Bone

Question 1

What part of the body acts as a storehouse for calcium?

Answer 1

Bone

Question 2

What does the ground substance of bone contain?

Answer 2

Compact bundles of Type I collagen fibers, stem cells, osteoblasts, osteocytes, osteoclasts

Question 3

What is osteoporosis?

Answer 3

Pathology of again bone, especially in elderly women, involves loss of bone mss resulting in greatly enhanced chance of fracture

Question 4

What are the two type of bone?

Answer 4

Compact and cancellous (trabecular)

Question 5

Where is cancellous bone found?

Answer 5

The center or ends (medulla or epiphysis) of long bones

Question 6

What are the branches in cancellous bone called which add strength to the structure?

Answer 6

Trabeculae

Question 7

Where is compact bone found?

Answer 7

In the cortical areas of bones

Question 8

Wha are the concentric layers of tissue in compact bone called?

Answer 8

Lamellae

Question 9

What is found in the central region of compact bone?

Answer 9

Central canal (Haversion canal)

Question 10

What is periosteum?

Answer 10

The bone surface

Question 11

What are sharpey’s fibers?

Answer 11

Type 1 collagen running perpendicular tot he surface which connect ct to bone

Question 12

What are the two layers of the periosteum?

Answer 12

Outer fibrous layer

Inner cellular layer

Question 13

What does the outer fibrous layer of periosteum composed of?

Answer 13

Dense irregular CT

Question 14

What does the inner (osteogenesis) cellular layer of periosteum consist of?

Answer 14

Osteoprogenitor (stem) cells

Osteoblasts

Osteoclasts

Question 15

What is the stem cell of bone?

Answer 15

Osteoprogenitor cell

Question 16

What is the endosteum?

Answer 16

A single layer of cells that adhere to all inner surfaces of bone

I.e. Line the cavity of all bones

Question 17

What does endosteum contain and where is it found?

Answer 17

Contains no fibrous components

Found on bony trvecular, in ha version and volkmanns cannas and on surfaces lining the medullary cavity

Question 18

What cells are found in the endosteum?

Answer 18

Osteoprogenitor cells
Osteoblasts
Osteoclasts

Question 19

What is osteomalacia? (Rickets in kids)

Answer 19

A condition occurring when bones do not mineralized properly due to lack of vitamin D (no sunlight)

Question 20

What does Vitamin D aid in the small intestine?

Answer 20

Absorption of calcium nod phosphorus

Question 21

How can soft bones no pain be treated? (Those with osteomalacia)

Answer 21

Dietary vitamin D supplements or exposure of the epidermis of the skin to sunlight

Question 22

What does the bone matrix consist of?

Answer 22

Type 1 collagen and glycosaminoglycans produced by osteoblasts

Question 23

What does the ground substance of bone consist of?

Answer 23

Mainly hydroxyappetite crystals formed of. Combination of glycosaminoglycans and calcium phosphate

Question 24

What lines the haversion canal?

Answer 24

Endosteum

Question 25

What is the haversian system or osteon?

Answer 25

A system that runs lengthwise in long bone used to carry nutrients and waste products

Question 26

What is the haversian system or osteon composed of?

Answer 26

Lamellae (rings of bone tissue) surrounding a Haversian canal

Question 27

What nourishes the haversian system?

Answer 27

A single capillary in the Haversian canal

Question 28

What are volkmann's canal?

Answer 28

A canal where blood vessels and nerve fivers run from the soft tissue outside the bone to the center of the bone

Question 29

What is the filopodia of osteocytes?

Answer 29

A long connection between osteocytes or capillary within the Haversian canal. It is a used for exchange between cells

Question 30

Where are osteoprogenitor cells found?

Answer 30

Periosteum and endosteum

Question 31

Where are osteoblasts found?

Answer 31

In periosteum and endosteum

Question 32

Where are osteocytes found and what is their function?

Answer 32

Found in lacunae to maintain matrix

Question 33

Where are osteoclasts found and what is their function?

Answer 33

Periosteum and endosteum Dissolve matrix

Question 34

What cells can be found in both the periosteum nod endosteum?

Answer 34

Osteoprogenitor cells Osteoblasts Osteoclasts

Question 35

Where are osteoprogenitor cells derived from and what do they produce?

Answer 35

Mesenchyme Produce: osteoblasts

Question 36

What cell shape are osteoblasts?

Answer 36

Cuboidal cells with basophilic cytoplasm

Question 37

Where do osteoblasts becoming embedded?

Answer 37

Lacunae

Question 38

When osteoblast becomes dormant in lacunae, what are they now called?

Answer 38

Osteocytes

Question 39

Osteoclasts are part of what system?

Answer 39

The mononuclear phagocyte (macrophage-like) system

Question 40

Where are osteoclasts formed from?

Answer 40

Blood stem cells in the marrow by several monocytes fusing together

Question 41

Describe an osteoclasts

Answer 41

A large, multinculeated and eosinophilic (stain red?)

Question 42

How do osteoclasts work?

Answer 42

Dissolves bone by exocytosing the contents of lysosomes Secrete HCl and hydrolytic enzymes (e.g. Collagenase) to break down hydroxyapatite and collagen fibrils

Question 43

Where are osteoclasts located t?

Answer 43

In a shallow indentation of bone called Howship's lacuna

Question 44

How is a new haversian system formed?

Answer 44

1. Osteoclasts cut a cylinder followed by a capillary loop 2. Osteoblasts lay down Lamellae 3. Once several layers are formed, the system is complete

Question 45

Explain how does intramembrnous bone forms (E.g. Skull bones)

Answer 45

Mesenchymal cells become osteoprogenitor cells then osteoblasts Osteoblasts surround themselves with matrix to become osteocytes Matrix calcifies into trabeculae with spaces holding red bone marrow Superficial layers of spongy bone are replaced with compact bone

Question 46

What is the simplified version of how intramembraous bone forms?

Answer 46

1. Development of center of ossification 2. Calcification 3. Formation of trabeculae 4. Development of the periosteum

Question 47

What kind of development do long bones experience?

Answer 47

Endochondral ossification

Question 48

Explain endochondral ossification

Answer 48

Cartilage template of bone first develops until a blood supply approaches the perichondrium The chondrogenic layer becomes an osteogenic layer, deposits bone on the outside of the template Cells in the center of the cartilage die, and capillaries, stem cells and osteoclasts take their place The template is converted to bone

Question 49

What do hot spots in bone scan indicate?

Answer 49

Areas of increased metabolic activity that may indicate cancer, abnormal healing or growth

Question 50

What do cold spot indicate in bone scans?

Answer 50

Decreased metabolism of bone E.g. Osteoporosis, bone infection

Question 51

How are bone scans given?

Answer 51

Radioactive tracer substance is given intravenously Amount of uptake of tracer is related to amount of blood to the bone