Skin

Question 1

In which epidermal layer are cells undergoing mitosis?

Answer 1

Stratum basale/Stratum germinativum

Question 2

The malphigian layer is another name for which epidermal layer?

Answer 2

Stratum basale/Stratum germinativum

Question 3

What are the nodes of Bizzozero?

Answer 3

Slight thickenings at the site of desmosomes between keratinocytes in the stratum spinosum as seen with a light microscope

Question 4

What are tonofilaments?

Answer 4

bundles of groups of keratin intermediate filaments

Question 5

In which epidermal layer do cells begin to die by losing their nuclei and cytoplasmic organelles?

Answer 5

Stratum granulosum

Question 6

What is the functional importance of the contents of keratohyalin granules and lamellar granules?

Answer 6

Keratohyalin granules contain keratin and other related proteins while lamellar granules contain lipids. Both types of granules release their contents out of the keratinocytes in the stratum granulosum to form a sheet that acts as a barrier to penetration and prevents water loss

Question 7

The amino acid from which melanin is synthesized is…?

Answer 7

Tyrosine

Question 8

What causes Psoriasis?

Answer 8

When T-cells attack skin cells, causes skin to respond by producing more skin cells than are shed, resulting in a shiny scale-like appearance

Question 9

In which epidermal layers are melanocytes located?

Answer 9

between stratum basale and stratum spinosum

Question 10

Name 2 functions of melanin.

Answer 10

1. Gives skin dark color

2. Protects cell nuclei from UV radiation

Question 11

What is the mechanism behind Addison’s disease causing hyperpigmentation?

Answer 11

Adrenal gland fails to produce enough cortisol and aldosterone.
Pituitary gland compensates by producing ACTH which is derived from a precursor of MSH.
More MSH is produced so that there is more production of melanin pigment.

Question 12

What is the precursor of Melanocyte Stimulating Hormone?

Answer 12

POMC - Propiomelanocortin

Question 13

Differentiate Albinism from Vitiligo.

Answer 13

In albinism, the melanocytes are present but there is a defect in tyrosinase or in the metabolic pathway of melanin synthesis so no melanin produced.
In vitiligo, the melanocytes disappear completely.

Question 14

Differentiate Malignant Melanoma from Merkel Cell Carcinomas.

Answer 14

Malignant Melanomas are cancers of melanocytes, while Merkel Cell Carcinomas are cancers of Merkel cells which are very rare.

Question 15

Explain how melanin is synthesized.

Answer 15

1. Tyrosinase converts tyrosine into DOPA (3,4-dihydroxyphenylalanine)
2. DOPA undergoes polymerization into the different kinds of melanin

Question 16

In which layer of the epidermis are Langerhans cells found?

Answer 16

All layers but most prominent in stratum spinosum

Question 17

Epidermal pegs interdigitate with ______________ of the dermis.

Answer 17

Epidermal pegs interdigitate with dermal papillae of dermis

Question 18

Differentiate Bullous Pemphigoid from Pemphigous.

Answer 18

In bullous pemphigoid, immune system attacks fibers connecting dermis and epidermis.
In pemphigous, immune system attacks desmosomes of keratinocytes.

Question 19

State the difference in the connective tissue found in the dermal papillary versus the reticular layer?

Answer 19

Papillary layer; loose areolar CT

Reticular layer; dense irregular CT

Question 20

What type of collagen is found in the papillary layer of the dermis?

Answer 20

Type 1, 3, and 7.

Question 21

What plexus supplies the epithelium of the epidermis?

Answer 21

The subpapillary plexus that extends into the dermal papillae just below the epidermis.

Question 22

What is the function of the arteriovenous anastomoses/shunts?

Answer 22

Thermoregulatory function; constriction during cold weather and dilation during hot weather

Question 23

What is the difference between unencapsulated nerve endings and encapsulated nerve endings?

Answer 23

Unencapsulated nerve endings - have no collagenous covering or Schwann cells
Encapsulated nerve endings - have collagenous covering and/or Schwann cells

Question 24

Name 3 types of unencapsulated nerve endings and their functions.

Answer 24

1. Merkel cells - pressure and texture of objects
2. Root hair plexuses - sense movement of hairs
3. Free nerve endings - for pain, itching, and high/low temperature