biology and chemistry of bone

Question 1

What is cortical bone?

Answer 1

Compact, high portportion of bone

Question 2

what is trabecular/spongy/cancellous bone?

Answer 2

Low porportion of bone with more space, made of trabeculae

Question 3

What is the bone matrix made of?

Answer 3

Type 1 collagen, hydroxyapaptite

Question 4

What is woven bone

Answer 4

An immature form with random fibre orientation from rapid growth and repair

Question 5

What bone is at the epiphysis

Answer 5

Cancellous

Question 6

Where is the epiphysis?

Answer 6

The heads of the bone, separated by epiphyseal plates

Question 7

What is the shaft of the bone called?

Answer 7

Diaphysis

Question 8

What region is between the epiphysis and the diaphysis

Answer 8

The metaphysis

Question 9

What covers bones?

Answer 9

Periosteum with osteogenic cells

Question 10

What do osteoblasts do?

Answer 10

Bone formation and synthesis

Question 11

What do lining cells do?

Answer 11

Osteoblasts that have completed osteoblastic activity and can be reactivated

Question 12

What are osteocytes?

Answer 12

Osteoblasts entombed in bone matrix, regulates calcium homeostasis

Question 13

What are osteoclasts

Answer 13

Cells responsible for resorpsion of bone

Question 14

how does bone grow

Answer 14

By apposition via epiphyseal growth cartilages. Cartilage undergoes interstitial growth and is replaced by bone. Modelled by osteoblasts and osteoclasts

Question 15

What pathway mediated bone modelling?

Answer 15

RANKL/OPG

Question 16

What does RANKL promote?

Answer 16

Osteoclast activation

Question 17

What does OPG promote

Answer 17

Prevention of osteoclast activation

Question 18

What happens in osteoporosis?

Answer 18

The bone is broken is absorped by osteoclasts, but less is restored by osteoblasts

Question 19

What is calcium stored in within bone?

Answer 19

Hydroxyapaptite

Question 20

Describe the measurements of calcium in blood

Answer 20

We measure total calcium, but only ionised calcium is relevant. Calcium adjusted for albumin is a better representation of ionised

Question 21

What 3 things regulate plasma calcium?

Answer 21

Binding to proteins/PO4
Parathyroid hormone
Vitamin D

Question 22

What happens when decreased calcium is detected?

Answer 22

PTH synthesis is stimulated, which promotes Ca reabsorption via kidney, osteoclast reabsorption of bone, and drives active vitamin D production in kidney

Question 23

What does OPG do?

Answer 23

Binds to RANKL to prevent it binding to RANK receptors on osteoclasts. Reduces bone resorption

Question 24

What are some signs of hypercalcaemia?

Answer 24

Nausea, mental disturbances, peptic ulcers, constipation, renal stones/failure, soft tissue calcification

Question 25

What can cause hypercalcaemia?

Answer 25

Hyperparathyroidism, malignancy

Question 26

What is the only treatment for primary hyperparathyroidism

Answer 26

Surgery

Question 27

What can cause hypocalcaemia

Answer 27

Renal failure, hypoparathyroidism, vitamin D deficiency

Question 28

What are some symptoms of hypocalcaemia?

Answer 28

Paraesthesia, muscle spasm, involuntary contraction of muscles/tetany