Bone (Nishi)

Question 1

How does bone repair?

Answer 1

produces new matrix, just like the previous matrix

Question 2

Bone remodeling is ______, which allows it to respond to stresses.

Answer 2

continuous

Question 3

Devitalized, demineralized bone contains:

Answer 3

growth and differentiation factors that will stimulate bone growth in ectopic sites (even under skin)

Question 4

What cells deposit bone matrix?

Answer 4

osteoblasts

Question 5

What is made in response to BMP?

Answer 5

Specific transcription factors for osteoblast differentiation
(BMP = developmental regulators)

Question 6

How does bone respond to a demand for Ca?

Answer 6

Demand for calcium stimulates bone matrix resorption by osteoclasts, which releases Ca2+

Question 7

Serves as Ca reservoir

Answer 7

bone

Question 8

How are osteoclasts formed?

Answer 8

via differentiation and fusion of monocytes, which involves cell-cell interaction with osteoblasts through a RANK-RANKL interaction

Question 9

How do osteoclasts act on bone matrix?

Answer 9

Release acid and protease into sealed off region of bone matrix below cell body, which allows for its reabsorption

Question 10

Bone is constantly remodeled in response to:

Answer 10

1. demands for calcium

2. mechanical stresses that demand enhanced or reduced bone mass

Question 11

Hormone which enhances calcium release

Answer 11

parathyroid

Question 12

Hormone which opposes the release of calcium

Answer 12

calcitonin

Question 13

What are the functions of calcitriol and vitamin D3?

Answer 13

calcium absorption and bone mineralization

Question 14

How does endochondral bone form?

Answer 14

1. cartilage becomes calcified
2. calcified cartilage then replaced by bone matrix and vasc bed at growing ends of bone

(Bone forms on a cartilage scaffold)

Question 15

Components of cartilage (like type II collagen and aggrecan) are replaced by:

Answer 15

bone specific proteins:

1. osteocalcin
2. osteopontin
3. bone sialoprotein
4. highly crosslinked type I collagen

Question 16

What is commonly used as a bone turnover measurement?

Answer 16

bone collagen crosslinks derived from HYL

Question 17

Bone remodeling occurs via concerted action of:

Answer 17

osteoblasts and osteoclasts

Question 18

Bone remodeling is regulated by what hormones?

Answer 18

PTH
calcitonin
active form of vitamin D

Question 19

Bone forms from a _______ in development.

Answer 19

cartilage scaffold

Question 20

Inbalance between formation and resorption can lead to:

Answer 20

bone disorders

Paget’s, osteoporosis, osteosclerosis, etc

Question 21

Ca+ is excreted via:

Answer 21

sweat
urine
lactation

Question 22

What is protective against osteoporosis?

Answer 22

Early buildup of bone mass in prepuberty and early adulthood

Question 23

How do you treat Paget’s and osteoporosis?

Answer 23

bisphosphonates

Question 24

Ca is stored in bone as:

Answer 24

HAP (hydroxyapatite, a hydroxyl calcium phosphate)

Question 25

Bone is characterized by:

Answer 25

specific bone proteins and a collagen that is highly crosslinked