Histology: Bone Tissue

Front 1

In which bones would red bone marrow be found? (5)

Back 1

1) Ileum (Hip)
2) Ribs
3) Sternum
4) Vertebrae
5) Metaphysis and epiphysis of long bones

Front 2

In a newborn all bone marrow is ______________ and involved in ______________?

Back 2

Red, hematopoiesis

Front 3

Long Bone:

The bone's long shaft or body. Located in between the two metaphyses?

Back 3

Diaphysis

-General compact (cortical) bone

Front 4

Long Bone:

The most proximal and distal portions of a bone?

Back 4

Epiphyses

-Generally spongy bone

Note: This is technically an apophysis until the bone stops growing and it fuses.

Front 5

Long Bone:

Regions between the diaphysis and epiphysis of a long bone?

Back 5

Metaphysis

-Generally spongy bone

Front 6

Long bone:

Layer of hyaline cartilage in the metaphysis of a growing bone that allows the diaphysis of the bone to grow in length?

Back 6

Epiphyseal plate (Growth Plate)

Front 7

Normal developmental outgrowth of a bone which arises from another ossification center?

Back 7

Apophysis

Note: Fuses to bone later in development
Note: Usually serves as an important insertion point for a tendon or ligament

Front 8

Fracture that occurs through a growth plate?

Back 8

Salter Harris fracture

Front 9

Structure left by completely ossified epiphyseal plate?

Back 9

Epiphyseal line (synostosis)

Front 10

Thin layer of hyaline cartilage covering the part of the epiphysis where the bone forms an articulation with another bone? What is its function?

Back 10

Articular cartilage

Function:
1) Reduce Friction
2) Shock Absorption

Front 11

Which bone in the body has an epiphyseeal line that does not complete ossify?

Back 11

1st rib attached to sternum

Front 12

Surrounds the external bone surface wherever it is not covered by articular cartilage?

Note: Contains blood vessels, nerves, osteogenic cells, serves as an attachment point for tendons/ligaments, and assists in fracture repair.

Back 12

Periosteum

Front 13

The periosteum is composed of an outer ____________ layer and an inner _______________ layer?

Back 13

1) Fibrous
2) Osteogenic

Front 14

What is the name of the fibers that connect the periosteum and the associated structures that are integrated with the periosteum to the underlying bone?

Back 14

Sharpey's fibers (perforating fibers)

Front 15

Sharpey's fibers are thick bundles of partially mineralized____________ fibers that extend from the extracellular bone matrix to the periosteum?

Back 15

collagen

Front 16

Hollow cylindrical space within the diaphysis that contains fatty yellow bone marrow in adults?

Back 16

Medullary cavity (marrow cavity)

Front 17

Thin layer of connective tissue that lines the internal bone facing the medullary cavity, Contains a single layer of cells and a small amount of connective tissues?

Back 17

Endosteum

Front 18

Most abundant mineral salt in bone?

Back 18

Calcium Phosphate

Front 19

What two compounds is hydroxyapatite composed of?

Back 19

Calcium phosphate and Calcium Hydroxide

Note: These and other minerals gives bone its hardness

Front 20

Unspecialized stem cell (derived from mesenchyme) that undergo cell division to become osteoblasts?

Back 20

Osteogenic Cells (Osteoprogenitor cell)

Front 21

Three places where osteogenic cells are found?

Back 21

1) Inner portion of periosteum
2) Endosteum
3) Canals within bone that contain blood vessels

Front 22

Bone building cells:

These cells synthesize and secrete collagen fibers and other organic components needed to build the extracellular matrix of bone tissue. They also initiate calcification?

Back 22

Osteoblasts

Note: Blast simply describes any connective tissue cell which is capable/currently of secreting extracellular matrix.

Front 23

How does an osteoblast become an osteocyte?

Back 23

As an osteoblast surround themselves with extracellular matrix, they become trapped and then become osteocytes

Front 24

Main cells in bone tissue that have a role in maintaining the tissue, its daily metabolism, and calcium homeostasis (exchange of nutrients and waste with blood)?

Back 24

Osteocyte


Note: Cyte simply refers to any cell that maintains a tissue.

Front 25

Do osteocytes or osteoblasts undergo cell division?

Osteogenic cell--------->Osteoblast-------------->Osteocyte

Back 25

No

Front 26

Cells that engage in bone resorption and contain lysosomal enzymes and acids necessary for bone resorption?

Back 26

Osteoclasts

Clast: This ending simply refers to any tissue that breaks down extracellular matrix

Front 27

Where are osteoclasts mainly concentrated?

Back 27

Endosteum

Front 28

What are osteoclasts composed of?

Back 28

Fusion of up to 50 monocytes

Front 29

How would one describe the surface of an osteoclast membrane that faces the bone surface?

Back 29

Ruffled

Front 30

Two types of bone tissue?

Back 30

1) Compact (Dense)/(Cortical)
2) Spongy (Cancellous)/ (Trabecular)

Front 31

Bone found beneath the periosteum of all bones and richly concentrated in the diaphysis?

Back 31

Compact bone

Note: This bone is harder to maintain

Front 32

Canal's that lymphatic vessels, blood vessels, and nerves from the periosteum penetrate compact bone?

Back 32

Volkman's canals (Perforating canals)

Front 33

Canals that run longitudinally through the bone and serve as a conduit for the vessels and nerves from the volkman's canals?

Back 33

Central Canals

Front 34

Rings of calcified extracellular matrix that wrap around central canals?

Back 34

Concentric Lamellae

Front 35

Spaces between lamellae that contain osteocytes?

Back 35

Lacunae

Front 36

Small channels that radiate in all directions from the lacunae. They are filled with extracellular fluid?

Back 36

Canaliculi

Important: It is the canaliculi that forms channels that allow osteocytes to communicate and for exchange of cellular nutrient and waste throughout compact bone.

Note: The projections of osteocytes run through canaliculi though typically we only see the lacunae and canaliculi on slides. Osteocyte is usually lost in preparation.

Front 37

Neighboring osteocytes communicated via ___________ junctions?

Back 37

Gap

Front 38

The repeating units of compact bone and all of its components?

Back 38

Haversion systems (Osteons)

Front 39

Components of a haversion system (Osteon)? (6)

Back 39

1) Central (haversion) canal
2) Concentric lamellae
3) Lacunae
4) Lamellae
5) Osteocytes
6) Canaliculi

Front 40

Osteons in compact bone are aligned in the same direction along lines of ______________?

Back 40

Stress

Front 41

What type of lamellae is stored in areas between haversion systems?

Note: These are fragments of older osteons that have been partially destroyed during remodeling or growth.

Back 41

Interstitial lamellae

Front 42

Lamellae that encircles the bones just beneath the periosteum?

Back 42

Circumferential lamellae

Front 43

The irregular lattice like arrangment of lamellae in spongy bone?

Back 43

Trabeculae

Note: Space in between may contain bone marrow and considerable vasculature

Front 44

Components within each trabecula?

Back 44

1) Concentric lamellae
2) Osteocytes in lacunae
3) And canaliculi

Front 45

Where is spongy bone found?

Back 45

1) Small layer around medullary cavity of diaphysis that is covered by compact bone
2) Major component inside flat, irregular, and short bones
3) Most epiphyses and metaphyses of long bones

Front 46

Spongy bone is always covered by a layer of ______________ bone for protection?

Back 46

Compact

Front 47

How are the trabecula of spongy bones arranged in terms of the stress bones receive?

Back 47

1) Parallel to the axis of stress
2) Generally located more towards areas that receive force in many directions

Front 48

Two main components of bone tissues?

Back 48

1) Cells
2) Mineralized extracellular matrix

Front 49

Collagen makes up about _____________% of bone tissue

Back 49

90%

Front 51

Components of bone ground substance?

Back 51

1) Proteoglycans
2) Multiadhesive glycoproteins
3) Bone-specific, vitamin K dependent proteins
4) Growth factors and cytokines
-Bone morphogenic proteins

Front 52

Proteins that help bone capture and store calcium and stimulate remodeling of bone?

Back 52

Bone specific vitamin K dependent proteins

Front 53

Function of multi-adhesive glycoproteins?

Back 53

Binds bone cells (osteocytes) to collagen in mineralized matrix

Front 54

Function of bone morphogenic proteins?

Back 54

Induce bone formation (especially during development)

Front 55

All components of bone ECM are mineralized? T or F

Back 55

True

Front 56

Also known as woven bone, this is nonlamellar bone that has many cells randomly arranged, more ground substance, and are sometimes found in adult alveolar sockets or oral cavity?

Back 56

Immature bone

Front 57

Volkman's canals run __________________ to osteons?

Back 57

Perpendicular

Front 58

What supplies blood supply for trabecular bone?

Back 58

Volkman's canals

Front 59

Trabeculae are thin anastomsing ____________?

Back 59

Spicules

Front 60

What is ground bone often dyed with?

Back 60

India ink...............or air is allowed to be trapped inside

Front 61

Ground bone allows one to visualize periosteum? T or F

Back 61

False

Front 62

Decalcified bone allows one to visualize periosteum? T or F

Back 62

True

Front 63

Inactive cells that line the periosteum?

Back 63

Periosteal cells

Note: these are osteoprogenitor cells often called bone lining cells

Front 64

Inactive cells that line the endosteum?

Back 64

Endosteal cells

Note: these are osteoprogenitor cells often called bone lining cells

Front 65

Differentiation factor that triggers osteoprogenitor--------------->osetoblast?

Back 65

Core binding factor alpha-1 (CBFA-1)

Front 66

Histological characteristics of osteroprogenitor cells?

Back 66

1) Squamous/flat
2) Elongated or Oviod Nuclei
3) Found on periosteum and endosteum

Front 67

Two main things osteoblasts secrete?

Back 67

1) Type I collagen
2) Bone matrix proteins

Front 68

What types of bone matrix proteins do osteoblasts secrete?

Back 68

1) Osteocalcin/Osteonectin
2) Multiadhesvie Glycoproteins
-Sialoproteins
3) Alkaline Phosphatase

Front 69

What is the purpose of osteocalcin and osteonectin?

Back 69

Calcium binding proteins

Front 70

Purpose of alkaline phosphatases?

Back 70

Proteins that induce calcification by triggering hydroxyapatite aggregation

Front 71

Osteoblasts communicate with osteocytes via ________________ junctions?

Back 71

Gap junctions

Front 72

Histological characteristics of osteoblasts?

Back 72

1) Cuboidal or polygonal shaped
2) Basophilic cytoplasm

Front 73

Three states of osteocytes?

Back 73

1) Quiescent
2) Formative
3) Resorptive

Front 74

What is occuring during the formative period of osteocyte activity?

Back 74

Matrix is deposited

Front 75

Osteocytes are involved in the initial stages of bone remodeling and use what enzyme to help engage this activity?

Back 75

Matrix metalloproteases

Front 76

What is the function of bone lining cells?

Back 76

1) Maintenance and nutritional support for osteocytes
2) Regulate movement of calcium and phosphate
3) Ultimately can differentiate and become osteoblasts and then osteoclasts

Front 77

Bone lining cells are connected to osteocytes via _____________ and communicate via gap junctions?

Back 77

Canaliculi

Front 78

Unmineralized matrix secreted by osteoblasts? Visualized as a thin pale staining matrix between osteoblasts and lamellae.

Back 78

Osteoid

Front 79

Which signalling pathway signals for the differentiation of monocytes into osteoclasts?

Back 79

Rank and Rank-L pathways

Front 80

What is the function of the drug osteoprotegenerin?

Back 80

Inhibits osteoclast formation

Front 81

Three distinct specialized regions of an activated osteoclast?

Back 81

1) Ruffled border
2) Clear Zone
3) Basolateral Region

Front 82

Osteoclasts are always found on the _____________ side of bone?

Back 82

Endosteal

Front 83

Depressed region in bone created by an osteoclasts?

Note: This is where the osteoclast is located

Back 83

Howship's lacunae

Front 84

What do the ruffled borders of the osteoclast secrete that degrade collagen and bone matrix proteins?

Back 84

1) Cathespin K
2) Matrix Metalloproteinases
3) Acid via ATP dependent proton pump

Front 85

What happens to the debris that is broken down by osteoclasts?

Back 85

Phagocytosed and exocytosed

Front 86

Which area of an osteoclast binds to a bone keeping the osteoclast bound to the howship's lacuna?

Note: Made of actin filaments and specialized proteins

Back 86

Clear Zone

Front 87

What is the end result of an osteoclast that is finished resorbing bone?

Back 87

Undergoes apoptosis

Front 88

Histological characteristics of an osteoclast?

Back 88

1) Large
2) Multinucleated
3) Ruffled border

Front 89

Chronic abnormal bone remodeling disease that tends to affect the elderly?

Back 89

Paget's disease

Front 90

Are there usually symptoms with Paget's Disease?

Back 90

No, usually discovered when many fractures begin occurring.

Front 91

Two blood tests to determine whether one has Paget's disease?

Back 91

1) TRAP
2) Alkaline Phosphatase

Front 92

What is TRAP in regards top osteoclasts?

Back 92

It is a marker of osteoclast activity

Front 93

Two RX treatments for Paget's disease?

Back 93

1) Calcitonin
2) Bisphosphonates

Front 94

The methods of bone formation?

Back 94

1) Intramembranous ossification
2) Endochondral Ossification

Front 95

Process of intramembranous ossification?

Back 95

1) Mesenchymal cells cluster and differentiate into osteoprogenitor cells
2) There is increased vascularization of surrounding connective tissues
3) Osteoprogenitor cells diffferentiate into osteoblasts when Core Binding Factor-1 arrives because of increased vascularization
4) Osteoblasts now secrete matrix until they are surrounded by it. Spicules are formed and the immature bone formed resembles spongy bone.
5) As osteoblasts secrete matrix and are surrounded by it, they become osteocytes
6) More osteoprogenitor cells are attracted. New osteoblasts lay down bone by appositional bone growth
7) This continues until the bone begins to resemble compact bone. Bone is still woven/immature
8) Eventually a thin layer of compact bone will be formed by remodeling spongy bone.
9) Mesenchyme condenses at periphery of the bone and develops into periosteum
10) More remodeling needed as bone becomes organized into organized compact bone.

Front 96

Which bones undergo intramembanous ossification?

Back 96

1) Flat bones of skull, face, mandible, clavicle, cranial fontanelles

Front 97

Process of endochondral ossification?

Back 97

1) Mesenchymal stem cells differentiate into chrondroblasts.
2) Cartilage precursor matrix of hyalin cartilage is laid down (Type II Collagen). Surrounded by perichondrium.
3) Growth occurs both by interstitial (from within) and appositional growth (growth at outer surface).
4) Chondrocytes in mid region hypertrophy and attracts calcium. It begins to ossify.
5) As the cartilage ossifies chondrocytes die and form lacunae. This is called cavitation.
6) A nutrient artery penetrates the perichondrium in the mid region stimulating perichondrium to differentiate into osteoprogenitor cells
7) Periosteum forms and its osteoprogenitor cells differentiate into osteoblasts as blood flow now carries Core Binding Factor-1. Periosteum extends bud in to cavitation site and osteoblasts fill the site with spongy bone.
8) Osteoblasts secrete matrix and form a layer of bone on top of cartilage (mid region of bone)
9) Alkaline phosphatase from osteoblasts continues the process of calcification of cartilage matrix
10) Blood vessels penetrates and form hollows in cartilage matrix. This is now a primary ossification center.
11) Initial bony matrix laid down resembles spongy bone and is immature
12) The medulllary cavity forms as osteoclasts break down some of the newly formed spongy bone trabecula.
13) Secondary ossification centers develop at the epiphyses of bones as epiphyseal arteries enter the epiphyses. These centers develop at about the time primary ossifications centers are forming.
14) The secondary ossification centers will maintain a spongy bone matrix while the primary ossification centers will mostly become cortical bone
15) Hyaline cartilage that covered the epiphyses becomes articular cartilage
16) Articular cartilage will remain between the epiphyses and metaphyses (epiphyseal plate)

Front 98

Four zones of epiphyseal growth plates?

Back 98

1) Zone of resting cartilage (Reserve zone)
2) Zone of proliferating cartilage
3) Zone of hypertrophic cartilage
4) Zone of calcified cartilage

Front 99

Layer nearest the epiphysis that contains small scattered chondrocytes. Main role is to anchor epiphyseal plate to epiphysis?

Back 99

Zone of resting cartilage

Front 100

Zone that contains chondrocytes that undergo interstitial growth as they divide and secrete extracellular matrix?

Note: These chondrocytes are replicating in response to chondrocytes that dies as bone is added to the diaphysis. They look like stacks coins

Back 100

Zone of proliferating cartilage

Front 101

Zone that consists of large maturing chondrocytes arranged in columns that are secreting a lot of matrix and attracting calcium?

Back 101

Zone of hypertrophic cartilage

Front 102

Zone that consists mostly of dead chondrocytes (underwent apoptosis) and is ossified?

Note: This region becomes the new part of the diaphysis and/or epiphysis through the process of endochondryl ossification

Note: Calcified cartilage is resorbed by osteoclasts and osteoblasts lay down new bone matrix.

Back 102

Zone of calcified cartilage

Front 103

Osteoblasts add new bone matrix to an osteon from the inside to the outside? T or F

Back 103

False, outside towards inside

Front 104

Steps in the process of mineralization of ECM?

Back 104

1) Calcium binds to osteocalcin and sialoproteins
2) Calcium causes osteoblasts to secrete alkaline phosphatase which attracts phosphates to area
3) Osteoblasts release further vesicles with alkaline phosphatase and pyrophosphate which cleave
phosphates
4) Hydroxyapatite crystals form
5) Hydroxyapatite is deposited in an interlocking fashion

Front 105

Hormone that stimulates osteoclasts activity?

Back 105

Parathyroid hormone

Front 106

Hormone that inhibits osteoclast activity?

Back 106

Calcitonin

Front 107

Type of fracture that breaks through the skin?

Back 107

Open fracture

Front 108

Type of fracture that does not penetrate the skin?

Back 108

Closed fracture

Front 109

Fracture in which bone is splintered/crushed leaving smaller bone fragments between the two main broken bone fragments?

Back 109

Communited fracture

Front 110

Partial fracture where one side of the bone is broken and the other side is bent?

Note: This happens in children whose bones are not fully ossified. They bones contain a considerable amount of organic vs. inorganic material making the bones more pliable.

Back 110

Greenstick fracture

Front 111

Fracture in which one end of a fractured bone is forcefully driven into the interior of the other end?

Back 111

Impacted fracture

Front 112

Fracture of the distal fibula?

Note: Causes serious injury of the distal tibial articulation

Back 112

Pott's fracture

Front 113

Fracture of the distal radius?

Note: Distal fragment is posteriorly displaced

Back 113

Colles fracture

Front 114

Steps in the process of fracture healing?

Back 114

1) Formation of a fracture hematoma
-Reduced blood flow
-Bone cells in region die
-Neutrophils and macrophages remove dead or damaged tissue
-This could last for several weeks

2) Fibroblasts and capillaries from periosteum invade the fracture site and produce collagen fibers

3) Cells from periosteum differentiate into chondroblasts and produce fibrocartilage in the region
-A fibrocartilaginous callus forms that bridges the gap between the two broken bones
-Could take three weeks to form

4) Near areas close to well vascularized bone tissue, osteogenic cells develop into osteoblasts which produce spongy bone trabeculae on outside surface of bones
-This is the bony callus
-This joins living and dead portions of bone fragments

5) Osteogenic buds invade fibrocartilagnious callus and replaces it with bone matrix

6) Bone is remodeled to appropriate content of compact and spongy bone through the action of osteoblasts and osteoclasts.

Front 115

Where are most bone cancers localized/started? Why?

Back 115

In areas of red bone marrow because of vascularization