Skeletal System Flashcards
conditions of adult cartilage
not innervated
high water content
surrounded by perichondrium
dense irregular connective tissue for blood supply
three types of cartilage
hyaline
elastic
fibrocartilage
functions of bone
support
protect
movement
mineral storage
blood cell formation
triglyceride storage
hormone production
support function
framework that supports body
protection function
protective case for brain, spinal cord, and vital organs
movement function
anchors/levers for muscles
mineral storage function
reservoir for minerals (calcium and phosphate) and growth factors
blood cell formation function
hematopoiesis in bone marrow
hormone production function
energy cycle and osteocalcin
axial skeleton
skull
vertebrae
rib cage
appendicular skeleton
upper and lower limbs
shoulders
hips
classification of bones by shape
long
flat
short
irregular
long bones
longer than wide
flat bones
thin, flattened, curved
sternum, scapula, skull, ribs
short bones
cube-shaped, wrist/ankle
sesamoid, inside tendons and joints
irregular bones
odd shapes
vertebrae
shape directly related to function
condyle
round prominence at end of bone
epicondyle
prominence on distal part of long bone
trochanter
protruberances which muscles attach or bones connect
tubercle
round nodule, small emience
tuberosity
rounded, long prominence
trochlea
grooved structure
fossa
depression or hollow
foramen
opening
meatus
external opening leading into body
compact bone
denser outer layer, smooth surface
spongy bone- diploe
inner honeycomb layer
trabeculae filled with red/yellow marrow
sandwich like structure
thin plates of spongy covering in compact bone
no defined marrow cavity
no diaphysis or epiphyses
covered by connective tissue layers
structure of flat, irregular, or short bones
sandwich like
structure of long bone
diaphysis and epiphyses
diaphysis
tubular shaft of long part
exterior is compact bone with thin layer of spongy bone
interior is medullary cavity with yellow marrow
epiphysis
rounded expanded ends of long bones
exterior is compact bone
interior is spongy bone
epiphyseal line/plate
growth plate
separates diaphysis from epiphyses
adding length to long bones during childhood
bone membranes
periosteum
endosteum
periosteum
two layers
outer fibrous layer- dense irregular connective tissue
inner osteogenic layer with osteogenic stem cells
supplied with nerve fibers, blood, and lymph vessels
anchors collagen
endosteum
delicate layer covering internal bone surfaces
covers trabeculae of spongy bone
lines canals of compact bone
contains osteogenic stem cells
hematopoietic tissue
red marrow
infants- medullary cavity of long bones and all areas of spongy bone
adults- in diploe of flat bones and head of femur and humerus
hemostatic help
yellow marrow can covert to red marrow under conditions of extreme anemia
4 types of bone cells
osteogenic cell
osteoblasts
osteocytes
osteoclasts
osteogenic cell
bone stem cells- actively dividing cells
gives rise to osteoblasts and more progenitors
osteoblast
bone building cells
responsible for bone growth
osteocyte
mature bone cells
monitor and maintain bone matrix
in lacunae or lining bone surfaces
osteoclast
bone digesting cell
resorption
lamella
weight bearing columns
collagen in opposite directions to resist twisting
haversian/central canal
contains blood vessels and nerves
volkmann’s canals
horizontal channels connecting medullary cavity to haversian canal and periosteum
osteon
haversian system
contain osteocytes, lacunae, canaliculi
lacunae
small cavities in bone containing osteocytes at lamella junctions
canaliculi
hair like canals that connect lacunae to each other and central canal
same direction as volkmann’s canal
spongy bone composition
trabeculae align along lines of stress
irregularly arranged lamella with osteocytes and canaliculi
organic components - resist tension
bone cells
osteoid- unmineralized bone matrix
osteoblasts secrete proteoglycans, glycoproteins, and collagen
about 1/3 of bone matrix
allows bone to resist stretching and twisting
sacrificial bonds
found between collagen
break and reform to prevent large scale fractures
inorganic components- resist compression
mineral salts
65% of bone by mass
calcium phosphate crystals packed around collagen
responsible for bone hardness
osteogenesis/ossification
formation of bony skeleton in embryos
bone growth until early adulthood
bone thickness, remodeling, and repair
embryonic development
most of skeleton first formed is cartilage or fibrous membranes
cartilage can divide and multiple quickly to grow as rapidly as fetus does
gradually replaced by bone in third month
when does bony skeleton formation occur
begins at week 8 of embryonic development
intramembranous ossification
bone develops from fibrous membrane
forms flat, cranial bones of skull
endochondral ossification
bone forms by replacing hyaline cartilage
forms all other bones of body
stages of intramembranous ossification
- mesenchymal cells produce fibrous membrane
- ossification center appears with osteoblasts
- bone matrix is woven in between blood vessels
- spongy bone and outer periosteum form
- compact bone forms (lamellar)
- red marrow appears in spongy bone
stages of endochondral ossification
- blood vessels infiltrate perichondrium converting it to periosteum- primary ossification center
- mesenchymal cells become osteoblasts
- formation of bone collar around diaphysis
- hyaline cartilage calcifies, matrix deteriorates, creates cavities as chondrocytes die
- invasion of internal cavities by periosteal bud, spongy bone formation by osteoclasts and osteoblasts
- formation of medullary cavity, elsewhere cartilage continues expanding
- at birth, secondary ossification center forms in epiphyses
- spongy bone replaces cartilage of epiphyses
where is the only place cartilage remains during endochondral ossification
epiphyseal plates and articular cartilage
appositional bone growth
outside in
cells secrete matrix against external face of existing cartilage
cells in periosteum
bones get thicker - strengthen area
interstitial bone growth
inside out
lacunae bound cells divide and secrete new matrix
expand tissue from within
long bones lengthen
two types of growth of bone/cartilage
appositional
interstitial
when is most bone/cartilage development complete?
adolescence
when does calcification of cartilage occur?
during normal bone growth
during old age
four distinct zones for postnatal bone growth
proliferative/growth
hypertrophic
calcification
ossification
proliferative/growth zone
chondrocytes divide
push epiphysis away from diaphysis
quiescent
resting
cartilage closest to epiphysis
transformation zones
hypertrophy- older chondrocytes enlarge
calcification- matrix becomes calcified, chondrocytes die
ossification zone
new bone formation by osteoblasts and osteoclasts
remodeling
resorption and deposition
as bone grows in length, remodeling maintains bone’s shape
appositional growth in remodeling
for width
osteoblasts- add bone from periosteum
osteoclasts- resorb bone near surface of endosteum
overall effect- bone increases with width, bone doesn’t get too heavy
epiphyseal plate closure
chondroblasts divide less often
plate becomes thinner
occurs at 18 in females, 21 in males
hormones for bone growth in infancy and childhood
growth hormone
thyroid hormone
hormones for bone growth at puberty
testosterone and estrogens
initially promotes growth spurts
causes masculinization and feminization of skeleton
later induces epiphyseal plate closure
bone recycling
5-10% bone is recycled each year for calcium storage and release
spongy replaced every 3-4 years
compact replaced every 10 years
high stress areas remodeled more frequently
bone deposition
occurs where bone is injured or added strength is needed
through diet (proteins, vitamins, calcium, phosphorus, magnesium) and enzymes (alkaline phosphatase for mineralization)
alkaline phosphatase
adds more bone matrix for bone growth
too much leads to bone cancer
bone resorption
osteoclasts secrete lysosomal enzymes and hydrochloric acid to release stored calcium to blood supply
lysosomal enzymes
digest organic matrix
roles of calcium
transmits nerve impulses
muscle contraction
blood coagulation
cell division
secretion by glands and nerve cells
intestine absorbs using vitamin D
control remodeling
hormonal mechanisms- decides whether and when remodeling occurs
mechanical forces- decides where remodeling occurs
one of hormonal mechanisms for control remodeling
maintain calcium homeostasis in blood
falling blood calcium level signal to parathyroid glands to release parathyroid hormone (PTH)
PTH signals osteoclasts to degrade bone matrix and release calcium into blood
second of hormonal mechanisms for control remodeling
rising blood calcium levels trigger thyroid to release calcitonin
stimulates calcium deposit and storage in bone
more pronounced in childhood
mechanical forces on control remodeling
act on skeleton
wolff’s law
curved bones thickest where most likely to buckle
atrophy when not used
projections used for muscle attachment
Wolff’s law
bones grow in strength in response to the forces placed upon them
how can you tell which hand is dominant?
higher density in right arm because it is used more often
boney processes get more dense, not necessarily larger
classification of bone fractures
position
degree
orientation
skin damage
position of break
displaced- not lined up
non-displaced- stays lined up
degree of break
complete- full break
incomplete- partial, crack
orientation of break
linear- length of bone
transverse- across bone
skin damage of break
compound- open, breaks skin
simple- closed, no break in skin
comminuted fracture
bone breaks into three or more pieces
shattered
common in elderly (brittle bones)
spiral fracture
ragged break when bone is severely twisted
common sports fracture
depressed fracture
bone is pressed inward
for flat bones
typical of skull fractures
compression fracture
bone is crushed
typical of osteoporosis in vertebrae
epiphyseal fracture
epiphysis separates from diaphysis along plate
occur where cartilage cells are dying
important in children still growing
greenstick fracture
incomplete fracture
one side of bone breaks and other side bends
common in children with flexible bones
treatment of fractures
reduction- realignment of broken bone ends
immobilization- cast or traction
stages of bone healing
- hematoma formation
- fibrocartilanginous callus formation
- bony callus formation
- bone remodeling
hematoma formation stage of bone healing
torn blood vessels hemorrhage, mass of clotted blood
cells without blood supply die off
pain, inflammation, swelling, and bruising
fibrocartilaginous callus formation stage of bone healing
forms splint across fracture
blood vessels form
phagocytic cells clean debris
fibroblasts secrete collagen across break
chondroblasts secrete cartilage - replaces with bone
bony callus formation stage of bone healing
osteoblasts form spongy bone
fibrocartilaginous callus converts to bony callus
continues similar to endochondral ossification
bone remodeling stage of bone healing
excess material removed
new compact bone rebuilds shaft walls
several months (longer for elderly)
treatments for damaged bones
electrical stimulation
ultrasound
fibular graft
VEGF
bone substitutes
electrical stimulation
speeds healing after large fractures using wolff’s law
ultrasound
reduces time to heal broken arms and shins
fibular graft
improved way to graft bone in areas with severe damage
donor tissue from fibula
VEGF
growth factor that increases blood supply
bone substitutes
implanted at damage sites
natural coral or synthetic materials
coated with BMP (bone morphogenic protein)
3D printed bones
perfectly designed to match patient
made of titanium powder, heated and fused by laser
includes passage of nerves and blood vessels
osteomalacia
not enough calcium crystals mineralized into bone matrix
weakened bones
pain when weight is put on affected bone
insufficient calcium or vitamin D
rickets
childhood forms of osteomalacia
softened weak bones
bowed legs and deforms pelvis, skull, rib cage
insufficient calcium or vitamin D
osteoporosis
group of disease which bone reabsorption outpaces bone deposit
light and porous bones
postmenopausal women
osteoporosis prevention
good diet early in life
weight bearing exercise
no smoking
fewer carbonated drinks/alcohol
fluoride
osteoporosis treatment
calcium and vitamin D supplements
weight bearing exercise
drugs that stimulate osteoblasts and inhibit osteoclasts
hormone replacement therapy (slows bone loss)
paget’s disease
excessive bone formation and breakdown
spotty weakness in bone
overabundance of spongy bone relative to compact bone
localized to spine, femur, pelvis, and skull
achondroplasia
form of genetic dwarfism
reduced cartilage formation reduces endochondral bone formation
mutation in gene important for cartilage changed to bone
osteogenesis imperfecta
insufficient collage deposition
bones become brittle and shatter easily
