The Integumentary System
What name is given to the rule for recognizing the signs of melanoma?
The ABCD rule helps one to recognize signs of melanoma.
Which type of skin cancer develops from the youngest epidermal cells?
Basal cell carcinoma develops from the youngest epidermal cells.
Although the anterior head and face represent only a small percentage of the body surface, burns to this area are often much more serious than those to the body trunk. Why?
Burns to the face are serious because damage to the lungs can occur in such burns.
The healing of burns and epidermal regeneration is usually uneventful unless the burn is a third-degree burn. What accounts for this difference?
First- and second-degree burns can heal uneventfully by regeneration of epidermal cells as long as infection does not occur. Third-degree burns destroy the entire epidermis and regeneration is not possible. Infection and loss of body fluid and proteins are problematic.
What is the difference between heat-induced sweating and a "cold sweat," and which variety of sweat glands is involved?
Heat-induced sweating occurs all over the body when we are over-heated. A cold sweat is emotionally induced sweating that begins on the palms, soles, and armpits and then spreads to other body areas. Both types of sweating are produced by the eccrine sweat glands, but activity of apocrine sweat glands is also likely during a cold sweat.
When Anthony returned home from a run in 85 degree weather, his face was dripping with sweat. Why?
His sympathetic nervous system activated his eccrine sweat glands and caused heat-induced sweating in order to cool the body.
Why are nails so hard?
Nails are hard because the keratin they contain is the hard keratin variety.
Which cutaneous glands are associated with hair follicles?
Sebaceous (oil) glands and apocrine glands are associated with the hair follicles.
How is sunlight important to bone health?
Sunlight causes the skin to produce a precursor of vitamin D from cholesterol.
What is the role of an arrector pili muscle?
The arrector pili muscles pull the hair (normally slanted) to the upright position (when cold or scared).
What epidermal cells play a role in body immunity?
The epidermal dendritic cells play a role in body immunity.
What is the function of the hair papilla?
The hair papilla contains a knot of capillaries that supplies nutrients to cells of the hair bulb.
What chemicals produced in the skin help provide barriers to bacteria? List at least three and explain how the chemicals are protective.
The low pH of skin secretions (acid mantle) inhibits division of bacteria, and many bacteria are killed by bactericidal substances in sebum or by natural antibiotics called defensins. Damaged skin secretes cathelicidins that are effective against a certain strain of strep bacteria.
Why is the lunule of a nail white instead of pink like the rest of the nail?
The lunule of the nail is white because the thick nail matrix that underlies it blocks the rosy color of the dermal blood supply from showing through.
Sebaceous glands are not found in thick skin. Why is their absence in those body regions desirable?
The palms of the hands and soles of the feet are thick skin areas. It would be dangerous to have oily soles, and oily palms would decrease the ability of the hands to hang onto things.
What are the concentric regions of a hair shaft, from the outside in?
The regions of a hair from outside in are the cuticle, cortex and medulla.
How does the skin contribute to body metabolism?
The skin carries out chemical conversions that supplement some of the protective conversions carried out by the liver, convert some chemicals into carcinogens, activate some steroid hormones, an dsynthesize the vitamin D precursor.
Why is having your hair cut painless?
There are no nerves in a hair, so cutting hair is painless.
