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Oral biology > D1 :Collagen lecture > Flashcards

D1 :Collagen lecture Flashcards

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1
Q

what is the definition of connective tissue?

A

defined as any supporting tissue that lies between other tissues and consists of cells embedded in a relatively large amount of extracellular matrix. Includes, bone cartilage and loose connective tissue

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2
Q

where does connective tissue come from?

A
  • Mesodermal origin (can be ectomesenchyme-only for head and neck)
  • loosely packed
  • unspecialized cells
  • gelatinous ground substance
  • from which connective tissue, bone cartilage and the circulatory and lymphatic systems develop
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3
Q

what is connective tissue?

A
  • Few cells within it, mainly fibroblasts
  • Made up of an extracellular matrix
  • Fibrous polymers mainly collagens
  • Framework of vertebrate body
  • Major component cartilage and bone
  • Minor component brain and spinal cord
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4
Q

what cells are found in connective tissue?

A

cells of mesenchyme

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5
Q

what is the definition of fibroblast?

A

A common cell type found in connective tissue. Fibroblasts secrete an extracellular matrix rich in collagen and other extracellular matrix macromolecules. Migrates and proliferates readily in wounded tissue and in tissue culture

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6
Q

what is the structure of fibroblasts?

A
  • Microtubules
  • Filaments
  • Junctions
  • Heterogeneity
  • Ageing
  • Contraction and Motility
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7
Q

Name some fibroblasts.

A

actin, tubules and the intermediate filament (vimentin)

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8
Q

Describe fibroblast heterogeneity.

A
  • Cell size
  • Cell Shape
  • Proliferative activity
  • Motility and attachment
  • Collagen and Extracellular Matrix proteins
  • Actin Isoforms
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9
Q

why might fibroblasts be termed as stem cells?

A

differentiate into :

  • bone cell (osteoblast/osteocyte)
  • fat cell (adipocyte)
  • cartilage cell (chondrocyte)
  • smooth muscle cell
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10
Q

what are the fibres around a fibroblast called?

A

cologen

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11
Q

what is the definition of extracellular matrix?

A

defined as- a complex network of polysaccharides (such as glycosaminoglycans or cellulose) and proteins (such as collagen) secreted by cells. Serves as a structural element in the tissues and also influences their development and physiology

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12
Q

what is extracellular matrix function?

A 
• Support for cells.
• Pattern of ECM regulates 
a) Polarity
b) Cell division,
c) adhesion
d) motility.
• Development 
a) migration
b) differentiation.
• Growth Factors
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13
Q

Name some different shapes and sizes of ECM molecules.

A
  • fibronectin
  • fibrillar collagen
  • laminin
  • tenascin
  • hyaluronan
  • decorin
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14
Q

what makes up extracellular matrix?

A
  • Not solely made up of cells
  • Intricate network of macromolecules
  • Secreted by cells locally
  • Assembled and organised into meshwork by cells producing them
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15
Q

what do varieties of extracellular matrix form?

A

bone, teeth, cornea and tendons

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16
Q

what is the extracellular matrix not and why?

A

-Not inert scaffold
• Active and complex role in regulating cell behaviour
• Influences: Cell survival, development, migration, proliferation, shape and function

17
Q

what is the connective tissue of oral tissues?

A
  • Mainly extracellular matrix
  • Matrix made up of proteins,
  • proteoglycans,glycoproteins and GAGs
  • Main protein: collagens
  • Main proteoglycans: decorin,
  • fibromodulin and lumican, CD44
  • Main GAG: hyaluronan
  • Main cell: fibroblast
18
Q

what are glycoaminoglycans (GAGs)?

A 
• Repeating disaccharide chains
• Amino sugar (N-acetylglucosamine or N-
acetylgalactosamine
• Uronic acid (glucuronic or iduronic)
• Highly negatively charged- sulphate or carboxyl
19
Q

what is hyaluronan (HA)?

A

non-sulphated glycosaminoglycan (main one in oral cavity)

20
Q

what is the structure of hyaluronan?

A
  • Disaccharide repeating units of N- acetylglucosamine linked with glucuronic acid.
  • Molecular weight 20000Da and 2000000Da
21
Q

how is hyaluronan synthesised?

A

through the cell membrane

22
Q

what are the functions of hyaloronan?

A

• Has ability to bind water molecules-
cosmetic industry
• Highly viscoelastic- treatment in osteoarthritis.
• Increased tumours and elevated at certain stages of wound healing.
• Linked increased fibroblast migration effect size dependent

23
Q

Give an overview of collagen. (remember this)

A
  • Fibrous proteins
  • Most abundant in mammals
  • Primary feature long, stiff triple stranded helical structure
  • At least 25 types of collagen (more likely 50)
  • 80-90% of all collagen Type I, II and III.
24
Q

what is the structure of collagen?

A
  • Collagen I: 330nm long and thin 1.5nm
  • Structural Unit is a triple helix
  • Three coiled subunits 1050 amino acids (closely intertwined so can’t break down by enzymes -very strong)
25
Q

describe how cologne structure comes about.

A
  • glycine:small (smallest AA because you want it tightly intertwined)
  • proline:fixed angle allows helix formation
  • hydroxyproline : fixed angle allows helix formation (no RNA gene with these AA so synthesised by the cell)
  • hydroxylysine: stabilises side by side packing (same as above)
26
Q

Name the different types of collagen.

A
  1. fibril-forming collagens (type I,II,III,V and XI)
  2. network-forming collagens (types IV, VIII and X)
  3. Fibril-associated collagens with interrupted triple helices (Type IX,XII,XIV,XVI and XIX)
  4. Transmembrane collagens (types XIII and XVII)
  5. other types of collagen
27
Q

how does it know where to start forming the coil (collagen biosynthesis) ?

A

Enzymes involved:
H glycosylation enzymes Protein disulphide
isomerase

28
Q

what signals the correct alignment?

A

15 amino acids which are non conserved in C pre-pro region

29
Q

Name one use of collagen in dentistry.

A

collagen gum grafting

30
Q

what are some diseases caused by collagen excess?

A
  • Scleroderma- rare chronic disease characterized by excessive deposits of collagen- growth factors
  • Oral submucosa fibrosis: chronic debilitating and precancerous caused by chewing habit- increase in type III and then type I collagen.
31
Q

what are some diseases caused by insufficient collagen?

A
  • osteogenesis imperfecta
  • Ehlers-danlos sydrome
  • collagenopathy
32
Q

what cause osteogenesis imperfecta?

A
  • brittle bones
  • Type 1- normal quality insufficient quantity A and B are when have dentinogenesis imperfecta (opalescent teeth).
  • Type 4 A and B quantity sufficient but not high enough quality
33
Q

what causes Ehlers-danlos syndrome?

A

-rare genetic disorder caused by defect in collagen synthesis
• Symptoms unstable, flexible joints- skin and tendons easily stretched.
• Mutations in ADAMTS2, Col1A1, Col1A2, Col3A1, Col5A1, Col 5A2, PLOD1 and TNXB

34
Q

what are symptoms of collagenopathy, type II and XI?

A

-poor bone development, problems with
hearing, sight, cleft plate, small lower jaw.
• Mutations: Col 11A1, Col 11A2 and Col 2A1.

35
Q

Name and Describe a disease associated with collagen in diet?

A
  • Scurvy: a deficiency disease lack of vitamin C- needed for hydroxylation proline to hydroxyproline.
  • If not present- form too few hydrogen bonds in collagen.
  • Skin, bone teeth weakness and malformation.
  • Blood vessels weakened-bleeding
36
Q

Name other matrix factors.

A
  • Fibronectin- glycoprotein, cryptic bioactivities.
  • Laminin- glycoprotein, cryptic bioactivities.
  • Growth factors- affect cell behaviour.
  • Integrins and signalling.
  • CD44

Oral biology (29 decks)

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