Ch 6 Bone Flashcards
Skeletal cartilage
water lends resiliency
no blood vessel or nerves
perichondrium
surrounds skeletal cartilage
contains blood vessels for nutrient delivery
resist outward expansion
type of skeletal cartilage
hyaline- support, flexibility, resilience
-collagen fiber only
elastic cartilage- similiar to hyaline but contains elastic fiber
fibrocartilage- thick collagen fiber, tensile strength
Growth of cartilage
appositional growth- osteoprogenitor cells in perichondrium produce new layers of cartilage tissue from outside
Interstitual Growth- chondrocytes increase number of cells (mitosis) and amount of matrix from within
Classification of bones
206 divided into 2:
Axial skeleton- long axis of body (skull, vertebral column, rib cage.)
Appendicular Skeleton- Bone of upper and lower limbs
(girdles attach limbs to axial skeleton)
Classification by shape
Long bone- longer than wide
(limbs)
Short bones- Cube shaped(wrist , ankle) sesamoid bone (tendon and patella)- vary in size and number if different people
flat bone- thin flat slightly curved(sternum, scapula, ribs, most of skull)
Irregular bone- complicated shape(vertebrae/ pelvic)
7 Bone function
support-for body and soft organ
protection- brain, spinal cord, organ
movement- lever for muscle
mineral growth factor storage- calcium and phosphorus, growth factor reservoir
blood cell formation-hematopoiesis in red marrow
triglyceride(fat) storage- energy
Hormone production- osteocalcin- regulate bone formation
bone tissues
bones contains: osseuos, nervous cartilage, fibrous, connective, muscle, epithelial
bone level structure
gross, microscopic, chemical
Gross bone anatomy
bone marking-projection, bulge, depression, fossa
Bone texture:
Compact(cortica)- dense outer layer, smooth and solid
Spongy(cancellous/trabecular)- honeycomb of flat pieces of bone
Periosteum- outer layer
endosteum- inner layer
Anatomy of short, irregular, flat bone
thin plate of spongy bone covered by compact bone
no shaft or epiphyses
bone marrow throughout spongy bone, no marrow
Diploë- spongy bone tissue of the internal part.
hyaline cartilage covers articular surfaces
Periosteum membrane
white double layered
covers external surface except joint
many nerve fiber and blood vesel
anchor tendon/ligament
sharpey’s fiber secure to bone matrix
Osetogenic contains prime stem cells
Endosteum membrane
delicate connective tissue covering internal bone surface
covers trabeculae of spongy bone
Line canals that pass through compact bone
contains osteogenic cells
Hematopoietic Tissue
Red marrow in trabecular cavity and diploë of spongy bone of irregular and flat bones, head of femur and humerus
Medullary Cavity- spongy bone of newborn,infant
adult long bone has less red marrow center than children
yellow marrow can convert to red if needed
bone marking
projection, depression openings
site of muscle, ligament, tendon attachment on external surface
joint surface
conduit for blood vessel and nerve
Microscopic Anatomy of bone
Specialized form of same basic cell
Osteogenic/osteoprogenitor/preosteoblast (stem cell)
Osteoblast
osteocyte
osteoclast
Osteoid- bone lining cell secreted by osetoblast
osteogenic / Osteoprogenitor cells
mitotically active stem cells in periosteum and endosteum
differents to osteoblast or bone lining cells
osteoblast
bone forming cells
bone mineralized by osteoblast
secret bone matrix or osteoid
-synthesize dense bone collage (90% of bone protein)
osteoid cell
bone lining
flat cell on bone surface help maintain matrix
on external bone surface called periosteal cell
lining internal surface called endosteal cell
osteoclast
derive from hematopoietic stem cell become macrophage
big multinucleated cell for bone resorption
ruffled border increase surface area for enzyme degradation
osteocyte
mature bone cell in lacunae
monitor/maintain bone matrix
stress or strain sensors by responding and communicating mechanical stimuli to osteoblast and osteoclast for bone remodeling
lamellae
interstitial lamellae- incomplete lamellae not part of complete osteon
fill gap between forming osteon
circumferential lamellae- deep to periosteum
superficial to endosteum
extend around diaphysis
resist twisting of long bone
Microscopic spongy bone
cancellous bone
Poorly organized
Trabeculae- align along stress to resist it
no osteon
contain irregular arranged lamellae and oesteocyte interconnected by canaliculi
capillaries in endosteum supply nutrient
Homeostatic imbalance
osteomalacia (adult)- bone poorly mineralized
not enough calcium salt
soft/weak bone/ painful
Rickets(children)- bow legged
bone abnormally large and long
vitamin D deficiency
osteoporosis
bone resorption outpaces deposit
spongy bone of spine and neck of femur (common: vertebral and hip fracture)
bone developement (ossification) 4 situation
- bone tissue formation
- formation of bony skeleton(2nd month developement)
- postnatal growth(until early adulthood)
- Bone remodeling and repair(lifelong)
2 types of Ossification
endochondral- bone form by replacing hyaline cartilage
-forms most of skeleton
Intramembranous- bone develops from fibrous membrane formed by mesenchymal cells
- ossification center appear
- osteoid secreted
- woven bone and periosteum form
- lamellar bone replace woven bone
- (form flat bone)
Postnatal bone growth
interstitial (longitudinal growth)
-increase length of lone bone
appositional growth- increase bone thickness
Interstitial Growth
requires epiphyseal cartilage
epiphyseal plate maintain thickness
result 5 zone in cartilage: Resting (quiescent) Proliferation (growth) Hypertrophic calcification ossification
Zones
Resting (Quiescent)- Cartilage on epiphyseal side of epiphyseal plate, inactive
Proliferation (growth)- cartilage on diaphysis side of epiphyseal plate
-rapidly divide pushing epiphysis away from diaphysis
Hypertrophic- Older chondrocyte closer to diaphysis and lacunae enlarge and erode
calcification- surround cartilage matrix calcifies, chondrocyte die
Ossification- Chondocyte deteriorate leaves calcified cartilage and epiphysis-diaphysis
- Spicule erode by osteoclast
- covered with new bone osteoblast
- replaced with spongy bone
Epiphyseal plate closure
bone lengthen cease (require cartilage)
bone epiphysis and diaphysis fuze
f-18 m-21
hormone regulation
GH- most important in epiphyseal plate activity in infancy
Thyroid- modulate activity of growth hormone
-ensure proper proportion
Testoserone(M)- promote adolescent growth spurt
-end growth by inducing epiphyseal plate
Bone homeostasis- bone remodeling
consist of bone deposit and bone resorption
occur at surface of periosteum and endosteum
remodeling unit- adjacent osteoblast and osteoclast
bone deposit
new matrix deposit by osteolast
Osteoid seam- unmineralized bone matrix
Calcification front- abrupt transition between osteoid and older mineralized bone
trigger not confirmed- mechanical signal involved
bone resorption
function of osteoclast:
Depression or grooves break down matrix
Secrete lysosomal enzyme digest matrix and proton
acidity convert calcium salts to soluble form
phagocytize demineralized matrix and dead osteocyte
after resorption, osteoclast undergo apoptosis
control remodeling
occurs continuously, regulated by genetic factor
negative feedback hormonal loop for calcium
response to mechanical and gravitational forces
Calcium importance
function: Nerve impulse transmission muscle contraction blood coagulation secretion cell division
hormonal control of blood calcium
parathyroid hormone (PTH) -remove calcium from bone regardless of integrity
calcithonin- produced by parafollicular cells of thyroid
calcium homeostasis
calcium homeostasis of blood: 9-11 mg/100ml
Hyperexcitability- level too low
nonresponsiveness- level too high
hypercalcemia- high blood calcium levels
- deposit of calcium salt in blood vessel, kidney interfere with function
Wolff’s Law
bone grow or remodel in response to demand
Reason for- handedness, thicker and stronger bone of that limb
curved bone thickest where most likely to buckle
trabeculae form trusses along stress lines
fracture and bone repair
fracture-break in bone
Reactive phase- early inflammation
Reparative phase- formatijon of fibrocartilaginous callus
bone remodeling phase– last step as bone callus removed
4 stage bone repair
hematoma formation
fibrocartilaginous callus formation
bony callus formation
bone remodeling
fracture classification
position of bone end after fracture
- nondisplaced-end retain normal position
- displced- end out of normal ligament
completeness/break
- complete- broken all the way
- incomplete- not broken all the way
skin penetration-
open- skin penetrated
closed- skin not penetrated
