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Organs are composed of what 4 basic tissues?
Muscle tissue
Connective tissue
Epithelial tissue
Nerve tissue
What is bone made up of? (2)
specialized cells (e.g. osteoblasts, osteoclasts) + mineralized extracellular matrix (e.g. protein fibers - collagen)
Bone
Functions (4)
internal support
protects
blood forming elements
reservoir
Ways to visualize bone (3)
X-ray
Ground bone section in Indian ink
must heat it up first to kill all cells and then add ink
H&E
must demineralize the bone first by adding hydrochloric acid (dissolves away all the calcium phosphate minerals)
Bone
Specialized cells arise from what 2 distinct lineages?
Mesenchyme
Hematopoetic
Bone: Specialized Cells
Mesenchymal Lineage
Types of Cells (3)
Osteoprogenitor
Osteoblast
Osteocyte
Bone: Specialized Cells
Osteoprogenitor
derived from what lineage/cells?
how?
characteristic/location?
become what?
Osteoprogenitor
derived from mesenchymal stem cells
Bone morphogenic stem cells (BMPs) stimulate mesenchymal stem cells to differentiate into osteoprogenitor cells
flattened cells that reside on the surface of the bone (bone matrix)
undergo mitotic division and differentiate into osteoblasts
Bone: Specialized Cells
Osteoblast
derived from what?
characteristic/location
functions? (3)
more characteristics (2)
Osteoblast
derived from mesenchymal stem cell
cuboidal cells on the surface of bone
functions:
secrete osteoid/matrix (ECM)!
osteoid not yet calcified!!
initiate bone calcification
when not actively secreting matrix → called bone lining cells - periosteal and endosteal cells (
squamous
)
characteristics:
appositional growth
(NOT interstitial)
only secretes matrix onto existing matrix!!
cytoplasmic extensions
Bone: Specialized Cells
Osteoblast
general fxn and express what?
significance?
When an osteoblast is surrounded by matrix, what happens?
Osteoblast: bone formation (osteoblast = build) and express alkaline phosphatase (AlkP)
serum AlkP correlates with osteoblast activity
it becomes an osteocyte
Bone: Specialized Cells
Osteocyte
formation
when an osteoblast is surrounded by matrix it becomes an osteocyte
Bone: Specialized Cells
Osteocyte
derived from what?
location?
characteristics (2)
Osteocyte
derived from mesenchymal lineage
located in structures, chambers, caves within the tissue known as canali (lacuna = cave)
characteristics:
have cytoplasmic projections/extensions that reside in little tunnels between the matrix (aka canaliculi)
Bone: Specialized Cells
Osteocyte
function (2)
Lacuna and canaliculi are important for the maintenance and health of the tissue
“-blast” meaning
its a secretory cell (matrix)!
osteoblast
fibroblast
etc
explain
label
Bone: Specialized Cells
