Connective Tissue Flashcards Preview

Histology Exam 2 > Connective Tissue > Flashcards

Flashcards in Connective Tissue Deck (109):
0

What are the four functions of CT?

Structural support, medium for exchange, aid in defense and protection of the body, and site of fat storage.

1

T or F: Leukocytes from the blood become active once in the CT

T

2

Embryonic CT is composed of what?

Mesenchyme (mostly fibroblasts, source of progenitor cells), mucous CT which sits below the surface of skin and helps in cell development. Wharton's Jelly, a very watery fluid in the umbilical cord

3

What is CT mesenchyme?

Mostly fibroblasts and the source of CT progenitor cells

4

What are the five types of CT proper?

Loose (areolar), Dense irregular, Dense regular, Reticular, and Adipose

5

How is CT proper type defined?

The density of connective tissue fibers

6

What are specialized CT?

Cartilage, bone, blood (hemopoietic and lymphatic tissue)

7

Where is dense irregular CT found?

Dermis of skin, sheaths of nerve, capsules of spleen, kidney, lymph nodes, testes, and ovaries

8

Where is dense regular CT found?

Tendons and ligaments

9

Where is loose irregular CT found?

Fills spaces just deep to skin, mesothelial lining of body cavity, blood vessels adventitia, surrounds parenchyma of glands, lamina propria of GI tract

10

What are the two general components of CT organization?

ECM and cells

11

What composes the ECM of CT?

Ground substance (no stain) and fibers (synthesized by fibroblasts)

12

What are the two types of CT cells?

Fixed/Resident (fibroblasts and adipocytes) and Transient/wandering (Macrophages of plasma cells that come from elsewhere e.g. blood)

13

What are the three major components of the ground substance?

Glycosaminoglycans, Proteoglycans, Glycoproteins

14

T or F: The fibers in the ground substance are visible in LM

F

15

What are GAGs?

Polysaccharides of repeating disaccharide subunits

16

What type of GAGs are in the CT ground substance?

Sulfated...e.g. keratin, chondroitin, and dermatan sulfate and unsulfated...e.g. hyaluronic acid

17

What is the function of GAGs in the CT ground substance?

Attracts water and resists compression (attracts water via its negative charge by attracting sodium)

18

What is the function of hyaluronic acid in the ground substance of CT?

Long chain, very large to make backbones for proteoglycan attachement, non-sulfated

19

What are proteoglycans?

Protein core with covalently bound sulfated GAGs

20

What is the function of PG in the CT ground substance?

Important for binding and activation of growth factors

21

What type of glycoproteins are in the ground substance of CT?

Fibronectin, laminin, and entactin

22

What is the function of glycoprotein in the ground substance of CT?

Contains domains for the components of ECM and integrins to bind, important for transport

23

What are the three types of CT fibers?

Collagen, reticular, elastic

24

T or F: Collagen fibers are visible in LM

T

25

What are the characteristics/function of collagen fiber in CT?

Major fibrous protein of CT and is flexible with extremely high tensile strength

26

What is the approximate size of collagen fibers?

Less than 10 microns in diameter with wavy structure that stains pink in H&E

27

Describe the structure of collagen fibers

Formed by an assembly of tropocollagen molecules. Each tropocollagen molecule is made up of a triple helix of 3 alpha-chains (alpha-chain subunits give the collagen its characteristics)

28

T or F: Every third AA in tropocollagen is glycine

T

29

What are the major AA of tropocollagen?

Proline, hydroxyproline, hydroxylysine, and glycine

30

What gives collagen its banding pattern?

Gap regions due to periodic gaps of the tropocollagen which lead to light (less dense) and dark bands

31

General CT, tendon, bone, ligament, and capsules or organs is covered by what type of collagen?

Type I

32

Morphology of Type I collagen

Large banded collagen fiber

33

What is the function of Type I collagen?

Resists tension (very strong)

34

What is Type II collagen?

Small banded collagen fiber that makes up hyaline and elastic cartilage and is in the vitreous of the eye

35

What is the function of Type II collagen?

Resists pressure

36

What is Type III collagen?

Small banded collagen fiber that makes up lymphoid tissue, bone marrow, spleen, liver, lung, cardiovascular system, and skin

37

What is the function of Type III collagen?

Forms a structural framework

38

What is Type IV collagen?

Sheet-like layers that make up the basement membrane and basal lamina

39

What is the function of Type IV collagen?

Forms meshwork of lamina densa and provides support and filtration function

40

What is Type V collagen?

Thin fibrils that make up the dermis, tendon, bone ligament, capsules of oran, and placenta

41

What is the function of Type V collagen?

Associates with Type I collagen, placental ground substance

42

What is Type VII collagen?

Thin fibrils that serve as the junction between the epidermis and dermis

43

What is the function of Type VII collagen?

Anchors fibrils in the basement membrane

44

Where is collagen synthesized?

Fibroblast

45

Follow the production of collagen

Transcription in nucleus, translation of preprocollagen in RER with the alpha chains having propeptides at amino and carboxy terminal ends, Hydroxylation in RER, Glycosylation in RER, Formation of procollagen triple helix in RER (spontaneous),
secretion of procollagen via trans Golgi network, Cleavage of propeptides by procollagen peptidase to form tropocollagen molecule. Spontaous self assembly of tropocollagen to form collagen fibril

46

What prevents collagen from forming inside fibroblasts?

Propeptides on the preprocollagen

47

Where are propeptides located on preprocollagen?

Carboxy and amino terminals

48

Where is the procollagen triple helix formed?

RER

49

What secretes procollagen?

Trans golgi network

50

Where does cleavage of procollagen to tropocollagen take place?

ECM

51

T or F: Collagen fibril assemble requires energy

F (spontaneous)

52

T or F: Procollagen triple helix forms spontanously in the RER

T

53

What color does collagen stain in an H&E?

Pink due to high affinity for eosin

54

What type of CT is located at myotendinous junctions?

Dense regular CT

55

What composes Reticular fibers?

Type III collagen

56

What is the structure of reticular fiber?

Thin (0.5 micron to 2 micron), branched

57

What stains reticular fibers?

H&E is poor, usually use silver and PAS stains

58

Reticular fibers are often prevalent in what tissue?

Lymphatic, hematopoietic, spleen, liver, and other glands

59

Elastic fibers in skin have what function?

Allow for resilience

60

T or F: Elastic fibers stain in H&E

F, require their own stain

61

Describe the structure of elastic fibers

Flexible elastin core with fibrillin skeleton. Elastin is deposited on the fibrillin core

62

What are two locations elastin is often found?

Ligaments and walls of arteries

63

What is scurvy?

Vitamin C deficiency leading to lack of proline hydroxylase leading to weak and unstable tropocollagen/collagen.

64

What is Ehlers-Danlos syndrome?

Mutation in collagen gene or enzyme related to collagen metabolism (general disease type). The gut is often ruptured in this syndrome

65

What is Marfan's syndrome??

Defect in fibrillin gene which can lead to rupturing of the gut or issue with artery walls. Can get aortic rupture.

66

Name five fixed resident cells in CT

Fibroblasts, pericytes, adipocyte, mast cell, histiocyte (macrophage)

67

Name 4 transient cells in the CT

Macrophage, monocyte, lymphocyte, granulocytes (neutrophils, eosinophils, basophils)

68

What is the principal cell of CT?

Fibroblasts

69

What are the two subtypes of fibroblasts in the CT?

Myofibroblasts and pericytes

70

What are myofibroblasts?

Resemble smooth muscle cells and play a role in wound closure and healing. Have very dense nuclei (not active)

71

What are pericytes?

Undifferentiated mesenchymal cells associated with capillaries and small venules. Left over mesenchymal cells that can be stimulated to make new fibroblasts or adipocytes. These cells are transcriptionally active (can see some euchromatin)

72

What are the two types of adipocytes?

Unilocular and Multilocular

73

What are unilocular adipocytes?

Single lipid droplet. White/yellow fat. Serve to store lipids

74

What are multilocular adipocytes?

Brown fat. Found in infants and newborns. Thermogenic. Multiple lipid droplets

75

Unilocular adipocytes store lipids as...?

TAGs that are synthesized in the adipocyte or synthesized in the liver and imported as VLDL

76

What happens in unilocular adipocytes upon mobilization of lipids by hormonal of neurogenic control?

TAGs broken down to FA and glycerol

77

T or F: Adipocytes produce leptin

T

78

What is leptin?

Produced by adipocytes to decrease food intake and increase metabolism

79

What percentage of newborn body weight is multilocular adipocyte?

2-5%

80

Why is multilocular adipocyte brown?

Due to high amoud of cytochrome present in mitochondria

81

How is heat generated in multilocular adipocyte?

Mitochondria contain thermogenin which allows flow of H back into MM from IM without producing ATP

82

T or F: Multilocular adipocytes are located in a rich capillary bed

T

83

How is heat production controlled in multilocular adipocytes?

Sympathetic innervation

84

What are the two types of obesity?

Hypertrophic (adult onset increase in cell size, liposuction!) and Hypercellular (childhood onset increase in cell number, harder to deal with because cells tend to retain ability to replicate)

85

What are histiocytes/macrophages?

Principal phagocytic cells of CT

86

Where do histiocytes come from?

Originate in bone marrow as monocytes. Part of the mononuclear phagocyte system (MPS)

87

T or F: Histiocytes can fuse to form foreign body giant cells

T (often multinucleate)

88

Where are histiocytes located?

CT

89

Where are Kupffer cells located?

Liver

90

Where are alveolar macrophages found?

Lung

91

Where are macrophages found?

Bone marrow, lymph node, spleen, and thymus

92

Where are pleural ad peritoneal macrophages found?

Serous cavities

93

Where are osteoclasts found?

Bone

94

Where are microglia found?

CNS

95

Where are langerhan's cells found

Epidermis

96

T or F: Plasma cells are transient

T

97

Where do plasma cells originate from?

B lymphocytes (become plasma cells upon interaction with antigen)

98

What is characteristic of plasma cells?

Cartwheel nucleus and basophilic cytoplasm

99

Where are plasma cells abundant? What is their function?

Sites of chronic inflammation and synthesize and secrete immunoglobulins.

100

Why is the cytoplasm of the plasma cell basophilic?

Huge Golgi apparatus

101

What are mast cells?

20-30 micron diameter cells that mediate inflammatory response

102

Where do mast cells originate from?

Bone marrow

103

What are the characteristics of mast cells?

Basophilic granules with primary mediators of inflammation (heparin, histamine, eosinophil, and neutrophil chemotactic factors).
Synthesize and secrete secondary mediators (leukotrienes, thromboxanes, and prostaglandins to cause contraction)

104

What is a hypersensitivity reaction facilitated by mast cells?

Anaphylactic shock

105

Generally describe mast cell activation

Binding of antigen, cAMP cascade leading to release of calcium to trigger release of primary mediators (histamine and heparin among others). Phospholipases are also activated to release secondary mediators like prostaglandins

106

What is the function of neutrophils?

Phagocytic and digest bacteria

107

What is the function of eosinophils?

Attack parasites

108

What is the function of basophil?

Inflammatory response