Brainscape's Knowledge GenomeTM

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


See full index

BB10005 > Epithelia and cell junctions > Flashcards

Epithelia and cell junctions Flashcards

1
Q

What are epithelia?

A

Avascular tissues composed of cells, usually organised into sheets or tubules 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 surfaces of the body do epithelia cover?

A

Internal and external surfaces of the body.

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

What are some epithelia modified to form?

A

Glandular structures (exocrine glands).

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

What are the types of epithelia?

A

Simple stratified, columnar, cuboidal and squamous.

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

What is the difference between columnar and cuboidal epithelia?

A

Cuboidal are cube shaped whereas columnar are longer cells.

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

What is the difference between simple and stratified epithelia?

A

Stratified is composed of multiple layers of cells, with thicker cells at the bottom being in direct contact with the basement membrane.

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

Where can cuboidal epithelia be found?

A

Kidney tubules.

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

Where can columnar epithelia be found?

A

In the small intestine.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Where can squamous cells be found?

A

In the lung alveoli.

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

Where can stratified epithelia be found?

A

In the oesophagus.

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

What are some of the functions of epithelia?

A

Mechanical protection, permeability barrier, absorption, filtration, secretion, diffusion of gases or fluids and sensory.

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

How is epithelia polarised?

A

Only one side touches the basal lamina, and the other side can secrete various substances. The composition of the lipids in the membrane is also different on either side. They may have microvilli on the other side as well.

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

What is a cell junction?

A

A specialised site on a cell which it is attached to another cell or the extracellular matrix (e.g. basal lamina).

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

What are cell junctions made up of?

A

Actin filaments and intermediate filaments.

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

What are the 4 different groups of cell junctions?

A

Anchoring junctions, occluding junctions, channel-forming junctions and signal-relaying junctions.

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

What do anchoring junctions do?

A

Link cells together or to the extracellular matrix.

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

What do occluding junctions do?

A

Seal the gaps between cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What do channel-forming junctions do?

A

Create passageways linking the cytoplasm of adjacent cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What do signal-relaying junctions do?

A

Allow signals to be communicated from cell to cell.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What makes up an Adherens junction?

A

Actin filaments, caherins, alpha catenin and beta catenin.

21
Q

What do linker proteins do?

A

They allow a join between the actin cytoskeleton and the cadherins.

22
Q

What are desmosomes made up of?

A

Intermediate filaments, cadherins (desmoglein), plakoglobin and desmoplakin.

23
Q

What are focal adhesion points made up of?

A

Actin filaments, integrins and focal adhesion kinases.

24
Q

What are hemidesmosomes made up of?

A

Intermediate filaments, integrins/collagen and dystonin.

25
Q

What do cadherins do?

A

Mediate cell to cell attachment. They are transmembranic protiens that undergo homophilic adhesion.

26
Q

What does homophilic pairing mean?

A

It is the same molecules attaching to eachother.

27
Q

What do cadherins link to?

A

The actin filaments of the cytoskeleton. via linker proteins.

28
Q

How can epithelia bend to form a tube?

A

The contraction of the junctions might cause the layer of the epithelia to bend.

29
Q

What the formation of epithelial tubes important for?

A

The formation of neural tubes that form the brain and spine.

30
Q

What do desmosomes do?

A

Link cadherins to intermediate filaments of the cytoskeleton.

31
Q

What do hemidesmosomes do?

A

They anchor epithelial cells to the basal lamina.

32
Q

What is a condition caused by defective desmosomes?

A

Pemphigus vulgaris.

33
Q

What happens in pemphigus vulgaris?

A

It’s an autoimunuse disease that causes destruction of desmosomal protein. It causes severe blistering, dehydration and infection and in some cases death.

34
Q

What do occluding junctions do?

A

Seal gaps between epithelial cells.

35
Q

What is the barrier function of occluding junctions?

A

It regulates the passage of debris, water and macromolecules.

36
Q

What is the fence function of occluding junctions?

A

Maintaining cell polarity.

37
Q

What are the transmembrane proteins involved in the occluding junctions?

A

Claudin and occludin.

38
Q

What other benefit do occluding junctions provide?

A

They help to maintain cell polarity.

39
Q

What are some diseases associate with the loss of function of tight junctions?

A

The loss of barrier function can result in Crohn’s disease and the loss of fence function can result in cancer.

40
Q

How can molecules pass directly from cell to cell?

A

Channel-forming junctions can allows ions and small molecules to pass from cell to cell.

41
Q

How are gap junctions involved in cardiac muscle?

A

Gap junctions allow the passage of ions that allows changes in membrane potential to pass from cell to cell, resulting in rhythmic contraction of the heartbeat.

42
Q

What are gap junctions made up of?

A

Connexin proteins.

43
Q

How do connexins form gap junctions?

A

6 connexins associate together to have a tube before them that pair up with another set of 6 on the adjacent cells membrane.

44
Q

What is the benefit of gap junctions being able to be closed or opened?

A

Cells in the epithelium can coordinate what they do.

45
Q

What disorders can abnormal gap junctions result in?

A

Cataracts and Vohwinkel syndrome - in the syndrome connexin 26 is overexpressed and drives hyperproliferation of the epidermis.

46
Q

What are channel forming junctions in plants called?

A

Plasmodesmata.

47
Q

What is linked through plasmodesmata?

A

The ER.

48
Q

What do signal-relaying junctions allow?

A

Communication of signals between cells.

49
Q

What is a disorder of signal-relaying junctions?

A

Myasthenia Gravis - an autoimmune destruction of neuromuscular junction.

BB10005 (22 decks)

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