Ch. 5.2-5.4 Skin Color, Sunlight, & EFG

Question 1

Carotene

Answer 1

• orange-yellow pigmant that accumulates in epidermal cells.
• Most apprent in stratum corneum of light-skinned individuals
• Also in fatty tissues of deep dermis and subcutaneous layer
• Can be converted to Vitamin A

Question 2

Melanocytes

Answer 2

• Located in stratum basale, between or deep to epithelial cells
• Convert tyrosine into melanin
• Package it into melanolsomes - intracellular vesicles - and transferred into keratinocytes
  
  • In dark skinned, transfer also occurs in stratum ganulosum - pigmentation thus more persistant
• Melanocytes: basal cells between 1:4 - 1:20 and same across individuals. Only activity differs.
• Synthesis peaks 10 days after sun exposure

Question 3

Freckles

Answer 3

areas with irregular borders with normal melanocytes that have higher synthetic actvity

Question 4

Lentigos

Answer 4

Have regular borders and contain abnormal melanocytes

Question 5

senile lentigos (liver spots)

Answer 5

variably pigmented areas that develop on sun-exposed skin of older individuals

Question 6

UV Radiation

Answer 6

Stimulates epidermal production of compounds for calcium ion homeostatis

UVA: least harmful

UVB:

UVC: germicide; most harmful. Highest frequency. Cannot pass intact ozone.

Question 7

hemoglobin

Answer 7

pigment in red blood cells

Question 8

Jaundice

Answer 8

Liver cannot excrete bile; yellowish pigment accumulates in body fluids. Skin and whites of eyes can turn yellow in advanced stages.

Question 9

Melanocyte-stimulating hormone

Answer 9

Tumors affecting pituitary gland. Hormome causes darkening of the skin (hyperpigmentation)

Question 10

Addison’s disease

Answer 10

pituitary gland secretes large quantities of adrenocorticotropic hormone (ACTH), similar to MSH

Question 11

Vitiligo

Answer 11

Individuals lose melanocytes, causing white spots. Tied to thyroid gland disorders; possible mAbs attacking melanocytes.

Question 12

cholecalciferol

Answer 12

Vitamin D₃

epidermal cells in stratum basale convert a steroid into this.

Question 13

calcitrol

Answer 13

Hormone produced by the kidneys.

The liver converts cholecalciferol into an intermediate product used by the kidneys to synthesize this hormone.

Essential for the normal absorption of calcium and phosphorus in the small intestines.

Question 14

Rickets

Answer 14

Caused by a lack of cholecalciferol (Vitamin D₃). Inadequate calcium and phosphorus absorption in the small intestine leads to inadequate bone growth and maintenance in children.

Question 15

Epidermal growth factor (EFG)

Answer 15

• Peptide. Affects epidermis, and other epithelia.
• Used to stimulate epithelial growth/tissue culture (epidermal burn sheets)
• Produced by salivary glands and glands of duodenum

1. Promote division of basal cells in stratum basale and stratum spinosum
2. Accelerates the production of keratin in differentiating keratinocytes
3. Stimulates epidermal development and repair
4. Stimulates synthetic activity & gland secretion

Question 16

Moles & Warts

Answer 16

Benign tumors of the skin

Question 17

actinic keratosis

Answer 17

a scaly area on sun-damaged skin. An indication that sun damage has occured. Not a sign of skin cancer.

Question 18

basal cell carcinoma

Answer 18

• A cancer that originates in stratum basale
• most common
• Least malignant
• Sun exposure and genetic

Question 19

Squamous cell carcinoma

Answer 19

• Restricted to areas of sun-exposed skin
• Metastasis seldom occurs
• Involves keratinocytes of stratum spinosum

Question 20

malignant melanoma

Answer 20

• cancerous melanocytes grow rapidly and metastasize in lymphatic system.

Question 21

ABCD Rule

Answer 21

To identify a malginant melanoma:

A - asymmetry

B - border (irregular or notched)

C - color (mottled, with combination of tones)

D - diameter (more than 5mm ~eraser pencil).