structural support, movement leverage, protection, mineral storage, bc formation, energy storage
List Function of bones:
osteocytes
-monitor/maintain protein and mineral content of bone matrix
occupy lacunae
-("little caves") between calcified layers of matrix
Osteoblasts
-actively produce and secrete organic portion of bone matrix or osteoid
-found on the inner or outer surfaces of bone
Osteogenic cells
-stem cells that differentiate into osteoblasts for healing
-randomly dispersed throughout bone matrix
-most concentrated at innermost lining of periosteum and endosteum
HCL, lysosomal enzymes
Osteoclasts secrete what?
organic components (35%); inorganic components (65%)
What is the makeup of the bone matrix?
compact bone
-dense/solid outer layer of bone
spongy bone
-honeycomb of small needle-like flat pieces (trabeculae) form internal network of bone
fibrous layer, osteogenic
What are the layers of the periosteum?
Fibrous layer
-covering on outside of bone (not present on sesamoid bones or where tendons, ligaments, or joint capsules are attached)
Osteogenic layer
-this layer contains osteoprogenitor cells for growth and repair
Perforating fibers (sharpey's fibers)
-secures periosteum; provides insertion points for tendons and ligaments
Endosteum
-covers trabeculae of spongy bone lining medullary cavity
diaphysis
"shaft" of a bone forms long axis
epiphysis
ends of a bone; covered with articular cartilage
Diaphysis
______ supplied by nutrient artery and vein; run through nutrient foramen (opening)
Epiphysis
______ supplied by epiphyseal arteries and veins
medullary cavity
-interior hollow cavity; filled with yellow marrow
no nerves/blood vessels, surrounded by dense ct, consists primarily of water, resilient
What are some properties of cartilage?
appositional growth
-growth from outside
-utilizes chondroblasts
interstitial
-growth from within
-maintained by chondrocytes
b
When does cartilage stop growing?
a. before puberty
b. late teens
c. adulthood
d. elderly age
Ossification
-bone tissue formation
Intramembranous ossification
-long bone ossification
mesenchymal
Membrane bones formed directly from ____________ membrane
endochondral ossification
-bones that develop initially from hyaline cartilage
parathyroid hormone
this hormone prevents serum calcium from falling and serum phosphate levels from rising
calcitonin
-inhibits calcium release from bone and by inhibiting osteoclast activity
a
Vitamin D2 (ergocalciferol) is converted to ________ via __________
a. intestine absorption, vit d3
b. skin, vit d4
c. liver, d3
d. kidney, d3
Skin
This organ converts UV radiation and converts 7-dehydrocholesterol D3 to Vitamin D3 (cholecalciferol)
liver/kidney
_____________ hydroxylates Vitamin D3 (cholecalciferol) to 1,25-dihydrovitamin D3 [1,25-(OH)2D3]