Lecture 1: Cartilage (Wronski) Flashcards Preview

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Flashcards in Lecture 1: Cartilage (Wronski) Deck (59)
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1
Q

Name the 3 types of cartilage recognized

A
  1. hyaline cartilage
  2. elastic cartilage
  3. fibrocartilage
2
Q

which type of cartilage is most common?

A

hyaline cartilage

3
Q

define chrondroblast

A

cells that are capable of producing cartilage-specific extracellular matrix

4
Q

define lacunae

A

celullar compartments surrounded and isolated by extracellular matrix produced by chondroblasts

5
Q

define chrondrocyte

A

chondroblasts that have become embedded in matrix within luncunae.

they maintain the ability to divide and produce extracellular matrix

6
Q

define perichondrium

A

a fibrous covering formed by by mesenchymal cells at the margins of the centers of chondrification.

7
Q

name the two different layers of cells recognized within the perichondrium.

A
  1. fibrous layer = most external, developed by differentiated fibroblasts. looks like dense irregular connective tissue
  2. chondrogenic layer or cellular layer - generates new chondroblasts.
8
Q

does perichondrium persist in adults?

A

yes, but its chondrogenic capacity decreases and eventually ceases.

9
Q

which type of cartilage lacks perichondrium?

A

articular cartilage

10
Q

Name the two different types of cartilage growth.

A
  1. appositional growth

2. interstitial growth

11
Q

define appositional growth

A

the deposition of new cartilage at the surface (perichondrium) by chondroblasts.

12
Q

define interstitial growth

A

the division of chrondrocytes within lacunae and the production of matrix, resulting in expansion by new cartilage from within.

13
Q

explain the development of isogenic clusters of chondrocytes

A

when chondrocytes divide, new matrix is produced that separates the daughter cells into separate lacunae. this division results isogenic clusters of chondrocytes - the progeny of a single chondrocyte

14
Q

what type of collagen dominates in hyaline cartilage?

A

type II collagen!

15
Q

what type of cell produces type II collagen in hyaline cartilage?

A

chondrocytes within the growth plate

16
Q

define aggregans

A

extremely large proteoglycan aggregates that contains embedded collagen fibers.

17
Q

what properties does the extracellular matrix provide to hyaline cartilage?

A

strength and resiliency of cartilage

18
Q

what properties do the collagen fibers provide to hyaline cartilage?

A

tensile strength and shape of cartilage

19
Q

what properties do the proteoglycans provide to hyaline cartilage?

A

ability to absorb compressive forces

20
Q

define chondronectin

A

a fibronectin-like connecting glycoprotein that specifically binds collagen fibers and proteoglycans to chondrocytes.

21
Q

territorial matrix

A

the matrix immediately surrounding lacunae (newest formed).

  • more basophilic
  • more peripherally placed
22
Q

interterritorial matrix

A

outlying matrix

23
Q

what provides the firm gel-like quality of cartilage?

A

the high concentration of very large proteoglycan aggregates

24
Q

explain what creates the compressive strength of cartilage

A

it is due to its high water content and negatively charged glycosaminoglycan side chains. when compressed, water is displaced. with the displacement of water, the repelling forces of the like negative charges are left to resist any further compression.

25
Q

is cartilage vascular or avascular?

A

avascular

26
Q

how do metabolites pass from capillaries to chondrocytes?

A

long distance diffusion

27
Q

explain the effect of deposition of insoluble salts in the matrix

A

this is the process of mineralization. it impedes diffusion and leads to degenerative changes because viable chondrocytes are essential for maintenance of cartilage matrix.

28
Q

what treatments for hyaline cartilage have been reasonably successful and why

A

allografts because it prevents large molecules (like immunoglobulins and CTL cells from coming into contact with chondrocytes due to its avascular nature.

29
Q

what type of cartilage is present in the external ear, auditory tube, and epiglottis?

A

elastic cartilage

30
Q

what are areas of degenerative cartilage replaced with?

A

fibrous connective tissue

31
Q

what is the main difference between elastic cartilage and hyaline cartilage?

A

elastic cartilage has elastic fibers rather than collagen that comprise the fibrillar component of the extracellular matrix.

32
Q

define fibrocartilage

A

a specialized connective tissue where tendons and ligaments insert on bone or cartilage

33
Q

what type of collagen is dominant in fibrocartilage?

A

type I collagen fibers

34
Q

what other substances are found in fibrocartilage other than collagen?

A

amorphous ground substance composed of chondroitin sulfate and dermatan sulfate

35
Q

where is fibrocartilage most commonly found?

A

the annulus fibrosis of the intervertebral discs and menisci of the stifle joint

36
Q

what are articular surfaces composed of?

A

articular cartilage supported by underlying subchondral bone

37
Q

what is articular cartilage composed of?

A

hyaline cartilage that is not covered by a perichondrium

38
Q

how is growth of articular cartilage achieved?

A

interstitial growth

39
Q

what happens at cessation of growth of articular cartilage?

A

chondrocytes are no longer able to divide but are capable of producing additional cartilage matrix

40
Q

what are the 4 zones of articular cartilage?

A
  1. tangential zone (most superficial)
  2. transition zone of chondrocytes
  3. radial zone of chondrocytes
  4. deep zone of calcified cartilage
41
Q

describe the tangential zone of articular cartilage

A

it is superficial, narrow and consists of a zone of small, flattened chondrocytes aligned parallel to the articular surface

42
Q

describe the transition zone of chondrocytes in articular cartilage

A

consists of an ovoid morphology

43
Q

describe the radial zone of chondrocytes in articular cartilage

A

they are aligned in longitudinal rows perpendicular to the articular surface

44
Q

describe the deep zone of calcified cartilage in articular cartilage

A

it interlocks with subchondral bone to anchor the articular cartilage

45
Q

define tidemark

A

the junction between the radial zone and the calcified cartilage

46
Q

how does the tidemark appear on x-ray? why?

A

appears as the “joint surface” because it is the junction between non-calcified (radial zone of articular cartilage) and calcified tissues

47
Q

how does articular cartilage receive nutrients? what is its main source?

A

by diffusion and the main source is synovial fluid of the joint cavity

48
Q

what is osteroarthritis or degenerative joint disease characterized by?

A

the degeneration of articular cartilage

49
Q

what are the 8 stages of osteoarthritis?

A
  1. proteoglycan and hyaluronic acid content of they hyaline cartilage matrix decreases
  2. fat is deposited in the interterritorial matrix and chondrocyte numbers decrease
  3. chondromalacia
  4. fibrillation
  5. brood capsules form at the margins of fissures to try and repair the damage
  6. resorption of cartilage matrix by chrondroclasts
  7. underyling subchondral bone is exposed
  8. osteophytes form at the periphery of the degenerative joint
50
Q

define chondromalacia

A

articular cartilage becomes soft

51
Q

define fibrillation

A

the formation of small fissures on the surface of the articular cartilage

52
Q

define brood capsules

A

clusters of chondrocytes

53
Q

define osteophytes

A

bony outgrowths

54
Q

what breed has particular issues with herniated intervertebral discs?

A

dachshunds

55
Q

what is the outer part of the intervertebral disc called? what type of cartilage is it composed of?

A

the annulus fibrosis. it is composed of fibrocartilage

56
Q

what happens in the early stages of herniated disc development?

A

the proteoglycan content within the fibrocartilage matrix of the annulus fibrosis is decreased AND the collagen content of the nucleus pulposus increases which results in fibrosis and dehydration causing loss of shock absorbency.

57
Q

what happens in time to a herniated disc?

A
  1. collagen fiber bundles become disorganized in the fibrocartilage of the annulus fibrosis and fissures develop.
  2. the nucleus pulposus extrudes through these fissures in the annulus fibrosis and compresses the spinal cord.
58
Q

what should be done if the patient is unresponsive to conservative therapy?

A

laminectomy

59
Q

what is done in a laminectomy?

A

certain parts of the bony vertebra are removed to expose the spinal cord within the vertebral canal, followed by removal of the extruded nucleus pulposus

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