Ch 6 Bone Tissue

Bone Tissue Anatomy

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Resilient tissue that is poorly vascularlized-Hyaline-Elastic -Fibrocartilage
Hyaline Cartilage
-Articular cartilages and coastal (rib) cartilage, larynx, trachea, and nose-Rich in collagen...
Elastic Cartilage
-Ear pinna and epiglottis -Contains many elastic/collage fibers-Able to tolerate repeated bending
-Intervertebral discs, knee menisci, pubic symphysis-Inermediate between hyaline and elastic...
Chondocyte in Lacunae
Produce additional cartilage tissue
Round; membrane of fibrous connective tissue that surrounds the external surface of cartilage
Appositional GrowthThink: new cartilage
Chondoblasts in surrounding perichondrium produce new cartilage; produce cartilage inside-Growth...
Interstitial GrowthThink: matrix
Chondrocytes within cartilage divide and secrete new matrix
Tissue in Bones
-Come from mesoderm-Dominated by bone connective tissue-Contain nervous tissue (ectoderm) and...
What germ layer is the inside layer of bone made out of?
Function of Bones
-Support, movement, protection, mineral storage, bone-cell formation (bone contains bone red...
Stimulates pancreas to produce more insulin and fat cells to become insulin sensitive
Extracellular Matrix
35% organic-Rich in collagen - provides tensile strength; contributes to flexibility65% inorganic-Mineral...
Osteogenic cells
-Stem cells that differentiate into osteoblasts-From or composed of any tissue concerned in...
Actively produce and secrete bone matrix (ground matrix and collagen fibrils)-Bone matrix is...
-Keep bone matrixes healthy -Mature bone cells-Spider shaped that occupy lacunae (small cavities...
Bone matrix secreted by osteoblasts and crystallized by salts
-Resorption of bones-Derived from white blood cells-Secrete HCl and lysosomal enzymes-Remove...
Long bones
Longer than wide; shaft plus 2 endsCommon on extremities
Short BonesThink: Cube
-Roughly cube-shaped-Wrist and ankles-Sesamoid bones: special type of short bone which are...
Flat bones
Thin and flattened, usually curvedEx: ribs, sternum, scapula, and some cranial bones
Irregular Bones
Various shapes, don't fit in other categoriesEx: vertebrae and hip bones
Compact Bone
Dense outer layer of bone
Spongy bone (cancellous or trabecular bone)
-internal 3D network of bone with small needle-like or flat pieces called traceculae are filled...
Red bone barrow
Mainly hematopooetic cells
Yellow bone marrow
Mainly adipose cells

Structure of Long Bone
• Diaphysis—“shaft” long axis of a bone• Epiphysis—ends of a bone with joint surfaces...
Shaft - Long axis of boneVery center has no spongy bone and is filled with yellow bone marriw...
Ends of a one with joint surfaces typically covered with think later of hyaline cartilage called...
Epiphyseal line
Runs in between diaphysis and epiphysis in adults and is remnant of epiphyseal
Blood vessels
Unlike cartilage, bones are well vascularized; nutrients arteries and nutrient veins service...
What's a big difference between cartilage and bone?
Bones are well vascularized
Medullary cavity
Interior of all bones consists largely of spongy bone with marrow in between traceculae
Periosteum, perforating fibers (Sharpey's fibers) and endosteum (inside medullary cavity)
Periosteum and Perforating FibersThink: external surface
-Connective tissue and membrane which covers external surface of bone, except the ends of epiphyses...
Superficial outer periosteum
Layer of dense irregular connective tissue which resists tension placed on bone
Deep inner periosteium layer
Abuts compact outer surface of compact bone; deep later is osteogenic and forms osteoblasts...
Perforating Fibers (Sharpey's Fibers)
Secure periosteum to underlining bone with thick bundles of collagen that run from periosteium...
EndosteumThink: Internal surface
-Thin connective tissue membrane layer which lines internal bone surfaces including trabeculae...
Osteons (Haverson System)Lamellae + Central = osteon
-Long cylindrical structures which run along axis of bone-Function in support-Structurally...

Microscopic Structure of Compact Bone
Long tube gives structural strength Smallest --> BiggestNerveVein Artery
Structure of Short, irregular, and flat bones
-No diaphysis-No epiphysis-Hard dense compact outer layer of bone -Diploe: Internal spongy...
Long bone vs. Short bone
Long Bone Short Bone -Diaphysis -Epiphysis ...
Trabeculae - Connective Tissue
-bony spicules in cancellous bone which form a meshwork of intercommunicating spaces that...
Bone Design: Compression and tension
Anatomy of bone reflects stresses-Compression and tension greatest at external surfaces-Compression...
Bone Markings
1. Projections for muscle and ligament attachment2. Surfaces that form joints3. Depressions...

Projections for muscle and ligament attachment
1. Tuberosity - Large rounded project; may be roughened2. Crest - Narrow ridge of bone; usually...

Surfaces that form joints
1. Head - any bony expansion carried on a neck2. Facet - smooth, nearly flat articular surface3....

Depressions and Openings
1. Foreamen - round or oval opening through a bone 2. Groove - furrow3. Fissure - narrow, slit-like...
Compact Bone
-Contains passage ways for blood vessels, lymph vessels, and nerves-Osteons that function in...
Concentric Tube OsteonCompact Bone
Each tube is a lamella with layer of bone matrix in which collagen fibers and mineral crystals...
Central Canal (Haversion System)
-Runs through each osteon-Lined with osteogenic endosteum layer with osteoblast-Lamella added...
-Connect neighboring lacunae to one another and to capillaries for nutrient supply-There are...
Some Lamellae not found in Osteons
1. Interstitial lamellae2. Circumferential lamellae
Interstitial Lamellae
-Between osteons-Groups of incomplete lamellae which lie between osteons; remains of old osteons...
Circumferential Lamellae
Extends around the entire circumference of diaphysis
Bone-tissue formation-Membrane bones-Endochondrial bones
Membrane Bones
Ex: Cranial bones, claviclesFormed directly from mesenchyme (from mesoderm) without first being...
Endochondrial Bones
Develop initially from hyaline cartilage which is replaced by a bone through endochondral ossification

Intramembranous Ossification
1. Ossification center appears in the fibrous  of connective tissue membrane-Mesenchymal...

Endochondrial Ossification
-All bones except skull and clavicles-Modeled by hyaline cartilage-Forms late in second month...

Epiphyseal Plates
-Cartilage organized for quick, efficient growth-Cartilage cells form tall stacks (chondroblasts)...
Resting ZoneEpiphyseal Plates
-Cells nearest to epiphysis that are small and inactive
Proliferation ZoneEpiphyseal Plates
-Made up of chondroblasts at top of stack which divide quickly, pushing epiphysis away from...
Hypertrophic ZoneEpiphyseal Plates
-Older chondrocytes deep in stack signals around cartilage matrix-Older cartilage cells enlarge...
Calcification Zone
Matrix becomes calcified; cartilage cells die; matrix begins deteriorating
Ossification Zone
 New Bone formed
Postnatal Endochondrial Bones
-Bones lengthen by epiphyseal plates; they maintain constant thickness-Cartilage replaced w/...
Osteoblast vs. Osteoclast
Osteoblast - add; external; bone depositionOsteoclast - remove; internal; bone resorption
Growth Hormone
-Produced by pituitary gland-Stimulates epiphyseal plates
Thyroid Hormones
-Ensure skeleton retains proper proportions
Sex Hormones (estrogen and testosterone)
-Promote bone growth-Induce closure of epiphyseal plates
What happens to long bones as adolescence ends?
Long bone stops lengthening when diaphysis and epiphysis fuse.-epiphyseal plates become thinner...
Bone remodeling
-500 mg calcium-Canellous (spongy) bone replaced every 3-4 yrs -Compact bone replaced every...
Where do bone deposit and resorption occur?
Periosteal (perosteum) and endoesteal (endosteum)
Simple fracture
Bone fracture without penetrating skin
Compound fracture
Bone fracture injury that breaks skin-Likelihood of infection increases -Treat with antibiotics
Treatment by reduction
Closed: handsOpen: surgically set with pins and wires
Phases of healing simple fracture
1. Hematoma formation: blood vessels break in periosteum and inside bone2. Fibrocartilage callus...
Mesoderm --> embryonic mesenchyme cellsMesenchyme --> membranes and cartilate that form...
Paget's Disease: makes bones soft and deformed
-Excessive rate of bone resorption and formation       ...
Bone cancer that occurs in long bones of lower or upper extremity
Osteomalcia "soft bones"
-AdultsBones inadequately mineralized
-Children w/ inadequate Vitamin D-B/c bones soft, child may have bowed legs and cranial form...
-Low bone mass-Resporption faster than deposition-Increased ratio of osteclasts/osteoblasts-Compact...

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