The Chemistry of Hair

Introduction

Hair is an essential part of the human body. It gives an insulating layer to the body, absorb radiation from the sun, and prevents dust and pathogens from getting in the nose and eyes. I chose to research hair, because it’s a universal trait. Everyone's lives are affected by their hair, because it requires continued maintenance from washing to combing to styling.


Composition of Hair

According to Hilda Sustaita at Houston community college, hair is “45.2 % carbon, 27.9% oxygen, 6.6% hydrogen, 15.1% nitrogen and 5.2a% sulphur.”Hair is composed of melanin,C18H10N2O4 , and keratin,C47H77N13O15 , which is made up of amino acids. The most important amino acid is cysteine, C3H7NO2S.


Main Compounds

Keratin

  • protein formed from 18 amino acids

    • cysteine- rich in sulfur, important in cohesion of the hair

  • Hardened Keratin in the cuticle and cortex

  • Made naturally in the root of hair by keratinocytes

  • 4 chains of keratin make up a protofibrils

    • held together by “bridges”

      • hydrogen bonds-weak

      • ionic bonds- stronger

      • sulphur bridges

Melanin

  • Gives color to the hair and skin

  • Grows from star shaped follicles

  • makes hair a uniform color

  • made in the bottom of the hair follicle by melanocytes, then given to keratincytes

  • 1% of hair

  • Two types- that give color by proportion and number of each

    • eumelanin- brown-red-black

      • tyrosine

    • phaeomelanin- yellow to red

      • cysteine

      • tyrosine


Chemistry’s role

Chemistry plays a major role in hair, because it is the bonds that connect the individual compounds together to make a strand of hair. There are three types of chemical bonds that make up hair

  • Hydrogen bond

    • An abundant Weak physical bond

    • Can break from water or heat

    • Reforms by drying or cooling

  • Salt bond

    • Broken by an acidic solution or change in pH (bleaching)

    • Reformed by normalizing pH

  • Disulfide bonds

    • Chemical bonds that can’t be broken by heat or water

    • Less common that Salt and Hydrogen bonds

    • The sulfur atoms of cysteine combine to make cystine

    • Give hair its strength and durability


Background Research

Hair is made naturally in hair follicles throughout the body. The blood stream drops off nutrients in the bulb of the hair, which is turned into keratinocytes. In turn, these keratinocytes harden into keratin. While the keratin is being formed, melanocytes also form and turn into melanin which works together with the keratin to makeup hair.


Resources

Foster, Niki, and Andrew Jones. "What Is a Hair Follicle." WiseGeek. Conjecture, n.d. Web. 06 Apr. 2016.

http://www.wisegeek.com/what-is-a-hair-follicle.htm

  • Basic’s of hair follicles

  • Hair follicle graphic

"HAIR COLOR: TWO MELANINS FOR AN INFINITE PALETTE." HAIR COLOR: TWO MELANINS FOR AN INFINITE PALETTE. Loreal, n.d. Web. 07 Apr. 2016.

http://www.hair-science.com/_int/_en/topic/topic_sousrub.aspx?tc=root-hair-science%5Eamazingly-natural%5Ecolor-palette&cur=color-palette

  • How hair colors work

  • The globalization of hair colors


James, Aj. "Right Sidebar." Ruggedly Groomed. N.p., 16 July 2015. Web. 07 Apr. 2016.

http://www.ruggedlygroomed.com/grooming-topics/hair-care/why-is-my-hair-curly/

  • Information on how straight or curly hair is


"KERATINE : SUPERB CHEMISTRY OF THE HAIR." KERATINE : SUPERB CHEMISTRY OF THE HAIR. Loreal, n.d. Web. Feb.-Mar. 2016.

http://www.hair-science.com/_int/_en/topic/topic_sousrub.aspx?tc=ROOT-HAIR-SCIENCE^PORTRAIT-OF-AN-UNKNOWN-ELEMENT^SUPERB-CHEMISTRY&cur=SUPERB-CHEMISTRY

  • Loreal hair science website

  • General information about hair


Sustaita, Hilda. "Chemical Composition of Hair." Topic 3. Houston Community College- NorthWest, n.d. Web. Feb.-Mar. 2016.

http://www.texascollaborative.org/hildasustaita/module%20files/topic3.htm

  • Chemical composition of hair- Hilda Sustaita

  • Teaching resource for Houston community college professors

  • The composition of hair and amino acid names

  • The bonds that make up hair


"The PubChem Project." PubChem RSS. PubChem, n.d. Web. Feb.-Mar. 2016.

https://pubchem.ncbi.nlm.nih.gov/

  • Open chemistry database

  • The chemical formulas of all the compounds of hair


About the Author

7th Julia.jpg

Julia Loudenburg is a senior at McCook Central High School. In the fall she plans to attend George Washington University for Interna

tional Affais. In high school she has participated in A

LA Girls State, Student Council, NHS, FFA, Band, Choir, Madrigal, Vocal Jazz Musicals, FCA, Oral Interp, One Act, Cheerleading, and Quiz Bowl.

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