session4 dr. maria zahiri
TRANSCRIPT
Session4
Dr. Maria Zahiri
↑ osteoblast ↓ osteoclast
osteoblast ↑ osteoclast
Vitamin D: increases calcium from gut
Parathyroid hormone (PTH): increases blood calcium (some of this comes out of bone)
Calcitonin: decreases blood calcium (opposes PTH)
Growth hormone & thyroid hormone: modulate bone growth
Sex hormones: growth spurt at adolescense and closure of epiphyses
Disorders of cartilage and bone Defective collagen
Numerous genetic disorders eg. Osteogenesis imperfecta (brittle bones) – AD (autosomal dominant) eg. Ehlers-Danlos (rubber man)
Defective endochondral ossification eg. Achondroplasia (short –limb dwarfism) – AD
Inadequate calcification (requires calcium and vitamin D) Osteomalacia (soft bones) in adults Rickets in children
Disorders of cartilage and bone Defective collagen
Osteogenesis imperfecta (OI - brittle bones) congenital bone disorder brittle bones that are prone to fracture defective connective tissue, or without the ability to make
it usually deficiency of Type-I collagen
Disorders of cartilage and bone Defective collagen
Ehlers-Danlos (rubber man) (EDS) is an inherited connective tissue disorder EDS is caused by a defect in the synthesis of collagen,
Disorders of cartilage and bone
Defective endochondral ossification Achondroplasia (short –limb dwarfism) – AD caused by a change in the DNA for
fibroblast growth factor receptor 3 (FGFR3), which causes an abnormality of cartilage formation
Disorders of cartilage and bone
Inadequate calcification (requires calcium and vitamin D) Osteomalacia (soft bones) in adults Rickets in children is the softening of the bones caused by defective bone mineralization secondary to inadequate amounts of available
phosphorus and calcium, or because of overactive resorption of calcium from the
bone as a result of hyperparathyroidism (which causes hypercalcemia,
Pagets disease – excessive turnover, abnormal bone
Osteosarcoma – bone cancer, affecting children primarily
Osteoporosis – usually age related, esp. females Low bone mass and increased fractures Resorption outpaces bone deposition
Normal bone
Osteoporotic bone
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