Thinning Hair
Thinning Hair

No one can stop hair loss completely. But you can have healthier, fuller and thicker hair while slowing down the rate of loss.

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What is Hair?

Whether male or female, we are hairy creatures—except for the palms of our hands and the soles of our feet, we are covered with hair. At any given moment, the average man or woman has between 100,000 to 150,000 hairs on their scalp alone.5-6

The Hair Shaft and Follicle

The hair we see may appear to be a simple structure, but in fact it is highly complex, especially at the microscopic level below the surface of the scalp. The part of human hair we see is made of multiple layers of cells grouped into three main sections (bound together by a cell membrane complex) that comprise the hair shaft:6-8

Figure1_remake_What_is_hair_Bekki

Human hair is primarily composed of keratin proteins, which are made of amino acids (of which cystine is one of the most important for hair). As hair grows, proteins are synthesized from amino acids in the hair bulb to form the shaft fiber. As these proteins move up through the follicle, disulfide bonds are formed between them to create the stable hair fiber (incorporating melanin pigments for color).8

The percentage of protein varies between 65% and 95%, depending on water content. Lipids, melanin pigments, and trace elements compose a tiny but important 3% of hair’s chemical composition, and each of the three sections of the hair shaft are comprised of a different mix of biochemicals:8

CHEMICAL COMPOSITION OF HAIR SHAFT

KERATIN PROTEINS
MEDULLA
CORTEX
CUTICLE
Amino acids

  • glutamic acid
  • lysine
  • leucine
  • aspartic acid
  • alanine
  • tyrosine
  • valine
  • glycine
  • serine
  • arginine
  • proline
  • threonine
  • isoleucine
  • histidine
  • methionine
  • cystine

Amino acids

  • cystine (disulfide bonded)
  • serine
  • glutamic acid
  • proline
  • threonine
  • arginine
  • leucine
  • valine
  • glycine
  • aspartic acid
  • alanine
  • isoleucine
  • lysine
  • tyrosine
  • phenylalanine
  • histidine
  • methionine
  • citruline

Amino acids

  • cystine (disulfide bonded)
  • serine
  • proline
  • glutamic acid
  • valine
  • glycine
  • threonine
  • leucine
  • arginine
  • aspartic acid
  • isoleucine
  • tyrosine
  • phenylalanine
  • cysteic acid
  • citruline
  • methionine
MELANIN
--------------------- ---------------------
Fatty acids
  • 18-methyleicosanoic acid
---------------------
Brown or Yellow/Red Pigments

CHEMICAL COMPOSITION OF HAIR SHAFT

TRACES ELEMENTS
  • Aluminum
  • Antimony
  • Arsenic
  • Boron
  • Calcium
  • Potassium
  • Selenium
  • Silver
  • Sodium
  • Strontium
  • Titanium
  • Tungsten
  • Vanadium
  • Zinc

Table 1: Chemical Composition of Hair Shaft


CELL MEMBRANE COMPLEX IN HAIR

KERATIN PROTEINS
Amino acids
LIPIDS
Fatty Acids
  • 18-methyleicosanoic acid
  • palmitic acid
  • stearic acid
  • oleic acid
Esters of Fatty Acids
  • wax esters
  • cholesteryl esters

Table 2: Chemical Composition of Cell Membrane Complex in Hair


There are three types of hair follicles:5

  • Vellus—found on most areas of the body
  • Terminal—primarily found on scalp, pubic area (after puberty), beard, and underarm areas
  • Sebaceous—contains a gland that produces natural oils called sebum; located in all the areas as terminal hair; also on other facial areas, chest, and back
Figure2_remake_What_is_hair_Bekki

Follicles naturally occur in groups. Each grouping of follicles, or follicular unit, contains a ratio of approximately seven terminal hairs to each vellus hair.6, 9 Below the skin is the hair follicle, the structure that holds the hair in place, contains the sebaceous glands, and provides nutrients to the hair during the growing phase via blood vessels located in the dermal papilla.5 Important to hair growth and loss, the hair follicle contains epidermal growth factor receptors, hormone receptors, vitamin D receptors.10 It can also produce its own hormones, including melatonin and growth factors (e.g., insulin growth factor-1).10-11

The dermal papilla contains androgen receptors, fibroblasts, collagen, fibronectin, glycosaminoglycans, and capillaries.6,,8 Research continues to uncover the importance of the dermal papilla cells to hair growth.12 In fact, one of the ways minoxidil works is by stimulating increased production of growth factors in dermal papilla cells that stimulate follicle cell proliferation. This prolongs the growth phase of hair.13

Disclaimer: This website is not intended to replace professional consultation, diagnosis, or treatment by a licensed physician. If you require any medical related advice, contact your physician promptly. Information at Thinninghair.com is exclusively of a general reference nature. Do not disregard medical advice or delay treatment as a result of accessing information at this site.
The cell membranes of each section's outermost cells and the intercellular adhesive material bonding the layers together.
Linked pair of sulfur atoms.
By declining order of prevalence.
By declining order of prevalence.
By declining order of prevalence.
Can be converted to cysteine (which then converts to cystine).
Can be converted to cysteine (which then converts to cystine).
Can be converted to cysteine (which then converts to cystine).