16) Bone Function and Repair

Question 1

What are rickets?

Answer 1

A vitamin D deficiency that occurs in children causwing poor calcium mobility, inneffective mineralisation and weakened bone development

Question 2

What are 4 symptoms of rickets?

Answer 2

Soft bones
Bowed legs
Short stature and height
Painful to walk

Question 3

What is osteomalacia?

Answer 3

Rickets in adults. Vitamin D deficiency disease, resulting in lower mineralisation and increased osteoid

Question 4

How can you increase calcium resorption?

Answer 4

Kidney diease
Protection from sunlight
Surgery
Drugs

Question 5

What is primary type 1 osteoporosis?

Answer 5

Decrease in bone density in postmenopause women, due to a decrease in oestrogen

Question 6

What is primary type 2 osteoporosis?

Answer 6

Decrease in bone density in older men and women due to a loss of function of osteoblasts, causing a loss of oestrogen and androgen

Question 7

What is achondroplasia?

Answer 7

An inherited disease in which there is a mutation in the FGF3 receptor gene, affecting collagen formation from cartilage and therefore endochondrial ossification, resulting in short stature bur normal head and limbs

Question 8

Describe the process of intramembranous ossification

Answer 8

1) Mesenchymal stem cells aggregate and form osteoprogenitor cells
2) The osteoprogenitor cells forms osteoblasts
3) Osteoblasts lay down a osteoid (extracellular matrix containing type 1 collagen)
4) The osteoid mineralises to form spicules
5) Spicules form trabeculae, which merge and form woven bone
6) The trabeculae are replaced by lamellae of mature compact bone

Question 9

Describe the process of fracture repair

Answer 9

1) Blood vessels break and a haematoma forms
2) Granulocytes enter the site to reduce inflammation and swelling
3) Clot removed
4) New blood vessels enter, the procallus forms and fibroblasts lay collagen fibres cartilage across the break. At the same time osteoblasts in the nearby periosteum are laying down new bone
5) Fibrocartilaginous callus replaces the procallus
6) Strong bone has been placed across the break, bone is ready for remodelling
7) Bone remodelling occurs, outside cancellous one replaced with corical bone

Question 10

How does bone remodelling occur?

Answer 10

Osteoclasts make a wide tunnel in the bone

Osteoblasts make a smaller tunnel of cortical bone