The Skeletal System- Bone Structure

Question 1

What is a long bone made up of?
(What is the middle shaft called and what are the ends called?)

Answer 1

Diaphysis- middle shaft.
Epiphysis- 2 ends

Question 2

What is the articulated region of the epiphysis covered in?

Answer 2

Thin layer of hyaline cartilage (Articular Cartilage)

Question 3

What is the outer bone covered in?

Answer 3

Covered with a membrane (periosteum)
It is dense irregular connective tissue.

Question 4

The inner surface of bone is covered by a thin membrane called…

Answer 4

Endosteum

Question 5

What bone marrow does the medullary cavity (in the diaphysis) contain?

Answer 5

Red and yellow bone marrow depending on bone and age of individual.

Question 6

What are the two bone textures?

Answer 6

Compact and spongy bone

Question 7

Does short, flat, irregular, and sesamoid bones have diaphysis, epiphysis, or medullary cavities?

What is the internal structure made up of?

Answer 7

No

Outer layer of thin compact bone, middle layer of spongy bone and bone marrow.

Question 8

How is blood supply to flat, irregular, and sesamoid bones provided?

Answer 8

Provided by the vessels in the periosteum

Question 9

Where do long bones get their blood supply from?

Answer 9

Get 1/3 of their blood supply from periosteum that supplies compact bone. The other 2/3 supplied by one or two nutrient arteries that enter bones in small hole in diaphysis (nutrient foramen)

Question 10

What type of CT is Red bone marrow and what is it the cite of?

Answer 10

Loose CT.

Hematopiesis (blood cell formation)

Question 11

Where is red Bone marrow in adults

Answer 11

Pelvis, proximal femur and humerus, vertebrae, ribs, sternum, clavicles, scapula, and some bones of skull.

Question 12

What type of CT is yellow bone marrow

Answer 12

Adipose tissue.

Question 13

What is bone tissue composed of?

Answer 13

Mostly extra cellular matrix with a small population of cells scattered throughout.

Question 14

The extra cellular matrix of the bone is made up of:

Answer 14

Inorganic Matrix- minerals make up about 65% of bones total weight.
Organic Matrix- consists of collagen fibres and usual ECM components. (35%)

Question 15

What is the inorganic matrix made of?

Answer 15

Calcium and phosphorus salts. They exit as large molecules of hydroxyapatite crystals. Bicarbonate, potassium, magnesium, and sodium are also found in inorganic matrix

Question 16

What is the organic matrix known as. What does it consist of?

Answer 16

Known as the osteoid. Consists of protein fibres, proteoglycans, glycosaminoglycans, glycoproteins.

Question 17

Is collagen the predominant protein fibre in the organic matrix?

Answer 17

Yes- it forms cross link with one another.

Question 18

Three types of bone cells

Answer 18

OsteBlasts- build bone
OsteoClasts- remove bone
Osteocytes- mature bone cells

Question 19

What are osteogenic cells?

Answer 19

Stem cells that differentiate into osteoblasts when stimulated by specific chemical signals.

Question 20

What do osteoBlasts secrete?

Answer 20

Organic matrix materials and assist in formation of inorganic matrix

Question 21

Do osteoblasts turn into osteocytes?

Answer 21

yes, osteoblasts eventually surround themselves with matrix in small cavities (lacunae) and become osteocytes that no longer actively synthesize bone matrix.

Question 22

What do mature osteocytes help with

Answer 22

Maintaining the extra cellular matrix of bone

Question 23

What are osteoclasts responsible for

Answer 23

Bone absorption

Question 24

What do osteoclasts secrete?

Answer 24

Hydrogen ions and enzymes. Hydrogen ions dissolve the inorganic matrix and enzymes break down the organic matrix.

Question 25

Where do the substances that get released from bone resorption go?

Answer 25

They are absorbed into the osteoclasts and then released into bloodstreams to be used elsewhere or excreted by body.

Question 26

What is compact bone organized by

Answer 26

osteoblasts

Question 27

What is spongy bone made from?

Answer 27

Made up of trabeculae that project into the marrow cavity. It is also called trabecular bone

Question 28

What is compact bone made of?

Answer 28

Osteons that are arranged in parallel to each other.

Question 29

What are osteons made up of?

Answer 29

Thin circular layers of bone called lamellae

Question 30

How many lamellae does each osteoblasts contain?

Answer 30

4-20 that are arranged in ring structures that make the bone very resistant to twisting and bending from many directions

Question 31

Where do osteocytes reside in?

Answer 31

Lacunae filled with extra cellular fluid

Question 32

What are canaliculi

Answer 32

Extensions of osteocytes that connect the lacunae to each other.

Question 33

What are perforating canals

Answer 33

Allow blood vessels and nerves to penetrate at the bone

Question 34

What does spongy bone do and what does it act as

Answer 34

Resists force from multiple directions. Acts as a protective structure for bone marrow tissue.

Question 35

What is spongy bone made of and does it have osteons?

Answer 35

Made up of trabeculae- projections of bone making a “web” to form the spongy bone. there are no osteons

Question 36

What are trabeculae made of

Answer 36

Made of lamellae with osteocytes localized to lacunae that communicate with each other through canaliculi