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I've got kidney disease > Lecture 9 > Flashcards

Lecture 9 Flashcards

1
Q

What are the four connections/attachments that make the epithelia a barrier?

A

tight junction
adhering junction
desmosome
gap junction

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2
Q

The epithelia is attached to a _________ _________. Describe this

A

basement membrane

this is part of the extracellular matrix that holds the cells in place

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3
Q

Describe the cell membrane

A

It is a lipid bilayer

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4
Q

What is the cell membrane permeable to?

A

non-polar, uncharged molecules such as O2, CO2 and steroid hormones

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5
Q

What is the cell membrane impermeable to?

A

ions and large, charged molecules

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6
Q

What are the three things that make up the lipid bilayer? What percentage of the membrane do each of these things make up?

A
  • phospholipids: 75%
  • cholesterol: 20%
  • glycolipids: 5%
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7
Q

Phospholipids have both a __________ region and a __________ region

A

hydrophilic

hydrophobic

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8
Q

What two things make up the hydrophilic region of phospholipids?

A

an alcohol and a phosphate

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9
Q

Where are the hydrophilic and hydrophobic regions of the phospholipids located?

A

The hydrophilic regions face the outside and inside of the cell and then the hydrophobic region faced each other, away from the aqueous inside and outside of the cell

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10
Q

Is the hydrophilic head on cholesterol big or small? Why is this?

A

it is small so that it can be embedded in the lipid region

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11
Q

There are ________ in the membrane which span the whole lipid bilayer. What are three examples?

A

proteins
GPI-anchored membrane protein
peripheral membrane protein
integral membrane protein

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12
Q

Which protein does not span the membrane but holds onto it?

A

the peripheral membrane protein

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13
Q

What is meant by the fluid mosaic of the lipid bilayer?

A

lipid molecules can move sideways in their own half of the bilayer

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14
Q

Can proteins such as channels, receptors, transporters, ECM proteins move in the bilayer?

A

yes

they are embedded in the lipid bilayer but can still move

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15
Q

What is the purpose of the fluid mosaic of the lipid bilayer?

it is __________ and __________ for changing _________ and _________ populations, cell _______, _________ and self-sealing

A

it is flexible and dynamic for changing protein and lipid populations, cell growth, secretion and self-sealing

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16
Q

What is another name for the basement membrane?

A

basal lamina

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17
Q

What joins the cells to the basement membrane?

A

hemidesmosomes

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18
Q

Where are tight junctions located?

A

these are located close to the apical membrane of the cells

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19
Q

Where do adhering junctions sit?

A

just below the tight junctions

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20
Q

What is the basement membrane? What is it comprised of?

A

it is an extracellular matrix structure comprised of collagens, laminins, proteoglycans and fibronectins

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21
Q

Where is the basement membrane secreted from?

A

from the epithelial cells themselves to help form the extra cellular matrix structure that they then sit on

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22
Q

What is a condition that results from issues with the basement membrane?

A

epidermolysis bullosa

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23
Q

What causes epidermolysis bullosa?

A

the collagen malfunctions so the anchoring of the basement membrane to the skin epithelia fails and blistering occurs

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24
Q

Patients presenting with epidermolysis bullosa present with severe blistering BECAUSE collagen dysfunction prevents proper anchoring of basement membrane to the epithelial cell

A

A- Both true and related

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25
Q

What are the three main functions of the tight junctions?

A
  • act as a barrier
  • act as a gate
  • act as a fence
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26
Q

Explain the tight junctions acting as a barrier (why is this needed?)

A

this limits the passage of ions and molecules between cells in the paracellular pathway

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27
Q

Explain tight junctions acting as a gate (why is this needed?)

A

it can allow certain solutes to flow through the paracellular pathway

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28
Q

Explain tight junctions acting as a fence (why is this needed?)

A

to prevent the movement of proteins between apical and basolateral domains

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29
Q

Tight junctions are ________ structures around each epithelial cell - formed by strands of _______ proteins linked to bilayers of two cells pulling the bilayers very close together

A

continuous

claudin

30
Q

What three things make up a tight junction?

A
  • claudin protein
  • occludin protein
  • JAMs
31
Q

What are claudin proteins, occludin protein, JAMs all connected to?

A

ZO proteins

32
Q

What are ZO protein connected to?

A

actin cytoskeleton

33
Q

What is the part of the tight junction that changes to make all 27 different kinds?

A

the claudin

34
Q

What does claudin 1 not allow through the tight junctions?

A

it does not allow transport of ions/water through the tight junctions

35
Q

What does claudin 2 allow through the tight junctions?

A

it allows the transport of many ions and water through the tight junctions

36
Q

Other claudins (not 1 or 2) control the passage of what?

A

Mg2+, Ca2+

37
Q

Describe the structure of the adherens junction

A

this is a belt structure beneath tight junction where two cells are close contact via cell-cell adhesion molecules (CAMs)

38
Q

What makes up the belt that forms part of the adherens junction?

A

actin filaments

39
Q

Formation of adherens junction initiates epithelia formation, true or false?

A

true

40
Q

What is an example of a CAM?

A

E - cadherin

41
Q

CAMs are held in place by what?

A

by anchor proteins which connect to actin cytoskeleton

42
Q

Why are CAMs important in cancer?

A

As the cancer progresses, the epithelia becomes mesenchymal and can cause metastasis due to the loss of adherence junctions so the epithelia become disorganised so the cells break off and go somewhere

43
Q

Describe the structure of desmosomes

A

There are desmosomal cadherins that hold cells together at single spots. There is an anchor point for intermediate filaments eg. keratin

44
Q

Describe the structure of a hemidesmosome

A

These connect the epithelial cells to the basement membrane and are directly involved with keratin intermediate filaments (these are embedded in a plaque and joined via the protein plectin to integrins)

45
Q

Describe gap junctions

A

These are tiny channels between cells made of connexin proteins

46
Q

Six connexins form a ________ that forms a _________

A

connexon

channel

47
Q

What do gap junctions allow the passage of?

A

ions and small molecules between cells

48
Q

What are the three main types of cytoskeleton?

A
  • actin filaments
  • intermediate filaments
  • microtubules
49
Q

What is the purpose of actin filaments in the cytoskeleton?

A

determines cell shape, and drive the movement of cells

50
Q

What is the purpose of the intermediate filaments in the cytoskeleton?

A

to provide mechanical strength and resistance to shear stress

51
Q

What is the purpose of microtubules in the cytoskeleton?
to position ___________, railroads for intracellular ________ transport, form a _________ spindle, motile components of _________

A

to position organelles, railroads for intracellular vesicle transport, form a mitotic spindle, motile components of cilia

52
Q

The cytoskeleton is ________ and can ________ to internal and external signals

A

dynamic

adapt

53
Q

____________ proteins regulate the _______/_________ and linking to other structures

A

accessory

assembly/disassembly

54
Q

Actin filaments form a ______ stranded _______ polymer of actin

A

2

helical

55
Q

What are myosins?
they are ________ proteins that bind to ________ filaments and use _______ for ________, and transport _______, vesicles and ________ along the _________ filaments

A

they are motor proteins that bind to actin filaments and use ATP for contraction, and transport proteins, vesicles and organelles along the actin filaments

56
Q

What are microtubules?

A

they are long straight hollow cylinders made from α and β tubulins

57
Q

Which is more rigid, actin filaments or microtubules?

A

microtubules

58
Q

What are microtubules needed for?

A

cell motility, cell division, vesicle movement

59
Q

What are two molecular motor that allow transport of vesicles and organelles around the cell using ATP?

A

kinesin and dynein

60
Q 
What type of cell junction is a tight junction: 
occluding
Anchoring
strength
communicating
A

occluding

61
Q 
What type of cell junction are adherens: 
occluding
Anchoring
strength
communicating
A

anchoring

62
Q 
What type of cell junction are desmosomes: 
occluding
Anchoring
strength
communicating
A

strength

63
Q 
What type of cell junction are hemidesmosomes: 
occluding
Anchoring
strength
communicating
A

strength

64
Q 
What type of cell junction is a gap junction: 
occluding
Anchoring
strength
communicating
A

communicating

65
Q

What are the transmembrane proteins for tight junctions?

A

claudin, occludin, JAM-1

66
Q

What are the transmembrane proteins for adherens?

A

E - cadherins

67
Q

What are the transmembrane proteins for desmosomes?

A

desmosomal cadherins

68
Q

What are the transmembrane proteins for gap junctions?

A

connexins

69
Q

What is the cytoskeletal attachment for adherens?

A

actin filaments

70
Q

What is the cytoskeletal attachment for desmosomes?

A

keratin filaments

71
Q

What is the cytoskeletal attachment for hemidesmosomes?

A

keratin filaments

72
Q

Desmosomes connect epithelial cells to the basement membrane BECAUSE the basement membrane consists of extracellular matrix proteins

A

False, true

I've got kidney disease (43 decks)

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