responsible for the skin being soft and pliable. More sebum is produced in puberty,
while less sebum is produced in old age. Sebum has antifungal and antibacterial
properties. If too much sebum accumulates in the sebaceous glands of the face,
causing these glands to get bigger, blackheads can develop. The air oxidizes the
sebaceous gland fatty material discoloring that fatty substance, hence blackheads. If
fatty substances accumulate in the sebaceous glands, pus-producing bacteria in those
substances can cause pimples to form. The skin problem acne is an inflammation of
sebaceous glands. A few blackheads or whiteheads on the face may be a sign of
Figure 1-4. Skin glands.
Sweat glands (sudoriferous glands).
(a) Characteristics. There are two principal types of sweat glands:
apocrine sweat glands and eccrine sweat glands. Both are simple, tubular glands
distributed throughout the skin. One difference is that apocrine sweat glands are
branched and eccrine sweat glands are coiled. Another difference is that apocrine
glands are located in the axilla, pubic region, and pigmented areas of the breasts. The
eccrine glands are located throughout the body except in the margins of the lips, nail
beds of fingers and toes, and the eardrums. Eccrine sweat glands are most numerous
in the skin on the palms of the hands and the soles of the feet. Sweat gland density in
the palms of the hands can be as high as 3,000 glands per square inch.