribs and Ex: ribs and sternum, sternum, pubis of pubis of pelvispelvis
– SynovialSynovial – –
»articulating bones are separated by articulating bones are separated by a fluid filled joint cavitya fluid filled joint cavity
»surrounded by surrounded by a sac (bursa)a sac (bursa)
» freely moveablefreely moveable»stability stability
influenced by influenced by articular articular surfaces, surfaces, ligaments and ligaments and muscle tone.muscle tone.
FunctionalFunctional
–SynarthrosisSynarthrosis – immovable – immovable–Amphiarthrosis Amphiarthrosis
– slightly – slightly moveablemoveable
–DiarthrosisDiarthrosis – – freely movablefreely movable
Types of Synovial Joints Types of Synovial Joints (structural plan)(structural plan)
PlanePlane – intercarpal, intertarsal, – intercarpal, intertarsal, vertebrae – slipping or sliding in vertebrae – slipping or sliding in all directionsall directions
HingeHinge – elbow, knee, – elbow, knee, interphalangeal, one plane interphalangeal, one plane of motion, round end fits in of motion, round end fits in concave surfaceconcave surface
PivotPivot – atlas an axis with head – atlas an axis with head to indicate “no”to indicate “no”
CondyloidCondyloid – radiocarpal, – radiocarpal, metacarpophalangeal, metacarpophalangeal, (“knuckle”), (“knuckle”), atlantooccipitalatlantooccipital
SaddleSaddle – thumb – more – thumb – more freedom of movementfreedom of movement
Ball-and-socketBall-and-socket – shoulder – shoulder and hip and hip
Types of Synovial Movements Types of Synovial Movements (functional)(functional)
GlidingGliding – plane joint – plane jointFlexionFlexion – bending that – bending that
decreases joint angle and decreases joint angle and brings bones together brings bones together (“dorsiflexion” of the foot(“dorsiflexion” of the foot
ExtensionExtension – opposite of – opposite of flexion (“plantarflexion” of flexion (“plantarflexion” of the foot, hyperextension of the the foot, hyperextension of the head)head)
AbductionAbduction – move away, arm or leg – move away, arm or leg laterally or up, spreading fingerslaterally or up, spreading fingers
AdductionAdduction – opposite of abduction, – opposite of abduction, move towardsmove towards
CircumductionCircumduction – flexion, – flexion, extension, and abduction extension, and abduction together in a cone shape together in a cone shape movement (thumb movement)movement (thumb movement)
RotationRotation – turning of bone around – turning of bone around its own axis (arm or leg)its own axis (arm or leg)
SupinationSupination – radius around ulna – radius around ulna (palms up)(palms up)
PronationPronation – – opposite of opposite of supination supination (palms down)(palms down)
InversionInversion – sole of foot turned – sole of foot turned mediallymedially
EversionEversion – opposite of – opposite of inversion, sole of foot faces inversion, sole of foot faces laterallylaterally
ProtractionProtraction – jutting your jaw – jutting your jaw or squaring your shouldersor squaring your shoulders
RetractionRetraction – opposite of – opposite of protractionprotraction
ElevationElevation – shrug your – shrug your shouldersshoulders
DepressionDepression – dropping your – dropping your jawjaw
ArthritisArthritis (osteoarthritis, rheumatoid) – (osteoarthritis, rheumatoid) – – a wearing down of bone surfaces in a a wearing down of bone surfaces in a
joint cavityjoint cavity
Pathologies
– Causes extreme pain, swelling, and Causes extreme pain, swelling, and deformitydeformity
GoutGout – – – accumulation of uric acid crystals accumulation of uric acid crystals
in the joints (usually in the feet)in the joints (usually in the feet)
Bursitis/tendonitisBursitis/tendonitis – – – inflammation of the bursa sac and/or inflammation of the bursa sac and/or
associated tendonsassociated tendons
–requires rest and/or anti-requires rest and/or anti-inflammatoriesinflammatories
Infected bursitis
DislocationDislocation – separation of – separation of bones within a joint cavitybones within a joint cavity
Sprain/strainSprain/strain – – tendons/ligamentstendons/ligaments
Kyphosis – humped curvature of the spine
Scoliosis – lateral curvature of the spine
Lordosis – “Sway back”