Chapter 6: Bones and Tissue Flashcards
Skeletal cartilage grows in two ways
Appositional
Insterstitial
cartilage forming cells in perichondrium secrete matrix against the external face of existing cartilage
-new matrix is laid down on surface cartilage
Appositional Growth
chondrocytes within lacuna divide+secrete new matrix, expands the cartilage from within
Interstitial Growth
Functions of Bone
- Supports
- Protects
- Movement
- Mineral growth
- Blood cell formation
- Triglyceride storage
- Hormone production
2 Groups of Bone
Axial: skull vertebrae, rib cage
Appendicular: bones of upper + lower limbs, girdles attaching to axial skeleton
Classifications of Bone
- long
- short- sesamoid bones form within tendons
- flat
- irregular
What does bone consists of besides osseous tissue?
- nervous tissue
- cartilage
- fibrous connective tissue
- muscle cells
- epithelial cells in blood vessels
3 Structural Levels of Bone
Gross (macroscopic)
Cell (microscopic)
Chemical
Shaft (surrounds medullary cavity)
Diaphysis
contains yellow bone marrow (yellow marrow cavity)
Medullary Cavity
ends of bones
Articulate cartilage coats the very ends
Epiphysis
Childhood bone growth occurs (metaphysis)
Epiphyseal plate
Short, irregular, and flat bones have these membranes
Periosteum
Endosteum
covers the outside of the compact bone, white, double-layered
made of: dense irregular connective tissue
Periosteum
secures bone matrix
Sharpey’s Tissue
inner layer abutting bone+ contains osteogenic cells that give rise to bone cells
Osteogenic layer
rich in nerve fibers and blood vessels. Connects through shafts vie
Nutrient Foramen
covers inside portion of compact bone + trabeculae
made of: a gentle connective tissue membrane
lines canals that pass through compact bone
Endosteum
red marrow that is found in trabecular cavities of spongy bones and diploe of flat bones
Hematopoeietic Tissue
Bone markings
projection (outward bulge)
depression (bowl/groove) (FOSSA) passageways for vessels, nerves, and joints
Opening: hole serves as passageways for blood vessels and nerves.
- mitotically active in periosteum+endosteum
- some remain osteogenic stem cells
- differentiate into osteblasts or bone-lining cells
Osteogenic Cells (osteoprogenitor/stem cells)
bone forming cells that secrete unmineralized bone matrix called osteoid
when they get trapped in calcified matrix, they turn into osteocytes
mitotically active
Osteoblast
maintain bone matrix and are stress and strain sensors
communicate information to osteoblasts + osteoclasts
live in lacunae
Osteocyte
developed from monocytes and macrophages
functions in bone resorbtion (break down)
multinucleate
strips calcium out of bone and puts it in blood stream if hypocalcemic
Osteoclasts
What does lamellar bone (compact bone) consist of?
osteon
canals + canaliculi
interstitial + circumferential lamella
structural unit of compact bone
consists of an elongated cylinder that runs parallel to long axis of bone
Osteon
rings of bone matrix in osteon cylinder
lamellae
run though center of osten
contains: blood vessels and nerve fibers
Central canals (haversian)
lined with endosteum that occur at right angles of canals
connects: blood vessels, nerves or periosteum, medullary cavity, and central canal
Perforating canals (Volkmanns)
tiny canals that connect lacunae to eachother
allows communication and permits nutrients and wastes from one cell to another
Canaliculli
lamella that is not part of the osteon
fill gaps between forming osteons
Interstitial lamellae
deep to periosteum, superficial to endosteum
extends around entire surface of diaphysis
Circumferential Lamellae
Fiber type is fine collagen fibers
consists of: articular cartilage (artic=joint), costal cartilage (ribs to sternum), respiratory cartlages (skeleton of larynx), nasal cartilage (external nose)
most abundant skeletal cartilage
Hyaline cartilage
fibers in matrix include fine collagen fibers, stretchy elastic fibers, and are able to repeatedly bend
Found in: external ear cartilage, and epiglottis
Elastic cartilage
highly compressible with great tensile strength.
consists of roughly parallel rows of condrocytes alternating with thick collagen fibers
Fibrocartilage
Organic parts of the bone
includes the cells of the bone
osteoid (organic part of the matrix) ⅓
collagen fibers
Inorganic parts of the bone
inorganic hydroxyapatites or mineral salts (calcium phosphates)
65% by mass
Before week 8 of bone formation
Bone is made from hyaline cartilage
replaces hyaline cartilage (first breaks it down making it complicated)
end result is called a cartilage or endochondral bone
begins late in the second month of formation
Endochondral Ossification
bone develops from a fibrous membrane and is called membrane bone
skull and clavicle is made like this
Intramembranous Ossification
center of the hyaline cartilage shaft
Primary ossification center
Bone collar forms around the diaphysis of the hyaline cartilage
1st step of Endochondral Ossification
Cartilage in the center of the diaphysis calcified (condrocytes die, matrix deteriorates) and then develops cavities
2nd step of Endochondral Ossification
The periosteal bud invades the internal cavities and spongy bone forms
Bud contains nutrient artery, vein, nerve fibers, red marrow elements, osteogenic cells (become osteoblasts) , and osteoclasts (erode calcified matrix)
3rd step of Endochondral Ossification
Dyaphysis elongates and a medullary cavity forms
As primary ossification center enlarges, osteoclasts break down sponge and make medullary cavity
Second ossification center appears in the epiphysis and periosteal bud invades
4th step of Endochondral Ossification
The epiphysis ossify
and cartilage remains only in the articular cartilage and epiphyseal plate
5th step of Endochondral Ossification
Ossification center appears in the fibrous connective tissue membrane
Centrally located mesenchymal cells clusters and some turn into osteoblasts forming the center and first trabechulae of bone
1st step of Intramembranous Ossification
Osteoid is then secreted within the fibrous membrane by osteoblasts and calcifies
Trapped osteoblasts become osteocytes
2nd step of Intramembranous Ossification
Woven bone and periosteum form
Osteoid forms in a manner that creates a network of trabechulae with blood vessels
Vascularized mesenchyme turn into periosteum
3rd step of Intramembranous Ossification
Lamellar bone replaces woven bone, just deep to the periosteum. Red marrow appears.
4th step of Intramembranous Ossification
5 Epihyseal Zones
Resting zone
Proliferation zone
Hypertrophic zone
Calcification zone
Ossification zone
cartilage is inactive on the side of epiphyseal plate
Resting zone
Side of the stack nect to the resting zones where cells divide quickly, (mitosis) pushing the epiphysis away from diaphysis and lengthening the bone
Proliferation zone
As older chondrocytes hypertrophy, their lacuna eorde and enlarge, leaving large interconnecting spaces
Hypertrophic zone
The surrounding cartilage matrix calcifies and these chondrocytes die and deteriorate producing the…
Calcification zone
Long slender spicules of calcified cartilage at the epiphysis-diaphysis are invaded by marrow elements from the medullary cavity.
Osteoclasts partly erode the cartilage spicules then osteoblasts quickly cover them with new bone
Ossification zone
most important hormone instimulating epiphyseal plate activity in infancy and childhood
Growth hormone
modulates activity of growth hormone, ensuring proper portions
Thyroid hormone
promote adolescent grown spurts
-end growth by plate closure
Sex hormones
controls blood calcium level
When levels are hypocalcemic, osteacalsts take Ca from bone and transfers it to blood
Parathyroid hormone
low levels of Ca
Hypocalcemic
High levels of calcium
Can results in kidney stones and calcium salts in blood
Hypercalcemic
Fracture classficiation
Position (non-displaced or displaced)
Completeness (complete(atwt) or incomplete(natwt))
Penetration of skin (open (penetrated) or closed (not penetrated))
3 or more pieces of fracture
Communited
bone is crushed
Compression
twisting of bone
Spiral
involves damage to epiphyseal plate
Epiphyseal fracture
one side of shaft breaks
Greenstick
Fracture Repair
- Hematoma forms
- Fibrocartilage callous forms
- Bony callus forms
- Bone remodeling occurs
