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MCT Exam 3 > Cartilage > Flashcards

Cartilage Flashcards

1
Q

Only cell type found in cartilage

A

Chondrocytes

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2
Q

Collagen type II and proteoglycans make up the __________ of cartilage

A

Matrix

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3
Q

~75% total weight of cartilage

A

Water

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4
Q

Does cartilage tissue contain blood vessels?

A

No

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5
Q

Does cartilage tissue contain blood or immune cells?

A

No

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6
Q

How do chondrocytes attain nutrients?

A

Diffusion from blood vessels outside the perichondrium

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7
Q

A dense CT layer surrounding hyaline cartilage

A

Perichondrium

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8
Q

Two layers of the perichondrium

A
  1. outer, dense CT, collagen I

b. inner chondrogenic layer, fibroblasts differentiate to chondrocytes

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9
Q

Mechanism for cartilage growth were new matrix is laid down on the cartilage surface by cells in the inner layer of the perichondrium.

A

Appositional growth

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10
Q

Mechanism for cartilage growth where chondrocytes in the interior divide and secrete matrix between them. Cartilage swells from within, like bread rising.

A

Interstitial growth

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11
Q

Actively secreting new matrix even in mature cartilage
Abundant RER - mostly secretes proteoglycans (and some cartilage type II)
Found in lacuna

A

Chondrocyte

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12
Q

What features can help tell you that you are looking outside of the cartilage and perichondrium?

A

Glands and blood vessels

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13
Q

Why are proteoglycans in the collagen matrix darkly staining?

A

They have a negative charge

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14
Q

Due to the increased concentration of proteoglycans, the territorial matrix of hyaline cartilage stains ______

A

Darkly

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15
Q

________ cartilage provides mechanical support, to keep the airway open

A

Tracheal

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16
Q

What is the function of cartilage in the ear?

A

Keeps the ear semi-rigid

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17
Q

___________ cartilage is the most important and is found in joints

A

Articular

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18
Q

Articular cartilage is important for two major things:

A
  1. Friction free movement at joint

2. Mechanical cushion at joint

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19
Q

Covers the bone surfaces where they “articulate” at a joint

Forms a slippery, friction-free surface
No perichondrium, cartilage matrix slides against cartilage matrix

Provides a shock absorbing cushion. The cartilage supports the full weight, same as the bone, but it is compressible (a lot of water - when compressed the matrix squeezes out water, when relaxed the water is sucked in)

A

Articular cartilage

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20
Q

Articular cartilage acts as a mechanical cushion - like an inner-spring mattress where:
____________ are the springs, and ____________ (2 things) make the framework

A

Proteoglycans are the springs

Collagen Type II and hyaluronic acid make the framework

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21
Q

A protein with one or more carbohydrate clusters covalently attached to asparagine and/or ser/thr residues.
Accounts for most extracellular proteins
Can be 1-60% carbohydrate by weight

A

Glycoprotein

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22
Q

A dozen or more sugar molecules attached to each other in a branched cluster

A

Carbohydrate cluster

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23
Q

Long (50-100 sugars), unbranched chain of repeating disaccharides
Many of the sugars have COO- and OSO2- groups, making an overall negative charge throughout
Almost all are attached to a protein

A

Glycosaminoglycan (GAG)

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24
Q

Hyaluronic acid and heparin are unusual in that they exist as free _________ not covalently attached to a core protein.

A

GAGs

25
Q

Most ________ are attached to a core protein to make a proteoglycan

A

GAGs

26
Q

Chondroitin sulfate and keratan sulfate are examples of _________

A

GAGs

27
Q

A protein with carbohydrate clusters

A

Glycoprotein

28
Q

A protein with GAGs attached and consists of a core protein (extended polypeptide) with several or many GAGs attached
Ex. Syndical, a cell surface receptor with 3-6 GAGs only (90% protein)

Negatively charged chains
Assistants for binding growth factors

A

Proteoglycan

29
Q

Large aggregating proteoglycan of cartilage

A

Aggrecan

30
Q

_____________ charged GAGs repel each other, both intra and inter molecularly. Pressure can compress the GAGs, squeezing out water.

A

Negatively

31
Q

_____________ molecules are already highly compressed in articular cartilage, to 1/3 their relaxed volume. Additional pressure on the joint causes a further compression, squeezes water into the joint capsule. When the pressure is releases, the proteoglycans expand and take back the water.

A

Aggrecan

32
Q

What is the basic structure of aggrecan?

A

Core protein, with protruding chondroitin sulfate chains and keratan sulfate chains, O-,N-lnked oligosaccharides, and a hyaluronic acid binding domain
300 nm long, but 700 nm if fully extended

33
Q

Cartilage matrix is pre-stressed. Aggrecan molecules are compressed and packed ____ their relaxed density in solution. This makes the articular cartilage very hard.

A

3X

34
Q

The two components of the framework that keeps aggrecans from flying apart:

A
  1. Attachement to hyaluronan

2. Collagen II network, entrapment

35
Q

How is hyaluronic acid (hyaluronan) a unique GAG?

A
  1. Not attached to a core protein (almost all are expect heparin and hyaluronic acid)
  2. COO- but no SO4- (less charged)
    c. Huge (25,000 sugars, 10,000,000 Da, 40 microns long)
36
Q

______________ is a major component of “ground substance” of loose CT. Makes a viscous hydrated gel and plays a key role in cartilage architecture. Traps proteoglycans through their binding domain. Long chain of repeating disaccharides that is 100x longer than collagen.

A

Hyaluronic acid

37
Q

A random 3D network of __________ fibrils entraps proteoglycan aggregates and prevents the loss of aggrecan.

A

collagen type II

38
Q

HA binding domain attaches aggrecans to a long hyaluronic acid molecule. This makes the:

A

proteoglycan aggregate

39
Q

___________ fibrils makes a 3D network. The proteoglycan aggregate is entrapped by snaking through the collagen network.

A

Collagen II

40
Q

Some loss of proteoglycans does occur. ______________ need to continuously synthesize new ones.

A

Chondrocytes

41
Q

Glassy
Found in trachea, bone primordia and growth plate
Articular cartilage
Most common type of cartilage

A

Hyalin cartilage

42
Q

Like hyaline, but includes elastic fibers

Found in the ear

A

Elastic cartilage

43
Q

A mixture of dense CT (collagen I) and small islands of chondrocytes surrounded by cartilage matrix
In tendons and ligaments, especially where subject to compression, and intervertebral disks

A

Fibrocartilage

44
Q

______________ makes tendons compressible

A

Fibrocartilage

45
Q

_______________ of the joint capsule secretes fluid into the joint cavity

A

Synovial membrane

46
Q

Torn tendons are readily repaired. If ends are reasonably juxtaposed, ____________ make new collagen fibrils, join them to the existing fibers. Remodeling molds tendon to match the forces it sees.

A

fibroblasts

47
Q

_______________ repairs only poorly. A fracture here may be filled in with fibrocartilage, but the friction-free movement is compromised.

A

Articular cartilage

48
Q

Broken bones repair if the ends are:

A

set in contact

49
Q

____-negataive neuroectoderm cells have enhanced regenerative capacity.

A

Hox

50
Q

Neural crest-derived cells may be able to be used for _____________ repair.

A

articular cartilage

51
Q

Inflammatory disease, focused on the joints
Activated macrophages and lymphocytes secrete proteases that attack the cartilage matrix
Systemic autoimmune disorder, principally affecting synovial joints

A

Rheumatoid arthritis

52
Q

Cytokine, originally discovered as a factor secreted by lymphocytes that kill tumor cells
When released in quantity, it causes cachexia
When released focally in RA joint, it induces other inflammatory cytokines - leads to erosion of articular cartilage and the underlying bone

A

TNF alpha

Tumor necrosis factor alpha, cachexin, cachectin

53
Q

TNF alpha released by ______________ is a key link to RA. TNFa is released with histamine and heparin and other cytokines.

A

mast cells

54
Q

Treatments for RA

A

Small molecule inhibitors of immune and inflammation: methotrexate (MTX)
Anti-inflammatory agents and analgesics: glucocorticoids, NSAIDS
Biologics

55
Q

Generally a protein with therapeutic properties
Made is bacteria or mammalian cell culture, purified and tested
(mAb or recombinant proteins)

A

Biologic
(biopharmaceutical)

Biosimilar = generic

56
Q

Two biologic treatments for RA

A
  1. mAB against TNF alpha: humira (adalimumab) - #1 selling drug in the world
  2. Recombinant protein, produced in bacteria or cultured cells: enbrel (entanercept), a decoy TNFalpha receptor that binds and sequesters TNFa
57
Q

A complex set of diseases, involving:
a. wear and tear degradation of articular cartilage
b. genetic factors
c. accompanied by inflammation, milder than in RA but similar in many respects (modern treatment bridges the two)
More common than RA

A

Osteoarthritis

58
Q

Treatments for osteoarthritis

A

Pain killers, corticosteroids, and/or anti-inflammatories injected into the joints
Eventually joint replacement
Treatments more limited than for RA

MCT Exam 3 (9 decks)

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