session 7-ossification and bone disease Flashcards
where does bone length growth occur?
epiphyseal (growth) plates
what are the differences between osteomalacia and rickets?
same disease but named rickets in kids and osteomalacia in adults
Children: growing bones, bone osteoid fails to calcify normally, epiphyseal plate becomes distorted due to body weight, bones deformed and fractured (vit D deficiency)
adults: bone remodelling, deficient calcification of recently formed bone, bone softens (Ca2+ or lack of vit D)
how is osteogenesis imperfecta caused?
-abnormal collagen (type 1) synthesis by osteoblasts and fibroblasts
what is osteogenesis imperfecta (OI)? Autosomal dominant
-disease characterised by bone fragility which increases the risk of fracture and deformity
-bowed bones and blue sclera
(FUN FACT: legally important-possible confusion between disease and deliberate injury)
what is the role of vitamin D?
involved in absorption of calcium and phosphate in the small intestine
osteomalacia is a consequence of inadequate intake of what 3 things?
calcium, phosphate and vit D
what kind of growth does achondroplasia impair?
endochondral bone formation=impairment of longitudinal growth
-epiphyseal growth plates are thin
what does lack of growth hormone cause?
pituitary dwarfism
BEFORE PUBERTY ONLY, excessive growth hormone causes what?
gigantism
in an adult why does excessive GH not cause gigantism?
no longer any epiphyseal plates
what does excessive GH cause in adults?
acromegaly- increase in bone width and thus thickness
what 2 sex hormones give rise to the pubertal growth spurt?
oestrogen and androgen
what does precocious sexual maturity do in terms of bone growth?
-premature closure of epiphyses and retards bone growth
what happens in terms of bone growth if sex hormone is deficient?
prolonged bone growth and tall stature
what can neonatal (referring to newborn) hypothyroidism cause?
cretinism-neurological,intellectual damage, short stature and other abnormalities
What is type 1 and type 2 osteoporosis?
Type 1-after menopause…less oestrogen so inc osteoclasts function
Type 2-both sexes after 70..Dec osteoblasts function
What type of inheritance is achondroplasia caused by, what kind of mutation is it and what does it affect?
- autosomal dominant
- point mutation
- FGFR3 (fibroblast growth factor receptor 3
In achondroplasia, what is a result of a gain of function in the FGFR 3 gene?
- Dec endochondral ossification
- inhibited proliferation of chondrocytes in growth plate cartilage
- Dec hyper trophy
- Dec cartilage matrix production
Describe what a person who has achondroplasia would look like.
- short limbs
- enlarged skull
- small face and flat nose
On an image of osteomalacia/rickets and osteoporosis, what difference would you see?
Osteomalacia/rickets-normal amount of bone matrix but decreased mineralisation
Osteoporosis-decreased amount of bone matrix and mineral
