(b) Secretion. The part of the apocrine gland that secretes sweat is
located in the dermis; for eccrine glands, that portion of the gland is in the subcutaneous
layer of skin. The substance secreted by both types of sweat gland is perspiration or
sweat. Pure sweat contains much the same elements as blood, but in lower
concentrations. The chief element is water, then sodium chloride, potassium, glucose,
ureas, and lactate. Pure sweat is odorless. Odor comes from sweat interacting with
bacteria on the skin.
(c) Function. The principal function of the sweat glands is to help
regulate body temperature. Sweating can cool the body because body heat is
necessary for the water in sweat to evaporate. The amount of water lost by sweating
can be as much as eight pounds of body weight per day. The function of apocrine
glands is to respond to emotional stimulation.
Modified sweat glands.
(a) Ceruminous (wax) glands. In some parts of the skin, sudoriferous
glands are modified and become ceruminous glands. These are simple, coiled, tubular
glands located in the external meatus of the ear canal. The substance secreted is wax,
also called cerumen. This substance may accumulate resulting in too much earwax.
The combination of hair and earwax helps prevent foreign objects from entering the ear.
(b) Ciliary glands. These glands are located on the edges of the
eyelids. The glands secrete a milky, alkaline sweat. The function of the sweat is to
moisten the inner eyelids.
FUNCTIONS OF THE SKIN
(1) Sensation refers to a state of awareness of conditions of the body. Four
prerequisite conditions must be present in order for a sensation to occur:
(a) Stimulus (or change in environment)--something capable of
initiating a response by the nervous system.
(b) Receptor or sense organ--something must be able to pick up the
stimulus and convert the stimulus to a nerve impulse. A sense receptor or sense organ
is specialized tissue that is very sensitive to conditions affecting the body.
(c) Conductor--the impulse must be conducted along a nerve pathway
from the receptor or sense organ to the brain.
Translator--a region of the brain must translate the impulse into a