MCB Lecture 36 Epithelial Tissue Flashcards Preview

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Flashcards in MCB Lecture 36 Epithelial Tissue Deck (55)
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Define organs

Coordination of tissues

1

Define tissues

Coordination of cell types

2

What are the different types of tissue? (5)

Epithelial
Connective
Blood/lymphatic
Muscle
Nervous

3

Where is epithelial tissue found?

Lining external and internal surfaces and ducts

4

What are the different morphologies of epithelial tissues?

Simple
Stratified
Pseudostratified


Columnar
Cuboidal
Squamous

5

What type of morphology are the epithelial cells in blood vessels?

Simple squamous

6

What type of morphology are the epithelial cells in intestine?

Simple columnar

7

What type of morphology are the epithelial cells in skin?

Stratified squamous

8

What type of morphology are the epithelial cells in the respiratory tract?

Ciliated pseudo stratified

9

Describe how the epithelium in the respiratory tract provides protection

The cells secrete mucous that traps dirt and detritus.
The cilia beat up, moving the mucous up to the mouth where it is swallowed and excreted

10

What are two genetic mutations that cause problems in the respiratory epithelium?

1. Mutation in Dynein, preventing the cilia from beating
2. Cystic fibrosis: ion channel mutation, mucous is too thick to be moved up

11

Describe the function of the epithelium in the digestive tract

Villi to increase surface area
Absorption of nutrients at apical end: active transporter
Basal end: passive transporters, nutrients move down diffusion gradient into the blood stream

12

Describe the polarisation of epithelial cells

The position of the nucleus

Also, apical end and basal end

13

What are the different types of cell junctions? (5)

1. Tight
2. Gap
3. Adherens
4. Desmosomes
5. Focal adhesions
6. Hemi desmosomes

14

Where are tight junctions localised?

Near the apical region of a cell

15

What is the function of tight junctions?

They prevent movement of materials between two cells

16

Describe the structure of tight junctions

Interaction between the proteins on the two adjacent cells
Claudin
Occludin

17

What is the function of Claudin and occludin?

These are the proteins presented on the outermembrane of cell that form tight junctions, preventing movement of materials between cells

18

What is the function of Adherens junctions?
(3)

1. Sticks cells together
2. Epithelial folding
3. Cell sorting

19

Describe the structure of Adherens junctions. Which protein is involved?

Classical cadherin proteins are involved. The cadherins on adjacent cells interact at the N terminus
Linker proteins connect the cadherins to the actin filaments inside the cell

20

Between which two things are Adherens junctions present?

Two cells

21

Cadherin interaction is ... dependent

Calcium

Without calcium, the cadherin chains are floppy and can't interact with the cadherins of the adjacent cell

22

What are junctional complexes?

These are the localisation of certain types of junctions in certain regions

A single cell can have different types of junctions

23

How does cadherin interact with the cell membrane and actin?

Through linker proteins

24

How do two cadherins interact?

At the N terminus

25

What are some of the linker proteins that connect cadherin to actin

Catenins
Alpha and beta

26

Describe the process of epithelial folding

There is a belt of actin and Adherens junctions in the apical region of cells
This belt contracts, and an invagination forms
This pinches off to form a tube

27

Describe Adherens junctions role in cell sorting

Cells presenting Adherens junctions will stick together
In this way, certain cells are grouped together

28

Which cell secretes mucus into the respiratory lumen?

Goblet cells

29

The epithelium in which two organs is important for absorption?

Kidneys
Small intestine

30

What are some generally features of the apical region of epithelial cell?

Absorption
Secretion
Ciliation

31

What are some generally features of the basal end of epithelium?

Adhesion to ECM
Diffusion of materials
Secretion into sub mucosa

32

In polarised cells, organelles are ...

Differentially distributed, polarised

33

How do tight junctions affect the polarity of membranes?

It separates the different ends of the membrane.
Eg. The cilia and the basal end

34

Which junction is vital for the apical-basolateral polarity?

Tight junctions

35

What sort of binding is there between Claudin and occludin in tight junction?

Non covalent

36

The more tight junction proteins, ...

The more impermeable

37

Why are Adherens junction said to be homophobic?

Interaction between with of the same molecule, classical cadherin

38

What gives skin it's high tensile strength?

Hemidesmosomes

39

Integrins will not engage ECM unless...

There is signalling

Eg. Activation of tallin

40

Outside - in signalling in focal adhesions requires other kinases because ...

What are these other kinases?

Because the integrins don't have kinase regions

FAK

41

Describe the tissue structure of the alimentary tract

Columnar epithelium
Basement membrane
Connective tissue (fibroblasts, collagen etc)
Muscle layer
Connective tissue
Surrounding layer of epithelium

42

What is transitional epithelium?

This is epithelium that has a different appearence depending on the state of the organ.

Ie, it can look squamous when stretched and cuboidal in the unstretched state

43

What is pseudo stratified epithelium?

All the cells connect to the basement, however, not all cells extend to the apical surface

44

What are the cell types in the respiratory tract?

Nucleates cells
Goblet cells (mucous secreting)
Basal cells (stem cells)

45

What type of epithelium is the thyroid?

Simple cuboidal

46

What type if epithelium is the bladder?

Transitional

47

What is the name of the disorder in which the cilia are immobile?

Kartagener's syndrome

48

A Claudin molecule in a tight junction bonds ... with a ... molecule

Non-electrostatic ally


Claudin

49

Which junctions are important for organogenesis?

Adherens junctions: epithelial folding and cell sorting

50

Which cadherin family proteins are present in Desmosomes?

Desmoglein
Desmocollin

51

Describe which junctions intermediate filaments connect to, and how they do so

Desmosomes: connects to the side of intermediate filaments
Hemidesmosomes: connects to the ends of intermediate filaments

52

What are the linker proteins in Desmosomes?

Desmoplakin
Plakoglobin
Plakophilin

53

How does inside out signalling affect outside-in signalling?

Once an ECM protein has been engaged through inside-out signalling, outside in signalling occurs

54

What sort of processes does outside-in signalling result in?

Change in gene expression:
- migration
- differentiation
- proliferation

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