Connective tissue Flashcards

1
Q

What is connective tissue made of?

A

Cells and ECM

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2
Q

What compromises ECM?

A

Protein fibres (e.g. collagen, elastic and reticular)

Ground substance (e.g. proteoglycans, glycoproteins, GAGs)

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3
Q

What is connective tissue bounded by?

A

Basal laminae of epithelia and basal laminae of muscle cells

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4
Q

What does ground substance entail?

A

Proteoglycan, GAGs, polysaccharides

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5
Q

What is the role of ground substance?

A

Resistance to compression

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6
Q

What is the role of fibres of the ECM?

A

Tensile strength, support and anchorage

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7
Q

What are the fibres of ECM?

A

Collagen, fibrillin, elastin

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8
Q

What are the cells of the connective tissue?

A

Resident cells synthesise ECM (fibroblast), migratory cells (mast cell), macrophages

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9
Q

What is the role of ECM?

A

Surround and support cells within connective tissue

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10
Q

What feature of tissue does ECM determine?

A

Mechanical properties

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11
Q

What are 4 types of connective tissue?

A

Loose, dense connective tissue
Elastic tissue
Adipose tissue

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12
Q

What is loose connective tissue known as?

A

Areolar tissue

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13
Q

What are types of dense connective tissue?

A

Dense regular, dense irregular

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14
Q

What type of connective tissue is more common: loose or dense?

A

Loose

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15
Q

Where does loose connective tissue lie?

A

Beneath epithelia covering body surface and line internal surface of body

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16
Q

Describe structure of collagen in loose connective tissue?

A

Loose/dense

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17
Q

Describe loose connective tissue and its resistance to stress

A

Delicate, flexible and well vascularsed, not resistant to stress.

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18
Q

What type of connective tissue is found deeper, dense or loose?

A

Loose found below dense tissue

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19
Q

Compare ground substance in loose and dense CT?

A

Less in dense CT

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20
Q

Which type of CT has more cell types, loose or dense?

A

Dense

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21
Q

Describe collagen arrangement in dense CT. What impact does this have on property?

A

Densely packed - less flexible and resistant to stress

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22
Q

Where is dense irregular CT found?

A

Dermis, anchoring epithelium

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23
Q

Describe structure of dense irregular connective tissue?

A

Collagen fibres packed densely, no orientation

Fibroblast arranged in rows between collagen fibre bundles

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24
Q

Describe dense regular connective tissue?

A

Collagen fibres aligned parallel manner, fibroblasts between bundles.

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25
Q

Compare resistance to stress of dense regular and irregular connective tissue

A

Dense irregular; resistant in all directions

Dense regular: resistance against forces pulling in a straight line

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26
Q

Where is dense regular connective tissue found?

A

Tendon, ligament, apopneuroses

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27
Q

What do tendons do?

A

Connect muscle to bone

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28
Q

Structure of tendons, how does this link to resistance against stress?

A

Parallel bundles of collagen fibres, provide resistance to tensile stress and proteoglycans allow resistance to compressive stress

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29
Q

In and H and E stain, what do H and E bind and what’s the colour change?

A

Hematocylin - -ve charged DNA and RNA (acidic) - blue

Eosin - +ve charged proteins (basic) - red/pink

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30
Q

What do ligmaents do?

A

Join bone to bone

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31
Q

Compare structure of ligaments and tendons?

A

Fibres arranged less regularly in tendons

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32
Q

Structure of ligaments?

A

Fibres and fibroblasts arranged in parallel

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33
Q

What do aponeuroses do?

A

Resemble flattened tendons (attach sheet like muscle)

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34
Q

Describe structure of aponeuroses?

A

Collagen fibres in neighbouring layers arranged at right angle (regularly)

35
Q

What does fascia do?

A

Separate muscles and internal organs

36
Q

What is structure of fascia?

A

Packed bundles of collagen fibres arranged in wavy pattern parallel to direction of pull.

37
Q

What produces collagen fibres?

A

Fibroblasts

38
Q

What is the consequence of wavy collagen fibre arrangement in fascia?

A

Resist great unidirectional tension forces

39
Q

What are the types of connective tissue fibre?

A

Collagen
Elastic
Reticular fibres

40
Q

Describe collagen, properties?

A

Thick, strong unbranched

provides great tensile strength

41
Q

What is collagen formed form?

A

Tropocollagen

42
Q

Describe structure and property of elastic fibres?

A

Small, thin, branching, low tensile strength compared to collagen

Random coiled structure, can stretch/recoil

43
Q

What are reticular fibres composed of?

A

Type 3 collagen

44
Q

What are reticular fibres for?

A

Form network in haematopoietic organs

e.g. spleen, liver, lymph nodes - filter blood and provide support for capillaries, muscles and nerve cells

45
Q

When are reticular fibres visible

A

When stained with silver

46
Q

What causes osteogenesis imperfecta?

A

Decrease in type 1 collagen as short alpha 1 chains, no stable triple helix

OR

Substitution of glycine residue blocks stable helix forming

47
Q

Symptoms of osteogenesis imperfecta?

A

Brittle bones, repeated fractures, bone deformities

48
Q

What causes Marfan’s syndrome?

A

Reduced fibrillin (needed for elastic fibres) or extra amino acids near C terminal of alpha 2 chain so compromises cross linking

49
Q

Symptoms of Marfan’s syndrome?

A

Loss of integrity of elastic fibres so aorta rupture,long + slender limbs/digits

50
Q

What causes Ehlers Danlos syndrome?

A

Fewer Hydroxylysinse residues so less cross linking

OR

Failure to process precollagen into tropocollagen

51
Q

Symptoms of Ehlers Danlos?

A

Hyperextensible skin, recurrent joint dislocation

52
Q

What happens to ground substance in bone and cartilage?

A

Mineralised by deposition of calcium containing crystals leading to increase in strength

53
Q

What are GAG?

A

Long unbranched, polysaccharaide chains (anionic) - attract Na+ which draws water - swelling and resist compression

54
Q

How are proteoglycans formed?

A

GAGs covalently linked to proteins

55
Q

What does cartilage consist of?

A

Proteoglycans and collagen

56
Q

What is the property of GAGs where is this important?

A

Attract water so help resist compresion - joints

57
Q

What is most abundant cell type in connective tissue?

A

Fibroblasts

58
Q

What do fibroblasts do?

A

Synthesise ECM (make collagen fibres, elastin and macromolecules e.g. GAGs, proteoglycans)

59
Q

What do adipose cells do in connective tissue?

A

Store triglycerides in connective tissue

Provide cushioning

Provide thermal insulation

60
Q

How do adipose cells appear histologically, why?

A

Cells appear empty because fat dissolved during staining slides

Nuclei at periphery of cell with small bit of cytoplasm on side

61
Q

What do macrophages do in connective tissue?

A

Phagocytosis and degrade ECM

Initiate inflammatory response to recruit WBC

62
Q

What are mast cells often associated with?

A

Blood vessels

63
Q

How do mast cells stain, why?

A

Dark, contain lots of secretory granules filled with bioactive molecules e.g. histamine

64
Q

What triggers activation of mast cells (which antibody)?

A

IgE receptors on surface which antigen binds to

65
Q

What do mast cells do?

A

Phagocytose bacteria, release histamine causing vasodilation and increased capillary permeability (so neutrophils can enter connective tissue and clear out pathogen)

66
Q

Differentiate between white and brown adipose tissue?

A

White: single large droplet of triglycerides, little cytoplasm, energy storage + insulation

Brown: more cytoplasm, more mitochondria, many small fat droplets, SNS innervation, heat generation

67
Q

What does cartilage do/where’s it found?

A

Cover and protect articulating surfaces of bone and forms septum of nose, external ear and embryological skeleton

68
Q

What is property of cartilage?

A

Bear Mechanical stress + shock absorber

69
Q

What makes/maintains ECM of cartilage?

A

Chondrocytes and chondroblasts

70
Q

What are chondroblasts?

A

Mesenchymal progenitor (more differentiated than stem cell) that synthesise ECM of cartilage

71
Q

When does chondroblast become chondrocyte?

A

In cartilage matrix are lacunae, when chondroblasts become surrounded by cartilage in lacunae - chondrocyte.

72
Q

Describe blood supply and thus nutrient supply for cartilage?

A

Avascular tissue, surrounded by vascular connective tissue so receives nutrients/transfers waste through diffusion

73
Q

Structure of fibrocartilage?

A

Irregular dense collagen fibres

74
Q

Where is fibrocartilage found?

A

Pubic symphysis, intrarticular disc at synovial joint, IV disc, annulus fibrosis

75
Q

What does hyaline cartilage do?

A

Low friction articular surface in synovial joint so friction free movement

76
Q

What is most common sort of cartilage

A

Hyaline

77
Q

What is hyaline cartilage made of?

A

Type 2 collagen and large aggregating proteoglycans

78
Q

What is role of hyaline cartilage in development?

A

Forms basic structure of bone which undergoes endochondral ossification in embryo to form bony skeleton

79
Q

What structures are made of hyaline cartilage in adult?

A

Nose, larynx, ribs, trachea, bronchi and articular surfaces of bone

80
Q

Describe structure of elastic cartilage?

A

Elastic fibres in its matrix

81
Q

Describe property of elastic cartilage?

A

Flexible

82
Q

Where is elastic cartilage found?

A

Auditory canal, parts of ear, vocal cords, larynx.

83
Q

Forms a delicate fibre meshwork holding tissue elements together…

A

Reticulin