Study Set Content:
Cleavage lines, or tension lines, in the skin, are more resistant to
stretch
If the skin is overstretched for any reason, the dermis can be damages, leaving
stretch marks
- are projections toward the epidermis found in the upper part of the dermis.
Dermal papillae
The dermal papillae contain many
blood vessels
The dermal papillae in the palms of the hands, the soles of the feet, and the tips of the digits are arranged in parallel, curving ridges that shape the overlying epidermis into
footprints and fingerprints
Factors that determine skin color include
- pigments in the skin, blood circulating through the skin, and the thickness of the stratum corneum.
The two primary pigments are
melanin and carotene
is the group of pigments primarily responsible for skin, hair, and eye color.
Melanin
- is a yellow pigment found in plants such as squash and carrots.
Carotene
Most melanin molecules are
brown to black
but some are
yellowish or reddish
Melanin provides protection against
ultraviolet light from the sun
Melanin is produced by
melanocytes
Melanin is produced by melanocytes and then packages into vesicles called
melanosomes
- phagocytize the tips of the melanocyte cell processes, thereby acquiring melanosomes.
Epithelial cells
Large amounts of melanin form
freckles or moles
Melanin production is determined by
genetic factors, exposure to light and hormones
Although many genes are responsible for skin color, a single mutation can prevent the production of melanin and cause
albinism
- is lipid-soluble; when consumed, it accumulates in the lipids of the stratum corneum and in the adipocytes of the dermis and subcutaneous tissue.
Carotene
If large amounts of carotene are consumed, the skin can become quite
yellowish
