Bone and Soft Tissue Flashcards
What types of bone are there?
Trabecular bone (cancellous bone, spongy bone) Cortical bone (compact bone = hard encasing bone)
The trabecular bone is separated by bone marrow and fat.
What is woven bown?
Bone being repaired, rapidly growing, immature bone.
What is the intramembranous model of ossification?
Bone that is mineralized fibrous tissue.
What is the endochondral model of ossification?
Cartilage that becomes mineralized.
What type of bone growth characterizes long bones typically?
Endochondral ossification.
What type of bone growth typically characterizes the bones of the skull?
Intramembranous ossification.
What do osteoclast do? What do osteoblasts do?
Consume or degenerate existing bone. Lay down new bone. Both are necessary to maintain and grow and develop bone.
Why is bone constantly remodeled?
Because there is a high degree of stress and pressure exerted on bone requiring near constant repair and reproduction.
Osteosarcomas are usually found
In the metaphysis
What inherited defect characterizes Achondroplasia
Is it autosomal recessive or dominant?
Dwarfism caused by an autosomal dominant condition whereby an inherited defect in collagen matrix proliferation at the growth plate, or physis, exists thereby preventing growth of long bones via endochondral ossification mechanisms. The head, however, remains normal sized as the bones of the skull form from a different mechanism.
What bones are most affected in achondroplasia?
long bones of the peripheral skeleton derived from cartilage. Axial and craniofacial skeleton is not affected.
What receptor is defective in achondroplasia?
Fibroblast growth factor receptor 3 aka FGF3
Osteogenesis imperfecta results from a defective type of which collagen?
Type I collagen
What is the hallmark symptom of osteogenesis imperfecta?
Brittle bones that break/fracture easily.
What other structures are composed of type I collagen that may be affected by osteogenesis imperfecta?
Sclera, Middle ear ossicles ( hearing loss)
Dentin - misshapen- hereditary opalescent dentin
Osteopetrosis is a group of disorders characterized by defect in activity of what cell?
Osteopetrosis is a problem of Osteoclastic activity.
What characteristics typify osteopetrosis ?
Bones that appear thick, but are really actually brittle and may fracture and break very easily.
What makes bones so brittle and weak in osteopetrosis?
Overactive, unopposed osteoblast activity leads to chronic laying down of bone with minimal bone resorption yielding thick ill-constructed bones.
What other complications may result from osteopetrosis?
Mylephthestic disorders- bone marrow is crowded out leading to :
Anemia
Decreased WBC count (increased risk of infection)
Decrease in bone vascularity
Foramina are narrowed and the nerves exiting and entering them may be pinched.
The bone is osteopetrosis is
Petrified
What are the main stages in bone repair?
Hematoma and inflammation (day 1-7) Soft callus (2-3 weeks) Hard callus (2-4 months) Remodeling (several months - years)
Osteonecrosis
avascular necrosis
aspetic necrosis
Infarction of the bone due to ischemia/anoxia leads to bone cell death early on, then bone marrow cells later in the course.
What histological hallmark is there of osteonecrosis ?
Absent nuclei in osteocytes
Osteomyelitis
infection of the bone
Acute osteomyelitis
Fever, malaise, elevated ESR
Histologically pus is seen
Bone can be destroyed eventually
Mostly neutrophilic infiltrate
Chronic osteomyelitis
unresolved acute infection- leads to dead bone = sequestrum
More lymphocytes and plasma cells infiltrate
