Underarm hair

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Underarm hair
Details
Identifiers
Latin hirci
TA98 A16.0.00.021
TA2 7061
FMA 70756
Anatomical terminology

Underarm hair, also known as axillary hair or armpit hair, is the hair in the underarm area (axilla).

Contents

Development

This is an illustration demonstrating the Wolfsdorf Staging for axillary hair development in children. Staging for Axillary Hair Development.jpg
This is an illustration demonstrating the Wolfsdorf Staging for axillary hair development in children.

Underarm or axillary hair goes through four stages of development, driven by weak androgens produced by the adrenal in males and females during adrenarche, and testosterone from the testicle in males during puberty. [2]

The importance of human underarm hair is unclear. It may naturally wick sweat or other moisture away from the skin, aiding ventilation. Colonization by odor-producing bacteria is thereby transferred away from the skin (see skin flora). [3]

Function

Reducing friction

Armpit hair prevents skin-to-skin contact during activities that involve arm motion, such as running and walking. The same applies to pubic hair. [4] [ better source needed ]

Spreading pheromones

The armpits release odor-containing pheromones, a naturally produced chemical that plays an important role in sexual attraction. Armpit hair traps odor, making the pheromones even stronger. A study in 2018 including 96 heterosexual couples found that there were stress-relieving benefits to smelling a romantic partner's natural scent. [5]

Impact of hair removal

Effect on odor

А 2012 study on the impact of hair removal on odor found that shaved armpits were rated the same as unshaved armpits. [6]

Chemical absorption

A 2017 study on chemical absorption from deodorants as a result of hair removal showed an increase in chemical absorption from .01% to .06% where skin has been damaged by recent shaving. [7]

A 2003 study on aluminum antiperspirant usage and the age of breast cancer onset tentatively concluded that "underarm shaving with antiperspirant/deodorant use may play a role in breast cancer." [8] However, this was later proven to be false. [9]

See also

Related Research Articles

<span class="mw-page-title-main">Pheromone</span> Secreted or excreted chemical factor that triggers a social response in members of the same species

A pheromone is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting like hormones outside the body of the secreting individual, to affect the behavior of the receiving individuals. There are alarm pheromones, food trail pheromones, sex pheromones, and many others that affect behavior or physiology. Pheromones are used by many organisms, from basic unicellular prokaryotes to complex multicellular eukaryotes. Their use among insects has been particularly well documented. In addition, some vertebrates, plants and ciliates communicate by using pheromones. The ecological functions and evolution of pheromones are a major topic of research in the field of chemical ecology.

<span class="mw-page-title-main">Pubic hair</span> Body hair in the genital region

Pubic hair is terminal body hair that is found in the genital area and pubic region of adolescent and adult humans. The hair is located on and around the sex organs, and sometimes at the top of the inside of the thighs, even extending down the perineum, and to the anal region. Pubic hair is also found on the scrotum and base of the penile shaft and on the vulva. Around the pubis bone and the mons pubis that covers it, it is known as a pubic patch, which can be styled.

<span class="mw-page-title-main">Hair removal</span> Temporary body hair removal

Hair removal is the deliberate removal of body hair or head hair. This process is also known as epilation or depilation.

A deodorant is a substance applied to the body to prevent or mask body odor caused by bacterial breakdown of perspiration, for example in the armpits, groin, or feet. A subclass of deodorants, called antiperspirants, prevents sweating itself, typically by blocking sweat glands. Antiperspirants are used on a wider range of body parts, at any place where sweat would be inconvenient or unsafe, since unwanted sweating can interfere with comfort, vision, and grip. Other types of deodorant allow sweating but prevent bacterial action on sweat, since human sweat only has a noticeable smell when it is decomposed by bacteria.

Body odor or body odour (BO) is present in all animals and its intensity can be influenced by many factors. Body odor has a strong genetic basis, but can also be strongly influenced by various factors, such as sex, diet, health, and medication. The body odor of human males plays an important role in human sexual attraction, as a powerful indicator of MHC/HLA heterozygosity. Significant evidence suggests that women are attracted to men whose body odor is different from theirs, indicating that they have immune genes that are different from their own, which may produce healthier offspring.

Adrenarche is an early stage in sexual maturation that happens in some higher primates, typically peaks at around 20 years of age, and is involved in the development of pubic hair, body odor, skin oiliness, axillary hair, sexual attraction/sexual desire/increased libido and mild acne. During adrenarche the adrenal glands secrete increased levels of weak adrenal androgens, including dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate (DHEA-S), and androstenedione (A4), but without increased cortisol levels. Adrenarche is the result of the development of a new zone of the adrenal cortex, the zona reticularis. Adrenarche is a process related to puberty, but distinct from hypothalamic–pituitary–gonadal axis maturation and function.

Pubarche refers to the first appearance of pubic hair at puberty and it also marks the beginning of puberty. It is one of the physical changes of puberty and can occur independently of complete puberty. The early stage of sexual maturation, also known as adrenarche, is marked by characteristics including the development of pubic hair, axillary hair, adult apocrine body odor, acne, and increased oiliness of hair and skin. The Encyclopedia of Child and Adolescent Health corresponds SMR2 with pubarche, defining it as the development of pubic hair that occurs at a mean age of 11.6 years in females and 12.6 years in males. It further describes that pubarche's physical manifestation is vellus hair over the labia or the base of the penis. See Table 1 for the entirety of the sexual maturity rating description.

Gonadarche refers to the earliest gonadal changes of puberty. In response to pituitary gonadotropins, the ovaries in females and the testes in males begin to grow and increase the production of the sex steroids, especially estradiol and testosterone. The ovary and testis have receptors, follicle cells and leydig cells, respectively, where gonadotropins bind to stimulate the maturation of the gonads and secretion of estrogen and testosterone. Certain disorders can result in changes to timing or nature of these processes.

<span class="mw-page-title-main">Axilla</span> Area of the human body beneath the joint between arm and torso

The axilla is the area on the human body directly under the shoulder joint. It includes the axillary space, an anatomical space within the shoulder girdle between the arm and the thoracic cage, bounded superiorly by the imaginary plane between the superior borders of the first rib, clavicle and scapula, medially by the serratus anterior muscle and thoracolumbar fascia, anteriorly by the pectoral muscles and posteriorly by the subscapularis, teres major and latissimus dorsi muscle.

Aluminium chlorohydrate is a group of water-soluble, specific aluminium salts having the general formula AlnCl3nm(OH)m. It is used in cosmetics as an antiperspirant and as a coagulant in water purification.

<span class="mw-page-title-main">Sweat gland</span> Small sweat-producing tubular skin structures

Sweat glands, also known as sudoriferous or sudoriparous glands, from Latin sudor 'sweat', are small tubular structures of the skin that produce sweat. Sweat glands are a type of exocrine gland, which are glands that produce and secrete substances onto an epithelial surface by way of a duct. There are two main types of sweat glands that differ in their structure, function, secretory product, mechanism of excretion, anatomic distribution, and distribution across species:

<i>Trichobacteriosis axillaris</i> Medical condition

Trichobacteriosis axillaris is a superficial bacterial colonization of the hair shafts in sweat gland–bearing areas, such as the armpits and the groin. It is a trivial disease of worldwide occurrence that is believed to be caused by the genus Corynebacteria.

<span class="mw-page-title-main">Body hair</span> Hair on the human body during and after puberty

Body hair or androgenic hair is terminal hair that develops on the human body during and after puberty. It is different from head hair and also from less visible vellus hair, which is much finer and lighter in color. Growth of androgenic hair is related to the level of androgens and the density of androgen receptors in the dermal papillae. Both must reach a threshold for the proliferation of hair follicle cells.

<span class="mw-page-title-main">Apocrine sweat gland</span> One of several types of glands, in humans and other animals, that secrete sweat

An apocrine sweat gland is composed of a coiled secretory portion located at the junction of the dermis and subcutaneous fat, from which a straight portion inserts and secretes into the infundibular portion of the hair follicle. In humans, apocrine sweat glands are found only in certain locations of the body: the axillae (armpits), areola and nipples of the breast, ear canal, eyelids, wings of the nostril, perineal region, and some parts of the external genitalia. Modified apocrine glands include the ciliary glands in the eyelids; the ceruminous glands, which produce ear wax; and the mammary glands, which produce milk. They are distinct from eccrine sweat glands, which cover the whole body.

Puberty is the process of physical changes through which a child's body matures into an adult body capable of sexual reproduction. It is initiated by hormonal signals from the brain to the gonads: the ovaries in a female, the testicles in a male. In response to the signals, the gonads produce hormones that stimulate libido and the growth, function, and transformation of the brain, bones, muscle, blood, skin, hair, breasts, and sex organs. Physical growth—height and weight—accelerates in the first half of puberty and is completed when an adult body has been developed. Before puberty, the external sex organs, known as primary sexual characteristics, are sex characteristics that distinguish males and females. Puberty leads to sexual dimorphism through the development of the secondary sex characteristics, which further distinguish the sexes.

<span class="mw-page-title-main">Prepubertal hypertrichosis</span> Medical condition

Prepubertal hypertrichosis, also known as childhood hypertrichosis, is a cutaneous condition characterized by increased hair growth, found in otherwise healthy infants and children. Prepubertal hypertrichosis is a cosmetic condition and does not affect any other health aspect. Individuals with this condition may suffer with low self esteem and mental health issues due to societal perceptions of what a "normal" appearance should be. The mechanism of prepubertal hypertrichosis is unclear, but causes may include genetics, systemic illnesses, or medications.

Underarm liners are an alternative to antiperspirants. The liners are applied directly to clothing. They contain absorbent material that wicks away moisture from sweat, keeping the axilla dry. Underarm liners were used more commonly before chemical antiperspirants, primarily by women, to preserve fine dresses from soiling. Sweat contains substances that stain yellow or fade dyes. Underarm liners are also known as underarm shields, underarm pads, sweat guards, dress shields, and pity protectors.

No study has led to the isolation of true human sex pheromones, although various researchers have investigated the possibility of their existence.

Edna Murphey was the creator of the Odorono brand of deodorant and originator of modern-day deodorant marketing strategies (1912). Murphey's father, Dr. Abraham D. Murphey, a physician, developed the liquid antiperspirant to help surgeons with sweaty hands. Edna subsequently found this antiperspirant useful on underarms and began marketing the product to women. There had been other previous deodorant/antiperspirant inventions previous to Murphey's, however, Murphey's was the product that became widely distributed. Murphey called the deodorant, Odorono (Odor-o-no) and started the company Odorono Co. At the time, antiperspirant products were not widely used, and Murphey was, for the most part, unsuccessful at selling the product in the office she rented in Cincinnati. Many potential users thought the item was either unnecessary, potentially harmful to their health, or that the red color of the product would damage their clothing.

The biochemistry of body odor pertains to the chemical compounds in the body responsible for body odor and their kinetics.

References

  1. Pineau, Jean-Claude (2020). "Age estimation of teenage boys during puberty". American Journal of Forensic Medicine and Pathology. 41 (3). Williams & Wilkins: 188–193. doi:10.1097/PAF.0000000000000573. PMID   32796206. S2CID   221257760.
  2. Auchus RJ, Rainey WE (March 2004). "Adrenarche - physiology, biochemistry and human disease". Clinical Endocrinology. 60 (3): 288–296. doi: 10.1046/j.1365-2265.2003.01858.x . PMID   15008992.
  3. Paye M, Maibach HI, Barel AO (2009). Handbook of cosmetic science and technology (3 ed.). Informa Health Care. p. 703. ISBN   978-1-4200-6963-1.
  4. "MRSA superbug? Part 1". PsycEXTRA Dataset. 2007. doi:10.1037/e721542007-001 . Retrieved 12 July 2022.
  5. Hofer MK, Collins HK, Whillans AV, Chen FS (January 2018). "Olfactory cues from romantic partners and strangers influence women's responses to stress". Journal of Personality and Social Psychology. 114 (1): 1–9. doi:10.1037/pspa0000110. PMID   29293018. S2CID   40410769.
  6. Kohoutová D, Rubešová A, Havlíček J (April 2012). "Shaving of axillary hair has only a transient effect on perceived body odor pleasantness". Behavioral Ecology and Sociobiology. 66 (4): 569–581. Bibcode:2012BEcoS..66..569K. doi:10.1007/s00265-011-1305-0. ISSN   0340-5443. S2CID   16607684.
  7. Klotz K, Weistenhöfer W, Neff F, Hartwig A, van Thriel C, Drexler H (September 2017). "The Health Effects of Aluminum Exposure". Deutsches Ärzteblatt International. 114 (39): 653–659. doi:10.3238/arztebl.2017.0653. PMC   5651828 . PMID   29034866.
  8. McGrath KG (December 2003). "An earlier age of breast cancer diagnosis related to more frequent use of antiperspirants/deodorants and underarm shaving". European Journal of Cancer Prevention. 12 (6): 479–485. doi:10.1097/00008469-200312000-00006. PMID   14639125. S2CID   24938503.
  9. Mousavi, Maryam; Vaghar, Mohammad I (January 2021). "The relationship between use of aluminum-containing anti-perspirant and hair color with breast cancer". Journal of Family Medicine and Primary Care. 10 (1): 182–186. doi: 10.4103/jfmpc.jfmpc_1219_19 . ISSN   2249-4863. PMC   8132781 . PMID   34017723.