Epithelium 1

Front 1

What are the main functions of epithelia?

Back 1

1. Cover body surfaces (internally and externally)
2. Boundary or interface (protect, absorb, transport, excretion, secretion, sensory reception, etc.)
3. Form all of glands in the body, both exocrine and endocrine

Front 2

What are the main characteristics of epithelia?

Back 2

1. Cellularity - lots of cells with very little extra cellular material and/or space
2. Specialised contact between cells - cell junctions
3. Polarity - apical, lateral and basal domains
4. Basal lamina (basement membrane) – all epithelia sit on a basal lamina sometimes called the Basement membrane but they are not exactly the same thing – more on this later
5. Supported by underlying connective tissue (lamina propria).
6. Avascular - receives nutrition from underlying connective tissue
7. Innervated - responds to stimuli (touch, pain, heat etc.)
8. Regeneration - can repair itself
9. Cell membrane specialisations - microvilli, cilia.

Front 3

What are the seven most common types of epithelia?

Back 3

1. Simple squamous
2. Stratified squamous
3. Simple cuboidal
4. Simple columnar
5. Pseudostratified ciliated columnar with goblet cells
6. Urinary or transitional

Front 4

What is simple squamous epithelium?
- appearance
- function
- where it is found in the body

Back 4

- Flat, interlocking
- Wider than tall
- Elongated nuclei
- One cell thick
- Function: smooth, frictionless surface for rapid diffusion
- Found in lungs, glomerulus of kidneys, capillaries (endothelium) and on the external surfaces of many organs such as lungs, GIT, heart = mesothelium

Front 5

What is simple cuboidal epithelium?
- appearance
- function
- where it is found in the body

Back 5

Round and centrally placed nucleus,
Cells are square with all cells in contact with the basement membrane.
Lines many ducts, renal tubules, thyroid follicles and parenchyma of most exocrine glands.
Secretory, excretory or absorptive functions. Apical (free) surface often has microvilli.

Front 6

What is simple columnar epithelium?
- appearance
- function
- where it is found in the body

Back 6

Cells are elongated with all cells contacting the basement membrane.
Their nuclei are elongated (oval shaped) usually found in a basal position forming a single row.
It is a common epithelium found lining the parts of the GIT, reproductive system and the larger ducts.
They may have microvilli and therefore play an absorptive and/or secretory role (eg small intestine). If ciliated they may also play a role in transport of surface fluids and structures (e.g. Uterine tube and the transport of the oocyte).

Front 7

What is psuedostratified columnar ciliated epithelium?
- appearance
- function
- where it is found in the body

Back 7

- Nuclei are arranged irregularly = appearance of multiple layers
- All cells touch basement membrane
- Found in the upper respiratory tract with cilia
- Involved in movement of surface fluids, absorption and secretion
- Non-ciliated type found in some of male reproductive ducts

Front 8

What is stratified squamous epithelium?
- appearance
- function
- where it is found in the body

Back 8

- Many laters of nuclei
- Progressive change in nuclear shape (classified according to shape of surface cells)
- Can be keratinised (e.g. skin)
- Found in skin, mouth, vagina and anal canal
- Cells at basement membrane are mitotically active

Front 9

What is stratified cuboidal epithelium?
- appearance
- function
- where it is found in the body

Back 9

- RARE
- 2-3 layers of cuboidal/columnar cells
- Line large excretory ducts of endocrine glands
- Found in parts of female reproductive system
- Provides robust strucutre

Front 10

What is stratified columnar epithelium?

Back 10

- RARE
- 2-3 layers
- Found in parts of pharynx, larynx, conjunctiva of eyelids, large exocrine ducts & parts of male urethra

Front 11

What is transitional epithelium?

Back 11

- Found in excretory passages of the urinary system (renal calyces & pelvis, ureters and bladder)
- Dome shaped or rounded cuboidal cells on surface
- Irregular shaped nuclei