Bone Disorders (quiz 4) Flashcards
Is rickets a childhood or adulthood disease?
childhood
What is rickets?
-usually genetic childhood disease
-bone matrix calcification is incomplete or absent (uncalcified matrix is called osteoid)
-resulting bone is very weak in compression/stress
-systemic- everything is rounded/abducted
-involves vitamin D3 cholecalciferol deficiency or resistance
What is the telltale sign of rickets in a young child?
bowing of femur
What are the 2 types of rickets?
vitamin D deficiency rickets
-vitamin D is necessary for calcification
-responds to supplementation
vitamin D resistant rickets
-caused by errors in metabolic pathways of calcification
-does not respond to supplementation
What is the adult form of rickets?
osteomalacia (bone softening)
has a similar etiology= osteoid not adequately mineralized, but adults do not have epiphyseal growth plates
new growth in adults affects width only because there is no growth plate anymore- the new osteons form but remain poorly or unmineralized and the newly formed bone is weaker than surrounding bone
Is osteomalacia localized or systemic?
localized, usually in weight-bearing long bones
What are the causes of osteomalacia?
-usually vitamin D deficiency
-inadequate dietary calcium
-hormonal imbalances
-pregnancy or lactation
What is osteoporosis?
-the amount of actual bone matrix per unit volume is reduced (bone becomes more porous, compact bone becomes thinner (cortical involution))
-bones become weaker
-systemic
What are the causes of osteoporosis?
-post menopausal (most common, loss of anabolic hormone estrogen)
-senile due to old age
-disuse due to lack of mechanical loads
-idiopathic (can be anyone at any age, osteoblasts and osteoclasts are dysregulated)
What is osteopetrosis?
-marble bone disease
-abnormally large amounts of bone matrix and highly mineralized bone matrix
-very thick cortical bone
-dense networks of cancellous bone
-large amounts of calcified cartilage
-bone is very brittle and easily fractures (high bone mineral to collagen fiber ratio)
-systemic
What is pagets disease?
-also called osteitis deformans
-disrupts the displacement of old bone with new bone
-usually due to poor nutrition
-thickened cortical bone
-coarse, thickened trabeculae
-similar to osteopetrosis but more localized (may affect single bone or multiple bones (foci))
What is osteogenesis imperfecta?
-congenital/genetic (inherited autosomal dominant trait)
-imperfectly formed bone
-collagen of bone matrix is affected
-bone is soft and brittle
What is ankylosing spondylosis?
ankylosis= abnormal condition of joints immobilized by bone production uniting the bones solidly to one another
ankylosing spondylosis= specifically the pathological ankylosis of the vertebral column (affects the intervertebral foramen and can cause stenosis of the nerves and spinal cord)
What are the causes of ankylosis?
-genetic
-induced by trauma
-disease
-surgery
What hormones can affect growth and remodeling disorders?
calcitonin, parathyroid hormone, and human growth hormone
Which hormone can cause disorders based on too much or little levels before the growth plate closes?
human growth hormone
What happens if someone has too little hGH before the growth plate closes?
dwarfism (genetic)
What happens if someone has too much hGH before the growth plate closes?
gigantism (usually the result of pituitary disorders)
After the growth plate closes, in abnormal conditions, subperiosteal bone deposition results in what?
acromegaly
-coarsening of facial features
-increased bone diameters
Which bone disorder is known as “imperfectly formed bone”?
osteogenesis imperfecta
Which bone disorder is the result of inherited autosomal dominant trait?
osteogenesis imperfecta
Which bone disorder is known as “marble bone disease” and has abnormally large amounts of bone matrix with highly mineralized bone matrix?
osteopetrosis
Which bone disorder has high bone mineral to collagen fiber ratio?
osteopetrosis
