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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
Too much ECM can lead to
Fibrotic disorders - liver fibrosis - cirrhosis - kidney fibrosis - diabetic nephropathy - lung fibrosis - idiopathic pulmonary fibrosis (IPF)
26
To little/loss of ECM can lead to
Lack of support e.g osteoarthritis
27
Taking a biopsy
remove tissue - scalpel, needle preserve with formalin - to keep integrity put in wax cut into tiny sections mount on a glass slide for microscopy
28
What is histopathology used for
Cancer diagnosis observing if treatment works
29
What stain is used to see leucocytes in a biopsy
H&E stain (Hematoxylin and eosin) - makes nuclei and cytoplasmic granules visible
30
What is the Ziehl-Neelsen stain used for in biopsies
Staining acid-fast bacteria red - aids diagnosis of tuberculosis infection
31
Resection specimens
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
Frozen specimens
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
Cytopathology
Observing individual cells
34
Histopathology
Observing tissues as a whole
35
Procedure of Cytopathology
1. Collect cells 2. Smear them on slide 3. Stain 4. Examine under microscope
36
Fine needle aspiration
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
Antibody structure
\\ // [] 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
Histochemistry
Using antibodies to detect specific molecules attach Fc part - called: conjugations
39
4 Types of conjugations
Enzymes (ELISA) Fluorescent probes (flow cytometry) Magnetic beads Drugs
40
Direct ELISA
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
Indirect ELISA
Secondary antibody conjugate - Antibody binds to antigen which has detectable molecule attached
42
ELISA is used to
determine levels/presence of a certain molecule
43
Flow cytometry
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
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?
Tough due to perpendicular fibre arrangement Withstand pressure during stretching and impact
45
10% of tendon is made up by elastin fibres, what property does this lend to tendons to make it useful for their role?
Tendon flexibility in order to contract and relax muscles
46
Why is a fine needle aspiration used instead of a biopsy?
Can penetrate relatively inaccessible tissues Obtain a sample without need for surgery
47
What are epithelial cells classified according to
layering and shape
48
layers of epithelial cells
simple, stratified, pseudostratified
49
shape of epithelial cells
squamous, cuboidal, columnar
50
type of epithelial cells in mouth, oesophagus and vaginal tissue
non-keratinised stratified squamous
51
type of epithelial cells in the stomach
Simple columnar
52
type of epithelial cells in the small intestsine
ciliated simple columnar
53
type of epithelial cells in large intestine
simple columnar
54
type of epithelial cells in the anal canal
upper 2/3: simple columnar lower 1/3: non-keratinised stratified squamous
55
type of epithelial cells in the epidermis of the skin
keratinised stratified squamous
56
type of epithelial cells in the trachea and main bronchi of lungs
ciliated pseudostratified columnar
57
type of epithelial cells in the alveoli of lungs
simple squamous
58
Biopsy
procedure removing tissue from a living body to be examined under a microscope time taken for results 2-3days
59
Post-mortem
examining cell type on a body after death
60
smear
microscopically studying a specimen which is thinly spread across the slide with a swab
61
H&E stain identifies
Haematoxylin stains nuclei blue Eosin stains cytoplasm pink
62
Gram stain identifies
Bacteria
63
Ziehl-Neelson stain identifies
Acid-fast bacteria (mainly myobacteria) - TB
64
Leishman stain identifies
Blood smears (contains eosin and methylene blue)
65
Antibody stain identifies
Detection of proteins in a sample
66
Osteoarthritis is an erosive disease caused by ECM degradation. What is the mechanism of degradation
Aggrecanases cleave aggrecan
67
How is aggrecan cleaved
Aggrecanases and metalloproteinases cleave aggrecan Fragments released into synovial fluid
68
Hyaline cartilage is rich in
aggrecan
69
GAG (Glycosaminoglycans) of aggrecan are
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
What happens to aggrecan in osteoarthritis
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
What would happen if the secretory machinery in epithelial cells wasn't polarised
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
How do integrins link the ECM
Collagen fibril > fibronectin > integrin dimers> adaptor proteins > actin filament
73
Primary function of cuboidal epithelial cells
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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