University:
Glendale Community College
Course:
BIO160 | Introduction to Human Anatomy and Physiology
Academic year:

2020
Views:

493

Pages:

5
Author:

boltakvf

Skin Color (Pigmentation) Dark Skin Pale Skin • Melanin produced by melanocytes can be brown, black or reddish depending on the chemical composition of the melanin. Eumelanin is black or brown. Pheomelanin is reddish. • Hemoglobin is the red pigment of red blood cells. Dermal blood vessels can be visible through a pale epidermis. • Carotene is a yellow-orange pigment found in vegetables and egg yolks that can become concentrated in the stratum corneum and in subcutaneous fat. Abnormal Skin Colors • Albinism is a genetic lack of melanin. • Vitiligo is a patterned albinism thought to be caused by an autoimmune disorder that kills melanocytes in specific regions of the skin. • Hematoma is a bruise caused by clotted blood that escaped into the connective tissue of the dermis and hypodermis. Skin Markings • Hemangiomas (birthmarks) – discolored skin caused by benign tumors of dermal blood capillaries – strawberry birthmarks usually disappear in childhood – port wine birthmarks last for life • Freckles and Moles – aggregations of melanocytes – freckles are flat; moles are elevated Tattoo Ink in Dermis Skin Cancers • Skin cancer can be induced by UV rays of the sun and is most common in fair-skinned and elderly people. • Basal Cell Carcinoma – arises from keratinocyes in the stratum basale that transform and invade the dermis – treated by surgical removal and/or radiation • squamous cell carcinoma – arises from keratinocytes in the stratum spinosum – metastasis to the lymph nodes can be lethal • melanoma (most deadly skin cancer) – arises from melanocytes – ABCD: asymmetry, border irregular, color mixed, diameter over 6 mm