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MCB > MCB10 - Assembly of Cells Into Tissues I > Flashcards

MCB10 - Assembly of Cells Into Tissues I Flashcards

1
Q

Define metazoans.

A

Multicellular organisms.

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2
Q

Define interstitial spaces.

A

Unspecialised matrix containing extracellular spaces in tissues.

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3
Q

What are the main functions of extracellular matrix.

A

Determines mechanic and physio chemical properties of tissue. Provides physical support. Influences growth, adhesion and differentiation of cells. Essential for development and tissue function.

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4
Q

Which types of tissue have high proportions of extracellular matrix.

A

Tissues with structural, mechanical and protective roles. E.g. tendons, ligaments, bones, fibrous layers and connective tissues.

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5
Q

What are the fibrillar and non fibrillar compartments of extracellular matrix.

A

Different properties of filaments that give structural and non structural properties.

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6
Q

What are the three major components of extracellular matrix.

A

Proteoglycans and Glycosaminoglycans.
Fibrils and fibres.
Modular adhesive glycoproteins.

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7
Q

Give general definition of collagen.

A

Most abundant family of fibrous proteins with many different types.

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8
Q

What is the main type of collagen in the body.

A

Type I

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9
Q

Where in tissue in collagen put together

A

Extracellular matrix

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10
Q

What sequence of amino acids is repeated in pro collagen chains

A

Glycine-X-Y where X is proline and Y is hydroxyproline

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11
Q

How is one collagen chain formed

A

3 protein alpha chains wind to form a stiff tripal helical structure, with every 3rd position occupied by glycine that does not get hydroxylation

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12
Q

What are the various structures and roles carried out by collagen.

A

Fibril formation. Networking forming, proteoglycan cores, transmembrane proteins.

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13
Q

Discuss in full, the formation of a collagen fibre.

A

Pro alpha chain formed by protein synthesis. Hydroxylation of selected prolines and lysine amino acid residues in the pro alpha chain occurs. Glycosylation of selected hydroxylysines occur. Self assembly occurs, forming the three pro alpha chains into one pro collagen triple helix. These are packaged into secretory vesicles then secreted. Propeptides at end are cleaved by peptidases. Spontaneously, form into fibrils which group into bundles to form fibres.

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14
Q

Which amino acids in pro alpha chains become hydroxylated.

A

Prolines and lysine.

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15
Q

Which amino acid, and in what form, becomes glycosylated, as part of collagen formation.

A

Hydroxylysines.

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16
Q

Discuss the different structural stages of a collagen fibre formation,

A

One pro alpha chain,
Three pro alpha chains into triple helical structure.
Cleaving, forming collagenfibril.
Fibrils bundle together to form fibre.

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17
Q

Which vitamins and minerals are required for formation of collagen and why.

A

Vitamin D and iron. Aid hydroxylation of specific amino acid residues and consequent cross bonding between and within fibres, giving collagen their characteristic strength.

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18
Q

What are the two types of bonds that form in collagen, giving it its characteristic strength.

A

Inter molecular bonds - cross links that form between collagen fibres.
Intramolecular bonds - cross links that form within collagen fibres.

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19
Q

What is the most common amino acid in collagen fibres.

A

Glycine.

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20
Q

Give types of non fibril collagens found in animal tissue. Give their functions.

A

Fibril associated collagen - associate with fibril is collagens and regulate their organisation.
Network forming collagens - present in basement membranes with different molecular constitutions in different tissues.

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21
Q

Where does the assembly of collagen fibres from pro collagen occur.

A

Extracellular space.

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22
Q

How is the stretching of elastin limited.

A

Elastin is interwoven with collagen, limiting its elasticity.

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23
Q

What is on the outside of elastin and what is its purpose.

A

Covered in microfibrils which are rich in fibril in protein. These consist of alternating stretches of hydrophobic and hydrophilic amino acids which aid stretching and relaxing of the elastin.

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24
Q

Discuss chemical interactions in the relaxed state of elastin.

A

Hydrophobic parts of elastin avoid being exposed to aqueous environment therefore they curl in, shortening the elastin.

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25
Q

Discuss chemical interactions in the stretched state of elastin.

A

Hidden hydrophobic regions are pulled ope, resulting in stretching of the elastin molecule, however they eventually recoil, back to the relaxed state.

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26
Q

How are strong elastic fibres formed in elastin.

A

Covalent cross linking occurs between single elastin molecules, resulting in the formation of strong elastic fibre.

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27
Q

What are GAGs in the extracellular matrix.

A

Glycosaminoglycans. Unbranched polysaccharides made from repeating disaccharides, each having an amino sugar and an uronic acid.

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28
Q

Give example of amino sugar that is present in GAGs.

A

N-acetylglucosamine or N-acetylgalactosamine.

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29
Q

Give example of uronic acid that is present in GAGs.

A

Glucoronic acid or iduronic acid

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30
Q

What are proteoglycans.

A

Glycosaminoglycans (GAGs) that are covalently attached to a protein.

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31
Q

What charge do sugars in GAGs have And how.

A

Negative. Commonly sulphate resulting in the negative charge. Many functional groups within the molecule are sulphate resulting in a strong negative charge.

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32
Q

What consistent do GAGs provide to the tissue, and how.

A

Spongy consistency - GAGs and proteoglycans are hydrated as they have many OH groups so can attract water. Large volumes of water result in sponginess, which when compressed means the water becomes removed, but can be rehydrated.

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33
Q

What are two types of proteoglycans.

A

Decorin and aggrecan.

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34
Q

What is decorin, discuss its structure, and its role.

A

Proteoglycan. Contains one core protein bound to one GAG chain. Binds to collagen and controls fibrillogenesis.

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35
Q

Define fibrillogenesis.

A

Development of fine fibrils present in collagen tissue of connective tissue.

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36
Q

What is aggrecan, giving its structure and role.

A

Proteoglycan. Contains long core proteins with numerous glycosaminoglycans (GAGs) attached to it. Key components of cartilage, which are resultant for its compressive properties

37
Q

Which molecule do aggrecan molecules commonly associate with.

A

Hyaluronan.

38
Q

What is hyaluronan. Give structure, formation and role.

A

Also known as hyaluronic acid . Major Glycosaminoglycan constituting the extracellular matrix.
Structure - carbohydrate chain with no core protein and is not sulphate so has no negative charge. Contains N-acetylglucosamine and glucuronic acid.
Location - synthesised at cell surface.
Role - vital for wound healing, filling up space in tissue and acting as a lubricant in synovial fluid at joints.

39
Q

What are glycoproteins.

A

Proteins with a carbohydrate gel can group attached.

40
Q

Difference between proteoglycans and glycoproteins in terms of what they are.

A

Proteoglycans - glycosaminoglycans with protein attached.

Glycoproteins - proteins with carbohydrate glycan group attached.

41
Q

Specific differences between proteoglycans and glycoproteins.

A

Glycoproteins have short highly unbranched glycan chains with no repeating units whereas proteoglycans have long unbranched chains with repeating disaccharide units.

Glycoproteins have 10-15% carbohydrate content whereas proteoglycans have 50-60% carbohydrate content.

42
Q

What are modular ECM glycoproteins.

A

Glycoproteins found in the ECM that are considered as modular - sequence made from identifiable protein domains, each with particular structures and functions. Commonly involved with matrix organisation.

43
Q

What are domains, in regards to modular ECM glycoproteins.

A

Sequences of polypeptides that aid the folding in a particular way of an ECM glycoprotein.

44
Q

How are domains named.

A

Domains are commonly named after where they are first found however important to note that eg. epidermal growth factors can be found in non epidermal tissue.

45
Q

Roughly how many ECM glycoproteins are there.

A

200

46
Q

Glycoproteins contain binding sites for what type of other molecules in ECM. Give example.

A

Allow binding of other matrix molecules and cell surface receptors e.g. fibronectin and laminin.

47
Q

What are the two major forms in which fibronectin exist in.

A

Exist as insoluble fibrillar matrix or soluble plasma protein.

48
Q

How are differing molecules from fibronectin formed from the same gene.

A

Alternative splicing occurs of the mRNA molecule produced.

49
Q

What is the role of fibronectin.

A

Regulate cell adhesion and migration in embryogenesis and tissue repair. Also important in wound healing and blood clotting.

50
Q

Is fibronectin an essential molecule. Give evidence.

A

Yes. No functional mutational form of fibronectin is known.

51
Q

Where are laminins present.

A

Present in basement membranes of epithelial, muscle fib and fat cells.

52
Q

What are the three chains present in basal lamina glycoproteins. How do they interact.

A

Alpha beta and lambdaf. Form cross shaped molecule.

53
Q

Give type of cell surface receptor that laminins interact with.

A

Integrins.

54
Q

Are there diseases associated with laminin chain mutations.

A

Yes. Muscular dystrophy. Epidermolysis bullosa.

55
Q

What is the basal lamina/basement membrane

A

Thin flexible mat of extracellular matrix which underlies various epithelial cells. Separates cells from interstitial environment.

56
Q

What molecules are present in the basal lamina.

A

Collagen IV fibres and laminin as well as integrity and nidogen.

57
Q

Give types of cells which contain basal lamina.

A

Muscle cells. Epithelial cells. Kidney glomerulus cells. Peripheral nerve cells.

58
Q

What constitutes tissue fluid and in what proportions.

A

Intracellular fluid - 55%
Extracellular fluid - 45%
Extracellular fluid contains: blood plasma 7%, trans cellular fluid (2%) institutional fluid (36%)
Trans cellular fluid constitutes cerebrospinal fluid, ocular fluid and synovial fluid

59
Q

What constitutes trans cellular fluid

A

Cerebrospinal fluid, ocular fluid, synovial joint fluid

60
Q

What constitutes extracellular fluid

A

Blood plasma, interstitial fluid and trans cellular fluid

61
Q

How is the extracellular environment compartmentalised.

A

Compartmentalised with different layers of cells with varying compositions and functions

62
Q

What are the major cations in tissue fluid and how are their respective levels maintained

A

Sodium, potassium. Levels maintained by the sodium potassium pump.

63
Q

What are the major anions of tissue fluid and how are their respective levels maintained.

A

Major anions are chloride and hydrogen phosphates. Membrane pumps and channels control and maintain levels of the anions.

64
Q

What is the role of Ca2+ in tissue fluid.

A

Vital for cell signalling processes and can cause changes to cytoskeletal elements, affecting cell structure and behaviour.

65
Q

Where are proteins more concentrated - plasma or interstitial fluid. By how much.

A

Proteins more concentrated in plasma than interstitial fluid by 10X.

66
Q

Define osmolarity.

A

Measure of the concentration of all solute particles in a solution.

67
Q

Define Tonicity.

A

Strength of a solution as it affects final cell volume, and is dependent on cell membrane permeability and composition of solution.

68
Q

How do proteins contribute to an osmotic difference. How do cells not burst although the osmotic difference is present.

A

Proteins are too large to cross many plasma membranes so will always be in higher concentration extracellularly. This leads to an osmotic difference, which would cause water to flood in and cell to burst. However, sodium ions are continuously pumped out therefore impermeable protein levels are balanced.

69
Q

Define hypertonic, any movements involved, and what happens to a cell.

A

Solution is hypertonic to the cell so has a higher concentration so has lower water. Water moves from the cell to the surrounding cell, causing the cell to shrivel.

70
Q

Define hypotonic, any movements involved, and what happens to a cell.

A

Solution is hypotonic to the cell so has a lower concentration so has higher water concentration. Water moves from the surrounding solution to the cell , causing the cell to burst.

71
Q

Definite isotonic.

A

Cell and surrounding solution are of same concentration so no movement of water between cell and surroundings.

72
Q

What are the three classifications of tonicity.

A

Hypertonic. Hypotonic. Isotonic.

73
Q

Which two vessel systems supply and drain tissues.

A

Blood and lymph.

74
Q

What are the three types of blood vessels.

A

Veins, arteries and capillaries

75
Q

Where does most exchange of fluids and solutes occur.

A

Between plasma and interstitial fluid, across capillary walls.

76
Q

Exchange of solutes causes what to leak out of blood vessels and how is it replaced.

A

Results in plasma leaking out of blood vessels into interstitial spac, which is then drained into lymph vessels and passed back into back circulation. Entirety of blood plasma does this cycle every 9 hours.

77
Q

Which two pressures determine fluid movement across a vessel well.

A

Hydrostatic pressure and colloidal osmotic pressure.

78
Q

Define hydrostatic pressure.

A

Pressure exerted by an aqueous fluid in a confined space.

79
Q

Define colloidal osmotic pressure.

A

Form os osmotic pressure exerted by proteins in blood vessels plasma that pulls water into circulatory system. Also referred to as oncotic pressure.

80
Q

What is the relation between the two main forces involved, when blood plasma leaks out of blood vessels into interstitial space.

A

Hydrostatic pressure is greater than colloidal osmotic pressure.

81
Q

What is the relation between the two main forces involved, when blood plasma flows into vessels from interstitial space.

A

Hydrostatic pressure is less than colloidal osmotic pressure.

82
Q

Why is there a high protein concentration in blood plasma.

A

Proteins cannot pass through capillary walls

83
Q

What are lymphatic capillaries

A

Subset of capillaries which drain blood vessels and return molecules to the blood via lymph nodes or lymphatic ducts.

84
Q

What do lymphatic capillaries do.

A

Collect interstitial flood from vessels whose ends are not directly connected to other vessels.

85
Q

Define lymphatic system

A

Complex system of lymph vessels that collect interstitial fluid, and return it to the blood via lymph nodes

86
Q

Define odema and what causes this condition.

A

Swelling of a tissue that occurs due to excess interstitial fluid this drained and not passed back into blood plasma.

87
Q

What are the two types of odema.

A

Hydrostatic and inflammatory.

88
Q

Discuss hydrostatic odema.

A

High blood pressure means increased hydrostatic pressure in vessels. This leads to an accumulation of interstitial fluid.

89
Q

Discuss inflammatory odema.

A

Local blood vessels become leaky leading to swelling which occurs as rate of leakage of vessels is greater than rate of drainage from lymphatic system.

MCB (13 decks)

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