Bone Diseases

Question 1

Name some types of bone cell and what they do

Answer 1

• Ostegenic cell = develops into an osteoblast
• Osteoblast = forms bone tissue
• Osteocyte = maintains bone tissue
• Osteoclast (ruffled border) = resorption and destruction of bone matrix

Question 2

Describe basic features of Woven bone

Answer 2

• Weak and greater tendency to fracture under stress
• Haphazard organisation of fibres = less efficient at withstanding stress
• Osteoblasts produce osteoid rapidly
• Woven bone is in all metal bones and is later replaced by lamellar bone
• Woven bone is the first bone formed after fractures

Question 3

Describe the basic features of lamellar bone

Answer 3

• Mechanically strong
• Lamellar bone is the secondary bone created by remodelling woven bone
• Highly organised alignment of collagen in sheets
• Fibres run in opposite directions in cross-section
• High tensile strength
• Less osteocytes

Question 4

AY BAWS CAN I HABE DE NOTE PLZ

Answer 4

Bone is constantly being refashioned by osteoblastic new bone formation and osteoclastic removal of old bone

Question 5

What are some mechanical factors related to the process of bone remodelling

Answer 5

• Gravitational Force
• Weight of an individual
• Muscular Contractility
• Effort
• Prolonged weightlessness-bedrest

Question 6

What are some non-mechanical factors related to bone remodelling

Answer 6

• Hormones
• Age/sex/genetics
• Diet
• Occupation
• Some disease like RA

Question 7

What are some hormones that are involved in bone remodelling

Answer 7

• Parathyroid hormone (PTH)
• Vitamin D
• Calcitonin
• Growth hormone, corticosteroids, androgens, oestrogen, insulin and vitamins

Question 8

What is the effect of parathyroid hormone in bone remodelling

Answer 8

PTH is secreted by parathyroid glands in response to a fall in blood calcium and restores blood calcium level by directly and indirectly stimulating bone resorption and increasing reabsorption of calcium and phosphate ions in kidneys

Question 9

What is the effects of vitamin D in bone remodelling

Answer 9

• Vit D acts as a hormone promoting the mineralisation of bone

Question 10

What is the effect of calcitonin in bone remodelling

Answer 10

• Hormone produced by the thyroid gland in response to a rise in plasma calcium and has the opposite effect to PTH.
• Depresses osteoclastic activity, used therapeutically and is used therapeutically to suppress bone resorption in disease like Paget’s

Question 11

Give examples of some metabolic bone disease

Answer 11

• Osteoporosis
• Osteomalacia
• Pagets disease of bones
• Hyperparathyroidism
• Renal osteodystrophy