FINAL: Bone Growth, Remodeling, And Repair

Question 1

What is the process of remodeling

Answer 1

Replacement of old bone tissue with new tissue

Question 2

What structures contain the cells required for remodeling

Answer 2

The periosteum and the endosteum

Question 3

Which cells does “remodeling” involve

Answer 3

All four cell types: osteogenic, osteocyte, osteoblast and osteoclasts

Question 4

What are osteogenic cells

Answer 4

Stem cell whose divisions produce osteoblasts
- in endosteum

Question 5

What are osteoblasts

Answer 5

Immature bone cell that secretes organic components of matrix
- outside of matrix

Question 6

What are osteocytes

Answer 6

Mature bone cell that maintains the bone matrix
- in the matrix

Question 7

What are osteoclasts

Answer 7

Multinuleate cell that secretes acids and enzymes to dissolve bone matrix
- located in medullary cavity

Question 8

What is the general process of remodeling

Answer 8

Activation of osteoclasts, followed by osteoblasts function

Question 9

Role of osteocytes in remodeling due to force

Answer 9

Osteocytes in lacunae sense the direction of force
Osteocytes secrete chemicals that activate osteoclasts in volksmann’s canal where force is high to initiate remodeling

Question 10

Role of osteoclasts in remodeling due to force

Answer 10

Break down matrix parallel to lines of force

Question 11

Role of osteoblasts in remodeling due to force

Answer 11

Fill in tunnels with more matrix -> more matrix

Question 12

What is the function of human growth hormone (HGH)

Answer 12

General growth of all body tissues, including bone

Question 13

What is the function of sex hormones (estrogens and testosterones)

Answer 13

Increase bone building activity of osteoblasts

Question 14

Function of insulin and thyroid hormones (T3, T4)

Answer 14

Promote normal bone growth and maturity

Question 15

Function of the parathyroid hormone

Answer 15

Increase the number and activity of osteoclasts, promotes recovery of Ca2+ absorption from blood and accelerates Ca2+ deposit by bones

Question 16

What is the majority of the inorganic matrix is made up of

Answer 16

Calcium hydroxyapatite = Ca5(PO4)3(OH)

Question 17

What affects the remodeling of the matrix

Answer 17

A combination of forces on the bones, hormones and nutrition

Question 18

What is osteogenesis imperfecta

Answer 18

Brittle bone disease

Question 19

What is cartilage

Answer 19

A connective tissue that consists of chondrocytes (cells) that secrete collagen intro a solid, (but not mineralized) matrix
Cells = chondrocytes
Fibers = collagen
Ground substance = solid but NOT mineralized (rubbery)
- also used to repair fractures

Question 20

Function of cartilage in bone development

Answer 20

Provides the framework for osseous tissue

Question 21

5 steps of ossification and vasularization

Answer 21

Question 22

What happens during interstitial growth

Answer 22

An epiphyseal plate contains chondrocytes that help to form new osseous tissue
Growth at epiphyseal plates - leading to increased bone length

Question 23

What is the resting zone of the growth plate

Answer 23

Toward the epiphysis, site of stem cells

Question 24

What is the proliferating zone of the growth plate

Answer 24

Massive chondrocyte division and cartilage matrix

Question 25

What is the hypertrophic zone of the growth plate

Answer 25

Chondrocytes enlarge, create large spaces in the matrix and eventually die

Question 26

What is the calcification zone of the matrix

Answer 26

Osteoblasts/osteoclasts replace cartilage matrix with osseous matrix

Question 27

What is appositional growth

Answer 27

Growth at the surface that allows our bones to become thicker (or maintain thickness but increase in diameter)

Question 28

What is hematoma

Answer 28

Mass of clotted blood that forms around a bone fracture

Question 29

What is a callus

Answer 29

Fibroblasts and chondrocytes that work to repair a fracture
- callus becomes ossified