Post-Mid Mod B2M3 Flashcards
(241 cards)
What is the primary composition of mineralized bone
Calcium and phosphate > hydroxyapatite
Type I collagen, Type V collagen
Noncollagenous proteins
Describe bone matrix structure
Osteocytes are housed within lacunae, which are pockets between rings of osteons (lamellae surrounding a central Haversian canal) that are connected by canaliculi
What are the four general classifications of bones
Long (femur, metacarpals)
Short (carpals)
Flat (scapula)
Irregular (vertebra)
What covers the articular surface of an epiphysis
Hyaline cartilage
What is the general trend of spongy and compact bone in bony structures
More compact bone in diaphysis
More spongy bone in epiphysis
Describe the composition of the periosteum
Fibrous connective tissue containing osteoprogenitor cells
What is the difference between red and yellow bone marrow
Red- consists of blood cells in different stages of development (mostly in spongy bone)
Yellow- consists mostly of fat cells
What connect the periosteum/endosteum to the Haversian canals
Perforating/Volkmann canals
Openings in the bone through which blood vessels pass to reach the marrow
Nutrient foramina
Where does most of the vascular supply to the bone come from (what canals)
Volkmann canals > Haversian canals > periosteal arteries
Where is the lymphatic drainage for bones
Periosteum
What are the major features of immature bone
No organized lamellated appearance (interlacing collagen fibers instead)
More affinity for hematoxylin stain
What is the relationship between Haversian and Volkmann canals
Haversian canals run longitudinally parallel, and are connected via perpendicular Volkmann canals
In compact bone
What is the origin of osteoprogenitor cells
Mesenchymal stem cells (expressing CBFA1)
What stimulates osteoprogenitor differentiation into osteoblasts
IGF-1/IGF-2 signaling
What compounds do osteoblasts secrete
Type I collagen
Bone matrix proteins (osteonectin, osteoponin, alkaline phosphatase)
What are some notable markers of osteoblast activity
Alkaline Phosphatase
Osteocalcin
Mature bone cell enclosed by bone matrix that was previously secreted as an osteoblast
Osteocyte
What are the functions of osteocytes
Mechanotransduction- dec. mechanical stimuli causes bone loss, whereas inc. stimuli promotes bone formation
Happens via a transient electrical potential flowing through the interstitial fluid, acted upon by mechanical forces > results in inc. intracellular Ca2+
What are the key histology characteristics of osteoclasts
Multinucleated
Acidophilic (especially TRAP staining)
Describe the process of activating osteoclasts
RANK receptors on the osteoclasts bind to RANKL being secreted from T lymphocytes/osteoblasts > induces monocyte fusion into a giant multinucleated osteoclast
What are the components of osteoclast lysosomes
Collagenase
Hydrochloric acid- dissolves hydroxyapatite
How do osteoclasts resorb bone, functionally?
ATP-dependent proton pumps excrete carbonic acid > degenerates hydroxyapatite crystals
What is the role of osteoprotegerin (OPG) in osteoclast functioning
OPG blocks RANKL from binding to RANK
Secreted by osteoblasts