Chapter 6: Skeletal System Flashcards
what are the five major functions of the skeletal system?
- support
- protection
- movement
- storage
- blood cell production
what type of cartilage is associated with bone?
hyaline cartilage
What is the role of hyaline cartilage
a. it is the precursor for most bones of the body
b. bone lengthening and repair often involve producing hyaline cartilage first, then replace with bone tissue
what cell type is produces hyaline cartilage
chondroblasts
When will chondroblasts convert to chondrocytes?
once matrix surrounds it which contains collagen and proteoglycan
What are lacunae?
spaces in matrix where chondrocytes resicle
What is perichondrium?
double layered connective tissue that covers cartilage
bone to muscle
tendon
bone to bone
ligament
tendons and ligaments both contain
dense regular connective tissue, containing collagen fibers produced by fibroblasts
what are the organic components of the matrix?
collagen and proteoglycan
What gives the matrix its flexible strength?
collagen
A bone’s inorganic material is mineral known as
hydroxyapatite
What is a hydroxyapitie
crystallized calcium phosphate which gives the bone matrix the quality of weight-bearing strength
What is the function of osteoblasts?
to form both organic and inorganic bone matrix
What is the function of osteclasts?
resorption (breakdown) of bone matrix
Where are osteoclasts located?
in lacunae, with extensions in canaliculi
What are canaliculi?
canals in matrix containing extensions of osteocytes and allow direct passage of material between osteocytes
What is the function of osteoclasts
reabsorption of bone matrix
a. secrete H+ ions to create an acidic environment that decalcifies matrix
b. secrete enzymes to digest the protein components of the matrix
Osteoblasts and osteoctyes are derived from what?
Osteochondral progenitor stem cell
What makes up the matrix?
osteoblasts
collagen
hydroxapatile
proteoglycan
What type of bone is lamellar and what does this mean?
Mature bone
its matrix is organized into thin sheets or layers
are sandwiched into layers between the lamellae
If collagen fibers are oriented into a single layer they are what?
parallel
if collagen fibers are oriented into one layer compared to adjacent layers?
at an angle to one another
What are trabeculae in spongy bone?
consists of interconnecting rods/plates
oriented within the bone along lines of stress
What fills the spaces between the trabeculae?
red bone marrow
What is compact bone comprised of?
osteon
What does each osteon contain?
- central canal: containing blood vessels and nerves and lined with endosteum
- concentric lamellae: around the central canal
- Osteocytes within lacunae, connected by canaliculi
the bone’s surface is surrounded by what?
circumferential lamellae
Blood vessels from the bone’s surface membrane or its medullary canal are in what?
perforating or Volkmann’s canal
In which direction do perforating or Volkmann’s canal run to the central canals for exchange of nutrients and wastes
transversely
what is a concentric lamallae?
part of the bones that surround central canal
where is the interstitial lamallae located?
between osteons
examples of long bone
upper and lower limbs
examples of short bone
carpals and tarsals
examples of flat bones
ribs, sternum and skull scapula
examples of irregular bones
vertebrae, facial
what is the diaphysis of a long bone?
the shaft composed primarily of compact bone tissue with a central canal medullary cavity containing mostly yellow marrow in adults
epiphyses of a long bone
the end of long bones composed primarily of spongy bone tissue
epiphyseal plate of long bone
the growth plate located between the diaphysis and epiphysis, where bone growth takes place until the plate becomes an ossified epiphyseal line
what happens to a long bone after it stops growing
becomes an ossified epiphyseal line
What are bone spaces filled with?
bone marrow
where is the best location to harvest red marrow for bone marrow transplant
hip bone, largest amount of spongy bone
what is the outer layer of a periosteum made out of and what does it contain?
dense irregular connective tissue and contains blood vessels and nerves
what does the inner layer of a periosteum consists of?
osteoblasts, osteoclasts, OPC
what is a endosteum?
single layer of cells lining internal surfaces of all cavities within bones
three types of endosteum
osteoblasts, osteoclasts, OPCs
what type of bone is interior spongy bone framework sandwiched between two layers of compact bone
flat bones
what type of bone is center composed of spongy bone, outer surfaces of compact bone
short and irregular bones
What is the intramembranous ossification
used to form many skull bones and the mandible and diaphyses of clavicles
Endochondral ossification is used to form what bones?
- base of skull
- part of mandible
- epiphysis of clavicle
- most of remaining bones of skeletal system
What are the two ways in which bone grow?
longitudinally (at growth plate) and appositionally (in width)
What are the four zones of a epiphyseal plate?
- zone of resting cartilage
- zone of proliferation
- zone of hypertrophy
- zone of calcification
- zone of ossification
on the diaphyseal side of the plate, calcification causes what to happen?
causes the hypertrophied chondrocytes to die and blood vessels invade the area
during longitudinal growth, what happens to the blood vessels?
they arrive from the endosteum and deposit bone matrix on the surface of the zone of calcification
what maintains the bone’s shape?
remodeling
where does the zone of resting cartilage?
nearest the epiphysis
what happens during the zone of proliferation
chondrocytes divide rapidly, forming columns and produce new cartilage
what happens during the zone of hypertrophy
chondrocytes produced in the zone to mature and enlarge
what happens during the stage of calcification?
matrix in mineralized with Ca
where also do long and short bones lengthen by a similar mechanism?
articular cartilage
what is the appositional bone growth?
beneath the periosteum increased the diameter of long bones and the size of other bones
what do osteoblasts from the periosteum form?
ridges with grooves between them
what eventaully happens to the ridges in the periosteum
they grow together, converting the grooves into tunnels filled with concentric lamellae to form osteons
what to osteoblasts from the periosteum do?
lay down circumferential lamellae, which can be remodeled
how is the potential size and shape determined?
genetically
What are the three factors that affect gone growth?
- size and shape
- nutrition
- hormones
what may nutritional deficiencies may prevent
full height and proper bone shape
What does Vitamin D deficiency inhibit?
Calcium absorption so mineralization of the bones is reduced
What does Vitamin C deficiency inhibit?
collagen synthesis so organic components of the bone matrix cannot be properly maintained
What happens to bones when you have too much Vitamin D? Vitamin C?
Vitamin D: bones are brittle
Vitamin C: bones bend
what are hormones essential in?
correct concentrations for bone growth
purpose of growth hormone?
cartilage and appositional growth
purpose of thyroid hormone?
stimulates growth of most tissue
purpose of estrogen and testosterone
initial growth and then ossification of metaphysis; grow fast and then quick
in bone remodeling osteoclasts remove old bone and osteoblasts lay down new bone in order to…
- convert woven to lamellar bone
- change a bone’s shape
- modify the bone’s strength in response to stresses
- repair fractues
- regulate body Ca+ ion to levels
When is parathyroid hormone released?
when blood Ca++ is low, to increase levels
What does PTH target?
a. bone: to break done matrix by increasing osteoclast activity
b. intestines: to increase Ca+ absorption
c. kidney: to produce vitamin D and to reabsorb Ca++ from filtrate
When does calcitonin hormone released?
when blood Ca++ is too high, to reduce levels
What does calcitonin target?
a. bone: to keep osteoclast activity low
b. intestines: to decrease Ca+ absorption
c. kidney: to increase Ca++ excretion in urine
What is the function of osteocytes?
main bone matrix
