Ossification and Bone Disease Flashcards
What is ‘intramembranous ossification’?
New bone made within condensations of mesenchymal tissue and not by replacing hyaline cartilage.
Describe the abnormality in someone suffering from Osteogenesis Imperfecta
Autosomal dominant group of heritable disorders of connective tissue. Mutations in the gene for type I collagen.
Before puberty, what does
i. ) excessive levels of growth hormone cause?
ii. ) insufficient levels of growth hormone cause?
i. ) Gigantism
ii. ) Pituitary Dwarfism
In an adult, what does excessive levels of growth hormone cause?
Acromegaly (widening of the bones)
What happens if a newborn has low levels of thyroid hormone?
Cretinism- intellectual damage and short stature
What is osteoporosis?
More bone mass is absorbed than formed so the bones have a loss of mass. They fracture more easily and are weaker.
What is the cause of Type 1 osteoporosis?
Oestrogen withdrawal in menopausal women
Osteoclast number increases
What is the cause of Type II osteoporosis?
Lessened osteoblast function due to old age
List 4 risk factors of osteoporosis
Genetic links Insufficient calcium intake Insufficient calcium absorption Lack of exercise Smoking
What is achondroplasia?
The most common form of short-limb dwarfism caused by a autosomal dominant point mutation in the gene for fibroblast growth factor.
Describe the process of Vitamin D metabolism
Vitamin D from the diet or sunlight
Liver -> Kidney -> (1,25(OH)2 D)
How does Vitamin D help the body?
Increases calcium absorption in the small bowel and promotes mineralisation of bone
What is rickets?
A childhood disease where the bones do not harden due to a vitamin D deficiency
What is osteomalacia?
Adult rickets
Caused by a calcium deficiency or lack of Vitamin D
Weakened bone, bone pain, back ache
What is ‘Endochondrial ossification’?
The replacement of a pre-existing hyaline cartilage template by bone
