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ANS 205: Physiology of the bone
ANS205

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Os


relating to bones


Cytes


mature cells


Blasts


immature cells


Removal of inorganic salts and minerals causes the bone to be


flexible/soft


The organic components of bones are


bone cells and osteoid


Bones cells include


osteocytes, osteoblasts, osteoclasts


Osteocytes


mature bone cells


Osteoblasts


immature bone cells


Osteoclasts


specialized cells derived from blood that eat away bone


Osteoid


organic part of the matrix that is made of collagen, polysaccharides and GAGS—contributes to resilience and toughness of the bones


GAGS


glycosaminoglycans, complex modified sugars


Inorganic components of bone


calcium and phosphorus salts (provide hardness and rigidity to the bone)


CaPO4 Calcium Phosphate is ____% of inorganic salt in the bone


80%


Inorganic component can be removed by soaking in dilute


acid


Decalcified bone_____ (maintains/loses) structure


maintains


When the osteoid is removed the bone becomes_____ and is prone to _____


brittle, breaking


Describe Osteoblasts


bone-forming cells found in all bone surfaces, they synthesize and secrete collagen fibers and other organic components of bone matrix (GAGS), serve as a framework for the deposition of calcium and phosphate salts


Osteoblasts are the _____ for the bone to be laid down and mineral deposition


mold


Describe Osteocytes


Mature, nondividing osteoblast surrounded by matrix, lying within lacunae. They still make bony matrix but are stuck in lacunae and do not continue to proliferate, continually lay down osteoid or organic substance


Describe Osteoclasts


large multinucleate cells that are responsible for the active erosion of bone minerals. Contain large numbers of mitochondria and lysosomes (eat away at bone). Formed by the fusion of macrophages.


_____ bone consists primarily of laminated tubes called osteonal systems


compact


Each _____ consists of a central canal (blood vessels and nerves) surrounded by circular plates of bone


osteon


The lacunae is a cavity containing _______ bone cells


Osteocytes


The lamellae are plates or rings around the


central canal


Canaliculi are tiny canals that radiate from the ______ to the ______


central canal to the lacunae


All central canals are connected perpendicularly by the


Volkmann’s canals


Define ossification


formation of true bone by deposition of calcium salts in a bony matrix of osteoid tissue


Define calcification


depositing calcium salts within tissues


What is the primary center of bone formation within the shaft


center of ossification


Endochondral ossification begins


within the cartilage model


Intramembranous ossification begins


as a thin membrane


List the five steps of endochondral ossification


1. Formation of bone collar around hyaline cartilage model, 2. Cavity formed in the hyaline cartilage model, 3. Invasion of internal cavities by periosteal bud and spongy bone, 4. Formation of medullary cavity and ossification continues, secondary ossification centers appear in epiphyses, 5. Ossification of the epiphyses and hyaline cartilage only left in epiphyseal plates and articular cartilage


List four steps of intramembranous ossification


1. Ossification center appears in fibrous connective tissue membrane, 2. Bone matrix secreted within fibrous membrane and calcified, 3. Woven bone and periosteum form, 4. Results in compact bone surrounding a cencellous bone core


Bone __________ is the continuous turnover of bone in mature animals


remodeling


During remodeling bone can


shrink (atrophy), increase in size (hypertrophy), repair, rearrange


The activity of bone cells is regulated by these two hormones


parathyroid hormone (PTH), calcitonin


The parathyroid hormone ________ serum calcium by _______ net release of calcium salts


increases, increasing


PTH increases the activity of what type of bone cells


osteoclasts (more eating of bone to add calcium in blood)


Calcitonin’s primary effect is to _______ osteoclast activity and ______ serum calcium


reduce, lowering


Calcitonin increases osteoclast activity so it is _______ calcium in the bone


depositing


Define fracture


a break in the continuity of bone


Define simple fracture


skin stays intact (unbroken)


Define open fracture


would from the exterior is in contact with the broken bone


Define greenstick fracture


one side of the bone is broken/splintered while the other side is intact but bent


Define complete fracture


bone is broken across into two parts


Define physeal fracture


located at the junction of an epiphysis and diaphysis


Define comminuted fracture


the bone is broken or shattered into smaller pieces


Granulation tissue consists of two things


fibroblasts and capillaries


Osteoblasts (from peri and endosteum) divide rapidly after injury to produce large amounts of


osteoid


Define callus


a lump of connective tissue formed around the granulation tissue


After apposition and immobilization occur, how does a fracture heal


the blood clot is invaded by connective tissue cells called granulation tissue. The osteoblasts produce osteoid and the callus forms and then in mineralized. After healing the spontaneous deformity correction occurs to return the bone to normal shape/size


The amount of spontaneous correction depends on these 5 factors


age of the animal, blood supply of the bone, degree of correction required, presence/absence of infection, amount of damage to tissues


itis


inflammation


Bone TB is an infection caused by _________ which attacks the ____ and ends of the ______


mycobacterium tuberculosis, spine, long bone


Osteomyelitis is the inflammation of bone and bone marrow that is caused by ______ that enters via blood vessels/wounds


bacteria (staphylococcus/streptococcus)


Osteodystrophy is an abnormality in bone development due to dysfunctional ___ and ___ regulation


calcium and phosphorus








Rickets occurs in young animals and osteomalacia occurs in old animals as a result of inadequate ____


mineralization of osteoid


Achondroplasia is a hereditary condition in which metaphyses fuse early but grow in diameter resulting in


dwarfism ex. dachshund dogs and dwarf cattle