2-ECM Flashcards

1
Q

what is the function of the ECM?

A

-structural
-signaling
-mechanical support
-scaffold
-regulation

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2
Q

what is one of the most defining features of the animal body

A

ECM

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3
Q

how does ECM function in structural support

A

-contains BM and interstitial matrix
-differs in strength and texture due to molecules in ECM and how they are arranged

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4
Q

how does ECM work in scaffolding?

A

-provides tissues with shape and provides scaffold to regenerate tissue

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5
Q

how does ecm work in cell signaling

A

-allows cell to know where it is and what it is
-transmits mechanical signals to cells that can alter their behavior

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6
Q

how does ecm work in regulation of growth factors?

A

-growth factors that are released from cells bind the ecm and are stored there until they are released in response to mechanical stress

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7
Q

what can activate/destroy growth factors in ecm

A

proteases

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8
Q

what relationship do cells and ecm have?

A

bidirectional

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9
Q

how do cells and ECM have a bidirectional relationship?

A

-ECM is synthesized and organized by the cells within it
-ECM then signals back to the cell

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10
Q

what cells make ECM

A

-fibroblasts, chondroblasts, osteoblasts, any cell can make ECM

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11
Q

what is the basement membrane?

A

specialized form of ECM that underlie virtually all epithelia

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12
Q

3 main classes of molecules in ECM

A

1.fibrous proteins
2. glycoaminoglycan polysaccharide chains
3. multidomain glycoproteins

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13
Q

2 types of fibrous proteins

A

collagen and elastin

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14
Q

what is the function of collagen

A

confer tensile strength

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15
Q

collagen _____ and ____ affects tissue structure

A

composition and arrangement

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16
Q

structure of collagens:

A

-triple helix composed of 3 alpha chains that wind around each other in rope-like structure
-rich in glycine and proline

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17
Q

small size of glycine allows for ______

A

tight packing of helices

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18
Q

ring structure of proline ______

A

stabilizes the helix

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19
Q

to assemble into functional collagen molecules , the alpha chains undergo _______

A

post-translational modifications

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20
Q

how are collagens assembled

A

into fibrils and then fibers

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21
Q

prolines and lysines undergo what?

A

hydroxylation

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22
Q

what does hydroxylation of prolines and lysines allow for?

A

intra and inter molecular cross linkage

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23
Q

individual alpha chains self assemble in ER which forms

A

procollagen

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24
Q

fibrils are strengthened by:

A

formation of cross links between lysine residues

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25
Q

what are 2 major types of collagen ?

A

fibrillar
network forming

26
Q

what is fibrillar collagen

A

long, rope-like fibrils
type 1, 2, 3, 5, 11 collagen
-bone, skin, tendons, cartilage

27
Q

what is network forming collagen?

A

-forms basement membranes
-anchors basement membrane to underlying tissue
-type 4 collagen

28
Q

how does collagen play a role in wound healing

A

-fibrillar collagens form a major portion of the connective tissue at repair sites

29
Q

________ collagen synthesis interferes with wound healing

A

impaired

30
Q

what is fibrosis

A

excessive collagen deposition

31
Q

what is the function of elastic fibers

A

allow tissues to stretch and recoil

32
Q

what are elastic fibers composed of

A

-elastin molecules covered with a sheath of glycoprotein microfibrils
-elastin has alternating hydrophobic and alpha helical segments
-hydrophobic regions confer elastic properties
-helical segments cross link

33
Q

glycosaminoglycan polysaccharide chains form what?

A

hydrated gels (ground substance)

34
Q

what are GAGs

A

-unbranched polysaccharide chains that are negatively charged

35
Q

what is the purpose of negatively charged on GAGs

A

hydrophilic, and allows them to stay in chains

36
Q

GAGs occupy a huge ______ relative to ______

A

volume
molecular weight

37
Q

____ is a major polysaccharide component of ECM

A

hylauronic acid

38
Q

HA is the simplest of ______

A

glycosaminoglycans

39
Q

HA function

A

joints

40
Q

what are proteoglycans?

A

long, unbranched GAG chains covalently linked to a core protein

41
Q

role of proteoglycans?

A

signaling roles

42
Q

examples of multidomain glycoproteins

A

-fibronectin
-laminin

43
Q

what are multidomain glycoproteins

A

glycoproteins with multiple domains that serve as binding sites for matrix proteins and for surface receptors
located in ECM

44
Q

________ is the most abundant ECM adhesive protein

A

fibronectin

45
Q

what does the ECM consist of

A

-fibrous proteins and multi-adhesive glycoproteins embedded in ground substance

46
Q

what is ground substance formed by?

A

glycoaminoglycans

47
Q

what is the main producer of the ECM constituents?

A

fibroblasts

48
Q

collagen synthesis:

A
  1. alpha chains are synthesized in a long precursor form with propeptides at the N and C terminus
  2. propeptides prevent triple helixes from associating with each other
  3. lysine and proline residues are hydroxylated
  4. select hydroxyprolines are glycosylated
  5. 3 pro alpha chains self assemble to form a procollagen triple helix
  6. procollagen molecules secreted
  7. cleavage of N and C propeptides allows for self-assembly of triple helices into fibrils
  8. fibrils assemble into fibers
49
Q

hydroxylation of lysine and proline residues allows for ____

A

formation of crosslinks between different alpha chains

50
Q

what do crosslinks do?

A

strengthen the collagen fibrils and fibers

51
Q

The enzyme required for proline hydroxylation requires ______ as a cofactor

A

vit. C

52
Q

collagen type 1 found in :

A

bones/skin

53
Q

collagen type 2 found in:

A

cartilage

54
Q

structure of fibril associated collagens

A

triple stranded helices are interrupted by non helical domains that allow flexibility.
-pro-peptides are not cleaved

55
Q

type 4 collagen is the major collagen of :

A

basement membranes

56
Q

which type of collagen is the most flexible structure

A

network forming collagen

57
Q

how does type 4 collagen interact

A

via uncleaved terminal domains to assemble into a flexible network

58
Q

what does anchoring collagens do?

A

anchor basement membranes to CT

59
Q

how is elastin arragned

A

fibers or discontiuous sheets

60
Q

the elastin protein is composed of :

A

alternating segments of hydrophobic and alpha helical regions

61
Q

elastic fibers are interwoven with _____

A

inelastic collagen fibrils

62
Q

process of elastic fiber formation

A

elastogenesis