Exam 2: Skeletal system Flashcards
four structures that make up the skeletal system
bones, cartilage, ligaments, joints
hyaline cartilage
only collagen fibers present, provides support, flex, resilience, and allows bones to grow
types: articular, costal, respiratory, nasal
articular hyaline cartilage
covers ends of long bones at moveable joints
costal hyaline cartilage
connects the ribs to the sternum
nasal hyaline cartilage
supports the nose
elastic cartilage
collagen and elastic fibers that maintain shape and structure while allowing flexibility
loc: external ear and epiglottis
fibrocartilage
rows of chondrocytes alternating with thick collagen fibers; lacks perichondrium since bv penetrate up to 40% of cartilage;
highly compressible w great tensile strength;
loc: knee menisci, intervertebral disks
all cartilage has
chondrocytes and ecm
interstitial growth of cartilage
growth from the inside; lacunae bound chondrocytes inside the cartilage divide and secrete new matrix, expanding cartilage from within
appositional growth of cartilage
growth from the outside; cells in perichondrium secrete matrix against the external face of existing cartilage
functions of the skeletal system
contrib to shape of body support/framework/cradle soft organs protective case movement-levers for muscles mineral storage-calc/phosphate able to store/release hematopoiesis in red marrow cavities triglyceride/energy storage in bone cavities cartilage for flexibility ligaments reinforce joints/connect bones joints provide mobility
compact bone
dense outer layer of bone that looks smooth and solid
osteon/haversian syst
supports/protects, provides levers for muscles, stores calc minerals and fat
spongy bone
honey comb of trabeculae (little beams) filled w red/yellow marrow; no osteons present; looks poorly organized; trabeculae align along lines of stress; irregularly arranged lamellae and osteocytes interconnected by canaliculi
site of hematopoiesis
diaphysis
tubular shaft forming the long axis of bone has cent medullary cavity w yellow fat marrow
epiphysis
expanded ends of long bones
exterior compact, interior spongy,
joint surface covered in articular hyaline cart; cushions opposing bone end and absorbs stress;
cont red bone marrow hematopoiesis
gross anatomy long bone
compact and spongy bone separated by epiphyseal line once growth stops; cont both peri/endosteum and has signif yellow marrow cavity
gross anatomy short/flat/irregular bones
thin plates of periosteum covered compact bone w endosteum covered diploe on the inside
has no diaphysis/epiphysis
cont red marrow bt trabeculae but no signif marrow cavity
red marrow
hematopoietic tissue
INFANTS- in medullary cavity+all areas of spongy bone
ADULTS- found in diploe of flat bones (sternum/ribs), irregular bones (os coxa/vert), and head of femur/humerus
no longer in diaphysis
yellow marrow
found in medullary cavity of adult long bones in diaphysis
functions in fat storage
articular cartilage
hyaline cartilage found only at the ends of long bones in moveable joints
periosteum
glistening white double layered memo that surrounds the bone
richly supplied w nerve fibers, nutrient bv, and lymph vessles that enter the bone via nutrient foramina
outer fibrous layer of periosteum
dens irregular ct
inner osteogenic layer of periosteum
contains osteogenic stem cells that give rise to osteoblasts, clasts, and cytes
sharpeys fibers of periosteum
perforating tufts of collagen extending from fibrous layer into the bone matrix that secure periosteum to underlying bone
endosteum
delicate ct memb on inside of bone that covers trabec of spongy bone and lines canals that pass thru compact bone
cont osteogenic cells that can be osteoblast/cyte/clasts
hemaotpoiesis during growth-infants
found in red marrow of medullary cavity and all areas of spongy bone
hematopoiesis during growth-adults
found in diploe of flat bones (sternum/ribs) some irregular bones (os coxa/vert) and in head of femur/humerus
osteogenic/osteoprogenitor cells
stem cells in peri/endosteum that give rise to osteoblasts
osteoblasts
bone forming cells that produce organic matrix/collagen fibers called osteoid
osteocytes
most abundant
mature bone cells in contact w eo via gap junx
are mechanosensory cells that monitor and maintain mineralized bone matrix
osteoclasts
giant multinucleate cells that break down and reabsorb bone matrix
compact bone structural unit
osteon/haversian syst
compact bone- lamellae
weight bearing column like matrix tubes
like growth rings in a tree trunk stacked inside eo
collagen fibers of adj lamellae run in opp directions to wstand torsion/twisting stresses
compact bone- cent/haversian canal
runs thru the core of each osteon cont the bv and nerves that serve the osteons cells; is surrounded by concentric lamellae
compact bone- perforating/volkmanns canals
run at right angles to cent canal connecting bv and nerves of periosteum to cent canal and medullary cavity
compact bone- lacunae
small cavities that cont osteocytes at junx of lamellae
compact bone-canaliculi
hairlike canals that connect lacunae to eo and to the cent canal
spongy bone
no osteons pres looks poorly organized; trabec align precisely along lines of stress to help resist; cont irregularly arranged lamellae and osteocytes interconnected by canaliculi
nutrients reach the osteocytes thru the canaliculi
organic matrix is made of
osteoid and cells
osteoid
1/3 or 35%
organic unmineralized bone matrix secreted by osteoblasts made up of ground subst (proteoglycans/glycoproteins) and collagen fibers for strength and flex
cells
osteogenic, osteoblast/clast/cytes, bone lining cells
inorganic matrix made of
hydroxyapetites
hydroxyapatites
2/3 or 65%
mineral salts
calc phosphate compounds pres in the form of tiny packed crystals in and around the collagen fibers
resp for bone hardness and resistant to compression
why bones last after death
bones of children are more flex than bones of elderly bc
kids have a higher quant of organic matrix
elderly have old hydroxyapetites that cause brittle bones
how 02 is carried from outside a bone to an individual osteocyte
bv enter thru the periosteum into a perforating volkmanns canal
follow along the axis of bone thru the cent canal and travels thru canaliculi cell to cell until it reaches the osteocyte in question
intramembranous ossification step 1
ossification centers appear in the fibrous ct memb selected cent loc mesenchymal cells cluster and differentiate into osteoblasts forming ossification center
intramembranous ossification step 2
bone matrix-osteoid is secreted w n the fibrous memb and calcifies
osteoblasts secrete osteoid which is calcified in a few days; trapped osteoblasts then become osteocytes
intramembranous ossification step 3
woven bone+ periosteum form- accumulating osteoid is laid down bt embyronic bv in a random manner
the result is a network of trabeculae called woven bone
vascularized mesenchyme condenses on the external face of woven bone and becomes periosteum
intramembranous ossification step 4
lamellar bone replaces woven bone just deep to the periosteum- trabeculae thicken and are replaced w mature lamellar bone that forms compact bone plates
diploe consisting of distinct trabeculae persists internally and its vascular tissue becomes red marrow
endochondral ossification step 1
hyaline cartilage is infiltrated by bv converting it to a vascular periosteum
endochondral ossification step 2
bone collar forms around hyaline cartilage model; is produced by osteoblasts encasing the cartilage with bone
endochondral ossification step 3
cartilage in the bone collar calcifies dies and forms cavities
endochondral ossification step 4
about month 3
the periosteal bud invades the internal cavities allowing the osteoblast/clasts to enter
osteoclasts remove the calcified cartilage
osteoblasts replace it w earliest version of spongy bone
endochondral ossification step 5
birth
diaphysis elongates and a medullary cavity forms as ossification continues
secondary ossification centers begin to appear in the epiphysis
endochondral ossification step 6
childhood-adolescence
epiphysis ossify
when completed hyaline cartilage remains only in the epiphyseal plates and articular cartilages
long bone growth that occurs at epiphyseal plate zones
interstitial growth
interstitial growth of bone RESTING ZONE
cartilage on the side of the epiphyseal plate is relatively inactive
interstitial growth of bone CARTILAGE ABUTTING THE DIAPHYSIS OF THE BONE
organizes into a pattern allowing fast efficient growth
proliferation zone of diaphysis
cartilage cells undergo mitosis and push epiphysis away from diaphysis
hypertrophic zone of diaphysis
older cartilage cells enlarge and begin to die
calcification zone of diaphysis
matrix becomes calcified, cartilage cells die, matrix deteriorates and osteoid is laid down
ossification zone of diaphysis
new bone formation
appositional growth of bones
growth of bones in width
osteoblasts beneath periosteum secrete bone matrix on external surface
osteoclasts in endosteum of diaphysis remove bone to widen canal and keep the weight proportionate to the height
remodeling cells
osteoblasts/clasts form remodeling units and coordinate bone remodeling w help from stress sensing osteocytes
they deposit and reabsorb bone and the periosteal and endosteal surfaces
wolffs law
a bone grows or remodels in response to the forces/demands placed on it
the more stress the stronger the bone in that area
type of growth in long bones of babies and kids
postnatal interstitial and appositional growth in long bones
seen at epiphyseal plate if interstitial growth (length)
seen at bone surface/cavity if appositional growth (width)
requirements for normal growth of bone
diet rich in protein; vit A C D and calcium+phosphorus, magnesuium and manganese
alkaline phosphatase-essential for bone mineralization; allows formation of hydroxyapetites (works best at basic ph)
lysosomal enzymes to digest organic matrix broken down by osteoclasts
hydrochloric acid to remove hydroxyapetites and convert calcium salts to soluble forms
epiphyseal plate activity is stimulated by
growth hormone during infancy and childhood
testosterone/estrogen promote
growth spurt and closing of epiphyseal plate
parathyroid hormone PTH
parathyroid gland signaled to release PTh when blood calcium levels fall
signals osteoclasts to degrade bone matrix and release calcium into the blood
calcitonin
thyroid triggered by rising calcium levels in the blood to release calcitonin
stimulates osteoblasts to deposit calcium and deactivates osteoclasts
the bones anatomy is a reflection of
the common stresses it encounters like muscle pull and gravity; serves the needs of the skeleton by keeping bones strong where stressors are acting
mechanical forces communicate w cells resp for remodeling via electrical signals
deposition occurs in regions negatively charged
resorption occurs in regions positively charged
fracture repair step 1: hematoma formation
torn bv hemorrhage–> mass of clotted blood forms at fracture site–> site becomes swollen painful and inflamed–> bathes area w nutrients/macrophages
fracture repair step 2: fibrocartilaginous callus
capillaries grow into tissue and phagocytic cells clean debris–> fibroblasts produce collagen fibers to connect broken ends–> chondrocytes make collagen matrix–>osteoblasts form spongy bone–> outside calcification begins
fracture repair step 3: bony callus formation
trabeculae begin to appear–> fibrocartilaginous callus converts into a bony hard callus 3-4 weeks after injury and continues until a firm union is achieved 2-3 mo later
fracture repair step 4: bone remodeling
bony callus is remodeled to resemble that of the original unbroken region bc it resp to same set of mechanical stress
joint/articulation
weakest point of skeleton
site where 2 bones meet
synarthroses
immovable joint
amphiarthroses
slightly moveable joint
diarthroses
freely moveable joint
fibrous joints
bones joined by fibrous tissue; no joint cavity; mostly immovable binding mat
fibrous joint: suture
skull joint held together w very short interconnecting fibers and interlocking bone edges
fibrous joint: syndesmoses
bones connected by a ligament can be immovable to slightly moveable
occurs bt tibia/fibula and radius/ulna
fibrous joint: gomphoses
peg in socket periodontal ligament; fibrous joint bt tooth and alveolar socket
cartilaginous joints
articulating bones united by cartilage binding material
lack a joint cavity
non or very slight movement
cartilaginous joint: synchondroses
synarthrotic bar/plate of hyaline cartilage that unites bone parts
epiphyseal plate of children and joint bt costal cartilage and first rib of sternum
cartilaginous joint: symphysis
fibrocartilage connecting tissue
amphiarthrotic joint designed for strength and flex in intervertebral disks/ pubic symphysis
6 structural char of synovial joints
articular cartilage joint cavity articular capsule synovial fluid reinforcing ligaments innervation/vascularization
articular cartilage of synovial joint
hyaline cartilage that cushions/absorbs compression and prevents bone ends from being crushed
joint cavity of synovial joint
space filled w synovial fluid that allows joints to be freely moveable
articular capsule of synovial joint
encloses joint cavity in 2 layers
fibrous capsule- dense irregular ct cont w periosteum
synovial memb- composed of synovial memb and lines all parts not hyaline cartilage
synovial fluid of synovial joint
fills all free spaces in joint capsule produced from synovial memb and blood filt (always fresh)
reduces friction bt cartilages
cont phagocytic cells
supplies nut to cartilage and removes waste
reinforcing ligaments of synovial joint
reinforce/strengthen and unite bones
prevent excessive and undesired motion
gives stability and alignment
innervation/vascularization of synovial joint
rich supply of sensory nerve fibers that monitor pain but mostly joint pos and stretch
and rich supply of bv
3 factors that stabilize synovial joints
articular surfaces-shape det possible movements
ligaments- more you have-stronger it is; prevents excessive motion
MUSCLE TONE-tendons are kept tight at all times bc of muscle tone; tendons pull and hold joint in place. very important in shoulder and knee
most important stabilizing factor of synovial joints
muscle tone
bursae
flattened fibrous sacs lined w synovial memb and filled w synovial fluid common where ligaments muscles skin tendons and bones rub together
tendon sheath
elongated bursae that wraps completely around a tendon subject to large amounts of friction
body mvmt: GLIDING
occurs when one flat/nearly flat bone surface glides/slips over another back and forth/ side to side
body mvmt: FLEXION
bending mvmt along sagittal plane that DECREASES the angle of joint and brings articulating bones together
body mvmt: EXTENSION
mvmt along sagittal plane that increases the angle bt the flexed bones and typically straightens the body part
body mvmt: ABDUCTION
mvmt of a limb away from the midline or median plane of the body
along the frontal plane
body mvmt: ADDUCTION
mvmt of a limb towards the body midline
body mvmt: CIRCUMDUCTION
moving a limb so that it describes a cone in space
distal end in a circle while proximal end is more or less stationary
rotation
turning of a bone around its own long axis
supination
turning palm to its anatomical pos
palms forward
pronation
turning palm away from anatomical pos
palms facing back posterior
dorsiflexion
pointing toes up toward back
plantarflexion
pointing toes down toward ground
inversion
turning sole of foot medially
eversion
turning sole of foot laterally
protraction
non angular anterior mvmt
push jaw forward
retraction
non angular posterior mvmt
pull jaw in
elevation
lifting a body part superiorly
depression
moving elevated body part inferiorly
opposition
allowed by saddle joint in thumb
touching thumb to other fingers of same hand
