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2nd shift lecs > Human Hair > Flashcards

Human Hair Flashcards

1
Q

is a flexible thin keratin thread present on almost all surfaces of the human skin

A

hair

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2
Q

hair is present in all surfaces of the human skin except

A

palms, soles, and vermillion part of lips (red part)

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3
Q
  • produced by rapidly multiplying matrix
    keratinocytes
  • Made up entirely of dead cells composed mainly
    of keratin which are held together by intracellular cement-like substance
A

Hair Shaft

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4
Q
  • Part of the pilosebaceous unit
    > Composed of a hair follicle, arrector pili muscle, and sebaceous gland
    > Sebaceous gland - secrete sebum
  • Covered by inner and outer root sheaths
  • Sebum produced by sebaceous glands coats
    the hair and skin
  • Contraction of the arrector pili muscle attached to the hair follicle causes hair to stand up (goosebumps)
A

Hair follicles

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5
Q

covered by hair follicle

A

hair root

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6
Q
  • Hair Papilla
  • Hair Matrix
A

parts of hair bulb

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7
Q

Contain blood vessels for nutrients and oxygen supply

A

hair papilla

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8
Q

Active cell division happens:
- When cells are pushed up, these are dead cells
- Access to nutrients

A

hair matrix

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9
Q

Shaving or cutting the hair can make it grow faster

A

Myth - (Hair shaft is dead cells so no impact)

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10
Q
  • Outermost structure
    or is translucent
  • Composed primarily of keratin
  • Translucent color
  • Target for conditioning product because it defines the outer structure of the hair
A

cuticle

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11
Q
  • protects the cortex
  • acts as a barrier from the entry of water
  • regulates the water content of the hair fiber
  • responsible for hair luster (shine) and texture
A

functions of cuticle

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12
Q
  • Major component of hair shaft (thickest part of hair)
  • Contributes to mechanical properties of hair fiber like
    strength, elasticity, and curliness
  • Cells rich in keratin filaments with amorphous matrix of sulfur proteins
  • Contains melanin; hair color is due to melanin
  • In older people: less melanin production and more spaces between the cortex, results in white hair
A

cortex

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13
Q

every cortical cells in the cortex contains ______

A

macrofibrils

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14
Q

macrofibrils consist of ______

A

microfibrils

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15
Q

microfibrils is made of ______

A

protofibrille

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16
Q

every 1 protofibrille has ______

A

4 keratin helix

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17
Q
  • known as the core
  • composed of flattened cornified cells
  • keratin framework supporting thin shells of amorphous material bonding air spaces
    >hollow
A

medulla

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18
Q

Thick hair is more resistant to stretching than thin hair

A

FACT: (thicker hair has thicker cortex, more resistant to
breakage or stretching)

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19
Q

Hair growth cycle and hair loss

A
  • anagen
  • catagen
  • telogen
20
Q
  • Growth phase
  • Nourishment of hair follicle via blood supply enables hair growth
  • Different for each type of hairs
  • Active growth, cells are pushed up
  • (lasts on scalp) Scalp: 2-6 years
    > continuous growth occurs so hair in this area can be long
  • Brows have a shorter anagen stage
A

anagen

21
Q
  • Transition phase
  • Hair follicle detaches from nourishing blood
    supply
  • Scalp: 2-3 weeks
A

catagen

22
Q
  • Resting phase
  • Hair fall out is normal (100-150 telogen hairs falling out in scalp)
  • Without nourishment, the hair dies and falls out
  • Scalp: 2-3 months
  • If anagen hair ang nagfall out of scalp: not normal
A

telogen

23
Q

scalp is 85-95% in what phase?

A

anagen

24
Q

How to know if anagen hair or telogen hair

A

Telogen hair:
- Has white ends
indicating melanin
production has
stopped
- Cannot feel the
fallout, no pain

25
Q

hair composition and properties

A
  • strong bonds
  • weak bonds
  • surface charge of human hair
  • physical properties of human hair
  • human hair types
26
Q
  • Disulfide bonds are formed between sulfur atoms of
    cysteine
    >Only type of strong bonds
    >Cysteine is an amino acid containing sulfur
    >Aligned by S-S linkages
  • Contribute to shape, stability, and texture of hair
  • Can only be broken up chemically
    >Altered by permanent hair straightening,
    waving, or coloring
    >Not altered by temporary treatments like
    blow-drying
  • Allows hair to resume its original shape
A

strong bonds

27
Q
  • Hydrogen Bonds (H-bonds)
  • Salt Bonds (Ionic bonds to Coulomb interaction)
  • Van der Waals force
A

Weak bonds

28
Q
  • Weak bonds that are easily broken by water and
    heat
    >Shower / blow dry hair
  • Can alter hair’s overall shape
  • Most abundant and common type of bond
A

Hydrogen Bonds (H-bonds)

29
Q
  • Sensitive to pH and readily broken by alkaline or
    acidic conditions
  • Alkalinizers (pH 9-10) are usually added to affect change for permanent formulations to straighten/add waves
A

Salt Bonds (Ionic bonds to Coulomb interaction)

30
Q
  • Weak attractive forces between neutral molecules
  • May be broken by water and head
A

Van der Waals force

31
Q

Wet hair is more vulnerable than dry hair

A

FACT
- Wet hair has altered weak bonds due to the
presence of water

32
Q
  • Untreated hair comprises proteins that exhibit an
    isoelectric point near pH ________
A

pH 3.7

33
Q

Hair usually carries a _______ charge

A

negative

34
Q

__________ ingredients are attracted to the hair more
readily than _______ ingredients

A

Cationic; anionic

35
Q
  • durable and strong
  • elasticity
  • water content
  • High electrical resistivity and low dielectric constant
A

physical properties of human hair

36
Q

due to keratin in the cortex
- Similar strength to copper wires of the same
diameter

A

durable and strong

37
Q

related to the diameter of hair shaft

A

elasticity

38
Q

causes cortex to swell and edges of the cuticle scales to lift

A

water content

39
Q

makes it easy to generate electrostatic charges by
brushing & combing

A

High electrical resistivity and low dielectric constant

40
Q
  • based on thickness
  • based on color
  • based on condition
  • based on shape size and color
  • based on curliness
  • based on greasiness
A

human hair types

41
Q
  • Fine
  • Medium
  • Coarse
A

Based on Thickness

42
Q

Function of melanin

A

Based on Color

43
Q
  • Damaged
  • Healthy
A

based on condition

44
Q
  • lanugo
    > very fine hair
    > babies only
    > shed moments after birth
  • vellus
    > fine hair
    > Seen in areas where hair is not too
    > Purpose: Thermal control through evaporation / perspiration visible
  • terminal hair
    > Scalp, brows
    > Darker, more visible
    > Distinct function is protection
A

Based on Shape, Size, and Color

45
Q

type of hair may change
(t or f)

A

Terminal → Vellus: Balding
Vellus → Terminal: Mustache

46
Q
  • Excess sebum production
  • Usually associated with dandruff
A

Greasy hair

2nd shift lecs (21 decks)

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