Musculoskeletal Bone Physiology

Front 1

What are 5 functions of bone?

Back 1

1. Support/shape
2. Protection (brain, heart, lungs)
3. Movement (muscle attachments and joints)
4. Calcium and Phosphate homeostasis (repository)
5. Blood cell production (bone marrow)

Front 2

This is a major reason why we see bone resorption throughout our lives.

Back 2

Calcium and Phosphate homeostasis.

Front 3

Name the 3 things making up the non-cellular portion of bone.

Back 3

1. Collagen matrix
2. Hydroxyapatite (mineral complex precipitated on matrix)
3. Ground substance

Front 4

What is the 'Ground Substance' of bone composed of?

Back 4

Chondroitin Sulfate & Hyaluronan

Front 5

Where are osteoblasts derived from?

Back 5

Osteoprogenitor cells.

Front 6

What is the first step in bone synthesis?

Back 6

Osteoblasts release collagen at the surface of the bone (its long axis).

Front 7

Name 4 things that the osteoblasts secrete at the bone surface.

Back 7

1. Collagen
2. Calcium ions
3. Phosphate ions
4. Hydroxyl ions

Front 8

What allows hydroxyapatite to precipitate?

Back 8

The high pH (due to OH ions) in the osteoid coupled with the presence of the calcium and phosphate ions.

Front 9

What is the formula for Hydroxyapatite?

Back 9

(Ca10(PO4)6(OH)2)

Front 10

How does bone remodeling deal with incorporation of heavy metals? What is the good and bad?

Back 10

Good: Heavy metals may be included in with hydroxyapatite precipitation. This helps in detoxification.

Bad: This can trap radioactive compounds in our bones. Prolonged exposure can lead to a risk of bone cancer.

This is what happens with fluoride.

Front 11

Name 2 proteins that are secreted by osteoblasts?

Back 11

1. Osteonectin
2. Osteocalcin

Front 12

What is the role of osteonectin?

Back 12

It is secreted by the osteoblast in bone formation.

It binds to the collagen matrix and acts as a precipitation point for binding of hydroxyapatite to collagen.

Front 13

What is the role of osteocalcin?

Back 13

It is secreted by the osteoblasts in bone synthesis.

It promotes the union of osteonectin and hydroxyapatite.

Front 14

This provides bone with its compressional strength.

Back 14

Hydroxyapatite.

Front 15

This provides bone with its tensile strength.

Back 15

Collagen.

Front 16

Where do osteocytes reside?

Back 16

The are embedded in mature bone canaliculi.

Front 17

What do the osteocytes do?

Back 17

Osteocytic osteolysis--this is where they send out syncitial processes that allow the osteocyte to transfer calcium from the core of mineralized bone out to the plasma.

Front 18

How is osteocytic osteolysis helpful to the body overall?

Back 18

It provides the body with access to a lot of stored calcium without altering the collagen matrix or decreasing the bone mass.

Front 19

Name 4 things that osteoclasts secrete?

Back 19

1. Protons
2. Type IV collagenase
3. Phosphatase
4. Lysosomal enzymes

Front 20

In bone resorption, what is the role of the secreted protons?

Back 20

They lower pH and raise the solubility of hydroxyapatite.

Front 21

In bone resorption, what is the role of Type IV collagenase?

Back 21

It digests the collagen protein matrix.

Front 22

In bone resorption, what is the role of Phosphatase?

Back 22

It helps break down hydroxyapatite.

Front 23

In bone resorption, what is the role of the Lysosomal enzymes?

Back 23

It helps digest collagen and osteonectin and osteocalcin.

Front 24

The digestion of collagen in bone resorption results in the substantial presence of these two amino acids in the urine.

Back 24

1. Hydroxyproline
2. Hydroxylysine

Used as markers for bone resorption.

Front 25

Where are osteoclasts derived from?

Back 25

They're derived from fusion of monocyte/macrophage precursor cells.

Front 26

Where can you find inactive osteoclasts?

Back 26

They can be found attached to periosteal surface. This attachment is mediated by integrins.

Front 27

How are osteoclasts activated (in general)?

Back 27

By endocrine and paracrine signaling.

Front 28

How does the following affect Osteoblasts and/or Osteoclasts:

Growth Hormone?

Back 28

Stimulates Osteoblasts

Front 29

How does the following affect Osteoblasts and/or Osteoclasts:

Insulin?

Back 29

Simulates Osteoblasts

Front 30

How does the following affect Osteoblasts and/or Osteoclasts:

Estrogen?

Back 30

Stimulates Osteoblasts

Inhibits Osteoclasts

Front 31

How does the following affect Osteoblasts and/or Osteoclasts:

Androgens?

Back 31

Stimulates Osteoblasts

Inhibits Osteoclasts

Front 32

How does the following affect Osteoblasts and/or Osteoclasts:

Vitamin D?

Back 32

Stimlates Osteoblasts and Osteoclasts.

Front 33

How does the following affect Osteoblasts and/or Osteoclasts:

Transforming Growth Factor beta?

Back 33

Stimulates Osteoblasts

Inhibits Osteoclasts

Front 34

How does the following affect Osteoblasts and/or Osteoclasts:

Skeletal Growth Factor?

Back 34

Stimulates Osteoblasts

Front 35

How does the following affect Osteoblasts and/or Osteoclasts:

Bone-derived growth factor?

Back 35

Stimulates Osteoblasts

Front 36

How does the following affect Osteoblasts and/or Osteoclasts:

Platelet-derived growth factor?

Back 36

Stimulates Osteoblasts

Front 37

How does the following affect Osteoblasts and/or Osteoclasts:

Calcitonin?

Back 37

Stimulates Osteoblasts

Inhibits Osteoclasts

Front 38

How does the following affect Osteoblasts and/or Osteoclasts:

Cortisol?

Back 38

Inhibits Osteoblasts

Stimulates Osteoclasts

Front 39

How does the following affect Osteoblasts and/or Osteoclasts:

Parathyroid Hormone?

Back 39

Stimulates Osteoclasts

Front 40

How does the following affect Osteoblasts and/or Osteoclasts:

Thyroid Hormone?

Back 40

Stimulates Osteoclasts

Front 41

How does the following affect Osteoblasts and/or Osteoclasts:

Prostaglandins?

Back 41

Stimulates Osteoclasts

Front 42

How does the following affect Osteoblasts and/or Osteoclasts:

Interleukins 1 & 6?

Back 42

Stimulate Osteoclasts

Front 43

How does the following affect Osteoblasts and/or Osteoclasts:

Tumor Necrosis Factors alpha and beta?

Back 43

Stimulate Osteoclasts

Front 44

How does the following affect Osteoblasts and/or Osteoclasts:

Interferon?

Back 44

Inhibit Osteoclasts

Front 45

How does the following affect Osteoblasts and/or Osteoclasts:

Nitric Oxide?

Back 45

Inhibit Osteoclasts