CARTILAGE AND BONE

Question 1

______ is a tough, durable form of supporting connective tissue, characterized by an extracellular matrix (ECM) with high concentrations of Glycosaminoglycans or GAGs and proteoglycans, interacting with collagen and elastic fibers.

Answer 1

Cartilage

Question 2

Structural features of its matrix make ______
ideal for a variety of mechanical and protective
roles within the adult skeleton and elsewhere.

Answer 2

cartilage

Question 3

______ has a firm consistency that allows the tissue to bear mechanical stresses without permanent distortion.

Answer 3

Cartilage ECM

Question 4

In the respiratory tract, ears, and nose, ______ forms the framework supporting softer tissues.

Answer 4

cartilage

Question 5

Because of its resiliency and smooth, lubricated surface, ______ provides cushioning and sliding regions within skeletal joints and facilitates bone
movements.

Answer 5

cartilage

Question 6

Cartilage consists of cells called ______ embedded in the ECM which unlike connective tissue proper contains no other cell types.

Answer 6

chondrocytes

Question 7

Chondrocytes synthesize and maintain all ECM components and are located in matrix cavities called ______.

Answer 7

lacunae

Question 8

The physical properties of cartilage depend on electrostatic bonds between ______, ______, and the sulfated GAGs on densely packed ______.

Answer 8

type II collagen fibrils, hyaluronan, proteoglycans

Question 9

CARTILAGE

Its semi-rigid consistency is attributable to water bound to the ______ charged hyaluronan and GAG chains extending from proteoglycan core proteins, which in turn are enclosed within a dense
meshwork of thin ______.

Answer 9

negatively, type II collagen fibrils

Question 10

The high content of bound ______ allows cartilage to serve as a shock absorber, an important functional role.

Answer 10

water

Question 11

TYPES OF CARTILAGE:

Answer 11

Hyaline Cartilage, Elastic Cartilage, Fibrocartilage

Question 12

The ______ is a sheath of dense connective tissue that surrounds cartilage in most places, forming an interface between the cartilage and the tissues supported by the cartilage.

Answer 12

perichondrium

Question 13

This harbors the blood supply serving the cartilage and a small neural component.

Answer 13

perichondrium

Question 14

______ cartilage, which covers the ends of bones in movable joints and which erodes in the course of arthritic degeneration, lacks perichondrium and is sustained by the diffusion of oxygen and nutrients from the synovial fluid.

Answer 14

Articular

Question 15

Many genetic conditions in humans or mice that cause defective cartilage, joint deformities, or short
limbs are due to recessive mutations in genes for ______, the aggrecan ______, the ______, and other proteins required for normal chondrocyte function.

Answer 15

collagen type II, core protein, sulfate transporter

Question 16

______ cartilage, the most common of the three types, is homogeneous and semitransparent in the fresh state.

Answer 16

Hyaline

Question 17

In adults ______ cartilage is located in the articular surfaces of movable joints, in the walls of larger respiratory passages (nose, larynx, trachea, bronchi), in the ventral ends of ribs, where they articulate with the sternum, and in the epiphyseal plates of long bones, where it makes possible longitudinal bone growth.

Answer 17

hyaline

Question 18

In the embryo, ______ cartilage forms the temporary skeleton that is gradually replaced by bone.

Answer 18

hyaline

Question 19

The ______ is part of the extracellular material found in connective tissues like cartilage. It is not a cellular component but rather a mixture of proteins, fibers, and other substances that provide structural and biochemical support to the surrounding cells.

Answer 19

matrix

Question 20

The dry weight of hyaline cartilage is nearly ______% collagen embedded in a firm, hydrated gel of proteoglycans and structural glycoproteins. The proteoglycan make the matrix generally basophilic and the thin collagen fibrils are barely discernible. Most of the collagen in hyaline cartilage is ______, although small amounts of minor collagens are also present.

Answer 20

40, type II

Question 21

______ (250 kDa), with approximately 150 GAG side chains of chondroitin sulfate and keratan sulfate, is the most abundant proteoglycan of hyaline cartilage. Hundreds of these proteoglycans are bound noncovalently by link proteins to long polymers of ______. These proteoglycan complexes bind further to the surface of type II collagen fibrils. Water bound to GAGs in the proteoglycans constitutes up to ______%-______% of the weight of fresh hyaline cartilage.

Answer 21

Aggrecan, hyaluronan, 60, 80

Question 22

Another important component of cartilage matrix is the structural multiadhesive glycoprotein ______.

Answer 22

chondronectin

Question 23

Like fibronectin in other connective tissues, ______ binds specifically to GAGs, collagen, and integrins, mediating the adherence of chondrocytes to the ECM.

Answer 23

chondronectin

Question 24

Staining variations within the matrix reflect local differences in its molecular composition. Immediately surrounding each chondrocyte, the ______ is relatively richer in GAGs than collagen, often causing these areas of ______ to stain differently from the intervening areas of ______.

Answer 24

ECM, territorial matrix, interterritorial matrix

Question 25

______ are the cells responsible for the synthesis and maintenance of the cartilage matrix. They are a specific type of cell found within cartilage tissue.

Answer 25

Chondrocytes

Question 26

Cells occupy relatively little of the hyaline cartilage mass. At the periphery of the cartilage, young chondrocytes or ______ have an elliptic shape, with the long axes parallel to the surface. Deeper in the
cartilage, they are round and may appear in
groups of up to ______ cells that originate from
mitotic divisions of a single chondroblast and are called ______. As the chondrocytes become more active in secreting collagens and other ECM components, the aggregated cells are pushed apart and occupy separate lacunae.

Answer 26

chondroblasts, eight, isogenous aggregates

Question 27

Cartilage cells and matrix may shrink slightly, leading to irregularly shaped chondrocytes and their retraction from the matrix, though in living tissue, chondrocytes fully occupy their ______. Due to the avascular nature of cartilage, chondrocytes respire under low-oxygen tension and metabolize glucose mainly through ______. Nutrients diffuse to chondrocytes from the cartilage surface, aided by the movement of water and solutes during tissue compression and decompression, which also defines the maximum thickness of ______ cartilage, typically found as small, thin plates.

Answer 27

lacunae, anaerobic glycolysis, hyaline

Question 28

In contrast to other forms of cartilage and most other tissues, ______ cartilage is susceptible to partial or isolated regions of calcification during aging, especially in the costal cartilage adjacent to the ribs.

Answer 28

hyaline

Question 29

______ of the hyaline matrix, accompanied by degenerative changes in the chondrocytes, is a common part of the aging process and in many respects resembles endochondral ossification by which bone is formed.

Answer 29

Calcification

Question 30

Chondrocyte synthesis of sulfated GAGs and secretion of proteoglycans are accelerated by many hormones and growth factors. A major regulator of hyaline cartilage growth is the pituitary-derived protein called ______ hormone or ______.

Answer 30

growth, somatotropin

Question 31

This hormone acts indirectly, promoting the endocrine release from the liver of insulin-like growth factors, or somatomedins, which directly stimulate the cells of hyaline cartilage.

Answer 31

somatotropin.

Question 32

Cells of cartilage can give rise to either benign (______) or slow-growing, malignant (______) tumors in which cells produce normal matrix components. ______ seldom metastasize and are generally removed surgically.

Answer 32

chondroma, chondrosarcoma, Chondrosarcomas

Question 33

The ______ is a dense layer of connective tissue that surrounds most types of cartilage, providing mechanical support and protection. It plays a crucial role in cartilage growth and repair by supplying new chondrocytes.

Answer 33

perichondrium

Question 34

Except in the articular cartilage of joints, all hyaline cartilage is covered by a layer of dense connective tissue, the ______, which is essential for the growth and maintenance of cartilage.

Answer 34

perichondrium

Question 35

The outer region of the perichondrium consists largely of collagen ______ fibers and ______, but an inner layer adjoining the cartilage matrix also contains ______ which provide a source for new chondroblasts that divide and differentiate into chondrocytes.

Answer 35

type I, fibroblasts, mesenchymal stem cells

Question 36

______ cartilage is essentially similar to hyaline cartilage except that it contains an abundant network of elastic fibers in addition to a meshwork of collagen type II fibrils, which give fresh elastic cartilage a yellowish color. With appropriate staining the elastic fibers usually appear as dark bundles distributed unevenly through the matrix.

Answer 36

Elastic

Question 37

More flexible than hyaline cartilage, ______ cartilage is found in the auricle of the ear, the walls of the external auditory canals, the auditory (Eustachian) tubes, the epiglottis, and the upper respiratory tract. This cartilage in these locations includes a perichondrium similar to that of most hyaline cartilage. Throughout this cartilage the cells resemble those of hyaline cartilage both physiologically and structurally.

Answer 37

elastic

Question 38

The chondrocytes (C) and overall organization of ______ cartilage are similar to those of hyaline cartilage, but the matrix (M) also contains elastic fibers that can be seen as darker components
with proper staining. The abundant elastic fibers provide greater flexibility to this type of cartilage. The section in part b includes perichondrium (P) that is also similar to that of hyaline cartilage.

Answer 38

elastic

Question 39

______ takes various forms in different structures but is essentially a mingling of hyaline cartilage and dense connective tissue . It is found in intervertebral discs, in attachments of certain ligaments, and in the pubic symphysis—all places where it serves as very tough, yet cushioning support tissue for bone.

Answer 39

Fibrocartilage

Question 40

The relative scarcity of proteoglycans overall makes fibrocartilage matrix more ______ than that of hyaline or elastic cartilage. There is no distinct surrounding ______ in fibrocartilage.

Answer 40

acidophilic, perichondrium

Question 41

______ varies histologically in different structures, but is always essentially a mixture of hyaline cartilage and dense connective tissue. In a small region of intervertebral disc, the axially arranged aggregates of chondrocytes (C) are seen to be surrounded by small amounts of matrix and separated by larger regions with dense collagen and scattered fibroblasts with elongated nuclei (arrows).

Answer 41

Fibrocartilage

Question 42

Cartilage forms from embryonic mesenchyme through ______. Initially, mesenchymal cells round up, retract extensions, multiply, and pack closely. These cells are termed “______” during proliferation and “______” afterward, both with basophilic cytoplasm rich in RER for collagen synthesis. As the extracellular matrix (ECM) forms, it encloses cells in lacunae, separating chondroblasts. Cartilage differentiation progresses from the center outward, with central cells becoming chondrocytes and peripheral cells remaining chondroblasts, while the perichondrium develops from ______ mesenchyme.

Answer 42

chondrogenesis, chondroblasts, chondrocytes, superficial

Question 43

Cartilage grows through ______ growth (mitotic division of chondrocytes) and ______ growth (differentiation of chondroblasts from perichondrium cells).

Answer 43

interstitial, appositional

Question 44

______ growth predominates postnatally, while ______ growth in long bones increases length. In ______ cartilage, where there is no perichondrium, worn-away cells and matrix are replaced from within.

Answer 44

Appositional, interstitial, articular

Question 45

______ tissue, the main constituent of the adult skeleton, provides solid support for the body, protects vital organs such as those in the cranial and thoracic cavities, and encloses internal (medullary) cavities containing bone marrow where blood cells are formed.

Answer 45

Bone

Question 46

______ (or ______) tissue also serves as a reservoir of calcium, phosphate, and other ions that can be released or stored in a controlled fashion to maintain constant concentrations in body fluids.

Answer 46

Bone, osseous

Question 47

______ is a specialized connective tissue composed of calcified extracellular material, the bone matrix, and following three major cell types.

Answer 47

Bone

Question 48

BONE

three major cell types :

Answer 48

OSTEOCYTES
OSTEOBLASTS
OSTEOCLASTS

Question 49

BONE CELL TYPE

______- found in cavities (lacunae) between bone matrix layers (lamellae), with cytoplasmic processes in small canaliculi (L. canalis, canal) that extend into the matrix

Answer 49

OSTEOCYTES

Question 50

BONE CELL TYPE

______- growing cells which synthesize and secrete the organic components of the matrix

Answer 50

OSTEOBLASTS

Question 51

BONE CELL TYPE

______- giant, multinucleated cells involved in removing calcified bone matrix and remodeling bone tissue

Answer 51

OSTEOCLASTS

Question 52

______
- originates from mesenchymal stem cells
- produce the organic components of bone matrix, including type I collagen fibers, proteoglycans, and matricellular glycoproteins such as ______.

Answer 52

OSTEOBLASTS, osteonectin

Question 53

______ osteoblasts are located exclusively at the surfaces of bone matrix where they are bound by integrins.

Answer 53

Active

Question 54

When their synthetic activity is completed:
-Some osteoblasts differentiate as osteocytes entrapped in matrix bound lacunae
-Some flatten and cover the matrix surface as ______ CELLS
-Majority undergo ______.

Answer 54

BONE LINING, apoptosis

Question 55

______
- layer of unique collagen-rich material
- produced when matrix components are secreted at the cell surface in contact with existing bone between the osteoblast layer and the preexisting bone surface.

This process of bone appositional growth is completed by subsequent deposition of ______ salts into the newly formed matrix.

Answer 55

OSTEOID, calcium

Question 56

______
- vitamin K-dependent polypeptide
- is prominent among the noncollagen proteins secreted by osteoblasts
- together with various glycoproteins binds Ca ions and concentrates this mineral locally.

Answer 56

OSTEOCALCIN

Question 57

______
- membrane-enclosed - released by osteoblasts
- rich in alkaline phosphatase and other enzymes whose activity raises the local concentration of PO ions

Answer 57

MATRIX VESICLES

Question 58

In the microenvironment with high concentrations of both these ions, ______ serve as foci for the formation of hydroxyapatite crystals, the first visible step in calcification. These crystals grow rapidly by accretion of more mineral and eventually produce a confluent mass of calcified material embedding the collagen fibers and proteoglycans

Answer 58

matrix vesicles

Question 59

Cancer originating directly from bone cells (a primary bone tumor) is fairly uncommon (______% of all cancer deaths), although a cancer called ______ can arise in osteoprogenitor cells. The skeleton is often the site of secondary, ______ TUMORS , however, arising when cancer cells move into bones via small blood or lymphatic vessels from malignancies in other organs, most commonly the breast, lung, prostate gland, kidney, or thyroid gland.

Answer 59

0.5, OSTEOSARCOMA, METASTATIC

Question 60

This is A cell found within the material of fully formed bone. It lives in a small chamber known as a lacuna, which is found in the calcified matrix of bone.

Answer 60

OSTEOCYTE

Question 61

During the transition from osteoblasts to osteocytes, the cells extend many long dendritic processes, which also become surrounded by calcifying matrix. The processes thus come to occupy the many ______, 250-300 nm, radiating from each lacuna .

Answer 61

canaliculi

Question 62

Diffusion of metabolites between osteocytes and blood vessels occurs through the small amount of interstitial fluid in the ______ between the bone matrix and the osteocytes and their processes. ______ also communicate with one another and ultimately with nearby osteoblasts and bone lining cells via gap junctions at the ends of their processes. These connections between osteocyte processes and nearly all other bone cells in the extensive lacunar-canalicular network allow osteocytes to serve as mechanosensors detecting the mechanical load on the bone as well as stress- or fatigue-induced microdamage and to trigger remedial activity in osteoblasts and osteoclasts.

Answer 62

canaliculi, Osteocytes

Question 63

______
- are very large, motile cells with multiple nuclei due to their origin from the fusion of bone marrow-derived monocytes which is essential for matrix resorption during bone growth and remodeling.

Answer 63

OSTEOCLASTS

Question 64

OSTEOCLAST DEVELOPMENT
- requires two polypeptides produced by osteoblasts:
1. ______
2. ______

Answer 64

Macrophage colony stimulating factor (M-CSF), Receptor activator of nuclear factor-κB ligand (RANKL)

Question 65

______ ( or ______)
- enzymatically etched depressions or cavities in the matrix where osteoclasts on the bone surface lie in , in areas of bone undergoing resorption

Answer 65

RESORPTION LACUNAE, HOWSHIP LACUNAE

Question 66

In an active osteoclast, the membrane domain that contacts the bone forms a circular ______ that binds the cell tightly to the bone matrix and surrounds an area with many surface projections, called the ______.

Answer 66

SEALING ZONE, RUFFLED BORDER

Question 67

This circumferential ______ allows the formation of a specialized microenvironment between the osteoclast and the matrix in which bone resorption occurs.

Answer 67

sealing zone

Question 68

In the genetic disease ______, which is characterized by dense, heavy bones (“______ bones”), the osteoclasts lack ruffled borders and bone resorption is defective. This disorder results in overgrowth and thickening of bones, often with obliteration of the marrow cavities, depressing blood cell formation and causing anemia and the loss of white blood cells. The defective osteoclasts in most patients with this disease have mutations in genes for the cells’ proton-ATPase pumps or chloride channels.

Answer 68

OSTEOPETROSIS, marble

Question 69

About 50% of the dry weight of bone matrix is ______ materials.

Answer 69

inorganic

Question 70

INORGANIC MATERIALS bone matrix

______ is the most abundant, but bicarbonate, citrate, magnesium, potassium, and sodium ions are also found. The surface of ______ crystals are hydrated, facilitating the exchange of ions between the mineral and body fluids.

Answer 70

Calcium hydroxyapatite, hydroxyapatite

Question 71

The organic matter embedded in the calcified matrix is ______% type I collagen, but also includes mostly small proteoglycans and multiadhesive glycoproteins such as osteonectin.

Answer 71

90

Question 72

Calcium-binding proteins, notably ______, and the ______ released from cells in matrix vesicles promote calcification of the matrix.

Answer 72

osteocalcin, phosphatases

Question 73

The association of minerals with collagen fibers during calcification provides the ______ and ______ required for bone function.

Answer 73

hardness, resistance

Question 74

If a bone is decalcified by a histologist, its shape is preserved but it becomes soft and pliable like other connective tissues. Because of its high collagen
content, decalcified bone matrix is usually ______.

Answer 74

acidophilic

Question 75

External and internal surfaces of all bones are covered by connective tissue of the ______ and ______, respectively.

Answer 75

periosteum, endosteum

Question 76

The ______ has an outer fibrous layer of dense connective tissue which contains mostly bundled type I collagen, fibroblasts, and blood vessels.

Answer 76

periosteum

Question 77

Bundles of periosteal collagen, called ______ (or ______) fibers, penetrate the bone matrix and bind the periosteum to the bone. Periosteal blood vessels branch and penetrate the bone, carrying metabolites to and from bone cells.

Answer 77

perforating, Sharpey

Question 78

The periosteum’s ______ layer is more cellular and includes osteoblasts, bone lining cells, and mesenchymal stem cells referred to as ______ cells.

Answer 78

inner, osteoprogenitor

Question 79

With the potential to proliferate extensively and
produce many new osteoblasts, ______ cells play a prominent role in bone growth and repair.

Answer 79

osteoprogenitor

Question 80

This is An imbalance in skeletal turnover wherein bone resorption exceeds bone formation and is Frequently found in immobilized patients and in
postmenopausal women.

Answer 80

OSTEOPOROSIS

Question 81

This Leads to calcium loss from bones and reduced bone mineral density (BMD) and is Tested through dual-energy x-ray absorptiometry (DEXA scans).

Answer 81

OSTEOPOROSIS

Question 82

TYPES OF BONE:

Answer 82

Woven bone
Lamellar bone
Compact bone
Cancellous bone

Question 83

______ (______)
(80% of total bone mass)
- a dense area near the surface

Answer 83

Compact, cortical

Question 84

______ (______)
(20% of total bone mass)
- deeper areas with numerous interconnecting cavities

Answer 84

Cancellous, trabecular

Question 85

______- made of cancellous bone covered by a thin layer of compact cortical bone.

Answer 85

Epiphysis

Question 86

______- cylindrical part that is almost totally dense compact bone with a thin region of cancellous bone on the inner surface around the central marrow cavity

Answer 86

Diaphysis

Question 87

______- thicker layer of cancellous bone in flat bones.

Answer 87

Diploë

Question 88

At the microscopic level both compact and cancellous bones typically show two types of organization: ______ bone, with matrix existing as discrete sheets, and ______ bone, newly formed with randomly arranged components.

Answer 88

mature lamellar, woven

Question 89

Macroscopic photo of a thick section of bone showing the cortical compact bone and the lattice of trabeculae in cancellous bone at the bone’s interior. The small ______ that make up highly porous cancellous bone serve as supportive struts, collectively providing considerable strength, without greatly increasing the bone’s weight. The ______ bone is normally covered externally with periosteum and all trabecular surfaces of the ______ bone are covered with endosteum.

Answer 89

trabeculae, compact, cancellous

Question 90

______ bone is nonlamellar and characterized by random disposition of type I collagen fibers and is the first bone tissue to appear in embryonic development and in fracture repair.

Answer 90

Woven

Question 91

______ bone is usually temporary and is replaced in adults by lamellar bone, except in a very few places in the body, for example, near the sutures of the calvaria and in the insertions of some tendons.

Answer 91

Woven

Question 92

In addition to the irregular, interwoven array of collagen fibers, ______ bone typically has a lower mineral content (it is more easily penetrated by x rays) and a higher proportion of osteocytes than mature lamellar bone. These features reflect the facts that immature ______ bone forms more quickly but has less strength than lamellar bone.

Answer 92

woven, woven

Question 93

Bone Development or Osteogenesis occurs by one of the two processes:

Answer 93

Intramembranous ossification
Endochondral ossification

Question 94

Bone Development or Osteogenesis occurs by one of the two processes:

______ ossification, in which osteoblasts differentiate directly from mesenchyme and begin secreting osteoid

Answer 94

Intramembranous

Question 95

Bone Development or Osteogenesis occurs by one of the two processes:

______ ossification, in which a preexisting matrix of hyaline cartilage is eroded and invaded by osteoblasts, which then begin osteoid production

Answer 95

Endochondral

Question 96

The names refer to the mechanisms by which the bone forms initially; in both processes ______ bone is produced first and is soon replaced by stronger
______ bone. During growth of all bones, areas of woven bone, areas of bone resorption, and areas of lamellar bone all exist contiguous to one another.

Answer 96

woven, lamellar

Question 97

______ ossification, by which most flat bones begin to form, takes place within condensed sheets (“membranes”) of ______ tissue. Most bones of the skull and jaws, as well as the scapula and clavicle, are formed embryonically by ______ ossification.

Answer 97

Intramembranous, embryonic mesenchymal, intramembranous

Question 98

INTRAMEMBRANOUS OSSIFICATION

Within the condensed ______ bone formation begins in ossification centers, areas in which
osteoprogenitor cells arise, proliferate, and form incomplete layers of osteoblasts around a network of developing ______. ______ secreted by the osteoblasts calcifies as described earlier, forming small irregular areas of woven bone with osteocytes in lacunae and canaliculi.

Answer 98

mesenchyme, capillaries, Osteoid

Question 99

INTRAMEMBRANOUS OSSIFICATION

Continued matrix secretion and calcification enlarges these areas and leads to the fusion of neighboring ossification centers. The ______ bone forms gradually as woven bone matrix is replaced by compact bone that encloses a region of cancellous bone with marrow and larger blood vessels. Mesenchymal regions that do not undergo ossification give rise to the ______ and the ______ of the new bone. In cranial flat bones, lamellar bone formation predominates over bone resorption at both the internal and external surfaces. Internal and external plates of compact bone arise, while the central portion (______) maintains its cancellous nature. The ______ or “______” on the heads of newborn infants are areas of the skull in which the membranous tissue is not yet ossified.

Answer 99

anatomical, endosteum, periosteum, diploë, fontanelles, soft spots

Question 100

______ (Gr. ______, within + ______, cartilage) ossification takes place within hyaline cartilage shaped as a small version, or model, of the bone to be formed. This type of ossification forms most bones of the body and is especially well studied in developing long bones, where it consists of the sequence of events.

Answer 100

Endochondral, endon, chondros

Question 101

ENDOCHONDRAL OSSIFICATION

• ______ cartilage within the joints between long bones, which normally persists through adult life
• The specially organized ______ cartilage (also
  called the ______ or ______), which connects each epiphysis to the diaphysis and allows longitudinal bone growth

Answer 101

Articular, epiphyseal, epiphyseal plate, growth plate

Question 102

Basic growth involves both the continuous resorption of bone tissue formed earlier and the simultaneous laying down of new bone at a rate exceeding that of bone removal. The sum of osteoblast and osteoclast activities in growing bone constitutes ______ or the process of ______, which maintains the bone’s general shape while increasing its mass.

Answer 102

osteogenesis, bone modeling

Question 103

the rate of bone turnover is very active in young children where it can be ______ times faster than adults. in adults, the skeleton is also renewed continuously in a process of ______ which involves the coordinated, localized, cellular activities for bone resorption and formation.

Answer 103

200, bone remodeling

Question 104

The constant remodeling of bone ensures that, despite its ______, this tissue remains plastic and capable of adapting its internal structure in the face of changing stresses. A well known example of bone ______ is the ability of the positions of teeth in the jawbone to be modified by the lateral pressures produced by orthodontic appliances. Bone forms on the side where traction is applied and is resorbed on the opposite side where pressure is exerted. In this way, teeth are moved within the jaw while the bone is being remodeled

Answer 104

hardness, plasticity

Question 105

Because it contains ______ cells in the periosteum, endosteum, and marrow and is very well vascularized, bone normally has an excellent capacity for repair. Bone repair after a fracture or other damage uses cells, signaling molecules, and processes already active in bone remodeling. Surgically created gaps in bone can be filled with new bone, especially when ______ is left in place.The major phases that occur typically during bone fracture repair include initial formation of ______ and its replacement with a tempo rary callus of ______ bone.

Answer 105

osteoprogenitor stem, periosteum, fibrocartilage, woven

Question 106

Because it contains ______ cells in the periosteum, endosteum, and marrow and is very well vascularized, bone normally has an excellent capacity for repair. Bone repair after a fracture or other damage uses cells, signaling molecules, and processes already active in bone remodeling. Surgically created gaps in bone can be filled with new bone, especially when ______ is left in place.The major phases that occur typically during bone fracture repair include initial formation of ______ and its replacement with a tempo rary callus of ______ bone.

Answer 106

osteoprogenitor stem, periosteum, fibrocartilage, woven

Question 107

______ are required for the activity of many enzymes and many proteins mediating cell adhesion, cytoskeletal movements, exocytosis, membrane permeability, and other cellular functions.

Answer 107

Calcium ions

Question 108

The ______ serves as the calcium reservoir, containing ______% of the body’s total calcium in ______ crystals. The concentration of calcium in the blood (9-10 mg/dL) and tissues is generally quite stable because of a continuous interchange between blood calcium and bone calcium.

Answer 108

skeleton, 99, hydroxyapatite

Question 109

The principal mechanism for raising blood calcium levels is the mobilization of ions from ______ to ______, primarily in cancellous bone. ______ mobilization is regulated mainly by paracrine interactions among bone cells, many of which are not well understood, but two olypeptide hormones also target bone cells to influence calcium homeostasis

Answer 109

hydroxyapatite, interstitial fluid, Ca2+

Question 110

two olypeptide hormones also target bone cells to influence calcium homeostasis:

Answer 110

PARATHYROID HORMONE
CALCITOSIN

Question 111

______
- raises low blood calcium levels by stimulating osteoclasts and osteocytes to resorb bone matrix and release Ca2+. The PTH effect on osteoclasts is indirect; PTH receptors occur on osteoblasts, which respond by secreting RANKL and other paracrine factors that stimulate osteoclast formation and activity

Answer 111

PARATHYROID HORMONE

Question 112

______
- produced within the thyroid gland, can reduce elevated blood calcium levels by opposing the effects of PTH in bone. This hormone directly targets osteoclasts to slow matrix resorption and bone turnover.

Answer 112

CALCITOSIN

Question 113

______ are regions where adjacent bones are capped and held together firmly by other connective tissues.

Answer 113

Joints

Question 114

The type of ______ determines the degree of movement between the bones.

Answer 114

joint

Question 115

Joints classified as ______ (Gr. ______, together + ______, articulation) allow very limited or no movement and are subdivided into fibrous and cartilaginous joints, depending on the type of tissue joining the bones.

Answer 115

synarthroses, syn, arthrosis

Question 116

Major subtypes of synarthroses include the following:

Answer 116

SYNOSTOSES
SYNDESMOSES
SYMPHYSES

Question 117

Major subtypes of synarthroses

______
- involve bones linked to other bones and allow essentially no movement. In older adults ______ unite the skull bones, which in children and young adults are held together by sutures, or thin layers of dense connective tissue with osteogenic cells.

Answer 117

SYNOSTOSES, synostoses

Question 118

Major subtypes of synarthroses

______
- join bones by dense connective tissue only. Examples include the interosseous ligament of the
inferior tibiofibular joint and the posterior region of the sacroiliac joints.

Answer 118

SYNDESMOSES

Question 119

Major subtypes of synarthroses

______
- have a thick pad of fibrocartilage between the thin
articular cartilage covering the ends of the bones. All
symphyses, such as the intervertebral discs and pubic symphysis, occur in the midline of the body.

Answer 119

SYMPHYSES

Question 120

Joints classified as ______ permit free bone move ment.

Answer 120

diarthroses

Question 121

______ such as the elbow and knee generally unite long bones and allow great mobility.

Answer 121

Diarthroses

Question 122

In a ______ ligaments and a capsule of dense connective tissue maintain proper alignment of the bones. The capsule encloses a sealed joint cavity containing a clear, viscous liquid called ______ fluid. The joint cavity is lined, not by epithelium, but by a specialized connective tissue called the ______ that extends folds and villi into the joint cavity and produces the lubricant synovial fluid.

Answer 122

diarthrosis, synovial, synovial membrane

Question 123

In different ______ joints the synovial membrane may have prominent regions with dense connective tissue or fat. The superficial regions of this tissue however are usually well vascularized, with many ______ (fenestrated) capillaries. Besides having cells typical of connective tissue proper and a changing population of leukocytes, this area of a synovial membrane is characterized by two specialized cells with distinctly different functions and origins:

_______ SYNOVIAL CELLS
_______ SYNOVIAL CELLS

Answer 123

diarthrotic, porous, MACROPHAGE-LIKE, FIBROBLASTIC

Question 124

two specialized cells with distinctly different functions and origins

______ CELLS
- are derived from blood monocytes and remove wear-and-tear debris from the synovial fluid. These modified macrophages, which represent approximately 25% of the cells lining the synovium, are important in regulating inflammatory events within diarthrotic joints.

Answer 124

MACROPHAGE-LIKE SYNOVIAL

Question 125

two specialized cells with dis tinctly different functions and origins

______ CELLS
- produce abundant hyaluronan and smaller amounts of proteoglycans. Much of this material is transported by water from the capillaries into the joint cavity to form the synovial fluid, which lubricates the joint, reducing friction on all internal surfaces, and supplies nutrients and oxygen to the articular cartilage.

Answer 125

FIBROBLASTIC SYNOVIAL

Question 126

The ______ fibers of the hyaline articular cartilage are disposed as arches with their tops near the exposed surface which, unlike most hyaline cartilage, is not covered by perichondrium. This arrangement of collagen helps distribute more evenly the forces generated by pressure on joints. The resilient ______ cartilage efficiently absorbs the intermittent mechanical pressures to which many joints are subjected.

Answer 126

collagen, articular