Skeletal Disorders Flashcards
Bone matrix is osteoid made of this
Type I collagen
These cells form new bone on surface of osteoid
Osteoblasts
These cells become osteocytes when senescent
Osteoblasts
These cells secrete acids into resorption pit to absorb bone and release calcium
Osteoclasts
Osteoclasts are derived from this
Hematopoietic cells, monocyte/macrophage
Type of bone formation that occurs in long bones
Endochondral
Fibroblast growth factor 3 promotes differentiation of these
Chondrocytes
Type of bone formation where growing cartilage at epiphyseal plates have provisional mineralization
Apoptotic chondrocytes are replaced by ingrowth of osteoblasts
Endochondral
Fibroblast growth factor 3 promotes this type of bone formation
Endochondral
Type of bone formation that occurs in flat bones
Intramembranous
Type of bone formation where mesenchymal cells differentiate into osteoblasts and pre-existing matrix undergoes mineralization
Intramembranous
Before remodeling, initial bone is of this type
Woven
These cells are activated by WNT/Beta-catenin signaling
Osteoblasts
Calcium deposition is mediated by this
Alkaline phosphatase
Alkaline phosphatase mediates the deposition of this
Calcium
Osteoblasts are activated by signaling of this
WNT/Beta-catenin
Parathyroid hormone stimulates these cells
Osteoclasts
Stimulation of RANK receptor activates these cells
Osteoclasts
Osteoclasts are activated by stimulation of this receptor
RANK
These cells are activated by M-CSF
Osteoclasts
What effect does estrogen have on bone mass?
Is protective
What effects does Vitamin D have on Calcium?
Increases renal Ca reabsorption
Increases bone deposition of Ca
Vitamin D increases bone deposition of Ca via osteoblast production of this calcium binding protein
Osteocalcin
This increases bone deposition of Ca via osteoblast production of the Ca binding protein osteocalcin
Vitamin D
Vitamin D increases bone deposition of Ca via these cells producing osteocalcin (Ca binding protein)
Osteoblast
Alkaline phosphatase is increased when this is occuring
Increased in bone deposition/turnover
E.g. tumor
What effect does Parathyroid Hormone have on bone resorption?
Causes bone resorption
These are precursors to osteoblasts
Mesenchymal cells
Osteoblasts or Osteoclasts?:
Eccentric nuclei
Osteoblasts
Osteoblasts or Osteoclasts?:
On osteoid surface
Osteoblasts
Osteoblasts or Osteoclasts?:
Mineralize bone with alkaline phosphatase
Osteoblasts
Osteoblasts or Osteoclasts?:
Osteocyte is senescent form
Osteoblasts
Osteoblasts or Osteoclasts?:
Monocytes are precursors
Osteoclasts
These are precursors to Osteoclasts
Monocytes
Osteoblasts or Osteoclasts?:
Multinucleated
Osteoclasts
Osteoblasts or Osteoclasts?:
Form resorption pits
Osteoclasts
Osteoblasts or Osteoclasts?:
Release Ca and P into serum
Osteoclasts
Type of bone:
Newly formed bone, disorganized, not as strong
woven bone
Type of bone:
Mature bone after remodeling, increased strength, compact bone cortex, cancellous in medullary cavity
Lamellar bone
Bone marrow fills this part of bone
Medullary cavity
What effect does RANK/RANK-L have on bone?
Stimulates bone resorption by osteoclasts
RANK/RANK-L stimulates bone resorption by these
Osteoclasts
Decoy molecule that inhibits bone resorption
Protects bone
Osteoprotegerin
This promotes osteoclast mediated bone resorption via increased RANK/RANK-L
PTH
This decreases RANK/RANK-L, increases osteoprotegerin
Estrogen
Most common form of dwarfism
Achondroplasia
Inheritance pattern of Achondroplasia
Autosomal dominant
Condition caused by a gain of function in FGF3 receptor
Most are new sporadic paternal mutations (advanced paternal age)
Achondroplasia
Gain of function in this can cause Achondroplasia
FGF3
What effect does Achondroplasia have on long bones?
Promotes endochondral ossification, so there is presence of shortened long bones - short extremities
Normal flat bones
More severe, lethal form of dwarfism
Thanatophoric dysplasia
What causes Achondroplasia?
Gain of function in FGF3 receptor
What causes Thanatophoric dysplasia?
Gain of function FGF3 mutation with greater effect
This condition has similar features as Achondroplasia, but death occurs in neonatal period due to respiratory insufficiency
Thanatophoric dysplasia
What causes Osteogenesis Imperfecta?
Switch of glycine with non-gly amino acid in type I collagen
Impairs formation of triple helix
Condition caused by a switch of glycine with a non-gly amino acid in collagen, impairing the formation of the triple helix
Osteogenesis Imperfecta
What type of collagen is affected in Osteogenesis Imperfecta?
Type I
What is the inheritance pattern of Osteogenesis Imperfecta?
Dominant negative
Condition that is also called Brittle bone disease
Osteogenesis Imperfecta
Condition where fusion of conductive ossicles may occur, leading to conductive hearing loss
Osteogenesis Imperfecta
Condition that can have thin, transparent sclera with visualization of underlying choroid vasculature = blue sclera
Osteogenesis Imperfecta
Blue sclera is seen in this condition
Osteogenesis Imperfecta
Diffuse skeletal sclerosis due to defective osteoclast absorption
Osteopetrosis
Osteopetrosis is diffuse skeletal sclerosis due to a defect in this
Osteoclast absorption
Condition where defective osteoclast absorption results in no bony remodeling
Osteopetrosis
Carbonic Anhydrase deficiency may cause this skeletal condition
Osteopetrosis
Why can Carbonic Anhydrase deficiency cause Osteopetrosis?
Deficiency results in lack of acidic environment in resorption pit
(also results in renal tubular acidosis)
Condition were there is a lack of bone resorption, so bone is DENSE
Osteopetrosis
Condition where neural foramen may be occluded, causing cranial nerve defects
Osteopetrosis
Condition where there is extremely sclerotic bone with no medullary cavity for hematopoiesis, leading to low platelet, WBC, etc. counts
Osteopetrosis
What is the treatment for Osteopetrosis?
Bone marrow transplant
What are the levels of platelets and WBCs in Osteopetrosis?
Low
Extremely sclerotic bone has no medullary cavity for hematopoiesis
Extramedullary hematopoiesis may occur
Condition described by a bone density less than 2.5 std below mean peak bone density of young adults
Osteoporosis
What race is most affected by Osteoporosis?
Caucasians
Much less common in African races
Risk of Osteoporosis is determined by these two factors
Peak bone mass at early adulthood
Rate of age-related bone loss
Primary or secondary Osteoporosis?:
Senile - males especially
Post-menopausal (estrogen deficiency)
Primary
Primary or secondary osteoporosis:
Can be caused by hyperparathyroidism, neoplasm, intestinal disorders with malabsorption, chronic steroid use, hypogonadism
Secondary Osteoporosis
Chronic steroid use increases risk of this condition
Secondary Osteoporosis
Condition where there is normal bone but less of it
Most significant change at lumbar/thoracic vertebral bodies
Osteoporosis
What are the levels of Ca, PTH, and Alkaline phosphatase in Osteoporosis?
All normal
Biphosphonates inhibit these and can be used as treatment for Osteoporosis
Osteoclasts
Biphosphonates inhibit osteoclasts and can be used as treatment for this condition
Osteoporosis
Condition characterized by normal amount of bone matrix but inadequate mineralization
Rickets/Osteomalacia
Usually caused by Vitamin D deficiency
In children, does Rickets affect endochondral or membranous bone?
Both
What are the levels of Ca, Phosphate, Alk phos, and PTH in Rickets/Osteomalacia?
Low/normal Ca
Low phosphate
High alk phos
High PTH
Normal levels of Ca, PTH, and alk phos but with low bone density indicate this condition
Osteoporosis
Low/normal levels of Ca, low phosphate, and high Alk phos and PTH are typical labs seen in this condition
Rickets/Osteomalacia
Epiphyseal cartilage overgrowth due to inadequate mineralization and failure of chondrocyte maturation is seen in this condition
Rickets
Growth plate cartilage and osteoid continues to expand laterally but does not mineralize or mature into bone is seen in this condition
Rickets