A&P Honors: Ch. 5.4 — Melanin, Carotene, and Hemoglobin

What is melanin?

A polymer made of an amino acid called tyrosine.

What are the two ranges in color for melanin?

Reddish yellow to brownish black.

What does melanin synthesis depend on?

An enzyme in melanocytes called tyrosinase.

What breaks down melanosomes? What does this cause?

Lysosomes. Causes melanin pigment to only be found in deeper layers of the epidermis.

What are freckles and pigmented nevi (moles) in relation to melanin?

Local accumulations of melanin.

What happens when we stimulate our skin to sunlight?

Keratinocytes secrete chemicals that stimulate melanocytes.

How is melanin like a natural sunscreen?

Prolonged sun exposure causes a substantial melanin buildup, which helps protect the DNA of skin cells from UV radiation by absorbing the rays and dissipating the energy as heat.

What can downsides does prolonged sun exposure causes?

Causes elastic fibers to clump, which results in leathery skin; temporarily depresses the immune system; and can alter the DNA of skin cells, leading to skin cancer.

What are carotenes?

Yellow to orange pigment found in certain plant products such as carrots. Tends to accumulate in the stratum corneum and in the fat of the subcutaneous tissue.

Where does carotene accumulate?

Tends to accumulate in the stratum corneum and in the fat of the subcutaneous tissue.

In the body, what can carotene be converted to? What is this essential for?

Vitamin A, a vitamin essential for normal vision and epidermal health.

What is hemoglobin?

Oxygenated pigment in the red blood cells circulating through the dermal capillaries.

What is cyanosis? When does it occur?

When hemoglobin is poorly oxygenated and the skin takes on a bluish-gray tint, especially in the mucous membranes and nail beds.

What can cyanosis be a sign of?

Respiratory or cardiovascular problems.

What is pallor?

When blood is diverted form the skin to internal organs, causing the person to look white.

What is anemia?

Decreased ability of blood to carry oxygen.

What is jaundice?

When yellow pigment accumulates in body tissues when liver doesn’t function properly. More noticeably, the sclerae or whites of the eyes turn yellow.

What is hematoma?

Bruises that occur when blood vessels are damaged and leak blood into the surrounding tissue.

What are the structures associated with the integumentary system?

Hair, hair follicles, nails, sweat glands, and sebaceous (oil) glands.