Histo Lecture 8 Bone And Connective Tissue

Front 1

Cartilage: composition

Back 1

composed of extracellular matrix and the chondrocytes (cartilage cells)

Front 2

Cartilage ECM composition

Back 2

The ECM of Cartilage is composed of 1) Collagen fibers + 2) ground substance + 3) water

Ground substance = chondromucoproteins (mucopolysaccharides + proteins) + hyaluronic acid

Front 3

What determines the sponginess of IV discs?

Back 3

The higher the water concentration, the bigger and spongier the matrix. The negative charge organizes water into stiff colloidal gel. This complex matrix functions like a shock absorber.

Front 4

Lacunae

Back 4

in both cartilage and bone. in cartilage: chambers occupied by chondrocytes they appear as empty spaces in cartilage as an artifact of preparation. in bone: osteocytes.

Front 5

3 Types of cartilage

Back 5

1) fibrous cartilage
2) elastic cartilage
3) hyaline cartilage

Front 6

Fibrous cartilage: type of collagen, description of tissue

Back 6

type I collagen, lots of fibrous material, NO perichondrium, vascular

Front 7

Elastic cartilage: type of collagen, description of tissue

Back 7

Type II cartilage, elastin fibers, contain perichondrium, avascular (nutrients must be diffused through the matrix-- thus limited in size by ability to receive nutrients)

Front 8

Hyaline Cartilage: type of collagen, description of tissue

Back 8

Found in respiratory tract (C rings), ventral ends of ribs, long bone epiphyseal plates, and synovial joints.
type II cartilage, homogenous mixture: no apparent fibers b/c refractive index of the colalgen is the same as the ground substance, contains perichondrium (except @ joint), avascular (nutrients must be diffused through the matrix-- thus limited in size by ability to receive nutrients)

Front 9

3 types of cartilage cells

Back 9

1) Perichondrial cells
2) Chondrocytes
3) Chondroblasts

Front 10

perichondrial cells

Back 10

flat mesenchymal precursor cells found at the perichondrium that will differentiate into round chondroblasts

Front 11

chondroblasts

Back 11

blast = "baby cell". divides, grows, and synthesizes the matrix

Front 12

chondrocytes

Back 12

maintains the matrix, derived from chondroblasts trapped within the matrix, clustered in "isogenous groups"

Front 13

Cartilage Growth

Back 13

Appositional: perichondrial --> chondroblasts --> chondrocytes
Occurs at epiphysis. NEEDS PERICHONDRIUM!

Interstitial growth: mitotic division of preexisting chondrocyte
chondrocyte makes matrix, pushing it apart from its sister cell. matrix expands from within because t is a pliable colloid. Occurs at metaphysis-- epiphysial growth plate

Front 14

Cartilage matrix vs. bone matrix

Back 14

Cartilage Matrix: contains water, cartilage (type I or type II), ground substance, NO Crystals (low mineral content)

Bone Matrix: contains some water, cartilage (type I), ground substance, LOTS of crystals

Front 15

Bone Osteoid

Back 15

Uncalcified "pre-bone" containing type I collagen, ground substance, and calcium phosphate: pretty much everything except the minerals

Front 16

What makes a long bone so strong but not very heavy?

Back 16

the tubular structure of long bones adds strength where forces are incurred (solid outer surface: cortical/compact bone), but middle is more hollow and filled with cancellous/spongy/trabecular bone.

Front 17

Cancellous bone structure, function, and composition

Back 17

Trabecular (spicules), formed of vertical plates bridges by horizontal struts
Functions to distribute force (rather than twist or bend)
Marrow of rat will have spaces between trabecular

Front 18

Where do trabeculae form?

Back 18

Found near joints of long bones, core of small bones, and diploe of flat bones

Front 19

Two different forms of compact bone: shape and form

Back 19

Circumferential Lamellae (inner endosteal and outer periosteal parallel plates). "Parfaits".

Haversian system osteons (concentric rings). Contain central canals. "Onions".

Front 20

Haversian systems (osteons) structure and contents

Back 20

Concentric lamellae arranged around a central Haversian canal which contains blood vessels and nerves. Canals run parallel to the long bone. Volkmann's canals run perpendicular to the long bone that connect Haversian canals.

Front 21

Cartilage vs Bone Cells

Back 21

Cartilage: doesn't resorb matrix, comes from small flat perichondrial cells, flat round chondroblast makes its matrix, and flat round chondrocytes are trapped in the matrix

Bone: Osteoclasts resorb the matrix, Come from small flat osteoprogenitor , osteocytes maintain the matrix and are trapped in chambers called lacunae

Front 22

How do osteocytes connect to adjacent cells

Back 22

via gap-junctions in long cell processes running in canaliculi. This allows nutrient, waste, fluid, signals, and ion exchange. Canaliculi do not cross cement line (boundary between osteons).

Front 23

What happens if osteocytes die

Back 23

Because they maintain the ion balance, if they die the surrounding bone is resorbed.

Front 24

Two types of bone found in spongy or compact bone and properties

Back 24

1) Lamellar
Normally in mature bone (3 yrs or older). More mineral, less cellular, layered arrangement. Contains alternating light/dark pattern under polarized light. Compact Lamellar Bone: concentric bone. Spongy Lamellar bone: trabeculae.

2) Woven bone
irregular arrangement, less mineral, more cellular, disappear by age 3 except for where tendons insert into bones and tooth sockets, it is the first bone to form in the fetus.
Woven compact bone:
Woven spongy bone:

Front 25

Sharpies fibers

Back 25

The fibers that tendons/muscles use to insert into woven bone