Cartilage And Bone

Front 1

Function of Bone

Back 1

Reservoir for calcium and phosphate

Protects vital organs

contains bone marrow

Front 2

Cartilage Functions and Characteristics

Back 2

1. Origin is Mesoderm
2. Consists of avascular matrix w/specialized cells (Chondryocytes) situated within Lacunae
3. Surrounded by periochondrium or synovial fluid.

Front 3

Chondrocytes

Back 3

Produce and maintain cartilaginous matrix.

Front 4

periochondrium

Back 4

1. Dense irregular connective tissue that surrounds cartilage of developing bone.
2.

Front 5

Cartilage Location

Back 5

1. Articular Surfaces (Joints)
2. Trachea
3. Nose and Ear
4. Epiglottis

Front 6

Appositional Grown

Back 6

Cartilage Growth
1. Surface growth which occurs at cartilage surface between perichondrium and previously formed cartilage.
2. Chondrogenic cells begin active synthesis and become chondroblasts and start creating new cartilage at boundaries.
4. New chondroblasts become trapped in lacunae and become a part of the main mass of cartilage.
INTERSTITIAL GROWN CAN BEGIN

Front 7

Interstitial Growth

Back 7

1. Internal Grwoth that occurs in young cartilage.
2. Mitosis and actively synthesizing matrix material to generate cells that are pushed apart by their new matrix.

Front 8

Cartilage Types

Back 8

1. Hyaline
2. Elastic
3. Fibrocartilage

Front 9

Hyaline

Back 9

1. Most common
2. Collagen II + Hyaluronic Acid + proteoglycogens
3. Found in articular ends of long bones, nose, larynx, and respiratory trace, and in embryo.
4. Homogeneous extracellular matrix (no fibers)
5. Most is surrounded by Perichondrium or synovial membrane

Front 10

Isogenous Groups

Back 10

groups of 4-8 chondrocytes derived from a single precursor chondrocyte

Front 11

Elastic Cartilage

Back 11

1. Fortified with elastic fibers
2. Found where support and flexibility are required: Pinnae of ear, auditory tube, apiglottis.
3. Often found with hyaline cartilage.
4. Surrounded by perichondrium and is abundant with elastic fibers.

Front 12

Fibrocartilage

Back 12

1. Associated with capsules and ligaments of joints
2. Tensile
3. Structurally intermediate between dense, regular connective tissue and cartilage.
2. Similar to regular connective tissue, but no perichondrium.
3. Pubic symphysis and intervertebral discs
4. Hockey Puck

Front 13

Bone Characteristics

Back 13

1. Can by spongy or Compact
2. Composed of hard, calcified Matrix that can be repaired or renewed
3. Froms the axial and appendicular parts of skeleton
4. Cells (osteocytes) are distributed within matrix

Front 14

Organic Portion of Bone Matrix

Back 14

95% type 1 collagen, glycoproteins SIALOPROTEIN and ESTEOCALCIN bind calcium

Front 15

Osteogenic Cells

Back 15

1. Spindle-shaped connective tissue cells derived from embryonic mesenchyme
2. Capable of Mitotic Division
3. Precursor Cells to Osteoblasts

Front 16

Inorganic Portion of Bone Matrix

Back 16

Calcium, phosphorus, bicarb, nitrate, magnesium, potassium, sodium, and hydroxyapatite crystals

Front 17

Osteoblasts

Back 17

1. Active, matrix secreting cells.
2. Found at the margins of growing bone
3. Basophilic appearance because of well developed RER and Golgi

Front 18

Osteocytes

Back 18

1. Mature Bone cells that cease secretory functions.
2. Occupy Lacunae in bone matrix
3. Linked together by processes that reside within canaliculi
4. gap gap gap junctions.

Front 19

Canaliculi

Back 19

small passageways in bone. Attach lacunae and allow osteocytes to gap junction. Look like hair.

Front 20

Osteoclasts

Back 20

1. Macrophage derived multinucleated cells that resorb bone matrix.
2. Releases Calcium
3. Derived from blood monocytes.
4. Characteristics:
a. ruffled border (active bone resorption)
b. Clear Zone (region of cytoplasm surrounding ruffled border
c. Vesicular Regoin (polymorphous vesicle like structure)
d. Basal Region (houses organelles and nuclei)

Front 21

Periosteum

Back 21

1. Non calcified connective tissue on external surface of bone except for articular surfaces.
2. Composed of outer fibrous layer and inner cellular layer.
3. Provides blood supply to bone and serves as source of osteogenic cells

Front 22

Organic Portion of Bone Matrix

Back 22

95% type 1 collagen, glycoproteins SIALOPROTEIN and ESTEOCALCIN bind calcium

Front 23

Bone Cells

Back 23

1. Osteogenic Cells
2. Osteoblasts
3. Osteocytes
4. Osteoclasts

Front 24

Endosteum

Back 24

1. Lines marrow cavities of bone
2. Similar to periosteum
3. Involved in bone growth and repair.

Front 25

Volkmanns Canals

Back 25

Blood vessels run through, perpendicular to Haversian Canals

Front 26

Haversian Canals

Back 26

1. Middle part of the Hippie bone.
2. Concentric Lamellae surround blood vessels.
3. Carries blood and lymph vessels

Front 27

Compact Bone

Back 27

1. Hard outer layer; smooth white appearance
2. Made up of Osteons (Haversian Systems)
3. 80% of total mass of adults

Front 28

Spongy (Cancellous or Trabecular) bone

Back 28

1. Lattice of thin traveculae w/in marrow spaces
2. Do not have Haversian systems
3. Hematopoietic tissue in cavities
4. Found in flat bones of skull, sternum, and epiphysus of long bones
5. Primary bone starts out spongy

Front 29

Intramembranous Ossification

Back 29

--Directly from membrane--dermal bones and initial stages of endochondral ossification.
--Direct deposition of bone by osteoblasts in mesenchyme
1. Mesenchmal cells condense to formprimary ossification center
2. Osteoblasts differentiate and secrete osteoid.
3. Osteoblasts are trapped in matrix and mature.
4.Bony trabeculae (fused spincules) join and form spongy bone.

Front 30

Endochondral Ossification

Back 30

--Replaces hyaline cartilage
--All skeletal bones except clavicles.
1. Development and growth of cartilage model (hyaline)
2. Primary Ossification: Endochondral bone forms at midriff of diaphysis. Osteoclasts etch holes in bone collar to allow osteogenic cells and vlood vessles to dig in. Osteoblasts elaborate bone matrix on degenerating cartilage core. Subperosteal bone caller becomes thicker and elongates toward epiphyses.
3. Secondary Ossification (after birth): Diaphysis and epiphyses of long bones separate by epiphyseal plate. At maturity all cartilage is replaced by bone, fusing the diaphysis and both epiphyses together.

Front 31

Epiphyseal Plate Zones

Back 31

1. RESTING cartilage: Chondracytes are inactive
2. PROLIFERATING cartilage: Chondrocytes are multiplying and arranging in long parallel columns. Main zone responsible for growth.
3. Hypertrophy and cell maturation: Chondrocytes are hypertrophying and secreting alkaline phosphate
4. Calcifying cartilage: matrix around hypertrophied chondroctyes solidify, traps cell in matrix. Chondrocytes being to die.
5. OSSIFICATION: Chondrocytes die once calcification is complete. New osteoblsts are recruited from blod supply. They deposit proteins into matrix.

Front 32

Primary or Woven Bone

Back 32

1. Deposited on hyaline cartilage
2. Irregular arrangement of collagen fibers, large number of osteocytes, and low mineral content
3. remodeled and replaced by secondary bones.

Front 33

Secondary or Lamellar Bone

Back 33

1. Replaces primary and may become spongy or compact.
2. Has Haversian systems or Osteons that transmit blood

Front 34

Streptyomycin

Back 34

Binds to 30s subunit, interferes with initiation of protein synthesis

Front 35

RNAi or RNA Interference

Micro-RNA
Si-RNA

Back 35

1/3 of human genes are target, helps regulate gene expression, linked to cancer, diabetes and differentiation

Micro-RNA --> Block initiation of protein synthesis

Si-RNA --> cleave mRNA

Front 36

Post Translational Modifications

Back 36

1. Cleavage of N or C terminal Peptide
2. Covalent Modifications (adding phosphate to Serine, Threonine, Tyrosine)
3. Glycosylation
4. Hydroxylation (adding OH to proline or lysine)
5. Ubiquitination (adding small proteins that signal it for breakdown)