Building Tissues from Cells

Question 1

What are the X4 main types of adult tissue?

Answer 1

Epithelial
Connective
Muscle
Nervous

Question 2

Where are epithelial cells found?

Answer 2

As part of the epithelium at the bodies surfaces (GI tract/epidermis) or surfaces that separate body cavities (endothelium in blood vessels).

Question 3

What do epithelial cells rest on?

Answer 3

A basement membrane.

Question 4

What is the basement membrane comprised of?

Answer 4

Extracellular matrix.

Question 5

What is another name for the basement membrane?

Answer 5

Basal lamina.

Question 6

Why does the epithelium rely on its luminal cell surfaces for nutrients?

Answer 6

The luminal surfaces are open to liquids, which is the way the epithelial obtain nutrients seeing as blood vessels NEVER cross the basement membrane.

Question 7

In which layer of tissue types do they blood vessels run?

Answer 7

The connective tissue layer.

Question 8

What are the X4 ways in which epithelial tissue can be classified?

Answer 8

• Cell shape
• Structure of the layers
• Surface specialisations
• Location of the tissue and its function

Question 9

What is a squamous cell shape?

Answer 9

Flattened and parallel to the basement membrane

Question 10

What is a columnar cell shape?

Answer 10

Long and tall like a column.

Question 11

What is a cuboidal cell shape?

Answer 11

Square like a cuboid.

Question 12

What does it mean if the cell layers is simple?

Answer 12

The epithelial sheet is a single layer of cells.

Question 13

What is a stratified cell layer structure?

Answer 13

There is a single basally attached (to the basement membrane) layer of epithelial cells which have proliferated to form multiple layers of daughter cells which extend to the luminal/apical surface layer.

Question 14

What is a pseudostratified cell layer structure?

Answer 14

It is a simple structure (X1 cell thick layer) but has the appearance of being stratified.

Question 15

On what surface of the epithelial cell are cell surface specialisations found, basal or apical/luminal?

Answer 15

Apical/luminal.

Question 16

What are X3 examples of surface specialisations?

Answer 16

Ciliated cells (cilia)
Brush boarders (microvilli)
Keratinised cells = stratified epithelium consisting of squames (dead keratinised cells)

Question 17

What are the characteristics of respiratory epithelia?

Answer 17

Columnar cells
Psuedostratified
With cilia and goblet cells

Question 18

How are glands related to the epithelial layer?

Answer 18

Glands are invaginations of the epithelial layer.

Question 19

Where do exocrine glands secrete their fluid to?

Answer 19

To a free surface

Question 20

Where do endocrine glands secrete to?

Answer 20

The blood stream

Question 21

Name X3 types of exocrine secretion mechanisms.

Answer 21

• Merocrine
• Apocrine
• Holocrine

Question 22

Explain merocrine release.

Answer 22

secretory product is bound in vesicles which merge with the cell membrane and release their contents via normal exocytosis.

Question 23

Explain apocrine release.

Answer 23

The secretory product is NOT vesicle bound and so the cell membrane creates a vesicle as it reaches the edge of the cell. The product therefore leaves the cell in a vesicle.

Question 24

Explain holocrine release.

Which are the only type of glands to utilise this type of release?

Answer 24

The whole cell breaks down and discharged it’s secretory content.

The only glands that do this are the sebaceous glands of the skin.

Question 25

Name the X4 types of cell junction?

Answer 25

• Tight junctions
• Adherents junctions
• Desmosomes
• Gap junctions
• Hemidesmosomes

Question 26

Which cell junctions are anchoring ones?

Answer 26

Adherens, desmosomes and hemidesmosomes

Question 27

Which cell junctions are non-anchoring ones?

Answer 27

Tight and gap.

Question 28

How do desmosomes and hemidesmosomes work?

Answer 28

They are junctions which anchor the cell to other cells (desmosomes) and to the basement membrane (hemidesmosomes) via intermediate filaments.

The only intermediate filament in epithelia is keratin.

Question 29

Which type of cell adhesion molecules do desmosomes use?

What do each of these do and where are they located?

Give X2 names of each type of molecule found in desmosomes.

Answer 29

Cadherins
= bridge between the cells
= demoglein
= desmocollin

Catenins
= link the cadherins to the intermediate filaments
= desmoplakin
= plakoglobin

Question 30

What type of adhesion molecules do hemidesmosomes use?

Answer 30

Integrins - these bridge the gap between the intermediate filaments in the epithelial cells and the ecm proteins (such as laminin or fibronectin). The intermediate filaments are joined to the integrins via plectin.

Question 31

What are focal adhesions?

Answer 31

These are similar to hemidesmosomes in that they link the epithelial cells to the ecm. They differ in that the integrins that link the two cells do NOT bind to IF’s in the epithelial cell, but rather actin.

Question 32

What structures in the epithelial cell are involved in adherens junctions?

Answer 32

Actin filament bundles

Question 33

What type of cell adhesion molecules link adjacent epithelial cells via adherens junctions?

Answer 33

Cadherins (E-cadherin)

Question 34

What cell adhesion molecules link the actin filament bundles to the cadherin molecules in adherens junctions?

Answer 34

Catenin (alpha and beta) and P120

Question 35

What is another name for tight junctions, and why?

Answer 35

Occludens junctions, as one of the proteins that links cells in tight junctions is called occludin.

Question 36

What X2 proteins link adjacent cells in tight junctions?

Answer 36

Claudius

Occludins