Bone

Question 1

Bone

Answer 1

a type of connective tissue, with an ossified (by deposition of calcium) extracellular matrix (ECM), that supports the body, protects internal organs, forms blood cells in bone marrow, and acts as the body’s Ca2+ and PO43– ion reservoir.

Question 2

Three major types of bone cells

Answer 2

Osteoblasts, Osteocytes, Osteoclasts

Question 3

Osteoblasts function

Answer 3

Secrete the matrix which then hardens by calcification, trapping the
differentiating cells now called osteocytes in individual lacunae.

Secrete osteoid rich in Type 1 collagen

Question 4

Osteocytes function

Answer 4

Maintain the calcified matrix and receive nutrients from vessels in the central canals of the osteons via tiny channels called canaliculi that connect the lacunae.

Question 5

Osteoclasts function

Answer 5

digestion and reabsorption of bone matrix in large resorption cavities (Howship lacunae) on the matrix surface.

Question 6

Two types of connective tissue covering bone that contain osteogenic cells

Answer 6

Periosteum and Endosteum

Question 7

Periosteum

Answer 7

A type of connective tissue covering bone that contains osteogenic cells.

A dense connective tissue. Bone is vascularized by vessels from the periosteum.

In the outer layer, bundles of collagen called perforating (or Sharpey)
fibers bind the periosteum to the bone.

The periosteum’s inner layer is more cellular and includes osteoblasts, and mesenchymal stem cells referred to as osteoprogenitor cells.

Question 8

Endosteum

Answer 8

A type of connective tissue covering bone that contains osteogenic cells.

Covers all trabeculae around the marrow cavities.

Contains osteoprogenitor cells and osteoblasts.

Question 9

Osteoblasts misc.

Answer 9

Osteoblasts originate from mesenchymal osteoprogenitor cells and
produce the organic components of bone matrix, including type I collagen fibers.

Osteoblasts are located exclusively at the surfaces of bone matrix as a
single layer of cuboidal cells. They produce a layer of collagen-rich, uncalcified material called osteoid between the osteoblast layer and the bone surface.

Question 10

Important components of osteoid

Answer 10

Produced from osteoblasts

Type I collagen, the protein
osteocalcin, and chondroitin sulfate, a GAG that forms part of proteoglycans. Chondroitin sulfate provides most of the resistance to compression in cartilage.

Question 11

Osteoclasts misc.

Answer 11

Large multinucleated cells which are derived by the fusion of several blood-derived monocytes.

Question 12

Inorganic matter

Answer 12

One of the two components of bone matrix.

About 50% of the dry weight of bone matrix is inorganic.

Calcium hydroxyapatite is the most abundant
inorganic compound.

The surface of hydroxyapatite crystals is hydrated, facilitating the exchange of ions within body fluids.

Question 13

Organic matter

Answer 13

One of the two components of bone matrix.

90% of calcified matrix is Type I collagen, but also includes small proteoglycans and multiadhesive glycoproteins.

Calcium-binding proteins, notably osteocalcin, promote calcification of the matrix.

Question 14

Types of bone

Answer 14

Woven bone, Lamellar bone, Compact (Cortical) bone, and Cancellous (Trabecular) bone

Question 15

Woven bone

Answer 15

Newly calcified

Locations: Developing and growing bones; hard callus of bone fractures

Synonyms: Immature bone; primary bone; bundle bone

Question 16

Lamellar bone

Answer 16

Remodeled from woven bone

Locations: All normal regions of adult bone

Synonyms: Mature bone; secondary bone, ossified

Question 17

Compact (cortical) bone

Answer 17

~80% of all lamellar bone

Locations: Thick, outer region (beneath periosteum) of bones

Synonyms: Cortical bone

Question 18

Cancellous (trabecular) bone

Answer 18

~20% of all lamellar bone

Locations: Inner region of bones, adjacent to marrow cavities

Synonyms: Spongy bone; trabecular bone; medullary bone

Question 19

Two types of organization for compact bone and cancellous bone based on the stage of development

Answer 19

Woven bone: newly formed, first bone tissue to appear in embryonic development and in fracture repair, weaker than lamellar bone because of lower mineral content.

Lamellar bone: Most bone in adults, whether compact or cancellous, is organized
as lamellar bone, characterized by multiple layers or lamellae of calcified matrix; like the orientation of wood fibers in plywood; this type of bone is fully ossified

Question 20

Osteons

Answer 20

constitute most of the compact bone. An
osteon (or Haversian system) refers to the
complex of concentric lamellae

Question 21

What is the epiphyses (the bulbous ends) in long bones composed of?

Answer 21

Composed of cancellous bone covered by a thin layer of compact (cortical) bone

Question 22

What is the diaphysis (the cylindrical part) in long bones composed of?

Answer 22

Almost totally dense compact (cortical) bone with a thin region of cancellous bone on the inner surface around the central marrow cavity

Question 23

Two Processes of Osteogenesis

Answer 23

Intramembranous ossification and Endochondral ossification

Question 24

Intramembranous ossification

Answer 24

Osteoblasts
differentiate directly from mesenchyme and begin
secreting osteoid. There is no cartilage precursor.

Question 25

Endochondral ossification

Answer 25

A preexisting matrix of hyaline cartilage is eroded and invaded by osteoblasts, which then begin osteoid production. Longitudinal growth at epiphyseal plate Appositional growth around diaphysis

Question 26

Two Patterns of Osteogenesis

Answer 26

Longitudinal growth and Appositional growth

Question 27

Longitudinal growth

Answer 27

in long bones is regulated by the epiphyseal plate, which separates the epiphysis from the diaphysis (shaft).

Question 28

Appositional growth

Answer 28

Occurs by formation of a periosteal bone collar around the diaphysis. Growth in the circumference of long bones does not involve endochondral ossification. It occurs through osteoblasts developing from osteoprogenitor cells in the periosteum by a process of appositional growth which begins with formation of the bone collar on the cartilaginous diaphysis.

Question 29

Fracture Repair

Answer 29

Repair of a fractured bone uses the cells and mechanisms already in place for bone growth and remodeling. (1) Blood vessels torn within the fracture release blood that clots to produce a large fracture hematoma. (2) The hematoma is removed by macrophages; a matrix of damaged, cell-free bone is resorbed by osteoclasts; the periosteum and the endosteum at the fracture site respond with intense proliferation and produce by a soft fibrocartilage-like mass called procallus tissue. (3) The procallus is invaded by regenerating blood vessels and proliferating osteoblasts. In the next few weeks the fibrocartilage is gradually replaced by woven bone which forms a hard callus throughout the original area of fracture. (4) The woven bone is then remodeled as compact and cancellous bone and fully functional vasculature is reestablished. Stresses imposed on the bone during repair and gradual return to activity help to remodel the bone callus.

Question 30

Primary bone tumor

Answer 30

Cancer originating directly from bone cells (a primary bone tumor) is fairly uncommon (0.5% of all cancer deaths), although a cancer called osteosarcoma can arise in osteoprogenitor cells.

Question 31

Secondary metastatic tumors

Answer 31

The skeleton is often the site of secondary, metastatic tumors, when cancer cells move into bones via small blood or lymphatic vessels from malignancies in other organs, such as the breast, lung, prostate gland, kidney, or thyroid gland.

Question 32

What causes rickets

Answer 32

Calcium deficiency in children can lead to rickets, a disease in which the bone matrix does not calcify normally and the epiphyseal plate can become distorted by the normal strains of body weight and muscular activity.

Question 33

Osteogenesis imperfecta

Answer 33

“brittle bone disease,” refers to a group of related congenital disorders in which the osteoblasts produce deficient amounts of Type I collagen or defective Type I collagen due to genetic mutations. Such defects lead to a spectrum of disorders, all characterized by significant fragility of the bones.

Question 34

Bone is a composite of

Answer 34

It is a composite of proteinaceous fibers and mineral.

Question 35

Howship lacunae are formed by

Answer 35

Osteoclasts

Question 36

What part of a long bone, such as the femur, is composed of cancellous bone covered by a thin layer of compact cortical bone?

Answer 36

Epiphysis

Question 37

Hydroxyapatite is the mineral component of bone. It is composed primarily of which ions?

Answer 37

Calcium and phosphate

Question 38

Endochondral ossification is not typical of these bones.

Answer 38

Flat bones of the skull, such as the frontal.

Question 39

What is a part of the mature haversian system?

Answer 39

Nerves, Central canal, Osteocytes

Question 40

Acromegaly is caused by

Answer 40

An increase in levels of growth hormone in adults.

Question 41

How much of the dry weight of bone matrix is inorganic?

Answer 41

50%

Question 42

Osteocytes have dendritic processes that communicate with each other by means of

Answer 42

Canaliculi

Question 43

Lacunae of bone tissue contain

Answer 43

Osteocytes

Question 44

After a long bone has undergone most of its development, the two principal regions of hyaline cartilage that remain are the articular cartilages at the joints, and the \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

Answer 44

Epiphyseal plate

Question 45

In a bone fracture, which cells remove the blood cells of a hematoma?

Answer 45

Macrophages

Question 46

What processes are part of appositional growth of a long bone?

Answer 46

Osteoblasts deposit bone on the periphery of the diaphysis, and osteoclasts enlarge the marrow cavity.

Question 47

How does osteoid differ from mature bone?

Answer 47

Mature bone is calcified (ossified); osteoid is not.

Question 48

Osteosarcomas arise in cells that are rapidly dividing in regions of bone growth. Typically these cells are the

Answer 48

Osteoprogenitor (mesenchymal) cells

Question 49

Periosteum (both layers) contains

Answer 49

Type 1 collagen and fibroblasts, Blood vessels, Osteoblasts and osteoprogenitor cells

Question 50

In a long bone, the primary ossification center is in the

Answer 50

Diaphysis

Question 51

About 90% of the organic part of bone matrix is type 1 collagen; the rest includes

Answer 51

Proteoglycans and multiadhesive glycoproteins

Question 52

The connective tissue that lines the bony trabeculae in the marrow cavity is called

Answer 52

Endosteum

Question 53

During healing of a bone fracture, which tissues produce the woven bone that forms the callus?

Answer 53

Periosteum and endosteum

Question 54

Somatotropin

Answer 54

Stimulates the production of IGF-1, it is also called growth hormone, it is produced by the anterior lobe of the pituitary gland

Question 55

In appositional growth of a developing long bone, the osteoblasts within the periosteum form the

Answer 55

Bone collar

Question 56

What secretes bone matrix?

Answer 56

Osteoblasts

Question 57

Cells that reside in the lacunae in bone tissue

Answer 57

Osteocytes

Question 58

Derived from monocyte blood cells

Answer 58

Osteoclasts

Question 59

Cells that maintain the calcified matrix of bone

Answer 59

Osteocytes

Question 60

Mesenchymal cells that give rise to osteoblasts

Answer 60

Osteoprogenitor cells

Question 61

A type of bone cell that is large and multinucleate

Answer 61

Osteoclasts

Question 62

These cells remodel bone tissue by breaking down the ossified matrix

Answer 62

Osteoclasts

Question 63

These bone cells are connected by canaliculi

Answer 63

Osteocytes

Question 64

These cells like the newly deposited osteoid

Answer 64

Osteoblasts

Question 65

Which type of bone forms the hard callus in a healing bone fracture?

Answer 65

Woven bone

Question 66

What is the function of Sharpey fibers?

Answer 66

They bind the periosteum to the bone.

Question 67

Which type of bone is formed from a cartilaginous precursor?

Answer 67

Endochondral bone

Question 68

# Reversed prompt a type of connective tissue, with an ossified (by deposition of calcium) extracellular matrix (ECM), that supports the body, protects internal organs, forms blood cells in bone marrow, and acts as the body’s Ca2+ and PO43– ion reservoir.

Answer 68

Bone

Question 69

# Reversed prompt Osteoblasts, Osteocytes, Osteoclasts

Answer 69

Three major types of bone cells

Question 70

# Reversed prompt Secrete the matrix which then hardens by calcification, trapping the differentiating cells now called osteocytes in individual lacunae. Secrete osteoid rich in Type 1 collagen

Answer 70

Osteoblasts function

Question 71

# Reversed prompt Maintain the calcified matrix and receive nutrients from vessels in the central canals of the osteons via tiny channels called canaliculi that connect the lacunae.

Answer 71

Osteocytes function

Question 72

# Reversed prompt digestion and reabsorption of bone matrix in large resorption cavities (Howship lacunae) on the matrix surface.

Answer 72

Osteoclasts function

Question 73

# Reversed prompt Periosteum and Endosteum

Answer 73

Two types of connective tissue covering bone that contain osteogenic cells

Question 74

# Reversed prompt A type of connective tissue covering bone that contains osteogenic cells. A dense connective tissue. Bone is vascularized by vessels from the periosteum. In the outer layer, bundles of collagen called perforating (or Sharpey) fibers bind the periosteum to the bone. The periosteum’s inner layer is more cellular and includes osteoblasts, and mesenchymal stem cells referred to as osteoprogenitor cells.

Answer 74

Periosteum

Question 75

# Reversed prompt A type of connective tissue covering bone that contains osteogenic cells. Covers all trabeculae around the marrow cavities. Contains osteoprogenitor cells and osteoblasts.

Answer 75

Endosteum

Question 76

# Reversed prompt Osteoblasts originate from mesenchymal osteoprogenitor cells and produce the organic components of bone matrix, including type I collagen fibers. Osteoblasts are located exclusively at the surfaces of bone matrix as a single layer of cuboidal cells. They produce a layer of collagen-rich, uncalcified material called osteoid between the osteoblast layer and the bone surface.

Answer 76

Osteoblasts misc.

Question 77

# Reversed prompt Produced from osteoblasts Type I collagen, the protein osteocalcin, and chondroitin sulfate, a GAG that forms part of proteoglycans. Chondroitin sulfate provides most of the resistance to compression in cartilage.

Answer 77

Important components of osteoid

Question 78

# Reversed prompt Large multinucleated cells which are derived by the fusion of several blood-derived monocytes.

Answer 78

Osteoclasts misc.

Question 79

# Reversed prompt One of the two components of bone matrix. About 50% of the dry weight of bone matrix is inorganic. Calcium hydroxyapatite is the most abundant inorganic compound. The surface of hydroxyapatite crystals is hydrated, facilitating the exchange of ions within body fluids.

Answer 79

Inorganic matter

Question 80

# Reversed prompt One of the two components of bone matrix. 90% of calcified matrix is Type I collagen, but also includes small proteoglycans and multiadhesive glycoproteins. Calcium-binding proteins, notably osteocalcin, promote calcification of the matrix.

Answer 80

Organic matter

Question 81

# Reversed prompt Woven bone, Lamellar bone, Compact (Cortical) bone, and Cancellous (Trabecular) bone

Answer 81

Types of bone

Question 82

# Reversed prompt Newly calcified Locations: Developing and growing bones; hard callus of bone fractures Synonyms: Immature bone; primary bone; bundle bone

Answer 82

Woven bone

Question 83

# Reversed prompt Remodeled from woven bone Locations: All normal regions of adult bone Synonyms: Mature bone; secondary bone, ossified

Answer 83

Lamellar bone

Question 84

# Reversed prompt ~80% of all lamellar bone Locations: Thick, outer region (beneath periosteum) of bones Synonyms: Cortical bone

Answer 84

Compact (cortical) bone

Question 85

# Reversed prompt ~20% of all lamellar bone Locations: Inner region of bones, adjacent to marrow cavities Synonyms: Spongy bone; trabecular bone; medullary bone

Answer 85

Cancellous (trabecular) bone

Question 86

# Reversed prompt Woven bone: newly formed, first bone tissue to appear in embryonic development and in fracture repair, weaker than lamellar bone because of lower mineral content. Lamellar bone: Most bone in adults, whether compact or cancellous, is organized as lamellar bone, characterized by multiple layers or lamellae of calcified matrix; like the orientation of wood fibers in plywood; this type of bone is fully ossified

Answer 86

Two types of organization for compact bone and cancellous bone based on the stage of development

Question 87

# Reversed prompt constitute most of the compact bone. An osteon (or Haversian system) refers to the complex of concentric lamellae

Answer 87

Osteons

Question 88

# Reversed prompt Composed of cancellous bone covered by a thin layer of compact (cortical) bone

Answer 88

What is the epiphyses (the bulbous ends) in long bones composed of?

Question 89

# Reversed prompt Almost totally dense compact (cortical) bone with a thin region of cancellous bone on the inner surface around the central marrow cavity

Answer 89

What is the diaphysis (the cylindrical part) in long bones composed of?

Question 90

# Reversed prompt Intramembranous ossification and Endochondral ossification

Answer 90

Two Processes of Osteogenesis

Question 91

# Reversed prompt Osteoblasts differentiate directly from mesenchyme and begin secreting osteoid. There is no cartilage precursor.

Answer 91

Intramembranous ossification

Question 92

# Reversed prompt A preexisting matrix of hyaline cartilage is eroded and invaded by osteoblasts, which then begin osteoid production. Longitudinal growth at epiphyseal plate Appositional growth around diaphysis

Answer 92

Endochondral ossification

Question 93

# Reversed prompt Longitudinal growth and Appositional growth

Answer 93

Two Patterns of Osteogenesis

Question 94

# Reversed prompt in long bones is regulated by the epiphyseal plate, which separates the epiphysis from the diaphysis (shaft).

Answer 94

Longitudinal growth

Question 95

# Reversed prompt Occurs by formation of a periosteal bone collar around the diaphysis. Growth in the circumference of long bones does not involve endochondral ossification. It occurs through osteoblasts developing from osteoprogenitor cells in the periosteum by a process of appositional growth which begins with formation of the bone collar on the cartilaginous diaphysis.

Answer 95

Appositional growth

Question 96

# Reversed prompt Repair of a fractured bone uses the cells and mechanisms already in place for bone growth and remodeling. (1) Blood vessels torn within the fracture release blood that clots to produce a large fracture hematoma. (2) The hematoma is removed by macrophages; a matrix of damaged, cell-free bone is resorbed by osteoclasts; the periosteum and the endosteum at the fracture site respond with intense proliferation and produce by a soft fibrocartilage-like mass called procallus tissue. (3) The procallus is invaded by regenerating blood vessels and proliferating osteoblasts. In the next few weeks the fibrocartilage is gradually replaced by woven bone which forms a hard callus throughout the original area of fracture. (4) The woven bone is then remodeled as compact and cancellous bone and fully functional vasculature is reestablished. Stresses imposed on the bone during repair and gradual return to activity help to remodel the bone callus.

Answer 96

Fracture Repair

Question 97

# Reversed prompt Cancer originating directly from bone cells (a primary bone tumor) is fairly uncommon (0.5% of all cancer deaths), although a cancer called osteosarcoma can arise in osteoprogenitor cells.

Answer 97

Primary bone tumor

Question 98

# Reversed prompt The skeleton is often the site of secondary, metastatic tumors, when cancer cells move into bones via small blood or lymphatic vessels from malignancies in other organs, such as the breast, lung, prostate gland, kidney, or thyroid gland.

Answer 98

Secondary metastatic tumors

Question 99

# Reversed prompt Calcium deficiency in children can lead to rickets, a disease in which the bone matrix does not calcify normally and the epiphyseal plate can become distorted by the normal strains of body weight and muscular activity.

Answer 99

What causes rickets

Question 100

# Reversed prompt “brittle bone disease,” refers to a group of related congenital disorders in which the osteoblasts produce deficient amounts of Type I collagen or defective Type I collagen due to genetic mutations. Such defects lead to a spectrum of disorders, all characterized by significant fragility of the bones.

Answer 100

Osteogenesis imperfecta

Question 101

# Reversed prompt Stimulates the production of IGF-1, it is also called growth hormone, it is produced by the anterior lobe of the pituitary gland

Answer 101

Somatotropin