Glands in the Skin
Skin consists of several layers. Some of the accessory structures of the skin, e.g. hair follicles, sweat glands and oil glands originate in the dermis layer (of the skin) and protrude through the epidermis layer (of the skin) resulting in hairs, sweat and sebum (oil) emerging from the surface of the skin.
There are several types of tiny structures call glands in the dermis. Different types of glands in the skin release different types of biochemicals. The chemicals emerge from the glands via pores (in the skin), which are tiny channels or openings through the outer (epidermis) layer of skin that open at the outer surface of the skin where they can release e.g. sweat, oils, etc.. This is important for many reasons incl. e.g. regulation of body temperature via release and evapouration of sweat and protection of the skin against fungal and bacterial infections by sebum.
There are millions of pores and associated glands throughout the surface of the skin. Different areas of skin (parts of the body) have different quantities and concentrations of the different types of glands in the skin.
How many different types of glands are located in and associated with the skin ?
Some sources say that there are only 2 types of glands in the skin: sweat glands (sudoriferous glands) and oil glands (sebacious glands). Other sources list 3 types of glands in the skin: sudoriferous glands, sebacious glands and ceruminous glands, of which the latter is present only in the external auditory canal i.e. the outer ear.
About each of the types of glands in the skin:
|
Sebaceous Glands - also known as 'Oil Glands' |
|
Most are associated with hair follicles.
They secret either into the neck of a hair follicle, or directly onto the surface of the skin via a pore. |
Where ? |
- |
Sebaceous glands are located over most of the surface of the skin/body but not in the palms of the hands or the soles of the feet. |
Secretion(s): |
- |
Sebaceous glands secret an oily substance called sebum. |
Why ? Good: |
- |
Sebum helps to protect skin and hair by: |
|
|
- preventing hairs from becoming too dry and brittle
- preventing the skin from becoming too dry (by preventing excessive evaporation of water from the surface of the skin), hence also helping to keep the skin soft and effective
- restricting the growth/development of certain bacteria.
|
Also note: |
- |
The activity of sebaceous glands increases during and sometimes beyond teenage years (adolescence). Over-active sebaceous glands can result in the accumulation of sebum in the glands and/or pores, causing the affected glands to become enlarged and the appearance of blackheads and other disturances to the skin, commonly around on the face. |
|
|
|
|
|
Sudoriferous Glands - also known as 'Sweat Glands' |
Different Types: |
- Apocrine Glands - ducts open in hair follicles
- Eccrine Glands - ducts terminate at a sweat pore at the outer surface of the epidermis
|
Where ? |
- |
Apocrine Glands :- |
Eccrine Glands :- |
- Armpits (skin of the axillae)
- Pubic region
- Pigmented areas of breasts (areolae)
|
- Throughout the skin
(except for margins of lips, eardrums, nailbeds of finger and toe nails)
|
|
|
Secretion(s): |
- |
Sudoriferous glands secret sweat, which is also called 'perspiration'. Apocrine glands secret a sticky viscous secretion while the secretion from eccrine glands is thinner; watery by comparison. |
Why ? Good: |
- |
The main functions of the secretion of sweat are to help regulate body temperature and to help eliminate from the body some of the waste products of metabolism (i.e. metabolic reactions). |
Also note: |
- |
Mammary glands (female breasts) are modified sudoriferous glands that produce breast milk. |
|
|
|
|
|
|
Ceruminous Glands - the 'Wax Glands' of the ear |
|
Ducts open either directly onto the surface of the external auditory canal or into the ducts of sebaceous glands. |
Where ? |
- |
The external auditory canal, also known (colloquially) as simply the 'outer ear'. |
Secretion(s): |
- |
The prefix 'cer-' means 'wax'.
The secretions from ceruminous glands combines with sebum secreted by nearby or associated sebaceous glands to form cerumen which is also known colloquially as 'ear wax'. |
Why ? Good: |
- |
Cerumen, assisted by the hairs in the outer ear, protects the ear from particles originating outside of the body e.g. of dust, fine sand, or similar in the air getting into the ear itself. Cerumen provides a sticky barrier that prevents many such particles from going further into the ear. |
Also note: |
- |
In some cases the body produces excessive amounts of cerumen. This can then accumulate, harden and compact, reducing the effectiveness of sound waves reaching the ear drum and therefore adversely affecting hearing.
People affected by excessive ear wax are warned against putting - neven soft - objects into the ear to dislodge the ear wax because this can cause further problems e.g. if compacted cerumen is unintentionally pushed further into the ear, or other objects such as cotton buds detach and also get stuck in the ear. |
|
|
|
|
Note: Knowledge
of the structure of skin is essential for successful
completion of accredited courses in many bodywork therapies,
such as massage, reflexology, aromatherapy, Indian head
massage, and others. In many cases the structure of
the skin is just a small part of a larger module that also includes information about the physiology
of these structures and associated aspects of pathology.
(It is important for therapists to be aware of and able
to recognise common skin conditions as these may constitute
contraindications, i.e. reasons not
to proceed with a treatment.)
See also page about What is the function of skin ?