Lecture 4 - Bone Tissue

Question 1

What is bone?

Answer 1

Bone is a living tissue that has cells, as well as a calcified extra cellular matrix. Bone can respond to the forces coming to your body.

Question 2

What sort of tissue is bone?

Answer 2

Bone is a hard connective tissue. It supports other tissues/organs and maintains form.

Question 3

What are the two extra cellular components of bone?

Answer 3

1. Organic (all connective tissue made and also proteins)

2. Inorganic (hard aspect of bone)

Question 4

What are extracellular components?

Answer 4

Anything in a tissue that is not a cell.

Question 5

If bone is organic what are its properties?

Answer 5

1. Collagen (protein) exists in fibers that run through the mineral part of the bone
2. Ground substance (proteoglycans)
3. Function = resists tension

Question 6

If bone is inorganic what is its properties?

Answer 6

1. Hydroxyapatite + other Ca minerals

Question 7

What is a mineral component?

Answer 7

The thing that makes your bones resistant to compression.

Question 8

What would happen to your bones if you soaked them in acid?

Answer 8

It would take out the inorganic part of the bone and make the bone loose and floppy and wouldn’t be able to hold weight and have a posture

Question 9

The cellular component of bone makes up what percentage of bone by weight?

Answer 9

2%

Question 10

What are the four types of cells in bone?

Answer 10

1. Osteogenic
2. Osteoblasts
3. Osteocytes
4. Osteoclasts

Question 11

Osteogenic cells are :

Answer 11

Stem cells that produce osteoblasts

Question 12

Osteoblast cells are :

Answer 12

MAKERS : produce new bone matrix

Question 13

Osteocyte cells are :

Answer 13

MAINTAINERS : recycle protein and minerals from matrix

Question 14

Osteoclast cells are :

Answer 14

DESTROYERS - remove bone matrix

Question 15

What is the gross structure of compact bone?

Answer 15

Osteon structure. Organized structure around osteons

Question 16

What is the gross structure of cancellous bone?

Answer 16

Trabecular structure. Laced and branching off each other

Question 17

Bone macroscopically is :

Answer 17

Outer surfaces seem dense and impenetrable (periosteum)

Foramina/holes for blood supply - nerve and nutrient supply

Question 18

Bone microscopically is :

Answer 18

Made up of circumferential lamellar and units called osteons

Question 19

What are osteons?

Answer 19

Osteons are cylindrical structures that contain a mineral matrix and living osteocytes connected by canaliculi, which transports blood. Each osteon consists of lamellar, which are layers of compact matrix that surround a central canal.

Question 20

Within an osteon, what holds blood vessel and nerves?

Answer 20

Central canal

Question 21

Within an osteon, a series of cylinders formed of ECM around the central canal are called…

Answer 21

Concentric lamellae

Question 22

The canaliculi…..

Answer 22

Channels for osteocytes through ECM and runs through the central canal to lamellae.

Question 23

The Lacunae is…

Answer 23

Lakes for osteocytes

Question 24

Why are cancellous bones trabecular?

Answer 24

The organization of trabecular resists force from multiple directions. Direct force from the body weight in single direction down the shaft. Trabecular helps spread out weight to the entire bone instead of in one specific place which is why cancellous bone is weight resistant.

Question 25

How do bones maintain homeostasis?

Answer 25

Bones maintain homeostasis by regulating blood calcium levels and producing the hormone osteon calcium which regulates bone formation

Question 26

What is lamellae?

Answer 26

Filled with collagen fibers that run in the sea,e directions

Question 27

What is an osteocyte?

Answer 27

Osteocytes are mature bone cells that monitor and maintain your bone matrix - two main work courses

Question 28

What is the process of bone growth and how does it begin?

Answer 28

Bone starts out as cartilage, creating a structure for bone to grow in. Osteocytes come into the cartilage and secrete collagen which absorb calcium, phosphate and other minerals from the blood. These minerals form calcium phosphate which crystalise on the cartilage framework and form a bone matrix which is ⅓ mineral and ⅔ protein.