Histology: Epithelial tissue

Question 1

Define the characteristics and types of epithelia

Answer 1

• Epithelia line and cover all body surfaces. Its derived from the ectoderm, mesoderm, and endoderm.
• Cells tightly bound together and rest on basement membrane.
• Nutrients delivered by diffusion.
• Protection, Absorption, Secretion, Excretion, Gas exchange

Question 2

Identify and describe the classifications of epithelia and relate to function and location

Answer 2

1) Simple squamous - Lining of vascular system, Body cavities, Bowman’s capsules, Lining of respiratory spaces in lung - Exchange, barrier in central nervous system, Lubrication
2) Simple cuboidal - Small ducts of exocrine glands, surface of ovary, kidney tubules - Absorption, Conduit, Barrier
3) Simple columnar - Lining of small intestine & colon, Stomach lining & Gastric glands, Lining of gallbladder - Absorption, Secretion
4) Pseudostratified - Lining of trachea & Bronchi, Ductus deferens, Efferent ductules of epididymis - Secretion, Conduit
5) Stratified squamous - Epidermis, Lining of oral cavity and esophagus, Lining of Vagina - Barrier, Protection
6) Stratified cuboidal - Sweat gland, Ducts, Largest ducts of exocrine glands, Anorectal junction - Barrier, Conduit
7) Stratified columnar - Largest ducts of exocrine glands and Anorectal junction - Barrier, Conduit
8) Transitional - Renal calyces, Ureters, Bladder, Urethra - Barrier, Distensible property

Question 3

Describe cell adhesion mechanisms and relate to function and location

Answer 3

Desmosomes & Hemi-Desmosomes
Tight Junctions
Gap Junction

Question 4

Differentiate histologically the features of skin and buccal epithelia

Question 5

Identify that epithelial cells can be specialised cells serving structural and endocrine functions