Anatomy 115 Review Lectures 7 & 8 (Cartilage And Bone)

Front 1

What are bones and cartilage made up of?

Back 1

Cells, fibers and ground substance.

Front 2

Compare and contrast cartilage and bone in terms of general characteristics.

Back 2

Cartilage - bounded by perichondrium, has no nerves or blood vessels, contains Type II collagen and proteoglycans.

Bones - bound by periosteum, rich in blood vessels and nerves, contains Type I collagen and proteoglycans, and is mineralized.

Front 3

What do cells and ground substance provide the skeleton?

Back 3

Cells provide fibers and proteoglycans.

Ground substance provide proteoglycans and water (adds firmness).

Front 4

What is the function of bone mineral?

Back 4

Rigidity to support weight.

Front 5

What is the function of cartilage?

Back 5

Provides firmness with flexibility.

Front 6

What makes up cartilage?

Back 6

Type II collagen + proteoglycans.

Front 7

What produces cartilage?

Back 7

Chondrocytes

Front 8

What are the two ways that cartilage may form?

Back 8

Interstitial (growth within main part of cartilage; chondrocytes divide and subsequently secrete the specialized ECM, which contains fibers and ground substance)

Appositional (growth at ends of cartilage)

Front 9

How does cartilage receive its nutrition?

Back 9

From diffusion of capillaries or synovial fluid (since cartilage has no blood vessels).

Front 10

What are the differences in morphology b/t cells in the perichondrium vs. chondrocytes?

Back 10

Perichondrium is more squished and elongated.

Front 11

What are the different ways that bone can be formed?

Back 11

Intramembranous - bone forms directly from mesenchymal cells (e.g. clavicle, parts of skull)

Endochondral - bone forms from a cartilagenous precursor (most of skeleton).

Front 12

Outline the steps of cartilage formation via interstitial growth.

Back 12

Mesenchyme (undifferentiated stem cells) --> Chondroblasts (immature cells that are actively synthesizing and depositing ECM materials) --> Chondrocytes (
mature cells of cartilage; completely surrounded by cartilage matrix and trapped in small spaces called lacunae) --> embedded in cartilage matrix

Front 13

Outline the steps of intramembranous bone formation.

Back 13

Mesenchymal cells develop into osteoblasts --> lay down bone matrix and type 1 collagen b/t cells --> forms matrix --> mineralization occurs and Ca-Phos deposited within matrix --> turns it into bone --> remodeling by osteoblasts and osteoclasts allows for shape changes and bone growth

Front 14

How does bone develop from a cartilage precursor?

Back 14

Process is known as endochondral ossification and has two centers of ossification (primary is in the diaphysis and secondary in the epiphysis).

(1) Cartilage model develops in embryo.
(2) Periosteum develops and has a layer of undifferentiated cells that later become osteoblasts.
(3) Osteoblasts secrete osteiod against the shaft of cartilage model.
(4) Cartilage calcifies, forms periosteal bone collar, and blood vessels sprout (some become the precursor of bone marrow and others branch out in opposite directions along the shaft).
(5) Secondary ossification center forms in epiphysis.
(6) Cartilage b/t the two centers of ossification (aka epiphyseal plate) continues to grow and is replaced by bone over time. This process extends the length of the bone and forms epiphyseal lines.

Front 15

What are the major events in endochondral bone formation in the epiphyseal plate?

Back 15

(1) formation of hypertrophic cartilage
(2) death of hypertrophic chondrocytes
(3) invasion by chondroclasts
(4) degradation of cartilage matrix
(5) vascular invasion
(6) recruitment of osteoblasts and mineralization

Front 16

How is cartilage converted to bone in the epiphyseal plate?

Back 16

Starts with cartilage model formed in embryo --> hypertrophy of chondrocytes at the epiphyseal plate occurs (in diaphysis) --> matrix surrounding these hypertrophied chondrocytes calcifies --> chondrocytes die --> region of dead cells is invaded by blood vessels and mesenchymal cells (that differentiate into osteoblasts) --> Osteoblasts secrete bone along surface of calcified cartilage matrix --> become osteoCYTES trapped in bone lacunae --> Secondary ossification centers develop in the epiphyses --> Cartilage b/t the two centers of ossification (aka epiphyseal plate) continues to grow and is replaced by bone over time. This process extends the length of the bone and forms epiphyseal lines.

Front 17

What is the function of osteoblasts?

Back 17

To produce the bone matrix

To produce the collagen and ground substance of bone at the edges of bone

Front 18

How are mature bones organized?

Back 18

Basically, in rings. (1) Concentric lamellae are rings of bone formation and in their center is a (2) Haversian canal that contains blood vessels and nerves running through the bone.

Front 19

What is the function of the canuliculi?

Back 19

They are cellular processes that extend through the bone, allowing signaling and nutrient exchange.

Front 20

What is the fx of osteoclasts?

Back 20

Osteoclasts are huge multi- nucleated cells with ruffled borders

They contain many lysosomes and secrete collagenase and acid proteases; their function is similar to macrophages - to reabsorb both mineral and organic components of bone.

Front 21

What are osteoids?

Back 21

Unmineralized bone matrix

Front 22

What are osteocytes?

Back 22

They are osteoblasts (cells that produce bone) after it is trapped within its secreted matrix.