Epithelial Cells and Tissues

Question 1

What 3 things do tissues consist of?

Answer 1

1. Cells
2. ECM
3. Fluid

Question 2

What is extracellular matrix?

Answer 2

Insoluble deposits by cells

Question 3

What 2 things does ECM consist of?

Answer 3

1. Fibrillar proteins
2. Hydrated gel

Question 4

Where is ECM poorly vs highly organised?

Answer 4

• Poor: loose connective tissue
• High: tendon, bone, basal lamina

Question 5

What are the 5 main cell types?

Answer 5

1. Connective tissue
2. Contractile
3. Haematopoietic
4. Neural
5. Epithelial

Question 6

What are the 6 types of tumours?

Answer 6

1. Carcinomas (epithelial)
2. Sarcomas (mesenchymal-connective/muscle)
3. Leukemias (bone marrow)
4. Lymphomas (lymphocytes)
5. Neuroblastomas (neurones)
6. Gliomas (glial)

Question 7

What do epithelial cells do?

Answer 7

Line surfaces
- Transport
- Absorption
- Secretion
- Protection

Question 8

What are the 3 types of epithelial cell shape?

Answer 8

1. Squamous
2. Cuboidal
3. Columnar

Question 9

What are the 2 types of epithelial cell layering?

Answer 9

1. Simple
2. Stratisfied

Question 10

What are the 5 types of epithelium?
recognise images

Answer 10

1. Simple squamous
2. Simple cuboidal
3. Simple columnar
4. Stratified squamous
5. Pseudo-stratified

Question 11

Where are the 3 locations of simple squamous epithelium and why?

Answer 11

1. Alveoli
2. Mesothelium (major cavities)
3. Bloos vessels
   - Thin for gas exchange

Question 12

What is the location of simple cuboidal epithelium?

Answer 12

Ducts

Question 13

Where is simple columnar epithelium found?

Answer 13

Gut
- Absorption/secretion

Question 14

What are the 2 types of stratified squamous epithelium and what are the differences in function, organelles, location, LM visibility?

Answer 14

Keratinised vs Non-keratinised
- Protective vs lining
- None vs all
- Epidermis (skin) vs mouth/oesophagus/anus/cervix/vagina
- Not visible vs visible

Question 15

Where is pseudo-stratified epithelium found and how can it be identified?

Answer 15

• Trachea, bronchi, urinary ducts, reproductive ducts
• Looks multi-layered but all cells have contact with basal lamina

Question 16

What are the 3 types of epithelium function?

Answer 16

1. Transporting
2. Absorptive
3. Secretory

Question 17

How do epithelial functions maintain directionality?

Answer 17

Plasma membrane polarity

Question 18

What are the 2 domains for polarity in epithelial cells and how are they distinguished?

Answer 18

1. Apical
   - Lumenal side
2. Basolateral
   - Basal lamina side (contact with ECM)

-Separated by cell-to-cell junction

Question 19

How are transporter epithelial cells polarised and what is the result of this?

Answer 19

• Ion pumps all on 1 domain
• Net unidirectional flow of ions

Question 20

How are secretory epithelial cells polarised and what is the result of this?

Answer 20

• Secretory vesicles all on 1 domain
• Net unidirectional flow of chemical

Question 21

What are 3 adaptations of transporting epithelium?

Answer 21

• Many ion transporters
• Many mitochondria near transporters
• Folded membrane inc SA

Question 22

What is the adaptation of secretory epithelium?

Answer 22

Mitochondria concentrated at basolateral domain end

Question 23

What are the 2 adaptations of absorptive epithelium?

Answer 23

1. Carrier proteins at brush-border membranes
2. Villi to inc SA

Question 24

What are the 2 types of secretory cells?

Answer 24

1. Exocrine —> into duct/lumen
2. Endocrine —> into bloodstream

Question 25

How is secretory epithelium arranged?

Answer 25

Tubules Glands Individual

Question 26

What is the difference between the organelle arrangement in exocrine vs endocrine secretory cells?

Answer 26

Exocrine: Nucleus at basal end and secretory vesicles at apical end Endocrine: Nucleus at apical end and secretory vesicles at basal end

Question 27

How are damaged/dead epithelial cells replaced?

Answer 27

Proliferation of stem cells in epithelium

Question 28

How are epithelial cells lost from tips of intestinal villi replaced?

Answer 28

By cells in intestinal crypts

Question 29

Why do some chemotherapies have gastro-intestinal side effects?

Answer 29

Inhibit proliferation of intestinal crypt cells ---> villi not replaced ---> flat intestinal mucosa

Question 30

What can form when the rate of epithelial cell proliferation is higher than death?

Answer 30

Adenoma

Question 31

Why might benign adenomas become cancerous?

Answer 31

High risk of acquiring mutations

Question 32

How are cells lost from surface epidermis replaced? (stratified squamous epithelia)

Answer 32

Basal layer cells divide ---> differentiate (squamous and keratinised) whilst migrating to skin surface

Question 33

What forms when there is hyperproliferation of epidermis cells?

Answer 33

Skin lumps (corns/callouses/warts)

Question 33

Which infection can induce hyperproliferation?

Answer 33

Papilloma virus

Question 34

What are 2 examples of normal physiological hypoproliferations/hyperproliferations?

Answer 34

1. Lose/make uterus lining during menstruation 2. Make/lose epithelial glands in breast post-pregnancy