Lecture 7: Connective Tissue (Hayward)

Question 1

main type of connective tissue in the MS system*

Answer 1

dense connective tissue (esp. dense REGULAR CT)

Question 2

2 main classifications of connective tissue*

Answer 2

ordinary and specialized CT

Question 3

“ordinary” CT consists of what 2 types of CT?*

Answer 3

loose and dense CT

Question 4

“specialized” CT includes:*

Answer 4

cartilage and bone

Question 5

2 types of dense CT*

Answer 5

regular and irregular CT

Question 6

difference b/w loose and dense CT*

Answer 6

dense CT has larger # of fibers compared to # of cells

Question 7

characteristics of regular dense CT*

Answer 7

parallel bundles of fibers. Present in tendons, ligaments, and aponeurosis

Question 8

chars. of irregular dense CT*

Answer 8

Allow more stretch and distension than regular dense CT. Present in dermis, submucosa of digestive tract, and fascia.

Question 9

3 types of fibers secreted by fibroblasts*

Answer 9

collagen, elastic fibers, reticular fibers

Question 10

role of amorphous ground substance in connective tissue**

Answer 10

imparts “spongyness” and capacity of connective tissue to take on compressive forces. Its negative charge draws Na+ and subsequently H2O towards it, giving it a characteristic gel-like property. Common in loose connective tissue

Question 11

which are more active: fibroblasts or fibrocytes?*

Answer 11

fibroblasts; they are actively producing intercellular fibers

Question 12

role of reticular fibers*

Answer 12

act as supportive meshwork/anchoring system between collagen and adjacent cells in the lamina

Question 13

general role of tendons and ligaments*

Answer 13

absorb stretching forces

Question 14

why does collagen have a banded appearance at light microscopic lvl?*

Answer 14

due to interconnection of individual filaments

Question 15

type 1 collagen fibers are present in:*

Answer 15

tendons, ligaments, bone, and fibrocartilage,

Question 16

type 2 collagen fibers are present in what type of connective tissue?*

Answer 16

Hyaline and elastic cartilage. (i.e. intervertebral discs)

Question 17

type 3 collagen fibers are present in:*

Answer 17

loose connective tissues, reticular fibers, blood vessels

Question 18

what are reticular fibers composed of?*

Answer 18

type III collagen with polysaccharide coating in a basal lamina

Question 19

How are elastic fibers able to undergo expansion and recoil?*

Answer 19

They have strong interfiber crosslinking which is mediated by LYSYL OXIDASE. They also automatically recoil when they don’t have any stretch on them.

Question 20

what are elastic fibers composed of?*

Answer 20

elastin and fibrillin

Question 21

role of fibrillin in elastic fiber composition*

Answer 21

help mold elastin molecules into elastic fibers

Question 22

Marfan’s syndrome*

Answer 22

a deficiency or defect in fibrillin. Leads to underdevelopment of elastin. Patient is predisposed to aortic rupture and joint instability

Question 23

Composition of amorphous ground substance**

Answer 23

glycosaminoglycans and proteoglycan. Has high neg. charge which attracts Na+ and thus H2O into it. High negative charge of GAGs imparts compressive strength to connective tissue**

Question 24

what is basal lamina? What is it composed of?

Answer 24

interface between conncective tissue and adjacent layer. Composed of type 4 and 7 collagen, laminin (which binds cell membrane to collagen and proteoglycans of laminae), and fibronectin (which attaches cell to basal laminae)

Question 25

where are fibroblasts, chondroblasts, and osteoblasts found?

Answer 25

fibroblasts: ordinary connective tissue (i.e. fascia, ligaments, tendons)
chondroblasts: cartilage
osteoblasts: bone

Question 26

3 main components of extracellular matrix

Answer 26

extracellular fibers, ground substance, and tissue fluid

Question 27

2 principal classes of intercellular substances that constitute the extracellular matrix

Answer 27

intercellular fibers and amorphous ground substances

Question 28

3 main types of intercellular fibers

Answer 28

collagen fibers, reticular fibers, and elastic fibers

Question 29

steps of collagen formation*

Answer 29

1) alpha chains are made in rough ER and transported to Golgi where they are packaged into procollagen triple alpha helix structure
2) procollagen excreted into extracellular space
3) procollagen cleaved by extracellular pepsidases, which allows for inter-chain bonding b/w collagen fibers
4) fibers combine together to form a fibril, which band together into larger fibers

Question 30

what enzyme allows for cross linking between adjacent collagen molecules?*

Answer 30

lysyl oxidase

Question 31

periodicity of collagen fibers under electron microscope. What is it caused by?

Answer 31

67nm. Created by alternating pattern of gap regions and overlap regions of collagen molecules

Question 32

most common type of collagen

Answer 32

type I

Question 33

what do elastin polymers form in the absence of fibrillin?

Answer 33

lamina

Question 34

what surrounds all muscle fibers, Schwann cells, endothelial cells, and adipocytes?

Answer 34

external lamina

Question 35

laminin

Answer 35

adhesive glycoprotein that binds the cell membrane of type IV collagen and heparin sulfate proteoglycans of the laminae

Question 36

fibronectin

Answer 36

adhesive glycoprotein that attaches the cell to the laminae as well as reticular fibers that project into the lamina from the underlying connective tissue

Question 37

6 principal glycosaminoglycans of connective tissue

Answer 37

1) hyaluronic acid
2) chondroitin-4-sulfate
3) chondroitin-6-sulfate
4) dermatan sulfate
5) keratan sulfate
6) heparin sulfate

Question 38

how are proteoglycan aggregates formed?*

Answer 38

via the attachment of numerous proteoglycan molecules to hyaluronic acid via linking proteins