Epithelia and skin

Question 1

What are the diameters of FOV for each objective lense?

Answer 1

x 4 = 4.5mm

x 10 = 1.8mm

x 40 = 0.45mm

Question 2

What are the different arrangements of epithelium?

Answer 2

1. Simple epithelium
2. Stratified epithelium

Question 3

What are the different types of simple epithelium?

Answer 3

1. Squamous (diffusion surfaces, e.g. alveoli, endothelium)
2. Cuboidal (absorption/secretion, e.g. small exocrine ducts, nephron)
3. Columnar (absorption/secretion, e.g. intestines, large exocrine ducts)
4. Pseudostratified (airway, e.g. trachea)

Question 4

What are the characteristics of transitional epithelium?

Answer 4

• Surface (umbrella) cells are large, dome-shaped and often overlap 2 or more cells beneath.
• Basal/intermediate cells are polygonal in shape and change size depending on distension.

Question 5

Where is transitional epithelium found?

Answer 5

• Bladder
• Ureters
• Parts of urethra

Question 6

How can cilia be distinguished from microvilli in EM?

Answer 6

Cilia contain microtubules while villi don’t

Question 7

What are the structures present in junctional complex?

Answer 7

1. Tight junction (zonula occludens)
2. Intermediate junction (zonula adherens)
3. Desmosome (macula adherens)
4. Gap junction

Question 8

What are the layers of skin?

Answer 8

1. Epidermis
2. Dermis
3. Hypodermis

Question 9

What are the layers of the epidermis?

Answer 9

1. Stratum corneum: Dead, flattened, innulceated cells full of keratin.
   (2. Stratum lucidum: Thick skin only)
2. Stratum granulosum: Cells containing dense cytoplasmic granules contributing to keratin formation.
3. Stratum spinosum: Cells containing cytoplasmic spines.
4. Stratum germinativum (stratum basale): Cuboidal cells anchored to the basement membrane that carry out active cell division.

Question 10

What type of epithelium is skin?

Answer 10

Stratified keratinised squamous epithelium

Question 11

What do the spines in the stratum spinosum represent?

Answer 11

Punctate desmosomes binding each adjacent cell

Question 12

What are the layers of the hair follicle?

Answer 12

1. External root sheath: Downward epidermal extension
2. Cuticle
3. Cortex
4. Medulla
5. Inner root sheath

Question 13

What structures are associated with the hair follicles?

Answer 13

• Sebaceous glands
• Arrector pili muscles

Question 14

What are the types of sweat glands?

Answer 14

1. Eccrine
2. Apocrine

Question 15

What is the function and location of Pacinian corpuscules?

Answer 15

Function: Detect deep pressure and vibration

Location: Hypodermis

Question 16

What type of epithelium is found in sweat glands?

Answer 16

• Secretory portion: Simple cuboidal epithelium
• Duct: Stratified (2 layers) cuboidal epithelium

Question 17

What are the places in the body that don’t have sweat glands?

Answer 17

• Lips
• External genitalia

Question 18

What is the function of the terminal web?

Answer 18

To allow for limited movement of cell apex and microvilli