NURS 8022 - PATHO - EXAM #5 STUDY GUIDE (100%
CORRECT).
, Exam 5 Study Guide
Musculoskeletal
Define differences between bone cells
• Osteogenic cell: stem cell
• Osteoblasts: bone forming cells, “bone-builders”
o Derived from mesenchymal cells
o Produce osteocalcin when stimulated by vitamin D
o Form new bone – synthesize osteoid – brings on the formation of new bone – nonmineralized bone
matrix
o Follow Wolfe’s law: bone is shaped according to its function
o Become osteocytes that are imbedded in bone
• Osteoclasts: bone resorbing, “bone-crushers”
o Large, multinucleated cells
o Attached to integrins by podosomes (helps bind to bone)
o Cause resorption of bone by secretion of HCl acid and a protease enzyme which help dissolve bone
minerals and collagenase
o Are “resting” when not resorbing
▪ Resting osteoclast = once reabsorption is complete then disappears by degeneration reverting
back to its parent cell or leaving the site
• Osteocytes: bone maintaining
o Develop dendritic processes that extend to either the bone surface or the bone’s vascular space
o Help maintain bone by signaling osteoblasts and osteoclasts to form and resorb bone
o Coordinate osteoblast and osteoclast functions
o Respond to parathyroid hormone
Understand basics of bone remodeling and bone repair
• Bone formation:
o First step: develop bone matrix; Final step: calcification or mineralization
▪ Mineralization phases: formation of the initial mineral deposit (initiation) - proliferation of
accretion of additional mineral crystals on the initial mineral deposits (growth)
▪ End-product of mineralization is hydroxyapatite: majority of the mineral content in the body
made of small crystals containing calcium and phosphate
• Modeling: when a bone is formed at one site and broken down in a different site, its shape and position is
changed
• Remodeling: removal and replacement of bone at the same site
o Regulation
▪ Genes, environment, diet, physical activity
▪ Hormones: calcium regulating (PTH, calcitriol [active vit.D], calcitonin); sex hormones (estrogen,
testosterone); other systemic hormones (GH, insulin-like GF, thyroid hormone, cortisol)
▪ Local regulation via cytokines, GF’s
• RANK/RANKL/OPG system
o RANK: receptor on osteoclast precursor and mature osteoclast cells
o RANKL: receptor ligand; secreted by osteoblasts
o OPG: decoy receptor produced by osteoblasts and stroll cells that binds to and
sequesters RANKL – inhibits osteoclast differentiation, fusion, and activation
, o Bone-remodeling units
o Repair of microscopic injuries and maintenance of bone integrity
o Phases:
▪ Activation of the remodeling cycle
▪ Resorption
▪ Formation of new bone (secondary bone)
▪ Takes 3-4 months
• Repair: bone heals itself
o Hematoma formation – clot forms
o Procallus formation – produces granulation tissue
o Callus formation – forms membranous or woven bone
o Callus replacement – replaces the callus with lamellar bone or trabecular bone
o Remodeling – periosteal and endosteal surfaces are remodeled to the size and shape of the bone before
the injury
, Understand difference between compact and spongy bone
• Bone matrix: 35% organic; 65% inorganic; 5-8% water
o Organic: collagen fibers, proteoglycans, glycoproteins, osteocalcin, osteonectin, osteopontin, cytokine,
growth factors; inorganic: calcium and phosphate minerals
▪ Collagen: essential for strength, form fibrils that twist, synthesized by osteoblasts
▪ Proteoglycans: strengthen bone by forming compression-resistant networks between collagen,
help calcium deposit in bone - act as a pump – permit fluid to be pressed out to ensure that fluid
film is always present on the surface of cartilage even after hours of weight bearing
▪ Glycoproteins: carb-protein complexes of bone, play a role in calcification
▪ Osteocalcin: most abundant non-collagenous protein, produced by osteoblasts, promotes
mineralization and formation of bone, attracts osteoclasts, signals vitamin D, inhibited by PTH;
marker of bone turnover, can be measured in urine or serum
▪ Osteonectin: secreted by platelets & osteoblasts, role in regulating calcium, organizing matrix
▪ Osteopontin: cell binding protein
▪ Cytokine and growth factors: aid in bone cell differentiation, activation, growth, and turnover
• Compact bone: cortical bone – outer bone, rigid
o 85% of skeleton
o Solid and extremely strong
o Haversian system: basic structural unit in compact bone
• Spongy bone: cancellous bone – inner bone, porous
o 15% of skeleton
o Filled with red bone marrow
o Trabeculae: plates or bars instead of Haversian system
• Periosteum: double-layered connective tissue that covers all bones
o Outer layer: contains blood vessels and nerves, some of which penetrate to inner bone structures
through channels called Volkmann canals
o Inner layer: anchored to the bone by collagenous fibers (Sharpey fibers) that penetrate the bone and
help hold or attach tendons and ligaments to the periosteum of bones
• Characteristics of bone
▪ Long bones
• Diaphysis: medullary cavity contains fat = yellow marrow
• Metaphysis: broad neck
• Epiphysis: epiphyseal plate – epiphysis is separated from metaphysis by cartilaginous
growth plate; after puberty, epiphyseal plate calcifies and the epiphysis and metaphysis
merge
CORRECT).
, Exam 5 Study Guide
Musculoskeletal
Define differences between bone cells
• Osteogenic cell: stem cell
• Osteoblasts: bone forming cells, “bone-builders”
o Derived from mesenchymal cells
o Produce osteocalcin when stimulated by vitamin D
o Form new bone – synthesize osteoid – brings on the formation of new bone – nonmineralized bone
matrix
o Follow Wolfe’s law: bone is shaped according to its function
o Become osteocytes that are imbedded in bone
• Osteoclasts: bone resorbing, “bone-crushers”
o Large, multinucleated cells
o Attached to integrins by podosomes (helps bind to bone)
o Cause resorption of bone by secretion of HCl acid and a protease enzyme which help dissolve bone
minerals and collagenase
o Are “resting” when not resorbing
▪ Resting osteoclast = once reabsorption is complete then disappears by degeneration reverting
back to its parent cell or leaving the site
• Osteocytes: bone maintaining
o Develop dendritic processes that extend to either the bone surface or the bone’s vascular space
o Help maintain bone by signaling osteoblasts and osteoclasts to form and resorb bone
o Coordinate osteoblast and osteoclast functions
o Respond to parathyroid hormone
Understand basics of bone remodeling and bone repair
• Bone formation:
o First step: develop bone matrix; Final step: calcification or mineralization
▪ Mineralization phases: formation of the initial mineral deposit (initiation) - proliferation of
accretion of additional mineral crystals on the initial mineral deposits (growth)
▪ End-product of mineralization is hydroxyapatite: majority of the mineral content in the body
made of small crystals containing calcium and phosphate
• Modeling: when a bone is formed at one site and broken down in a different site, its shape and position is
changed
• Remodeling: removal and replacement of bone at the same site
o Regulation
▪ Genes, environment, diet, physical activity
▪ Hormones: calcium regulating (PTH, calcitriol [active vit.D], calcitonin); sex hormones (estrogen,
testosterone); other systemic hormones (GH, insulin-like GF, thyroid hormone, cortisol)
▪ Local regulation via cytokines, GF’s
• RANK/RANKL/OPG system
o RANK: receptor on osteoclast precursor and mature osteoclast cells
o RANKL: receptor ligand; secreted by osteoblasts
o OPG: decoy receptor produced by osteoblasts and stroll cells that binds to and
sequesters RANKL – inhibits osteoclast differentiation, fusion, and activation
, o Bone-remodeling units
o Repair of microscopic injuries and maintenance of bone integrity
o Phases:
▪ Activation of the remodeling cycle
▪ Resorption
▪ Formation of new bone (secondary bone)
▪ Takes 3-4 months
• Repair: bone heals itself
o Hematoma formation – clot forms
o Procallus formation – produces granulation tissue
o Callus formation – forms membranous or woven bone
o Callus replacement – replaces the callus with lamellar bone or trabecular bone
o Remodeling – periosteal and endosteal surfaces are remodeled to the size and shape of the bone before
the injury
, Understand difference between compact and spongy bone
• Bone matrix: 35% organic; 65% inorganic; 5-8% water
o Organic: collagen fibers, proteoglycans, glycoproteins, osteocalcin, osteonectin, osteopontin, cytokine,
growth factors; inorganic: calcium and phosphate minerals
▪ Collagen: essential for strength, form fibrils that twist, synthesized by osteoblasts
▪ Proteoglycans: strengthen bone by forming compression-resistant networks between collagen,
help calcium deposit in bone - act as a pump – permit fluid to be pressed out to ensure that fluid
film is always present on the surface of cartilage even after hours of weight bearing
▪ Glycoproteins: carb-protein complexes of bone, play a role in calcification
▪ Osteocalcin: most abundant non-collagenous protein, produced by osteoblasts, promotes
mineralization and formation of bone, attracts osteoclasts, signals vitamin D, inhibited by PTH;
marker of bone turnover, can be measured in urine or serum
▪ Osteonectin: secreted by platelets & osteoblasts, role in regulating calcium, organizing matrix
▪ Osteopontin: cell binding protein
▪ Cytokine and growth factors: aid in bone cell differentiation, activation, growth, and turnover
• Compact bone: cortical bone – outer bone, rigid
o 85% of skeleton
o Solid and extremely strong
o Haversian system: basic structural unit in compact bone
• Spongy bone: cancellous bone – inner bone, porous
o 15% of skeleton
o Filled with red bone marrow
o Trabeculae: plates or bars instead of Haversian system
• Periosteum: double-layered connective tissue that covers all bones
o Outer layer: contains blood vessels and nerves, some of which penetrate to inner bone structures
through channels called Volkmann canals
o Inner layer: anchored to the bone by collagenous fibers (Sharpey fibers) that penetrate the bone and
help hold or attach tendons and ligaments to the periosteum of bones
• Characteristics of bone
▪ Long bones
• Diaphysis: medullary cavity contains fat = yellow marrow
• Metaphysis: broad neck
• Epiphysis: epiphyseal plate – epiphysis is separated from metaphysis by cartilaginous
growth plate; after puberty, epiphyseal plate calcifies and the epiphysis and metaphysis
merge
