Basic Cell Types

Question 1

What are the four basic tissue types?

Answer 1

Epithelial tissue
Supporting tissue
Muscular tissue
Nervous tissue

Question 2

What are epithelial tissues?

Answer 2

A diverse group of tissues including surface epithelia and solid organs

Question 3

What exactly do surface epithelium cover?

Answer 3

All body surfaces, cavities and tubes and are therefore the interface between different compartments

Question 4

What is the function of surface epithelium?

Answer 4

Containment, selective diffusion, absorption, secretion and physical protection

Question 5

What is cytokeratin and what is it involved in?

Answer 5

Cytokeratin is present in all epithelial cells as an intermediate filament and allows for recognition by immunohistochemistry

Question 6

All epithelium are supported by a…

Answer 6

basement membrane

Question 7

What does the basement membrane do?

Answer 7

Separates the epithelium from the underlying supporting tissue

Question 8

Blood vessels never cross epithelial basement membranes so how do epithelial cells obtain their needs?

Answer 8

They are dependent on diffusion of nutrients and oxygen from connective tissue for survial

Question 9

Epithelial cells are polarised, what does this mean?

Answer 9

One side faces the basement membrane and one side is towards the surface

Question 10

What is the side of the epithelial cell that faces the BM called and what is the side of the epithelial cell that faces the surface called?

Answer 10

The basal surface and the apical surface

Question 11

Epithelial cells are classified according to three morphological characteristics, what are these?

Answer 11

1. Number of cell layers
2. Shape of component cells
3. Presence of surface specialisations

Question 12

When epithelial cells are classified according to the number of cell layers, what does this mean?

Answer 12

They can either be simple which means they consist of one layer or they can be stratified which means they are multilayered

Question 13

When epithelial cells are classified according to the shape of the component cells what does this mean?

Answer 13

Based on appearance at right angles to the epithelial surface. They can be squamous, cuboidal or columnar - simple epithelia. In stratified the surface shape determines the name

Question 14

When epithelial cells are classified according to the presence of surface specialisations what does this mean?

Answer 14

It means the presence of specialisations such as cilia / keratin

Question 15

There are different types of simple epithelia, list them.

Answer 15

1. Simple squamous epithelium
2. Simple cuboidal epithelium
3. Simple columnar
4. Pseudostratified columnar ciliated epithelium

Question 16

Describe the structure of simple squamous epithelium

Answer 16

Flattened, irregular shaped cells forming a continuous surface often called pavemented epithelium

Question 17

Where are simple squamous epithelium found and why?

Answer 17

Found as lining surfaces involved in diffusion of gases .g. lungs or fluids e.g. blood capillaries

Question 18

Sometimes simple squamous epithelial cells are difficult to recognise because they are too flattened. How do they sometimes show up under the microscope?

Answer 18

They can only be recognised by the nucleus which bulges into the lumen

Question 19

What are simple cuboidal epithelial cells?

Answer 19

They are the intermediate between simple squamous and simple columnar

Question 20

Describe the nucleus in a simple cuboidal cell.

Answer 20

Round and located in the centre of the cell

Question 21

Where are simple cuboidal epithelium cells found and what functions do they play? Give an example

Answer 21

Line small ducts and may have excretory, secretory or absorptive functions, e.g. collecting tubules of kidney

Question 22

The cell borders in simple cuboidal cells are often indistinct so how would you be able to recognise these cells under a microscope?

Answer 22

The nuclei gives a clue to the cell shape, the nucleus is round and located in the centre of the cell

Question 23

Describe simple columnar epithelial cells

Answer 23

They are like cuboidal cells but they are taller

Question 24

Describe the nucleus in a simple columnar epithelial cell

Answer 24

They are elongated and may be located towards the base, apex or centre of the cytoplasm

Question 25

Where are simple columnar epithelial cells found and give examples?

Answer 25

On absorptive surfaces e.g. small intestine, gall bladder (absorbs water) or play a secretory role, e.g. the stomach

Question 26

Explain why the pseudostratified columnar ciliated epithelium are considered to be a true simple epithelium

Answer 26

All the cells rest on the basement membrane. The nuclei are all at different levels giving the appearance of different cell layers.

Question 27

Where are pseudostratified columnar ciliated epithelium found?

Answer 27

Confined to airways so known as respiratory epithelium.

Question 28

The pseudostratified columnar ciliated epithelium have cilia on them which propel the mucus to the pharynx, what is the term applied to this?

Answer 28

Mucociliary escalator

Question 29

What are stratified epithelia?

Answer 29

Defined as epithelia consisting of two or more layers

Question 30

What is the main function of stratified epithelia?

Answer 30

Mainly a protective function

Question 31

Why are stratified epithelia poorly suited for absorption and secretion?

Answer 31

Due to the thickness of all the cell layers

Question 32

What is the classification of stratified epithelium based on?

Answer 32

Cell shape and structure

Question 33

What are the three types of stratified epithelium mentioned on the lecture slides?

Answer 33

1. Stratified squamous epithelium 2. Stratified cuboidal epithelium 3. Transitional epithelium (urothelium)

Question 34

Describe stratified squamous epithelium

Answer 34

Flattened cells at the top (surface) and cuboidal cells at the base (basement membrane)

Question 35

Which type of stratified squamous epithelium constitute the epithelium of the skin?

Answer 35

Keratinising stratified squamous epithelium

Question 36

How are keratinising stratified squamous epithelium specialised for their function?

Answer 36

Specialised to withstand constant abrasion and desiccation due to touch non living surface layer composed of keratin wrapped in plasma membrane

Question 37

What happens to the nucleus of the epithelium of stratified squamous epithelium as they mature?

Answer 37

The nuclei are eventually lost

Question 38

Describe the structure of stratified cuboidal epithelium

Answer 38

Thin stratified epithelium usually two or three layers of cuboidal cells only

Question 39

Where are stratified cuboidal epithelium cells found?

Answer 39

Lining of larger excretory ducts of exocrine glands, e.g. salivary glands

Question 40

The stratified cuboidal epithelium is more robust than simple epithelium. Also, they are not involved in any significant

Answer 40

secretory or absorptive activity

Question 41

Where are transitional epithelium found?

Answer 41

Only in the urinary tract in mammals

Question 42

Why are transitional epithelium only found in the urinary tract?

Answer 42

Because they are highly specialised to accommodate stretch and the toxicity of urine

Question 43

What are the features of transitional epithelium like?

Answer 43

Intermediate between stratified squamous epithelium and stratified cuboidal epithelium

Question 44

Describe the structure of transitional epithelium found in the urinary tract when stretched and relaxed.

Answer 44

When relaxed, they are rounded and large (u - like an umbrella lol) when stretched the surface layers and intermediate layers are extremely flattened

Question 45

List three membrane specialisations of epithelia

Answer 45

1. Cilia 2. Microvilli 3. Goblet cells

Question 46

What are cilia?

Answer 46

Motile structures that project from the luminal surface of epithelial cells

Question 47

Where are cilia mostly found?

Answer 47

In the female reproductive tract and the respiratory tract

Question 48

Cilia may be how many micrometres long and a cell may have up to how many cilia?

Answer 48

10 micrometres, and a cell may have up to 300 cilia

Question 49

Are cilia easily seen via light microscopy?

Answer 49

Yasss!

Question 50

What are microvilli?

Answer 50

Minute fingerlike projections of the luminal plasma membrane found in epithelia that are specialised for absorption

Question 51

Up to how many times can microvilli increase the surface area?

Answer 51

x30 times

Question 52

Can cilia be resolved by a light microscope?

Answer 52

No and they appear as a brush border

Question 53

Give an example of where microvilli are found

Answer 53

The small intestine

Question 54

What are goblet cells?

Answer 54

Modified columnar epithelial cells that synthesise and secrete mucus

Question 55

Where are goblet cells found?

Answer 55

Scattered amongst many simple epithelia particularly the GI and respiratory tract

Question 56

What is PAS staining?

Answer 56

A staining method used to detect polysaccharides such as mucosubstances - glycoproteins, glycolipids

Question 57

What colour do goblet cells stain with PAS staining?

Answer 57

Bright pink

Question 58

Why do goblet cells stain bright pink with PAS staining?

Answer 58

Due to the secretions of mucus

Question 59

Epithelium that is primarily involved in secretory purposes is arranged into...

Answer 59

glands

Question 60

What are glands?

Answer 60

Invaginations of the epithelial surface which proliferate into the underlying connective tissue

Question 61

All glands have a continous basal rate of secretion which is then modulated by...

Answer 61

nervous and hormonal influences

Question 62

What are exocrine glands?

Answer 62

Glands that release their contents onto an epithelial surface either directly or via a duct

Question 63

Where are exocrine glands found?

Answer 63

Vary from microscopic swear glands of the skin to large solid organs such as the liver

Question 64

The exocrine glands are divided and classified according to two traits what are these?

Answer 64

The secretory component and the duct system

Question 65

The secretory component of a gland may be

Answer 65

tubular or acinar, coiled or branched

Question 66

The duct system of an exocrine gland may be

Answer 66

branched (compound) or unbranched (simple)

Question 67

Where are simple tubular glands found?

Answer 67

In the large intestine

Question 68

Describe a simple tubular gland

Answer 68

A single straight tubular lumen into which the secretory products are discharged - the secretory cells line the entire duct

Question 69

Give an example of a simple coiled tubular gland

Answer 69

Sweat glands are the only type of example

Question 70

Describe a simple coiled tubular gland

Answer 70

Tightly coiled in 3d so different portions are seen in each plane of section

Question 71

Where are simple branched tubular glands found?

Answer 71

Mainly in the stomach, mucus secreting glands

Question 72

Describe a simple branched tubular gland

Answer 72

Several tubular secretory portions which converge onto a single unbranched duct

Question 73

What are endocrine glands?

Answer 73

Glands that have lost their connection to the epithelial surface during development and release secretions directly into the blood

Question 74

Give an example of an endocrine gland

Answer 74

The thyroid gland

Question 75

What are secretions from endocrine glands mainly controlled by?

Answer 75

Metabolic factors such as glucose, secretion of other hormones and/or the nervous system

Question 76

Describe what endocrine glands look like

Answer 76

Contain clusters of secretory cells, each with their own basement membrane, surrounded by a rich network of blood vessels

Question 77

Where do endocrine glands release their secretions such as hormones?

Answer 77

Into the intercellular spaces from where they diffuse rapidly into the blood