cartilage

Question 1

similarities of cartilage and bone

Answer 1

• cells embedded in ECM they have produce (within lacunae)
• functions rely on composition/structure of ECM
• can be covered by a thin layer of dense irregular CT containing lineage-restricted progenitor cells
  
  • cartilage: perichondrium
  • bone: periosteum
• come from mesenchymal cells -> xprogenitor cell -> xblast -> xcyte
• blasts lay down matrix

Question 2

synovial joints

Answer 2

no perichondrium -> no regeneration

Question 3

diff b/w cartilage and bone

Answer 3

cartilage ECM: firm, hydrated, gel with high diffusion index
- avascular
- few stem cells
bone ECM: solid and mineralized (calcium phosphate) with low diffusion index
- richly vascularized
- more stem cells - better regeneration

Question 4

cartilage

Answer 4

supports soft tissues, reduces friction in joints, forms growth plates

Question 5

growth/epiphyseal plates

Answer 5

in long bones, made of cartilage

Question 6

chondrogenic progenitor cells

Answer 6

derived from mesenchymal progenitor cells, found in perichondrium

Question 7

chondroblasts

Answer 7

derived from chondrogenic progenitor cells
- proliferate and secrete ECM

Question 8

chondrocytes

Answer 8

secrete large amounts of basophilic ECM
- high in proteoglycan
- cells trapped in lacunae derived by chondroblasts

Question 9

hyaline cartilage

Answer 9

most abundant; joints, nose, trachea, bronchii
- model for endochondral bone formation
- growth plates
- has perichondrium except in capsulated synovial joints
- organic ECM
- 70% water
- 20% collagen, mostly II
- 10% proteoglycan
- moderately compressible, low friction, some tensile strength due to collage II

Question 10

dense connective tissue

Answer 10

collagen I, thick fibers

Question 11

reticular CT

Answer 11

collagen III, thin fibers

Question 12

elastic cartilage

Answer 12

similar to HC, found in ear pinna
- elastic fibers
- more chondrocytes than HC, less matrix than HC
- well-defined perichondrium (regeneration)
- greater flexibility

Question 13

fibrocartilage

Answer 13

type I collagen, intervertebral diks and sites of bone attachment
- similar to dense CT, but contains chondrocytes
- collagen fibers all parallel - high tensile strength
- resistance to compression
- no regeneration

Question 14

nucleus pulposus

Answer 14

core of intervertebral disks
- remnant of notochord
- few cells, high water + HA
- gelatinous, compresses and expands with weight

Question 15

annulus fibrosis

Answer 15

fibrocartilage surrounding + protecting nucleus pulposus
- gives disk tensile strength

Question 16

herniation

Answer 16

tear in fibrocartilage (annulus fibrosis) -> leaking nucleus pulposus

Question 17

osteoarthritis

Answer 17

injury/wear and tear of HC in joints
- mesenchymal SCs can migrate from BM into wounded HC
- can diff into fibro chondrocytes
- fibrocartilage eventually wears away
- replaced by bone on joint surface