Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Cell Biology > Epithelia & cell junctions > Flashcards

Epithelia & cell junctions Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

What are epithelia?

A

Avascular tissues composed of cells, usually organised into sheets/tubule, attached to an underlying ECM basement membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are epithelia modified to form?

A

Glandular structures (exocrine glands)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How many types of epithelia are there?

What are they?

A

5

Layers:
> simple
>stratified

Cell shape:
>columnar
>cuboidal
>squamous

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Where are simple cuboidal epithelia found?

A

Around kidney tubules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Where are simple columnar epithelia found?

A

Small intestine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Where are squamous epithelia found?

A

Lung alveolus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Where are stratified epithelia found?

A

Oesophagus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the 7 functions of epithelia?

A 
> mechanical protection
> permeability barrier
> absorption 
> filtration
> secretion 
> diffusion
> sensory
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How are epithelia polarised?

A

Apical-basolateral

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How are the apical & basal membranes different?

A

Composition of lipids & membrane proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How is the cytoskeleton organised in epithelia?

A

So that secreting vesicles are produced & driven towards apical surface ready to be secreted

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How is physical integrity of the epithelium maintained?

A

Epithelia held together by cell junctions

= specialised site attached to another cell or extracellular matrix

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the 4 different types of cell junctions?

A

> anchoring junctions
occurring junctions
channel-forming junctions
signal-relaying junctions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the role of anchoring junctions?

A

Linking cells together or to the ECM

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the role of occluding junctions?

A

Sealing gaps between cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the role of channel-forming junctions?

A

Creating passageways (for ions & small molecules) linking the cytoplasm of adjacent cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the role of signal-relaying junctions?

A

Allowing signals to be communicated from cell to cell

18
Q

What are the 2 types of ‘strengthening’ junctions?
(between cells)

What are the 2 types of anchoring junctions?
(between cell & basal lamina)

A

> Adherens junction
Desmosome

> Focal adhesion
Hemidesmosome

19
Q

What are the 3 components of an adherens junction?

A

> Actin filaments

> Cadherin

> alpha & beta catenin

20
Q

What are the 3 components of a desmosome?

A

> intermediate filaments

> cadherin (desmoglein)

> plakoglobin & desmoplakin

21
Q

What are the 3 components of a focal adhesion?

A

> actin filaments

> integrin

> focal adhesion kinase

22
Q

What are the 3 components of a hemidesmosome?

A

> intermediate filaments

> integrin/collagen

> dystonin

23
Q

What do cadherins do?

A

Mediate cell-cell attachment

24
Q

Which type of junction links cadherin to the actin filaments of the cytoskeleton?

A

Adherens junction

25
Q

How can epithelial sheets form a tube/vesicle?

A

Invagination of sheet due to an organised tightening along adhesion belts in selected regions of sheet

–> epithelial tub pinches off from sheet of cells

26
Q

Which type of junction links cadherins to intermediate filaments of cytoskeleton?

A

Desmosomes

27
Q

What is the role of integrin?

Which junction is it found in?

A

Mediates cell-matrix contacts

Hemidesmosomes
- anchor epithelial cells to basal lamina

28
Q

Give an example of a disease caused by defective desmosomes

What are the symptoms?

A

Pemphigus vulgaris
- autoimmune destruction of desmosomal protein

> severe blistering 
> dehydration & infection 
- gaps open up between cells & fill w/ fluid
--> blisters burst = infection 
> death
29
Q

What are the 2 functions of occluding junctions?

A

Barrier: regulate passage of ions, water & macromolecules

Fence: maintains cell polarity

30
Q

What are the 2 components of occluding junctions?

A

> Claudin & occludin

> Zona occludin scaffold protein

31
Q

Which disease is loss of barrier function in occluding junctions associated with?

A

Crohn’s disease

  • inflammation of bowels
  • permeability disorder
32
Q

Which disease is loss of fence function in occluding junctions associated with?

A

Cancer

  • loss of cell polarity
  • loss of cell contacts
  • increase in motility
  • eventual metastasis
33
Q

What are the components of channel-forming junctions?

A

Connexin formed of 6 subunits

34
Q

Explain the role of channel-forming junctions in cardiac muscle

A

Allow passage of ions
–> permits changes in membrane potential to pass from cell to cell
= rhythmic contraction of heartbeat

35
Q

Which inherited disorders can abnormal gap junctions cause?

A

Cataracts

Vohwinkel Syndrome

36
Q

What causes cataracts?

A

Dominant mutation in CX50
= no gap junctions, but hemichannels form
–> disrupted connections

37
Q

What causes Vohwinkel Syndrome?

A

Upregulated CX26 in epidermis
–> hyper proliferation
(over production of epidermal cells)

38
Q

What are channel-forming junctions in plants called?

Which organelle projects across them?

A

Plasmodesmata
- cytoplasm physically connected across junction

Smooth endoplasmic reticulum

39
Q

What are the components of a signal-relaying junction in a neuromuscular junction between 2 neurones?

A

> cadherin

> neuroligin & neurexin

40
Q

What happens when signal-relaying junctions are lost?

What are the symptoms?

A

Myasthenia Gravis
= autoimmune destruction of neuromuscular junction

> droopy eye
severe muscle weakness

Cell Biology (23 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions