Bone Tissue Flashcards
Function of bone tissue
support protect movement mineral homeostasis (Ca and P) blood cell production (red bone marrow) stores triglyceride (yellow bone marrow)
metaphysis
epiphysial plate (where diaphysis meets epiphysis)
medullary cavity
where yellow marrow is located (adipocyte generation)
embolus
a thing floating through the blood stream that shouldn’t be there causes a clot (PE)
-fat embolus can occur after fraction of a long bone that contains lots of fatty tissue
articulate cartilage
contains hyaline cartilage
-long healing due to lack of blood flow
periosteum
CT surrounding bone
- outer layer has dense irregular CT
- inner osteogenic layer for growth in thickness
appositional growth
growth in thickness of bone
sharpey’s fibers
think bundles of collagen that attach periosteum to underlying bone
endosteum
thin membrane lining medullary cavity (surrounds inner membrane)
-where bone forming cells are located
matrix of bone cell contains
15% water
30 % collagen
55% crystallized mineral (Calcium phosphate and crystals of hydrozyapatite)
hydrozyapaptite
combination of calcium phosphate and hydroxide
minerals contained in the bone tissue
calcium carbonate magnesium fluoride potassium sulfate
hardness of bone depends on
amount of mineralized salts
flexibility of bone depends on
amount of collagen
osteoclast derives from
monocyte (many come together-50)
used to reabsorb bone tissues
-primarily in endosteum
osteogenic cell
unspecialized stem cell derived from mesenchyme,
- daughter cells are osteoblasts
- located in periosteum, endosteum and blood vessel canals within bone
osteoblasts
secrete collagen and matrix
initiate process of calcification
osteoid
matrix of bone tissue
osteocyte
so named when osteoblast has matured and it maintains current environment
osteon
haversion systems-repeating unit of compact bone
lamellae
rings surrounding Haversian canal
- concentric (surrounding canal)
- outer circumferential (outer layer of whole thing)
- interstitial (in between concentric lamellae)
lacunae
spaces between concentric lamellae contain cell body of osteocytes
caniliculi
radiate in all directions from lacunae
-contain extracellular fluid
how do osteocytes communicate?
gap junctions
Volkman canals
connect central Haversian canals
trabeculae
found in spongy bone
consists of concentric lamellae and osteocytes in lacunae
have no central canals
where is spongy bone located?
interior of flat bones
short bones
irregular bones
sesamoid bones
what does spongy bone contain?
red bone marrow
which bone gets weakened first in osteoporosis
spongy bone
diploe
spongy bone sandwiched between layers of compact bone
trabeculae is organized so that it
resists stress without breaking
final arrangement of bone is finalized when
child is upright and walking
where is red bone marrow located in adults?
hip bones (pelvis) ribs sternum vertebrae proximal ends of humerus and femur
bone scan is read by looking at
hot and cold spots
- hot spots indicate metabolisms that absorb more tracers (cancer, healing fractures, abnormal bone growth)
- cold areas indicate decreased metabolism (weak area of bone, degenerative disease, decalcified bone, Paget’s disease, rheumatoid arthritis)
ossification or osteogenesis
bone formation process used during infancy, childhood and adolescence throughout life and when repairing a fracture
intramembranous ossification
bones form within mesenchyme which is arranged in sheetlike membranes
endochondral
bones form within hyaline cartilage that develops from mesenchyme (replacing cartilage with bone)
bones that use intramembranous ossification to form are
flat bones of skull facial bones mandible medial portion of clavicle closing fontanelles of babies
interstitial growth
cells begin to separate from their neighbors in the example of chondrocytes
hyaline cartilage is laid down by
chondroblast
secondary ossification sites don’t start working in infants until
after birth
in long bones, you would find hyaline cartilage
along epiphysial plates AND
at articular cartilage areas
perichondrium
precursor to the periosteum
vertical long bone growth stops at
puberty
zone of resting cartilage
place holder cartilage
does not play an active role in bone growth
(closest to epiphysis)
zone of proliferating cartilage
slightly larger chondrocytes and arranged like stacks of coins, they secrete matrix and they undergo interstitial growth
zone of hypertrophied cartilage
large, mature chondrocytes arranged in columns
zone of calcified cartilage
a few cells thick and contains dead chondrocytes that are surrounded by calcified matrix (closest to the diaphysis)
fractures through epiphyseal plate in childhood can result in
unequal bone lengths
especially in lower extremities
appositional growth
making bones grow thicker
creation of new osteons making periosteal cells differentiate into osteoblasts
at any given time how much bone mass is being remodeled?
5%
renewal rate of compact bone
4% per year
renewal rate of spongy bone
20%
pathological fracture
when minor trauma or nothing causes a fracture (bone tumor, osteoporosis)
sequence of physiological growth of babies
1, neurological
- weight bearing (muscles)
- standing upright
contour/shaping of bones influenced by
muscles
spasticity
rigidity in the muscle (resist passive movement)
inability to walk
will cause problems with bone density, correct contour of bone)
osteoporosis
breakdown of bone occurs faster than making new bone
Rickets
Vitamin D deficiency in children
osteomalacia
vitamin D deficiency in adults
excess bone tissue
bone spurs (heals mostly)
Paget’s disease
excessive proliferation of osteoclasts (too much spongy bone compared to compact bone)
- pathologic fracture
- deformity
function of vitamin A in bone
stimulates osteoblasts
function of vitamin C in bone
synthesis of collagen
function of vitamin K and B12 in bone
synthesis of bone proteins
function of vitamin D in bone
calcium absorption in the gut
insulin like growth factor (IGFs)
produced by liver and bone tissue HGH pathway (human growth hormone)-anterior pituitary
function of thyroid hormones in bone
affects bone growth
function of insulin in bone
helps build bone (anabolic)
function of sex hormone in bone
estrogen has protective affect in bone
puberty helps to grow bone
open (compound) fracture
penetrated the skin
greenstick fracture
torsion fracture (hair line fracture)
impacted (compression) fracture
pieces pushed together
common in vertebrae of old ladies
Pott’s fracture
ankle fracture
Colle’s fracture
wrist fracture
comminuted fracture
does not break through the skin, but breaks into 3 or more pieces
4 stages of bone fracture repair
- a hematoma forms
- fibrocartilaginous callus forms
- bony callus forms
- bone remodeling occurs
ORIF
open reduction internal fixation (realigns and places hardware to allow bone to heal correctly)
closed reduction
resetting bone without surgery
open reduction
resetting bone with surgery
osteogenic sarcoma
common in kids (lower femur or upper tibial)
normal serum Calcium level
9-11 mg/dl
high serum calcium could cause
cardiac arrest
low serum calcium could cause
respiratory arrest
places where PTH acts when it is called on by the PT
osteoclasts in bone
gut to absorb calcium from food
kidney to promote vitamin D which promotes calcium absorption from the gut