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POM 2: Molecular biology of the cell > 6: ECM, Histopathology (Tissues) > Flashcards

6: ECM, Histopathology (Tissues) Flashcards

1
Q

Extracellular matrix (ECM)

A

Everything that surrounds cell
Not mobile
Cell deposit proteins and carbohydrates around themselves
Communicates with nearby cells via surface receptors

Helps keep structural support of tissue
Helps cells function and influences what they do

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2
Q

Connective tissue is composed of (2)

A

ECM
Component cells

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3
Q

4 components of ECM

A

Collagen - fibril forming, non-fibril forming
Multiadhesive glycoprotiens - laminins, fibronectins
Elastic fibres - elastin, fibrillin
proteoglycans

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4
Q

4 connective tissues in ECM

A

Bone
Cartilage
Tendon
Vitreous humour

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5
Q

Collagen

A

Fibrous
28 types
Multiple genes
Most abundant protein

Fibre layering affects strength

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6
Q

Collagen structure

A

Triple helix
three a chains
gly-x-y
stiff helix
glycine - H side chain =pack together

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7
Q

Composure of collagen fibre

A

One alpha chain –> 3 alpha chains–> collagen fibril –>collagen fibre

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8
Q

Collagen synthesis

A

1)one alpha chain
2) hydroxylation (add OH) - Vit C is a cofactor{scurvy}, glycosylation (add carbohydrate chain) x3
3) Become triple helix, bonds form between chains
[4) IF not secreted: keep non collagenous domains- unless fibrillar collagens]
4) IF secreted: cleavage of non collagenous domains
5) Fibrils form, crosslinking occurs

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9
Q

Basement membranes

A

Non fibrillar collagens - type IV
flexible / bendy
join together laterally & head to tail
rotary shadowing = self assembly
form a sheet

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10
Q

Where are basement membranes found

A

Flexible ECM around tubes/under epithelium
Essential to kidney for GBM

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11
Q

Diabetic nephropathy

A

thick/too much ECM in membrane, Filtrate unable to enter nephron
results in renal failure

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12
Q

Alport syndrome

A

Collagen IV disorder
GBM becomes split and laminated

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13
Q

Elastic tissues are required in

A

Arteries/vessels
in skin
lungs

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14
Q

Elastic fibres

A

In absence of stretching force = elastin proteins in compact conformation
When subject to stretching force - elastin proteins elongate, but remain attached by cross links

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15
Q

Elastic fibres consist of

A

elastin core
microfibrils (fibrillin)

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16
Q

Marfans syndrome

A

Fibrillin disorder- affects elastin production, loss of elastic tissue

Tall, slender people-tissues collapse, e.g eye lens dislocate, aneurisms burst, vessels not elastic due to lack of elastin

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17
Q

Two types of glycoproteins

A

Laminins
Fibronectins

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18
Q

Laminins

A

3 different chains
large proteins
cross shaped
bind to many other ECM components

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19
Q

Fibronectins

A

In fluids
soluble and insoluble
U shaped
Interact with other ECM components

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20
Q

Fibronectins are involved in

A

Involved in embryogenesis, tissue repair and clotting

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21
Q

Laminin infection causes

A

muscular dystrophy
epidermolysis bullosa

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22
Q

Proteoglycans

A

core protein + GAG chain
Often negative
depending on repeating unit there are 4 categories of GAGs

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23
Q

GAG chains are

A

two amino sugars joined together = disaccharide unit

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24
Q

types of GAGs

A

Hyaluronan - vitreous humour and synovial fluid
Chondroitin sulphate and Dermatan sulphate
Heparan sulphate
Keratan sulphate

  • dependant on varying repeating unit
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25
Q

Too much ECM can lead to

A

Fibrotic disorders
- liver fibrosis - cirrhosis
- kidney fibrosis - diabetic nephropathy
- lung fibrosis - idiopathic pulmonary fibrosis (IPF)

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26
Q

To little/loss of ECM can lead to

A

Lack of support
e.g osteoarthritis

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27
Q

Taking a biopsy

A

remove tissue - scalpel, needle
preserve with formalin - to keep integrity
put in wax
cut into tiny sections
mount on a glass slide for microscopy

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28
Q

What is histopathology used for

A

Cancer diagnosis
observing if treatment works

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29
Q

What stain is used to see leucocytes in a biopsy

A

H&E stain (Hematoxylin and eosin)
- makes nuclei and cytoplasmic granules visible

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30
Q

What is the Ziehl-Neelsen stain used for in biopsies

A

Staining acid-fast bacteria red

  • aids diagnosis of tuberculosis infection
31
Q

Resection specimens

A

Specimens used to observe efficiency of treatment. more treatment needed?

allowing definitive diagnosis of disease from tissues surgically removed
5-7 days for results

32
Q

Frozen specimens

A

Remove tissue in surgery
Freeze with cryostat machine
Cut & place on microscope
stain

rapid diagnosis of mass during surgery
30min until results
needs to be free of any chemicals

33
Q

Cytopathology

A

Observing individual cells

34
Q

Histopathology

A

Observing tissues as a whole

35
Q

Procedure of Cytopathology

A
  1. Collect cells
  2. Smear them on slide
  3. Stain
  4. Examine under microscope
36
Q

Fine needle aspiration

A

least invasive - doesn’t purse
can access relatively inaccessible tissues
N: only singular cells removed, cannot comment on architecture of tissue and cell interactions

37
Q

Antibody structure

A

\ //
[]
bottom - heavy chain Fc- attaches to self cells
top -antigen binding site, top half of Y is variable, bottom half is constant
top outside - light chain

38
Q

Histochemistry

A

Using antibodies to detect specific molecules
attach Fc part - called: conjugations

39
Q

4 Types of conjugations

A

Enzymes (ELISA)
Fluorescent probes (flow cytometry)
Magnetic beads
Drugs

40
Q

Direct ELISA

A

Primary antibody conjugate - directly binds to antigen
1. Antibodies attached in bottom of well
2. Addition of patient sample
3. Sample washed, Enzyme-labeled antibody added
3. Sample washed, Reaction observed

41
Q

Indirect ELISA

A

Secondary antibody conjugate - Antibody binds to antigen which has detectable molecule attached

42
Q

ELISA is used to

A

determine levels/presence of a certain molecule

43
Q

Flow cytometry

A

Antibodies are fluorescent
1. Add antibodies
2. Run sample through laser
3. Flourophores excited
4. Colour (what is in sample) and scattering (molecular surface) measured

44
Q

Bone consists of 70% water and 30% dry mass, up to 80% of which is collagen. what architectural property of collagen fibres suits it best for this role?

A

Tough due to perpendicular fibre arrangement
Withstand pressure during stretching and impact

45
Q

10% of tendon is made up by elastin fibres, what property does this lend to tendons to make it useful for their role?

A

Tendon flexibility in order to contract and relax muscles

46
Q

Why is a fine needle aspiration used instead of a biopsy?

A

Can penetrate relatively inaccessible tissues
Obtain a sample without need for surgery

47
Q

What are epithelial cells classified according to

A

layering and shape

48
Q

layers of epithelial cells

A

simple, stratified, pseudostratified

49
Q

shape of epithelial cells

A

squamous, cuboidal, columnar

50
Q

type of epithelial cells in mouth, oesophagus and vaginal tissue

A

non-keratinised stratified squamous

51
Q

type of epithelial cells in the stomach

A

Simple columnar

52
Q

type of epithelial cells in the small intestsine

A

ciliated simple columnar

53
Q

type of epithelial cells in large intestine

A

simple columnar

54
Q

type of epithelial cells in the anal canal

A

upper 2/3: simple columnar
lower 1/3: non-keratinised stratified squamous

55
Q

type of epithelial cells in the epidermis of the skin

A

keratinised stratified squamous

56
Q

type of epithelial cells in the trachea and main bronchi of lungs

A

ciliated pseudostratified columnar

57
Q

type of epithelial cells in the alveoli of lungs

A

simple squamous

58
Q

Biopsy

A

procedure removing tissue from a living body to be examined under a microscope
time taken for results 2-3days

59
Q

Post-mortem

A

examining cell type on a body after death

60
Q

smear

A

microscopically studying a specimen which is thinly spread across the slide with a swab

61
Q

H&E stain identifies

A

Haematoxylin stains nuclei blue
Eosin stains cytoplasm pink

62
Q

Gram stain identifies

A

Bacteria

63
Q

Ziehl-Neelson stain identifies

A

Acid-fast bacteria (mainly myobacteria) - TB

64
Q

Leishman stain identifies

A

Blood smears (contains eosin and methylene blue)

65
Q

Antibody stain identifies

A

Detection of proteins in a sample

66
Q

Osteoarthritis is an erosive disease caused by ECM degradation. What is the mechanism of degradation

A

Aggrecanases cleave aggrecan

67
Q

How is aggrecan cleaved

A

Aggrecanases and metalloproteinases cleave aggrecan
Fragments released into synovial fluid

68
Q

Hyaline cartilage is rich in

A

aggrecan

69
Q

GAG (Glycosaminoglycans) of aggrecan are

A

highly sulphated leading to multiple negative charges
these charges attract cations such as Na+
Large quantities of water are attracted to the osmotically active cations
Retained water creates a cushioning effect
under compressive load, water is given up, but retained as load is reduced

70
Q

What happens to aggrecan in osteoarthritis

A

Aggrecanases and metalloproteinases cleave aggrecan with age leading to loss of aggrecan fragments to synovial fluid
lack of cushioning at the end of long bones leads to joint pain and swelling

71
Q

What would happen if the secretory machinery in epithelial cells wasn’t polarised

A

secretion would occur through both apical and basolateral compartments

  • without polarisation , cell is unable to distinguish between the apical and basolateral surfaces for secretion, leading to secretion through both compartments
72
Q

How do integrins link the ECM

A

Collagen fibril > fibronectin > integrin dimers> adaptor proteins > actin filament

73
Q

Primary function of cuboidal epithelial cells

A

secretion
absorption
barrier functions

commonly found lining ducts of glands and small tubule organs e.g kidneys, thyroid

POM 2: Molecular biology of the cell (9 decks)

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