Module 5.3 - Hair Care
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45 Terms
T/F: All mammals have hair.
true
What are the 2 main funcs of hair?
regulate body temp
protects skin
T/F: Hair is lifeless
true!!! like nails, claws, feathers, etc
Hair is composed of what protein?
keratin!
Keratin contains a lot of this amino acid :________
Hint: heavy in sulfur content
cysteine!
Cysteine’s suflur groups form disulfide bonds with each other, this forms the dimer: __________
HInt: similar name
cystine!
Cystine vs cysteine
Cystine = a dimer btwn 2 cysteine molecules
What gives hair its strength and stability?
the disulfide bonds linking neighboring keratin chains
Hair isn’t living but it grows from a living….
living bulb / follicle!
Hair eventually ends its growth cycle, falls out, and is replaced by a new hair.
What is the part that forms the main body of hair and contains its pigments?
the hair cortex!
What is the outer layer of hair that protects the hair shaft?
the hair cuticle!
Near each follicle are sebaceous glands. These produce sebum.
Too much sebum —>
Too little sebum —>
Too much sebum —> greasy
Too little sebum —> dry flaky
Shampoos remove dirt and excess sebum, while conditioners
conditioners restore lost moisture and lubrication
What is the ideal pH of hair?
pH 4-6! slightly acidic
Shampoo could contains anionic surfactants. Being…
anionic surfactants (ammonium lauryl sulfate, TEA (triethanalammonium) lauryl sulfate)
Ammonium NH4+ based surfactants are better than ________ Na+based surfactants
than sodium based surfactants
Why are ammonium based surfactants better?
cuz they’re more soluble in cold water, gentler on skin, and less drying
Ingredients of shampoo:
…
What is dandruff?
an overgrowth of a scalp fungus known as Malassezia fungi
What does the Malassezia fungi do?
it metabolizes trigylcerides found in sebum —> interfering by-product produces that penetrates epidermis —> inflammation —> increases cell turnover aka DANDRUFF
What ingredient does anti-dandruff shampoo contain to inhibit growth of Malassezia fungi?
zinc pyrithione
Ingredients of conditioner:
….
Hair shape is influenced by genetics, hormones, and … structure.
and hair follicle structure.
Why is hair straight vs curly?
Straight: follicles are circle
Curly: follicles are oval
Structure of keratin proteins also determine straight vs curly
What are the 3 bonds / interactions that determine hair shape (name weakest to strongest)?
weakest: hydrogen bonds
middle: ionic bond (salt bridges)
strongest: covalent bond (disulfide bonds)
What are hydrogen bonds?
H of an OH or NH group bonding with O/N of another OH or NH group
What are disulfide bonds?
sulfur-sulfur covalently linked
What are salt bridges?
charged amino acids ionically (positive-negative) linked
Hydrogen bonds are individually weak but…
Hydrogen bonds are individually weak but collectively strong.
Water disrupts which bond?
Water disrupts hydrogen bonds!
Water disrupts hydrogen bonds. This allows hair to…
to be easily reshaped!
T/F: When hair dries, new hydrogen bonds form and temporarily hold hair in its new shape.
true!
why temporary? cuz everyday styling like washing, drying, setting rely on breaking and reforming of H bonds
What is a permanent way of shaping hair?
hair relaxers (use alkaline chemicals to break disulfide bonds in keratin) or perms (breaks bonds and reforms them in new posns)
T/F: Perms are not resistant to water.
FALSE. perms are much more resistant to water after letting it set for a few days.
Are hydrogen bonds covalent?
no
How do perms work?
When these disulfide bonds are broken --> they form thio or SH grousp --> allows protein strand to move more freely --> then hair is wrapped around rollers --> easily takes shape --> oxidizing soln like H2O2 converts thio groups back into disulfide bonds --> locks into new arrangement
Hair’s natural color comes from the melanin stored in the ….
Hair’s natural color comes from the melanin stored in the cortex
Dyeing aims to alter natural hair color by removing or lifting natural color or adding a new color or both.
Temporary vs permanent vs semi-permanent?
Temporary dye: adheres to cuticle; doesn’t penetrate to color cortex
Permanent: penetrate to color cortex
Semi-permanent: dye cuticle and also partially enter cortex
Hair dyes causing allergic rxns affect less than ___% of the popln.
less than 0.5%
What is a common allergen in hair dyes (especially permanent dyes)?
Para-phenylenediamine (PPD)
To test allergy with PPD, conduct permanent dye test on skin first ____ hrs before dying your hair.
48 hrs
What is the most common hair growth drug
Hint: Zohran Mamdani is on it
Minoxidil!
Minoxidil was originally known from its medicinal name … and its use to ….
Minoxidil was Rogaine, an oral treatment for high blood pressure.
its hair growth side effects were a bonus and thus companies isolated / refined for it further.
Minoxidil is effective and safe for male and female pattern hair loss at a conc of ___ to ____ %.
1-5%
T/F: Cutting/shaving hair reduces growth rate.
FALSE. Hair is dead cuz of its distance from bulb/shaft. So removing them doesn't affect hair growth rates.