Epithelia

Question 1

What are epithelia?

Answer 1

Sheets of continuous cells, of varied embryonic origin, that cover the external surface of the body and line internal surfaces, including the blood vessels

Question 2

Where are Mucous membranes, what do they do?

Answer 2

Line certain internal tubes which open to the exterior

Have mucus secreting cells

Question 3

What are serous membranes?

What do they do?

Answer 3

• Thin, 2 part membranes which line certain closed body cavities
• Secrete a lubricating fluid that promotes friction-free movement of the structures they surround.

Question 4

Where are serous membranes found?

What do they consist of?

Answer 4

• Lining the Peritoneum, Pericardial sac, Pleural sacs

- Parietal Serosa and Visceral Serosa

Question 5

Describe Structure and Function of Simple Squamous Epithelium.
Identify 4 locations where this is found

Answer 5

• Single thin layer of flat epithelial cells. Fast material exchange, filtration
• Bowman’s capsule, Endothelium, Alevoli lining, Mesothelium (lining of closed body cavities

Question 6

Describe structure and function of Simple Cuboidal Epithelium
Identify 4 places this can be found

Answer 6

• Single layer of of cells as wide as they are tall. Absorption and Secretion
• Exocrine glands, Ovary, Kidney Tubules, Thyroid

Question 7

Describe the structure and function of Simple Columnar Epithelium
Identify 3 places this is found

Answer 7

• Single layer of tall cells in a row. Absorption, Secretion, Lubrication, Transport
• Small intestine, Stomach Lining, Oviduct

Question 8

Describe structure, explain appearance of Pseudostratified Epithelium

Answer 8

• 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.

Question 9

What are the functions of Pseudostratified Epithelia?

Identify 3 locations it is found

Answer 9

• Absorption, Mucus Secretion, Particle Trapping and removal
• Vas Deferens, Lining of nasal cavity, Trachea and Bronchi

Question 10

How are stratified Epithelia formed?

Where are they found?

Answer 10

• Basal cells divide and push towards apical surface, flattening apical cells.
• Found where body linings withstand mechanical/ chemical abrasion.

Question 11

What are the functions of Stratified Squamous Non-Keratinised Epithelia
Identify 6 locations where this is found

Answer 11

• Protection against abrasion, Reducing H2O loss but maintaining moisture
• Oral cavity
• Oesophagus
• Vagina
• Anal Canal
• Inner Eyelid
• Cornea Surface

Question 12

What are the functions of Transitional Epithelium?

Where is this found?

Answer 12

• Distensibility, Protection of underlying tissues from toxic chemicals
• Tissues that undergo distension (Bladder, Ureters, Urethra)

Question 13

What are the characteristics of transitional epithelium?

Answer 13

Appears stratified cuboidal/ columnar when tissue is unstretched
Appears stratified squamous when is tissue is stretched

Question 14

Name 6 Cell Surface Specialisations

Answer 14

Keratin
Cilia
Stereocilia
Goblet cells 
Club cells
Microfold cells

Question 15

How do Cl- ions affect Goblet cell production?
Which disease is thIs characteristic of?
What is the genetic basis for this disease?

Answer 15

Cl- deficiency causes sticky mucus.

Characteristic of Cystic Fibrosis due to mutation in CTFR gene

Question 16

Where are Club cells?

What do they do?

Answer 16

• At terminal bronchioles
• Secrete a substance that reduces surface tension between substances, detoxify harmful substances, Act as a stem cell, differentiating into ciliated cells.

Question 17

What do Microfold Cells do?

Answer 17

Trap pathogens, present to Lymphocytes and macrophages

Question 18

What are the cell renewal rates for Trachea, Alveoli, Goblet Cells, Club Cells

Answer 18

Trachea: 1-2 months
Alveoli: 8 days
Goblet Cells: 10 days
Club Cells: Never