MSK Stuff Flashcards
Difference between heliotropic rash in dermatomyositis and malar rash in SLE?
Heliotropic rash: extends pass the nasallabial folds
Malar rash: does NOT extend pass the nasallabial folds
How to differentiate joint pain of RA from SLE?
RA: xrays show corrosive joint deformities (joint space is narrowed)
SLE: xrays show NO corrosive joint deformities (joint space is the same or larger)
- also RA shows anti-citrullinated antibodies in serum, SLE doesnt show this*
What is the precursor cells for osteoblasts?
Mesenchymal stem cells in the periosteal layer of the bone (outer layer)
What are the precursor cells for osteoclasts?
Hematopoietic stem cell progenitor fusion
- fusion of monocytes and macrophage precursor cells.
Brief general overview of bone remodeling
1) osteo blasts secrete KB-ligand (RANK-L)
2) RANK-L stimulates osteoclast movement which breaks down bone by secreting H+ ions and collagenases
3) once enough bone remodeling is done, osteoblasts secrete osteoprotegerin (OPG) which functions to do three things
- stop osteoclast activity
- causes osteoblasts to secrete alkaline phosphate ions to make the environment alkaline
- causes osteoblasts to secrete osteoid matrix (which is primarily hyaline cartilage and collagen)
4) hydroxyapatite (phosphate and calcium ions fused together) spontaneously bind and accurate on the osteoid, forming bone.
What is the chief regulator of osteoclast maturation?
Parathyroids and the PTH levels it secretes
- indirectly influences osteoclast maturation by directly regulating RANK-L and OPG release from osteoblasts
Low vs high PTH levels
Low levels = anabolic bone growth
High levels = catabolic bone resorption
What is the environment required to be like for bone growth and bone breakdown respectively ?
Bone growth (osteoblast activity) = alkaline
Bone breakdown (osteoclast activity) = acidic
