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96 Cards in this Set
- Front
- Back
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Skeletal Cartilage |
- Mostly water -Contains no blood vessels or nerves |
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Perichondrium |
-Surrounds -Dense connective tissue girdle -Contains blood vessels for nutrient delivery -Resists outward expansion |
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Skeletal Cartilages |
All contain chondrocytes in lacunae and extracellular matrix |
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3 Types of Skeletal Cartilages |
-Hyaline Cartilage -Elastic Cartilage -Fibrocartilage |
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Hyaline Cartilage |
-Provides support, flexibility, and resilience -Collagen fibers only; most abundant type -Articular, costal, respiratory, nasal cartilage |
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Elastic Cartilage |
-Similar to hyaline cartilage, but contains elastic fibers -External ear and epiglottis |
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Fibrocartilage |
-Thick collagen fibers~ has great tensile strength -Menisci of knee; vertebral discs; Pubic symphysis |
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Appositional Growth |
Bones getting thicker -Cells secrete metric against external face of existing cartilage |
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Interstitial Growth |
-Increases the length of long bones -Chondrocytes divide and secrete new matrix, expanding cartilage from within |
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Classification of Bones: 2 Groups |
-Axial skeleton -Appendicular skeleton (appendages) |
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Axial Skeleton |
-Long axis of body -Skull, vertebral column, rib cage |
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Appendicular Skeleton (Appendages) |
-Bones of upper and lower limbs -Girdles attaching limbs to axial skeleton |
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Classification of Bones by Shape |
-Long bones -Short bones -Flat bones -Irregular bones |
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Long bones |
-Longer than they are wide -Limb, wrist, and ankle bones -EX: Humerus, Femur |
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Short bones |
-Cube-shaped bones (in wrist & ankle) -Sesamoid bones (within tendons ex: Patella) -Vary in size and number in different individuals -EX: Carpals, Tarsals |
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Flat bones |
-Thin, flat, slightly curved -EX: Sternum, scapulae, ribs, most of skull |
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Irregular bones |
-Complicated shapes -EX: Vertebrae, Coxal bones |
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Functions of Bones: 7 Important Functions |
-Support -Protection -Movement -Mineral and growth factor storage -Blood cell formation -Triglyceride (fat) storage -Hormone production |
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Functions of Bones: Support |
-For body and soft organs |
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Functions of Bones: Protection |
-For brain, spinal cord, and vital organs |
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Functions of Bones: Movement |
-Levers for muscle action |
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Functions of Bones: Mineral & Growth Factor Storage |
-Calcium and Phosphorus, and growth factors reservoir |
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Functions of Bones: Blood Cell Formation |
Hematopoiesis -In red marrow cavities of certain bones |
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Functions of Bones: Triglyceride (fat) Storage in Bone Cavities |
-Energy source |
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Functions of Bones: Hormone Production |
*Osteocalcin -Regulates bone formation -Protects against obesity, glucose intolerance, diabetes mellitus |
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Bones |
-Are organs -Contain different types of tissues: Osseous tissue, nervous tissue, cartilage, fibrous connective tissue, muscle (smooth muscle) tissue, and epithelial cells in its blood vessels |
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Bones: 3 Levels of Structure |
-Gross Anatomy -Microscopic -Chemical |
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Gross Anatomy |
-Compact (shaft) & Spongy (towards the outside in the center) bone -Compact: dense outer layer; smooth and solid -Spongy (cancellous or trabecular): honeycomb of flat pieces of bone deep to compact called Trabeculae |
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Periosteum vs. Endosteum |
Periosteum: outer layer Endosteum: inside facing spongy bone |
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Structure of Short, Irregular, and Flat Bones |
-No shaft or Epipyses: external ends -Hyaline cartilage covers articular surfaces -Bone marrow throughout spongy bone; no marrow cavity |
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Structure of Typical Long Bone: Diaphysis |
Diaphysis: shaft -Tubular shaft forms long axis -Compact bone surrounding medullary cavity |
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Structure of Typical Long Bone: Epiphyses |
Epiphyses: Epiphysis (singular) -Bone ends -External compact bone; internal spongy bone -Articular cartilage covers articular surfaces |
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Epiphyseal Line |
-Remnant of childhood bone growth at Epiphyseal plate= (metaphysis, part of growth plate) |
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Membranes: Periosteum |
-Covers external surfaces except joint surfaces -Outer fibrous layer of dense irregular connective tissue -Sharpey's fibers: secure to bone matrix -Osteogenic Layer: Contains primitive stem cells- Osteogenic cells |
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Membranes: Periosteum Cont. |
-Many nerve fibers and blood vessels -Anchoring points for tendons and ligaments |
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Membranes: Endosteum |
-Delicate connective tissue membrane covering internal bone surface -Covers trabeculae of spongy bone -Lines canals that pass through compact bone -Contains osteogenic cells the can differentiate into other bone cells |
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Hematopoietic Tissue in Bones: Red Marrow |
-Found within trabecular cavities of spongy bone and Diploe of flat bones (ex: sternum) -In medullary cavities and spongy bone of newborns |
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Red Marrow Cont. |
-Adult long bones have little red marrow (heads of femur and humerus only) -Red marrow in diploe and some irregular bones is most active -Yellow marrow can convert to red, if necessary |
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Bone Markings |
-Sites of muscle, ligament, and tendon attachment on external surfaces -Joint surfaces -Conduits (pipe) for blood vessels and nerves |
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Bone Markings: Projections |
-Most indicate stresses created by muscle pull or joint modifications -Depressions and Openings -Usually allow nerves and blood vessels to pass |
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Cells of Bone Tissue: 5 Major Cell Types |
-Osteogenic cells -Osteoblasts -Osteocytes -Bone lining cells -Osteoclasts- macrophages |
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Osteogenic Cells |
-Also called Osteoprogenitor cells: "Ancestor cell" -Mitotically active stem cell i periosteum and endosteum -When stimulated differentiate into osteoblasts or bone lining cells |
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Osteoblasts |
-Bone forming cells -Secretes unmineralized bone matrix or Osteoid -Actively mitotic: (undergoing mitosis) |
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Osteocytes |
-Mature bone cells in lacunae -Monitor and maintain bone matrix -Act as stress or strain sensors: respond to and communicate mechanical stimuli to osteoblasts and osteoclasts so bone remodeling can occur |
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Osteoclasts- Macrophages |
-Cells that destroy bone -Derived from hematopoietic stem cells that become macrophages -Giant, multinucleate cells for bone resorption -When active rest in resorption bay and have ruffled border (ruffled border increases surface area for enzyme degradation of bone and seals off area from surrounding matrix) |
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Bone Lining Cells |
-On external bone surface called periosteal cells -Lining internal surfaces called endosteal cells -Flat cells on bone surfaces believed to help maintain matrix |
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Compact Bone |
-Also called Lamellar Bone -Osteon or Haversian system: structural unit of compact bone -Central (Haversian) canal runs through core of osteon: contains blood vessels and nerve fibers |
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Perforating (Volkmann's) Canals |
-Canals lined with endosteum at right angles to central canal -Connect blood vessels and nerves of periosteum, medullary cavity, and central canal |
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Lacunae |
-Small cavities that contain Osteocytes |
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Canaliculi |
-Hair-like canals that connect lacunae to each other and central canal |
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Canaliculi Formation |
-Osteoblasts secreting bone matrix maintain contact with each other and osteocytes via cell projections with gap junctions -When matrix hardens and cells are trapped the canaliculi form -Allow communication -Permit nutrients and wastes to be relayed from one osteocyte to another throughout osteon |
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Lamellae: 2 Types |
-Interstiitial Lamellae -Circumferential Lamellae |
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Interstitial Lamellae |
-Incomplete lamellae not part of complete osteon -Fill gaps between osteons -Remnants of osteons cut by bone remodeling |
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Circumferential Lamellae |
-Just deep to periosteum -Superficial to endosteum -Extend around entire surface of diaphysis -Resist twisting of long bone |
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Spongy Bone |
-aka trabecular bone because it contains trabecular -Appears poorly organized -Trabeculae: Align along lines of stress to help resist it, no osteons, contain irregularly lamellae & osteocytes interconnected by canaliculi, capillaries in endosteum supply nutrients |
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Bone |
-Half as strong as steel in resisting compression -As strong as steel in resisting tension -Last long after death because of mineral composition: reveal information about ancient people, can display growth arrest lines (horizontal lines on bones, proof of illness- when bones stop growing so nutrients can help fight disease |
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Bone Development: Ossification |
-Process of bone tissue formation -Formation of bony skeleton: begins in the 2nd month of development -Postnatal bone growth: until early adulthood -Bone remodeling and repair: Lifelong |
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Ossification: 2 Types |
-Endochondral ossification -Intramembranous ossification |
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Ossification: Endochondral Ossification |
-Bones forms by replacing hyaline cartilage -Bone called cartilage (endochondral) bones -Forms most of skeleton |
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Ossification: Intramembranous Ossification |
-Bone develops from fibrous membrane -Bones called membrane bones -Forms flat bones (ex: clavicles and cranial bones) |
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Endochondral Ossification |
-Forms most all bones inferior to base of skull (except clavicles) -Requires breakdown of hyaline cartilage prior to ossification |
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Intramembranous Ossification |
-Forms frontal, parietal, occipital, temporal bones, and clavicles -Begins within fibrous connective tissue membranes formed by Mesenchymal cells -Ossification centers appear -Osteoid is secreted -Woven bone and periosteum form |
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Diploe |
Another word for spongy bone and it is found in the flat bone in the skull |
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Postnatal Bone Growth |
-Interstitial (longitudinal) growth: increases in length of long bone -Appositional growth: increase in bone thickness |
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Interstitial Growth |
-Requires presence of epiphyseal cartilage -Epiphyseal plate maintains constant thickness (rate of cartilage growth on one side balanced by bone replacement on the other) -Concurrent remodeling of epiphyseal ends to maintain proportion |
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Results of 5 Zones Within Cartilage |
-Resting (quiescent) zone -Proliferation (growth) zone -Hypertrophic zone -Calcification zone -Ossification (osteogenic) zone |
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Resting (Quiescent) "Quiet" Zone |
-Cartilage on epiphyseal side of epiphyseal plate -Relatively inactive |
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Proliferation (Growth) Zone |
-Cartilage on diaphysis side of epiphyseal plate -Rapidly divide pushing epiphysis away from diaphysis --> lengthening |
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Hypertonic Zone |
- Older chondrocytes closer to diaphysis and their lacunae enlarge and erode--> interconnecting spaces |
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Calcification Zone |
-Surrounding cartilage matrix calcifies, chondrocytes die and deteriorate |
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Ossification (OSTEOGENIC) Zone |
-Chondrocyte deterioration leaves long spicules of calcified cartilage at epiphysis-diaphysis junction -Spicules eroded by osteoclasts -Covered with new bone by osteoblasts -Ultimately replaced with spongy bone |
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Epiphyseal Plate Closure |
-Bone lengthening ceases: requires presence of cartilage -Bone of epiphysis and diaphysis fuses -Female ~18 yrs -Male ~ 21 yrs |
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Appositional Growth |
-Allows lengthening bone to widen -Occurs throughout life |
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Growth Hormone |
-Most important in stimulating epiphyseal plate activity in infancy and childhood |
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Thyroid Hormone |
-Modulates activity of growth hormone -Ensures proper portions -Testosterone & Estrogen: promote adolescence growth spurts -End growth by inducing epiphyseal plate closure -Excesses or deficits of any cause abnormal skeletal growth |
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Bone Homeostasis |
-Consists of bone remodeling & bone repair -Recycle 5-7% of bone mass each week -Older bone becomes more brittle: calcium salts crystalize, fractures more easily |
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Bone Remodeling |
-Consists of both bone deposit & bone resorption (resorption is the breakdown and absorption of old bone) -occurs at surfaces of both periosteum & endosteum |
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Remodeling Units |
-Adjacent osteoblasts: putting down bone tissue & osteoclasts breaking down bone tissue. When one is outpacing the other, it could cause osteoporosis or can cause very thick bones |
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Bone Deposit |
-Osteoid seam: unmineralized band of bone matrix -Calcification front: abrupt transition zone between osteoid seam and older mineralized bone |
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Bone Resorption |
- Is function of osteoclasts: dig deep depression or grooves as break down matrix -Osteoclasts also phagocytize demineralized matrix and dead osteocytes |
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Control of Remodeling |
-Occurs continuously but regulated by genetic factors and 2 control loops: negative feedback hormonal loop for Ca2+ homeostasis--> controls blood Ca2+ levels, Not bone integrity -Responses to mechanical and gravitational forces |
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Importance of Calcium |
Functions in: -Nerve impulse transmission -Muscle contraction -Blood coagulation -Secretion by glands and nerve cells -Cell division |
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Parathyroid Hormone (PTH) ^ [Ca2+] |
-Produced by parathyroid glands - Removescalcium from bone (bone resorption byosteoclasts so calcium is mobilized from bone to blood) regardless of boneintegrity |
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Calcitonin [Ca2+] |
– Producedby parafollicular cells of thyroid gland – Inhigh doses lowers blood calcium levels temporarily |
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Calcium Homeostasis |
• Even minute changes in blood calciumdangerous – Severeneuromuscular problems • Hyperexcitability (levels too low) • Nonresponsiveness (levels too high) |
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Hypercalcemia |
• Sustained high blood calcium levels • Deposits of calcium salts in blood vessels,kidneys can interfere with function – can lead to kidney stones |
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Wolff's Law |
• Bones grow or remodel in response to demandsplacedon it • Explains– Handedness(right or left handed) results in thicker and stronger bone of that upper limb |
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Hormonal Controls |
• Determine whether and when remodeling occursto changing blood calcium levels |
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Mechanical Stress |
determines where remodeling occurs |
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Stages of Bone Repair: Hematoma Forms |
• Torn blood vessels hemorrhage • Clot (hematoma) forms • Site swollen, painful, and inflamed |
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Stages of Bone Repair: Fibrocartilaginous Callus Forms |
•Capillaries grow into hematoma•Phagocytic cells clear debris•Fibroblasts secrete collagen fibers to spanbreak and connect broken ends • Fibroblasts, cartilage, and osteogenic cells beginreconstruction of bone– Createcartilage matrix of repair tissue– Osteoblastsform spongy bone within matrix•Mass of repair tissue called fibrocartilaginouscallus (“soft callus”) |
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Stages of Bone Repair: Bony Callus Forms |
•Within one week new trabeculae appear infibrocartilaginous callus • Callus converted to bony (hard) callus ofspongy bone •~2 months later firm union forms |
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Stages of Bone Repair: Bone Remodeling Occurs |
•Begins during body callus formation •Continues for several months •Excess material on diaphysis exterior and withinmedullary cavity removed •Compact bone laid down to reconstruct shaftwalls •Final structure resembles originalbecause responds to same mechanical stressors |
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Osteomalacia |
– Bonespoorly mineralized – Calciumsalts not adequate – Soft,weak bones – Painupon bearing weight |
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Rickets: Osteomalacia of Children |
– Bowedlegs and other bone deformities – Bonesends enlarged and abnormally long – Cause:Vitamin D deficiency or insufficient dietary calcium |
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Osteoporosis |
– Boneresorption outpaces deposit – Spongybone of spine and neck of femur most susceptible • Vertebral and hip fractures common |
