Chapter 8: Bone Flashcards
Provides solid support for the body, thoracic cavities, and encloses internal cavities containing bone marrow where blood cells are formed
Bone tissue
Serves as a reservoir of calcium, phosphate, and other ions that can be released or stored in a controlled fashion to maintain constant concentrations in body fluids
Bone(osseous) tissue
Found in lacunae between lamellae, with cytoplasmic processes in small canaliculi that extend into the matrix
Osteocytes
Growing cells which synthesize and secrete the organic components of the matrix
Osteoblasts
Giant, multinucleated cells involved in removing calcified bone matrix and remodeling bone tissue
Osteoclasts
B/c metabolites can’t diffuse thought calcified matrix of bone, the exchanges btw osteocytes and blood capillaries depend on communication through the very thin, cylindrical spaces of the ___________
Canaliculi
The internal surface surrounding the marrow cavity; connective tissue containing osteogenic cells
Endosteum
External surface lining of bones; connective tissue containing osteogenic cells
Periosteum
Produce the organic components of bone matrix including type I collagen fibers, proteoglycans, and matricellular glycoproteins, such as osteonectin
Osteoblasts
Active osteoblasts are located exclusively at the ________ of bone matrix, to which they are bound by ______, typically forming a single layer of _______ cells joined by ______ and ____ junctions
Surfaces; integrins; cubodial; adherent; gap
Unique collagen-rich material, between the osteoblasts layer and the preexisting bone surface
Osteoid
Prominent among the noncollagen proteins secreted by osteoblasts is the vitamin K-dependent polypeptide _________, which together with various glycoproteins binds _____ ions and concentrates this mineral locally
Osteocalcin; Ca2+
Long dendritic processes, surrounded by calcifying matrix - radiating from each lacuna
Canaliculi
Osteoblasts also release membrane-enclosed _____ ______ rich in alkaline phosphatase and other enzymes whose activity raises the local concentration of phosphate ions
Matrix vesicles
Matrix vesicles serve as a foci for the formation of ________ crystals, the 1st visible step in calcification
Hydroxyapatite
Osteoblasts surrounded by the material secrete and then differentiate as _______
Osteocytes
Osteocytes communicate with one another, nearby osteoblasts, and bone lining cells through ____ ______
Gap junctions
Most abundant cells in bone
Osteocytes
Very large, motile cells with multiple nuclei that are essential for matrix resorption during bone growth and remodeling
Osteoclasts
Osteoclasts’ origin from the fusion of bone marrow-derived _______
Monocytes
Osteoclast development requires two polypeptides produced by osteoblasts: ________ and the __________
M-CSF (macrophage-colony-stimulating factor) and RANKL(receptor activator of nuclear factor-kB ligand)
In areas of bone undergoing resorption, osteoclasts on the bone surface lie within enzymatically etched depressions or cavities in the matrix known as _____ ______
Howship lacunae
In active osteoclasts, the membrane domain that contacts the bone forms a circular ____ ____ that binds the cell tightly to the bone matrix and surrounds an area with many surface projections, called the ____ _____
Sealing zone; ruffled border
Around the ruffled boarder is a ring of _____, adhering the cell to the bone “microenvironment”
Actin
Osteoclast pumps ____ to acidify and promote dissolution of the adjacent hydroxyapatite
Protons
Breakdown organic components
Collagenases
Most abundant inorganic material in the bone matrix
Calcium-hydroxyapatite
The organic matter embedded in the calcified matrix is 90% ___ _ collagen, but also includes mostly small proteoglycans and multiadhesive glycoproteins such as _______
Type I; osteonectin
External surfaces of all bones are covered by connective tissue of the ______
Periosteum
Internal surfaces of all bones are covered by connective tissue of the ______
Endosteum