4.4 Bone Flashcards
what are the 4 functions of bone?
Protection, support, locomotion, mineral reservoir (Ca2+, PO4, Mg2+)
bone is _____ vascular and ____ inntervated
Highly, IS
composition of bone ECM?
50% organic, 50% inorganic
inorganic components of bone ECM (3)
- Hydroxyapatite crystals
- Citrate and carbonate ions
- Mg2+, K2+, Na2+
organic components of bone ECM (2)
- collagenous proteins (90%)
- non-collagenous proteins (10%)
what are 2 examples of collagenous proteins in bones?
type 1 and V collagen
______ are glycosaminoglycan side chains + core protein
Proteoglycans
_______ mediate matrix assembly/mineralization (DMP1, OPN, BSP)
Sibling proteins
________ capture calcium from plasma (ex:osteocalcin)
Bone specific vitamin-K dependent proteins
____ is a thin CT layer that lines all _____ surfaces
and Contains bone forming cells
Endosteum, inner
______ is the dense CT layer that is attached to bone via Sharpey’s layers
Periosteum
the inner osteogenic layer of the periosteum contains _______ and the outer fibrous layer contains ______
bone forming cells, fibroblasts
_______ are the source of new osteoblasts that are located on or near free surface
Osteoprogenitor cells (Opc)
where do osteoprogenitor cells come from?
mesenchymal cells in bone marrow
______ synthesize/secrete osteoid (Os), release matrix vesicles, and are found in actively forming bone surfaces
osteoblasts
what are osteoblasts originated from?
Osteoprogenitor cells
______ are mechanosensors and orchestrators of the bone remodeling process that communicate with osteoblasts via Canalicuae. They are located ________
- osteocytes
- within lacunae surrounded by mineralized bone
Osteocytes are derived from ____
osteoblasts
______ function in bone reabsorption and are loated in pits in the bone surface which are called resorption bays (Howship’s lacunae)
Osteoclasts
Osteoblasts have a ___ amount of golgi, RER and mitochondria and secrete a large amount of _____
Large, ECM
differences between Quiescent, Formative, and resorptive osteocytes??
- Quiescent
- Surrounded by bone matrix
- Filopodia extend away from cell body, links cells by gap jxns
- Decreased golgi/ER - Formative (right pic)
- Contain RER/golgi
- Small amt osteoid visible in space surrounding cell
- Un-mineralized collagen fibrils present in osteoid - Resorptive
- Many mitochondria
- Lysosomes containing enzymes in cytoplasm
- dissolve/chew away bone
- NO fibrils in pericellular space
- Large Golgi
______ are giant multinucleated cells that have many golgi/lysosomes, a ruffled border facing the bone surface, and communicate via _____
osteoclasts
gap jxns
_______ are the spaces between lamellae containing an osteocyte
Lacunae
____ are the tiny canals that connect all lacunae
Canaliculi
______ are thin, actin-rich plasma-membrane protrusions that function as antennae for cells to probe their environment
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