Exam #2 Chapter 6 Flashcards
during long bone growth what happens on the diaphyseal side?
cartilage is replaced by bone at the same rate
if pressure in bones causes electrial changes that increase activity of osteoblasts what does it mean if you have a broken bone and apply weight to it?
it can speed up the heeling process
what does PTH cause osteoblasts to release?
RANK ligand
what does circumferential lamellae do to the bone surface?
it makes it smooth
does increasing mechanical stress on bones increase or decrease osteoblast activity?
increases
what cell becomes more active when blood calcium levels are too high?
osteoblasts
what do blood vessels grow into during endochondral ossification?
the perichondrium
who does the acceleration of bone growth from reproductive organs happen sooner?
females
where are hairline fractures common?
in the skull
how is spongy bone arranged?
into trabeculae
what substance makes up a major portion of the bone?
hydroxyapatite
how much of the weight of bone do bone cells account for?
2%
what type of ossification forms the epiphysis of the clavicle?
endochonral
what does spongy bone contain?
trabeculae of bone oriented on lines of stress
what is the difference between intramembranous and endochondral ossification?
in intramembranous ossification, bone forms from preexisting connective tissue membranes and in endochondral ossification bone forms from a preexisting cartilage model
what type of cells can reabsorb bone?
osteoclasts
what is the epiphysis?
the part of the long bone that develops from a center of ossification distinct from that of the diaphysis
what is the process of events to create woven bone? (3) (COO)
1) Connective tissue membrane is formed
2) osteochondral progenitor cells become osteoblasts
3) osteoblasts produce woven bone
what does compact bone cover?
the spongy bone of the epiphysis
when someone is bedridden or paralyed (reduced stress on bones) what does that do for osteoblast activity?
it decreases, resulting in less bone density
where does cartilage grow in bone?
at the surface underneath the perichondrium or in the center
how is compact bone organized?
into osteons
what is the hollow space within the diaphysis of a long bone called?
the medullary cavity
what is used to produce bone in humans for the first time?
ossification
what attaches to the periosteum?
tendons and ligaments
what is another name for brittle bone disorder?
osteogenesis imperfecta
when is bone mass at its highest?
around age 30
what is an example of a short bone?
carpal or wrist bone or sesmoid
what do both methods, intramembranous and endochonral produce?
woven bone which is then remodeled into lamellar bone
what does calcitrol cause?
the gut to absortb more calcium
when cartilage grows at the surface underneath the perichondrium what is it called?
appositional growth
what is the most significant age related changes in the skeletal system?
the quality and quantity of bone matrix
what provides the bone from the periosteum?
blood vessels and nerves
since spongy bone has no osteons what does it also lack?
a central canal
what do blood vessels, osteoblasts and osteoclasts do during endochondrial ossification?
they penetrate the center to form the primary ossification center and woven bone
what is concentric lamellae?
circular layers of bone matrix that surround the central canal
what happens to the woven bone during bone repair?
it’s remodeled to make a strong repair
what happens to the chondrocytes in the center during endochondrial ossification?
they enlarge, calcify and die
what do osteoblasts form during appositional growth?
ridges around a periosteal blood vessel
after ossification forms woven bone, what takes place?
bone is then remodeled into lamellar bone
bone is broken into at lease 2 fragments
complete fracture
what is bone modeling done by?
BMUs of osteoblasts and osteoclasts
what factors affect bone growth? (3)
1) adequate nutrition
2) level of growth hormone and thyroid hormones
3) reproductive hormones
what are the ossification regions formed during early fetal development?
primary ossification centers
what does intramembranous ossification form? (3)
1) the flat bones of the skull
2) some facial bones
3) part of the clavicles and mandible
what happens to the hyaline cartilage during endochondral ossification?
it remains at the ends and in the epiphyseal plates
how is woven bone formed?
from ossicfication
how does cartilage often occur?
in thin plates or sheets
what forms between the ends of the bone during bone damage?
a cartilage callus
where are chondrocytes located within?
lacunae
what does compact bone have?
osteons parallel to lines of stress
what is the function of the red marrow?
site of blood cell production
what are bones classified by?
shape
does the removal of mechanical stress on bones increase or decrease osteoblast activity?
decreases
what does calcitonin do?
inhibits osteoclasts and causes the kidneys to excrete more calcium
what do osteoblasts do first?
secrete the organic part of the matrix (collagen)
hyaline cartilage that covers long bone
articular cartilage
how does long bone grow?
in length
what is the structure of spongy bone?
it’s strong and light
what does spongy bone have?
bone marrow around the trabeculae
when cartilage grows in the center what is it called?
interstitial growth
what is the process of events to create bone? (5) (CCCBO)
1) Chondrocytes hypertrophy
2) Cartilage matrix calcifies
3) chondrocytes die
4) blood vessels grow into lacunae
5) Osteoblasts deposit bone
what does the epiphyseal plate consist of?
zones resting cartilage (nearest the epiphysis), proliferation, hypertrophy and calcification.
what does messenchymal cells do during intramembranous ossification? (3) (BSF)
1) become osteoblasts in an ossification center
2) secrete bone matrix
3) form trabeculae of woven bone
what does messenchyme form during endochonral ossification?
a hylaine cartilage model of the bone
what is an example of an irregular bone?
sphenoid bone from the skull or scapula
what initially accelerates bone growth?
reproductive hormones
in the zone of hypertrophy during long bone growth what is happening?
chondrcytes enlarge
how do reproductive hormone accelerate bone growth?
eventually the zone of calcification catches the zone of proliferation and the epiphyseal plate closes
what is red marrow and where is it located?
connective tissue in the spaces of spongy bone or medullary cavity (in diaphysis)
what do blood vessels, osteoblasts and osteoclasts penetrate the epiphysis to form?
secondary ossification centers
what is the diaphysis composed of?
primarily compact bone but it can also contain spongy bone
which cells are very large and multinucleate?
osteoclasts
what does osteoblasts do?
build bone (ossification or osteogenesis)
what does endochondral ossification form?
most of the bones of the skeleton
to maintain calcium homeostasis what are blood calcium levels important for?
proper muscle and neuron function
what shapes can bone be?
long, flat, short and irregular
what is an example of reduced mechanical stress on bones?
someone who is bedridden or paralyzed
what does pressure in bones cause?
electrical changes that increase the activity of osteoblasts
what is the body from all the calcium?
a calcium reserve
where do osteocytes live?
in lucunae between lamellae
how does growth work with the epiphyseal plate?
cartilage growth followed by endochondral ossification results in growth in bone length
what are calcium levels regulated by?
two hormones with opposite effects
if blood calcium levels fall what do the parathyroids secrete?
PTH
what do chondrocytes derive from?
chondroblasts
what are the components of the skeletal system?
1) bones
2) cartilages
3) ligaments (bone to bone)
4) tendons (muscle to bone)
5) joints
overactivity of which cells can cause hypocalcemia?
osteoblasts
what does bone undergo?
repair when damaged
when blood calcium level rises what does the thryoid release?
calcitonin
what do osteons contain?
a central canal with blood vessels
what is required for bone growth?
adequate nutrition
when does bone formation begin?
8 weeks after fertilization as a connective tissue model is replaced by bone
if secretion of PTH increases and osteoclast activity increases what happens to blood calcium levels?
it increases
an incomplete fracture on the convex side of the curve of the bone
greenstick fracture
what does short and irregular bones have?
spongy bone overlaid with compact bone
what can be attributed to increased pressure on bone?
increased osteoblast activty and electrical charge changes
is spongy bone random?
no
what does woven bone tend to resemble?
spongy bone
in the zone of proliferation during long bone growth what is happening?
hyaline cartilage grows by interstitial growth- increasing the length of the bone
what type of lamellae are found in osteons?
concentric
what eventually happens to the blood vessel during appostional growth?
it is enclosed and further growth forms an osteon
what cell does PTH cause to become more active?
osteoclasts
what happens to the osteochondral progenitor cells after blood vessels grow into the periochondrium during endochonrial ossification?
they become osteoblasts which lay down a thin layer of bone
what is the englarged end with an epophyseal (growth) plate/line and articular cartilage on the end called?
the epiphysis
what is woven bone formed with?
randomly oriented collagen fibers
what is circumferential lamellae?
forms the outer surfaces of compact bone and are thin plates that extend around the bone.
does calcitonin inrease or decrease blood calcium levels?
decreases
do bones store vitamin D?
no
during, long bone growth what occurs in adults?
the epiphyseal plate become the epiphyseal line
what is interstitial lamellae?
remnants of concentric or circumferential lamellae that were partially removed during bone remodeling.
how would bone be affected if the ratio of collagen to hydroxyapatite increased?
it would become less strong, more flexible and and less brittle
during growth in length of long bone, cartilage forms and then ossifies, which zone does ossification occur?
calcification
when someone is bedridden or paralyzed (reduced stress on bones) what does that do for osteoclast activity?
it continues at a nearly normal rate
characteristics of the periosteum of a long bone
1) has an outer layer of dense irregular connective tissue
2) has an inner cellular layer with osteoblasts, osteoclasts and stem cells
where does long bone growth occur?
at the epiphyseal (growth) plate
which cells respond directly to mechanical stress?
osteocytes
if the soft tissues around a closed fracture are damaged
complicated fracture
what is yellow marrow and where is it found?
fat stored within the medullary cavity or the spaces of spongy bone
occurs when an open wound extends to the site of fracture or when a fragment of bone protrudes through the skin
open fracture (compound)
what extends into the bone from the periosteum?
collagen (preforating) fibers
what does bone matrix contain?
collagen fibers (strong and flexible) and a calcium phosphate crystal called hydroxyapatite (hard and brittle) and has properties of both components
what is another name for diaphysis?
shaft
what does PTH cause? (3) (KOK)
1) the kidneys to retain more calcium
2) osteoclasts to release more calcium from bone
3) the kidneys release more calcitrol
what does vitamin D do?
increases the absorption of calcium from the small intestine.
what is bone remodeled into lamellar bone with?
collagen fibers arranged along lines of stress
what does messenchyme form during intramembranous ossificatoin?
a membrane/sheet with then ossifies
what does flat bones consist of?
a center of spongy bone between compact bone
what type of process is bone remodeling?
a continuous process
how does bone grow in the periosteum?
in diameter
what is the bone remodeled to form during endochondrial ossification?
compact bone and marrow cavity
what type of tissue is bone?
a living tissue
how much of the skeleton is the body’s calcium?
99%
when is the periosteum no have a double layered connective tissue membrane covering it?
when articular cartilage is present
where does interstitial lamellae occur?
between osteons
one fragment is driven into the spongy portion of another fragment type of fracture
impacted fracture
what would chemical analysis reveal about someone with osteoperosis compared with someone with normal bones?
no difference because the problem with osteoporosis is one of bone quantity not chemical makeup
what is an example of a long bone?
femur or thigh bone
are all 3 types of cartilage associated with bone?
yes
during long bone growth what grows on the epiphysis side of the epiphyseal plate?
cartilage
what are the functions of the skeletal system? (5)
1) body support (ligaments)
2) organ protection
3) body movement (tendons)
4) mineral storage
5) blood cell production
what two passageways or canals extend from the periosteum to the medullary canal?
volkmann canals and perforating canals
what does hyaline cartilage form in bone?
1) growth plate in some bones
2) articular cartilage and most bones begin formation from a hylaine cartilage model
what is the endosteum composed of?
osteoclasts, osteoblasts and stem cells
what type of ossicication forms the inferior part of the occipital bone?
endochondral
where are osteocytes found?
encased in empermeable matrix in lacunae connected to other osteocytes by cell extensions in canalicuil.
what is an example of a cavity lined by an endosteum?
medullary cavity of the diaphysis and the smaller cavities in spongy and compact bone
what are the zones of growth in the epiphyseal plate in order from starting in the epiphysis and ending in the diaphysis? (5)
1) Zone of resting cartilage
2) zone of proliferation
3) zone of hypertrophy
4) zone of calcification
5) zone of ossified bone
what is the cartilage callus replaced by?
woven bone by osteoblasts
what does spongy bone lack?
osteons
what cells does calcitonin cause to become less acrive?
osteoclasts
what is the structure of the long central part of a long bone?
composed mostly of compact bone, with a marrow cavity is the diaphysis
a fracture where the skin is not perforated
closed fracture (simple)
what attaches through the periosteum?
ligaments and tendons
in the zone of calcification during long bone growth what is happening? (3) (CBO)
1) chondrocytes die
2) blood vessels invade the tissue
3) osteoblasts deposit new bone matrix
what bone is damaged what happens?
blood forms a hematoma of clotted blood
what happens during bone remodeling?
old matrix is degraded by osteoclasts and osteoblasts build new matrix
what is associated with osteoclast resorption?
hydrogen ions form an acid environment in bone matrix
what is an example of a flat bone?
parietal bone from roof of skull or sutural bone in the skull
a fracture that does not extend completely across the bone
incomplete fracture
what does spongy bone have many of?
small spaces
a complete fracture in which the bone breaks into more than two pieces- usually two major fragments and a smaller fragment
comminuted fracture
what is the epiphysis of the bone?
the part of the bone that develops from a center of ossification distinct from the diaphysis
what cells are found in bone?
1) osteoblasts
2) osteocytes
3) osteoclasts
4) messenchymal cells
does calcitrol increase or decrease blood calcium levels?
increases
if the secretion of parathyroid hormone (PTH) increases what happens to osteoclast activity?
it increases
what is the skeleton usually thought to be?
the framework of the body
when does a slow loss of compact bone begin?
around 40 and increases after 45
what does compact bone look like?
it’s solid looking
incomplete fracture in which two sections of bone do not separate
hairline fractures
what does compact bone form?
the diaphysis
where does red bone marrow form during intramembranous ossification and what happens ?
between the trabeculae and a periosteum forms
what does adequate nutrition include for bone growth?
vitamins D and C
what would be a consequence of a vitamin D deficiency ?
bones become soft and pliable
what does compact bone have?
dense bone with few internal spaces
what is the epiphyseal plate?
an area of hyaline cartilage between the diaphysis and epiphysis.
what does osteoblasts do second?
encourage the deposition of calcium salts (calcification) and become osteocytes
where is spongy bone mainly found?
in the epiphysis
characteristics of the endosteum of long bone
1) single layer of connective tissue
2) lines internal surfaces of all cavities within bons
what does appositional growth beneath the periosteum increase?
bone width
how does mechanical stress placed on a bone affect bone remodeling?
makes it stronger
a disease in adults that is characterized in sofenting of bones resulting from calcium depletion
osteomalacia
