Looks like no one added any tags here yet for you.
dynamic tissue
continually being formed and brocken down
Two subdivisions of the skeleton
axial: central
appendicular: arms+legs
Compact bone
cortical “solid bone”
Spongy bone
cancellous/trebecular “holey”
spaces contain RBM
no osteon but include lacunae (osteocytes inside) and canaliculae
Bone Function
Support
Protection
Motion
Mineral Homeostasis
Blood Cell Production: hemopoiesis in RBM
Triglyceride Storage: energy storage in YBM
Types of bones
Long Bone
Short Bone
Flat Bone
Irregular Bone
Diaphysis
medullary cavity contains YBM
Epiphysis
distal and proximal ends
Metaphysis
Neck of bone
Articular cartilage
Hyaline, covers epiphysis, repair minimal, friction
Periosteum (gurth)
Outside covering, forms new bone thickness/diameter only, protection, nourish, attachment; Sharpey Fibers, secure periosteum to bone
Medullary Cavity
Hollow cylinder of diaphysis; fatty YBM adults (contains RBM in infants)
Endosteum
Thin membrane that lines medullary cavity; single layer of bone forming cells
central/ haversian canal
blood vessels, nerves, lymphatics (up and down)
volksman canal
perforating canals connect with those of medullary cavity (right to left)
concentric lamellae
(tree) rings; layers of hard calcified matrix
lacunae
lakes containing osteocytes
canaliculae
radiating from lacunae (little canals)
finger-like proj from osteocytes, connect all bone cells to a nutrient supply
diffusion is slow so canal system vital to pass nutrients, oxygen to osteocytes and carry waste away
Ossification
bone formation
begins with osteogenic cells from mesenchyme
remodel and repair
resorption by osteoclasts and deposition by osteoblasts
Blood Calcium functions
muscle contraction
nerve stimulation/conduction
blood clotting
bone density: Wolff’s Law; increase stress to bone leads to increased osteoblast bone deposition
Calcium Homeostasis
negative feedback loops:
parathyroid hormone: if blood Ca+2 decreases, stimulates increased osteoclasts activity and decreased loss of Ca+2 in urine; leads to increased Ca+2 blood
calcitonin: causes decreased osteoclast activity and increased -blast and -cyte; grab calcium out of blood and deposits as bone
comminuted
bone breaks into many fragments
compression
bone is crushed
depressed
broken bone portion is pressed inward
impacted
broken bone ends are forced into each other
spiral
ragged break occurs when excessive twisting forces are applied to a bone
greenstick
bone breaks incompletely, much in the way a green twig breaks
parathyroid hormones
secreted by the parathyroid glands; promotes bone resorption by osteoclasts; enhances recovery of calcium from urine; promotes formation of the active form of vitamin D
Calcitonin
Secreted by the thyroid gland; inhibits bone resorption by osteoclasts