Histology/cartilage And Bone

Front 1

Where do you find elastic cartilage?

Back 1

Where support and flexibility are required. Specifically, in the pinnae of the ear, auditory tube, and epiglottis.

Front 2

How does elastic cartilage grow?

Back 2

It possesses perichondrium and grown by apposition. It possesses chondrocytes located in lacunae.

Front 3

When stained, how do elastic fibers appear?

Back 3

Black and hairy; they are randomly scattered in the matrix.

Front 4

This type of cartilage is associated with capsules and ligaments of joints.

Back 4

Fibrocartilage.

Front 5

Where is fibrocartilage located and why is it useful?

Back 5

Located where strength and support are needed. Examples are the pubic symphysis of the pelvis and the annulus fibrosus of the intervertebral discs.

Front 6

This type of cartilage is structurally intermediate between dense regular CT and cartilage.

Back 6

Fibrocartilage. It is organized like dense regular CT: visible bundles of collagen separate lacunae that are located in rows.

Front 7

Does fibrocartilage have perichondrium?

Back 7

No.

Front 8

Does fibrocartilage have chondrocytes?

Back 8

Yes. They sit in lacunae arranged in rows.

Front 9

What are the two types of cartilage growth?

Back 9

Appositional and interstitial.

Front 10

Where does appositional growth occur?

Back 10

At the cartilage surface between the perichondrium and the previously formed cartilage.

Front 11

____ of the perichondrial surface become chondroblasts.

Back 11

Chondrogenic cells.

Front 12

What do chondroblasts become?

Back 12

They secrete matrix and become encased with lacunae, thus becoming chondrocytes.

Front 13

Relative to appositional growth, where does interstitial growth occur? Mechanistically, how are the two methods different?

Back 13

Appositional growth occurs at the boundaries; interstitial growth occurs from within. It involves proliferation of existing chondrocytes rather than creation of new ones.

Front 14

How does interstitial growth occur?

Back 14

Inside the lacunae, chondrocytes multiply and secrete matrix material, generating clusters of cells. Ultimately, matrix partitions develop and will separate these cells into separate lacunae.

Front 15

What are isogenous groups?

Back 15

Groups of 4-8 chondrocytes (derived from a single chondrocyte) found in young cartilage.

Front 16

What embryonic tissue layer becomes bone?

Back 16

Mesoderm (Neural crest-ectoderm-for cranial bones).

Front 17

What is the histologic and functional difference between bones originating from mesoderm and those from ectoderm?

Back 17

None.

Front 18

What's the basic structure of bone?

Back 18

Cells (osteocytes) embedded in a calcified matrix.

Front 19

What are the most important functions of bone?

Back 19

Protect visceral organs; provide locomotion via joints/muscle attachment sites; matrix serves as Ca depot; marrow is site of hematopoiesis.

Front 20

What's the basic structure of long bone?

Back 20

A shaft with a head at both ends.

Front 21

What makes up the axial skeleton?

Back 21

Skull, vertebral column, sternum.

Front 22

What makes up the appendicular skeleton?

Back 22

Pectoral and pelvic girdles, plus limb bones.

Front 23

What's the head of a long bone called?

Back 23

Epiphysis.

Front 24

What's the shaft of a long bone called?

Back 24

Diaphysis.

Front 25

What are some other names for compact bone?

Back 25

Cortical or Dense.

Front 26

What are some other names for spongy bone?

Back 26

Cancellous or Trabecular.

Front 27

What's the most abundant type of bone found in the body?

Back 27

Compact bone makes up 80% of adult bone mass.

Front 28

Which type of bone has Haversian systems?

Back 28

Compact.

Front 29

What are osteons?

Back 29

aka Haversian systems. Concentric cylindrical arrays arranged in parallel; major component of compact bone.

Front 30

What are the major characteristics of spongy bone?

Back 30

A delicate lattice of thin trabeculae within marrow spaces; do not form Haversian systems; have hematopoietic tissue in cavities.

Front 31

Where do you find spongy bone?

Back 31

The heads of long bones, flat bones of skull, sternum.

Front 32

What's the relative makeup (by weight) of the organic and inorganic portions of bone matrix?

Back 32

Organic=50-70%
Inorganic=30-50%

Front 33

What makes up the organic portion of bone matrix?

Back 33

Type I collagen and amorphous ground substance containing proteoglycans and glycoproteins.

Front 34

What are the specific bone glycoproteins and what do they do?

Back 34

Sialoprotein and osteocalcin. They help bind calcium.

Front 35

What makes up the inorganic portion of the bone matrix?

Back 35

Calcium phosphate in the form of hydroxyapatite crystals. Also, bicarbonate, nitrate, Mg, K, Na, Ca, and P.

Front 36

What's the only part of the body that's harder than bone?

Back 36

Tooth enamel.

Front 37

What cells are in the bone matrix?

Back 37

Osteoprogenitor cells (osteogenic cells), osteoblasts (become osteocytes), and osteoclasts.

Front 38

Where do osteoclasts come from?

Back 38

From blood monocytes.

Front 39

What type of cells are osteoprogenitor cells?

Back 39

They are mesenchyme stem cells. They derive from embryonic mesenchyme.

Front 40

What do osteoblasts do?

Back 40

They secrete organic material into the matrix and surround themselves with it, thus becoming osteocytes within lacunae. They maintain the matrix of bone tissue.

Front 41

What determines the matrix characteristics in cartilage and bone?

Back 41

Their macromolecules, fibers, and (in bone) mineral deposits.

Front 42

What's the origin of cartilage?

Back 42

Mesoderm.

Front 43

What are some functions of cartilage?

Back 43

Shock absorption, flexible/cushioning support.

Front 44

Where do you find cartilage in the body?

Back 44

Joint surfaces, respiratory tract, ear, nose, epiglottis, pinnae.

Front 45

Name three components of cartilage.

Back 45

Avascular matrix, chondrocytes within lacunae, bounded by periochondral CT or synovial fluid.

Front 46

What kind of collagen is in the matrix of cartilage?

Back 46

Collagen II.

Front 47

What are the 3 categories of cartilage?

Back 47

Hyaline, elastic, and fibrocartilage.

Front 48

What's the most common type of cartilage?

Back 48

Hyaline.

Front 49

Where do you find hyaline cartilage?

Back 49

Most joint surfaces, respiratory tract, nasal cavity.

Front 50

What color is hyaline?

Back 50

It's translucent.

Front 51

Where do you find elastic cartilage?

Back 51

Epiglottis and external ear.

Front 52

Where do you find fibrocartilage?

Back 52

Intervertebral discs (annulus) and pubic symphysis.

Front 53

What kind of cartilage makes up the embryological skeleton?

Back 53

Hyaline.

Front 54

What is characteristic about the appearance of hyaline matrix?

Back 54

Amorphous, homogenous, glassy appearance. No fibers visible on stained section.

Front 55

Name 4 components of hyaline matrix.

Back 55

Type 2 collagen, hyaluronic acid, proteoglycans (chondroitin sulfate, keratan sulfate) and chondronectin (a glycoprotein). It also contains some Type I collagen.

Front 56

This component of cartilage matrix acts as a cement to bind the proteoglycans together into large hydrated aggregates.

Back 56

Hyaluronic acid, which is a gelatinous mucopolysaccharide.

Front 57

What is perichondrium?

Back 57

A layer of dense irregular CT that surrounds the cartilage of developing bones. Literally means "next to cx tissue."

Front 58

Why can't you see collagen fibers in sections of cartilage?

Back 58

Collagen is at the same refractive index as other matrix components.

Front 59

Can nutrients diffuse through CT matrix?

Back 59

Yes, in fact that's one of the major purposes of the matrix--supplying nutrients to chondrocytes.

Front 60

How does elastic cartilage grow?

Back 60

It grows by apposition.

Front 61

Does elastic cartilage matrix possess perichondrium?

Back 61

Oh, yes.

Front 62

What do elastic fibers look like on slides?

Back 62

Like hairs kind of.

Front 63

What's another word for osteogenic cells? What do they do? What are they derived from?

Back 63

AKA Osteoprogenitor cells. They are capable of differentiating into osteoblasts that then secrete organic material, entrapping cells within lacunae. They're derived from embryonic mesenchyme.

Front 64

What do osteogenic cells look like?

Back 64

They're spindle shaped.

Front 65

Where are osteoblasts found?

Back 65

At the margins of growing bone spicules.

Front 66

How do osteoblasts appear on slides?

Back 66

Basophilic, with well developed RER and Golgi.

Front 67

What are osteocytes?

Back 67

Mature bone cells that occupy lacunae.

Front 68

What cell do osteocytes come from?

Back 68

Osteoblasts.

Front 69

How do osteocytes communicate with each other?

Back 69

They have cellular processes that radiate from the cell bodies and form gap junctions.

Front 70

What does trabeculae describe?

Back 70

Winding, branched configuration. Spongy bone.

Front 71

What do osteoclasts derive from?

Back 71

Macrophages (blood monocytes).

Front 72

What cells cause bone remodeling? How do they do it?

Back 72

Osteoclasts. They resorb bone matrix, releasing Ca.

Front 73

Describe the border of an active osteoclast.

Back 73

It's ruffled and faces the bony matrix. Only visible by EM. Gives the cell increased surface area. Creates sealed-off areas into which resorptive enzymes can be secreted. Secretes enzymes in an acidic environment.

Front 74

What kind of enzymes do osteoclasts secrete?

Back 74

They create an acidic environment that decalcifies the surface bone layer. There, they secrete acid hydrolases that break down the decalcified material.

Front 75

What role does the endocrine system play in bone remodeling?

Back 75

Hormones influence osteoblast/osteoclast activity. PTH/Calcitonin?

Front 76

What are the two ways bone can develop?

Back 76

Intramembranous ossification (develops within mesenchyme) and endochondral ossification (develops within a cartilage model).

Front 77

What is intramembranous ossification?

Back 77

Bone formation within mesenchyme. Direct deposit of bone by osteoblasts in mesenchyme without a cartilage precursor.

Front 78

Where does intramembranous ossification occur?

Back 78

Cranial bones and the clavicles, and in initial stages of endochondral ossification.

Front 79

With the exception of ____, all skeletal bones below the base of the skull develop by ____.

Back 79

The clavicles; endochondal ossification.

Front 80

Name the 6 steps of endochondral ossification.

Back 80

1) Hyaline cartilage model is established.
2) Mesenchymal cells adjacent to middle portion of diaphysis form osteoblast cells that form a bony belt by intramembranous ossification.
3) Blood vessels penetrate belt and enter primary ossification center.
4) Osteoblasts and osteoclasts enter primary ossification center.
5) Osteoblasts make bone matrix.
6) Epiphyseal plates are established.

Front 81

What is the epiphyseal plate? How is it established?

Back 81

A growing zone of cartilage that separates the diaphysis and epiphyses of long bones. Around the time of birth, a secondary ossification center appears at each epiphysis and in parts of irregular and flat bones.

Front 82

What are the zones of the epiphyseal plate?

Back 82

1) Resting chondrocytes in hyaline cartilage area.
2) Proliferating chondrocytes, multiplying by interstitial growth. Become arranged in parallel columns. This creates bone length.
3) Hypertrophic chondrocytes. Cells get big, stop secreting collagen/proteoglycans and begin secreting alkaline phosphatase.
4) Calcifying cartilage. Chondrocytes die. Matrix calcifies.
5) Ossification. Osteoblasts deposit bone matrix in areas vacated by dying cartilage.

Front 83

What is primary bone?

Back 83

Characterized by irregular arrangement of collagen fibers, many osteocytes, low mineral content. It gets remodeled and replaced by secondary bone.

Front 84

Is primary bone spongy or compact?

Back 84

Spongy, or trabecular.

Front 85

Is primary bone acidophilic or basophilic?

Back 85

Acidophilic.

Front 86

How do bones heal? What disadvantage comes along with bone healing?

Back 86

Woven bone is rapidly laid down. It is weaker than lamellar bone because it has a small number of randomly oriented collagen fibers.

Front 87

What is diploe?

Back 87

The soft, spongy material between the inside and outside bony plates, or tables, of the skull. It contains bone marrow.

Front 88

Compact secondary bone contains ____which house blood vessels.

Back 88

Haversian systems (center of osteons).

Front 89

What does lamellar mean?

Back 89

Layered. Osteons are layered in cylinders.

Front 90

What role do trabeculae play in compact bone?

Back 90

They are marrow cavities.

Front 91

How does blood get into bone?

Back 91

Blood vessels entering the periosteum and endosteum penetrate the bony matrix via Volkmann's canals which run perpendicularly to Haversian canals.

Front 92

Describe the makeup of an osteon.

Back 92

Consists of concentric cylinders of bone matrix (lamellae) arranged around a central canal (Haversian) that runs the length of a long bone.

Front 93

Where do Volkmann's canals carry blood vessels?

Back 93

B/t the marrow cavity, Haversian canals, and the periosteum.

Front 94

Osteocytes are located in ____ surrounded by ____.

Back 94

Lacunae; lamellae.

Front 95

What are canaliculi?

Back 95

Tiny canals that connect lacunae to each other and to the Haversian canal. The contain osteocyte processes and allow adjacent layers of osteocytes to share nutrients.

Front 96

Where are interstitial lamellae found and what function do they serve?

Back 96

Found in the matrix areas between osteons; they fill in the gaps between osteons. They contain osteocytes within their lacunae but are not organized in rings around Haversians.