What are epithelia?
Sheets of continuous cells, of varied embryonic origin, that cover the external surface of the body and line internal surfaces, including the blood vessels
Where are Mucous membranes, what do they do?
Line certain internal tubes which open to the exterior
Have mucus secreting cells
What are serous membranes?
What do they do?
- Thin, 2 part membranes which line certain closed body cavities
- Secrete a lubricating fluid that promotes friction-free movement of the structures they surround.
Where are serous membranes found?
What do they consist of?
- Lining the Peritoneum, Pericardial sac, Pleural sacs
- Parietal Serosa and Visceral Serosa
Describe Structure and Function of Simple Squamous Epithelium.
Identify 4 locations where this is found
- Single thin layer of flat epithelial cells. Fast material exchange, filtration
- Bowman’s capsule, Endothelium, Alevoli lining, Mesothelium (lining of closed body cavities
Describe structure and function of Simple Cuboidal Epithelium
Identify 4 places this can be found
- Single layer of of cells as wide as they are tall. Absorption and Secretion
- Exocrine glands, Ovary, Kidney Tubules, Thyroid
Describe the structure and function of Simple Columnar Epithelium
Identify 3 places this is found
- Single layer of tall cells in a row. Absorption, Secretion, Lubrication, Transport
- Small intestine, Stomach Lining, Oviduct
Describe structure, explain appearance of Pseudostratified Epithelium
- Single layer of tall columnar cells with nuclei appearing at different heights.
This is because all cells touch basement membrane, but not all reach apical surface.
What are the functions of Pseudostratified Epithelia?
Identify 3 locations it is found
- Absorption, Mucus Secretion, Particle Trapping and removal
- Vas Deferens, Lining of nasal cavity, Trachea and Bronchi
How are stratified Epithelia formed?
Where are they found?
- Basal cells divide and push towards apical surface, flattening apical cells.
- Found where body linings withstand mechanical/ chemical abrasion.
What are the functions of Stratified Squamous Non-Keratinised Epithelia
Identify 6 locations where this is found
- Protection against abrasion, Reducing H2O loss but maintaining moisture
- Oral cavity
- Oesophagus
- Vagina
- Anal Canal
- Inner Eyelid
- Cornea Surface
What are the functions of Transitional Epithelium?
Where is this found?
- Distensibility, Protection of underlying tissues from toxic chemicals
- Tissues that undergo distension (Bladder, Ureters, Urethra)
What are the characteristics of transitional epithelium?
Appears stratified cuboidal/ columnar when tissue is unstretched
Appears stratified squamous when is tissue is stretched
Name 6 Cell Surface Specialisations
Keratin Cilia Stereocilia Goblet cells Club cells Microfold cells
How do Cl- ions affect Goblet cell production?
Which disease is thIs characteristic of?
What is the genetic basis for this disease?
Cl- deficiency causes sticky mucus.
Characteristic of Cystic Fibrosis due to mutation in CTFR gene
Where are Club cells?
What do they do?
- At terminal bronchioles
- Secrete a substance that reduces surface tension between substances, detoxify harmful substances, Act as a stem cell, differentiating into ciliated cells.
What do Microfold Cells do?
Trap pathogens, present to Lymphocytes and macrophages
What are the cell renewal rates for Trachea, Alveoli, Goblet Cells, Club Cells
Trachea: 1-2 months
Alveoli: 8 days
Goblet Cells: 10 days
Club Cells: Never
