Bone - growth, injury and repair

Question 1

what produces cartilage?

Answer 1

chondrocytes

Question 2

what is endochondral ossification?

Answer 2

formation of bone within hyaline cartilage

Question 3

what is intramembranous ossification?

Answer 3

bone forms directly from mesenchymal tissue and doesn’t require a prior cartilage model, no growth plates, occurs in flat bones inc. skull bones, clavicle and scapula

Question 4

what does the primary ossification centre form?

Answer 4

The Diaphysis

Question 5

outline the process of primary ossification…

Answer 5

Hpertrophy of the chondrocytes o Invasion by blood vessels – forms the nutrient artery system o Conversion to bone starts circumferentially

Question 6

outline the process of secondary ossification

Answer 6

• At the epiphyseal regions, vascular infiltration also occurs • The process of enchondral ossification occurs via the growth plate • A central mass is then formed in the epiphysis

Question 7

what are the differetn types of physis and thheir function in growth

Answer 7

• Horizontal – produces longitudinal growth • Spherical – producing circumferential growth

Question 8

what is the zone of reserve?

Answer 8

contains spherical chondrocytes, lipids and glycogen and collagen

Question 9

what is the xone of proliferation?

Answer 9

Flattened stacking of chondrocytes, Become columnar, Less extra-cellular matrix than reserve zone, Longitudinal growth occurs – cellular proliferation, Increased circulating proteoglycans inhibits calcification, Increasing pO2.

Question 10

what is the zone of hypertrophy?

Answer 10

• Zone of Maturation/Degeneration: Preparation for calcificationm, Chondrocytes increase in size, Progressive decreased in pO2 and blood supply • Zone of provisional calcification: Calcification of intercellular matrix – reducing proteoglycan levels, Chondrocyte death, Very low pO2, No blood supply.

Question 11

what is the metaphysis?

Answer 11

Expands with skeletal growth, Osteoblasts align on cartilage bars, Primary spongiosa – calcified cartilage bars, Secondary spongiosa – remodelled bone

Question 12

what factors effect growth?

Answer 12

GH, sex hormones, thyroid hormones, parathhyroid hormones, vit c - collagenm synthesis, vit d - calcium metabolism, calcitonin, previous trauma, blood supply.