Flashcards in Bone Developmental Disorders- Handorff Deck (48)
What is osteoid
All of the inorganic matrix that is laid down beore bone is mineralized
What are the active cell types in bone?
Osteoblasts, Osteocytes, Osteoclasts
What are osteoprogenitor cells?
Pluripotent mesenchymal stem cells
What can drive osteoprogenitor cells into becoming osteoblasts?
Osteoblasts do what
Sense mechanical stress and regulate serum calcium and phosphate
What bone cell synthesizes osteoid?
What is osteoid
Type I Collagen which makes up about 90% of the 35% organic bone
Osteoblasts mediate osteoclast activity, they hyave PTH receptors
true. this can be significant during diseases such as hyperparathyroidism where too much PTH is developed
Remember that in certain diseases, the communication between osteoblasts and osteoclasts is screwed up
Osteocytes are encased in?
How do osteocytes communicate?
What do osteoclasts do?
remodel and resorb bone
Osteoclasts require what cytokines for differentiation?
IL-1, IL-3, IL-6, IL-11, GM-CSF, M-CSF
Osteoclasts reside where?
What do osteoclasts look like?
How does Osteoclast differentiation occur?
Osteoclasts are derived from the same cells that make macrophages. RANK ligand binds to RANK receptor. This occurs in the background of M-CSF and causes precursor cells to produce functional osteoclasts.
What is OPG
Osteoprotegrin, It protects bone from resorption by acting as a decoy receptor for RANKL, preventing it from binding the RANK receptor on osteoclast precursors.
Osteogenesis Imperfecta is a ------- of diseases which share common mutatins in what?
family, type 1 collagen
Type 1 OI...
Make too little pro-alpha1. Normal stature, lax joints, deafness
Type 2 OI
Pro-alpha 1 is too short, collagen is made but degraded intracellularly. The bones break in utero which kills the child
Triple Helix doesn't form well.
Child is short, many fractures, kyphosis, hard of hearing, bad cases are lethal
Pro alpha 2 is too short, short stature, somewhat fragile bones.
OI is usually autosomal ...... except for........
dominant, type II (either auto recessive or new autosomal dominant
What are the four major clinical criteria for OI
osteoporosis, blue sclerae, dentigenesis imperfecta, premature otosclerosis
Must have two of these for clinical diagnosis
Blue sclerae are associated with
heritable disorders of connective tissue. They appear predominantly in OI and to a lesser extent in pseudoxanthoma elasticum, Ehlers Danlos, Marfan disease
Why are the sclera blue?
The sclera are so thin that the underlying choroid is visible
What are the two types of OI?
Congenita- bad, Tarda- not as bad