Epithelial Cells and Tissues Flashcards
What 3 things do tissues consist of?
- Cells
- ECM
- Fluid
What is extracellular matrix?
Insoluble deposits by cells
What 2 things does ECM consist of?
- Fibrillar proteins
- Hydrated gel
Where is ECM poorly vs highly organised?
- Poor: loose connective tissue
- High: tendon, bone, basal lamina
What are the 5 main cell types?
- Connective tissue
- Contractile
- Haematopoietic
- Neural
- Epithelial
What are the 6 types of tumours?
- Carcinomas (epithelial)
- Sarcomas (mesenchymal-connective/muscle)
- Leukemias (bone marrow)
- Lymphomas (lymphocytes)
- Neuroblastomas (neurones)
- Gliomas (glial)
What do epithelial cells do?
Line surfaces
- Transport
- Absorption
- Secretion
- Protection
What are the 3 types of epithelial cell shape?
- Squamous
- Cuboidal
- Columnar
What are the 2 types of epithelial cell layering?
- Simple
- Stratisfied
What are the 5 types of epithelium?
recognise images
- Simple squamous
- Simple cuboidal
- Simple columnar
- Stratified squamous
- Pseudo-stratified
Where are the 3 locations of simple squamous epithelium and why?
- Alveoli
- Mesothelium (major cavities)
- Bloos vessels
- Thin for gas exchange
What is the location of simple cuboidal epithelium?
Ducts
Where is simple columnar epithelium found?
Gut
- Absorption/secretion
What are the 2 types of stratified squamous epithelium and what are the differences in function, organelles, location, LM visibility?
Keratinised vs Non-keratinised
- Protective vs lining
- None vs all
- Epidermis (skin) vs mouth/oesophagus/anus/cervix/vagina
- Not visible vs visible
Where is pseudo-stratified epithelium found and how can it be identified?
- Trachea, bronchi, urinary ducts, reproductive ducts
- Looks multi-layered but all cells have contact with basal lamina
What are the 3 types of epithelium function?
- Transporting
- Absorptive
- Secretory
How do epithelial functions maintain directionality?
Plasma membrane polarity
What are the 2 domains for polarity in epithelial cells and how are they distinguished?
- Apical
- Lumenal side - Basolateral
- Basal lamina side (contact with ECM)
-Separated by cell-to-cell junction
How are transporter epithelial cells polarised and what is the result of this?
- Ion pumps all on 1 domain
- Net unidirectional flow of ions
How are secretory epithelial cells polarised and what is the result of this?
- Secretory vesicles all on 1 domain
- Net unidirectional flow of chemical
What are 3 adaptations of transporting epithelium?
- Many ion transporters
- Many mitochondria near transporters
- Folded membrane inc SA
What is the adaptation of secretory epithelium?
Mitochondria concentrated at basolateral domain end
What are the 2 adaptations of absorptive epithelium?
- Carrier proteins at brush-border membranes
- Villi to inc SA
What are the 2 types of secretory cells?
- Exocrine —> into duct/lumen
- Endocrine —> into bloodstream
How is secretory epithelium arranged?
Tubules
Glands
Individual
What is the difference between the organelle arrangement in exocrine vs endocrine secretory cells?
Exocrine: Nucleus at basal end and secretory vesicles at apical end
Endocrine: Nucleus at apical end and secretory vesicles at basal end
How are damaged/dead epithelial cells replaced?
Proliferation of stem cells in epithelium
How are epithelial cells lost from tips of intestinal villi replaced?
By cells in intestinal crypts
Why do some chemotherapies have gastro-intestinal side effects?
Inhibit proliferation of intestinal crypt cells —> villi not replaced —> flat intestinal mucosa
What can form when the rate of epithelial cell proliferation is higher than death?
Adenoma
Why might benign adenomas become cancerous?
High risk of acquiring mutations
How are cells lost from surface epidermis replaced? (stratified squamous epithelia)
Basal layer cells divide —> differentiate (squamous and keratinised) whilst migrating to skin surface
What forms when there is hyperproliferation of epidermis cells?
Skin lumps (corns/callouses/warts)
Which infection can induce hyperproliferation?
Papilloma virus
What are 2 examples of normal physiological hypoproliferations/hyperproliferations?
- Lose/make uterus lining during menstruation
- Make/lose epithelial glands in breast post-pregnancy
