Robbins Flashcards
(207 cards)
What is the inorganic mineral component of bone?
Calcium hydroxyapatite
What is the role of calcium hydroxyapatite in bone?
Strength + hardness to bone
Storehouse of 99% of bodys calcium + 85% phosphorus + 65% magnesium
What cells express RANK?
Preosteoclasts + mature osteoclsts
RANK Ligand is expressed by what cells?
Osteoblasts and marrow stromal cells
Stimulation of RANK by its Ligand leads to?
Activation of transcription of factor NF-kB, which drives expression of genes to stimulate osteoclast formation + diff + function + survival
What up upregulates RANKL?
Osteoclast stimulating factors
Overall function of RANK + Ligand?
Up-reguate OSTEOCLAST activity
what is OPGs function?
Osteoprotegerin–> Blocks RANKL from binding to RANK
What competitively binds to RANKL to prevent bone resorption?
OPG
Problems in migration of mesenchymal cells and formation of condensations is called?
Dysostoses –> results from Homeobox mutations
Mutations interfering with bone or cartilage formation/ growth and/or maintenance of normal matrix?
Dysplasia (not precancerous)
“Brittle bone disease?”
Osteogenesis imperfecta
Genetic disorder caused by defective synthesis of alpha 1 +2 chains of type I collagen?
Osteogenesis imperfecta
What is the role of type I collagen?
it is a main component of Matrix all over the body
Fundemental abnormality is Too little bone–> extreme skeletal fragility?
Osteogenesis imperfect
What is a pathooneumonic characteristic of Osteogenesis imperfecta Type I patients?
BLUE sclera
What is pg of pt with pathopneumonic BLUE SCLERA?
OI–> caused by decreased collagen content causing transparency allowing underlying choroid to be seen
What are some deficits attributed to OI?
Hearing loss–> conduction defect in middle ear and inner ear bones
Small misshapen teeth–> dentin deficiency
BLUE SCLERA + bone disease?
Osteogenesis Imperfecta
What is the most common form of dwarfism?
Achondroplasia
What is Pg of achondroplasia (dwarfism)?
Activating point mutation in FGFR3
What is the function of FGFR3?
inhibits the proliferation and function of growth plate chondrocytes–> normal epiphyseal plate is suppressed + long bone is Severely stunted
Disproportionate shortening of proximal extremities+ bowing legs+ frontal bossing+ midface hypoplasia?
Dwarfism (achondroplasia)
Genetic disorders characterized by defective OSTEOCLAST-mediated bone resorprtion?
Osteopetrosis