Transcript Integumentary System Skin Color

Body Bugs
NOVA | Bugs That Live on You
Follicular Mites – found in
all hair follicles
Dust Mites – found
on your body, your
bed, any fluffy
surface that you
spend time with
Skin color
Normal Skin Color Determinants
 Determined by a combo of:
Types of pigments present
Blood circulation
Stratum corneum thickness
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4.14
Normal Skin Color Determinants
 Melanin
 Yellow, brown or black pigments
produced in melanocytes found in
stratum basale – transferred to
keratinocytes
 Local accumulations form freckles &
pigmented moles
 Amount of melanin produced depends
upon genetic and exposure to sunlight
 Solar elastosis – clumping of elastin
fibers = leathery looking skin
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4.14
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Normal Skin Color Determinants
 Carotene
 Orange-yellow
pigment from some
vegetables
 Vitamin A precurser
– vitamin A forms
retinal which is
needed for sight
 Accumulates in
adipose and
stratum corneum
cells
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Normal Skin Color Determinants
 Hemoglobin & blood circulation
Red coloring from
oxygenated blood cells in
dermis capillaries
Oxygen content determines
the extent of red coloring
More obvious in fair skinned
individuals
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Blood flow

Vasodilation causes increase in
flow
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Vasoconstriction causes
decrease in flow
Skin as a Diagnostic
 Skin color is influenced by emotional &
disease states: You should know the
states that cause these.
 Cyanosis – bluish color - lack of oxygen
 Erythema – redness – heat, inflammation,
fever
 Add this -Pallor – paleness – lack of
blood flow
 Jaundice – yellowish color – liver damage
 Bronzing – bronze (tan) – Addison’s
disease
 Hematomas – black & blue – blood under
skin
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Skin Derivatives
Hair Anatomy
 Central medulla
 Cortex surrounds
medulla
 Cuticle on outside of
cortex
 Single layer of
overlapping cells
 Split ends – cuticle
flakes off – fibers in
cortex fray out
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Figure 4.7b
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Hair anatomy
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Hair shaft –
above skin
Hair root –
below skin
Appendages of the Skin
 Hair
 Shaft – projects from
skin
 Add in margins: Shape
determines hair
curliness
 Flat = curly
 Oval = wavy
 Round = straight
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Figure 4.7c
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4.18
Hair Follicle
 Hair - Extends into
dermis & hypodermis
 Produced by hair
bulb- expanded
end
 Papilla contains
capillaries in bulb
for hair nourishment
(fix in notes!)
 Matrix = growth
zone – directly
surrounds papilla
Figure 4.7c
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4.18
Associated Hair Structures
 Arrector pilli
 Smooth muscle regulated
by emotions
 Contraction pulls hair
upright - Normally at
angle
Figure 4.7a
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Arrector Pili Muscle
Hair Color
 Caused by proportions
of 3 types of melanin
 Determined by
genetics
 Melanin is replaced by
air bubbles in
gray/white hair –
causes different
texture
Figure 4.7b
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4.19
Hair Types
 Vellus hair – softer body
hair
 Terminal hair – coarser
hair found in axillary &
anogenital regions &
other body regions
 Lanugo – newborn baby
fuzz
Figure 4.7a
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Hair Growth
 Influenced by (in order):
Nutrition: main
influence
hormones
Blood flow
Figure 4.7a
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Cycles
Thought Question: know the
answers to these questions!!

Why is the hair on your head longer than the
hair in your eyebrows?

Why does some hair fall out every day?

Approx 100 hairs per day are lost from your
head! That is why your sink is stopped up!
Androgenetic Alopecia
 Male pattern
baldness
 Sex linked,
recessive trait
 Punnett Square!
Causes thinning
hair in women
Figure 4.7a
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Androgenetic Alopecia
Increased activity in androgen receptors
causes hair loss & increases other health risks
such as coronary heart disease and prostate
cancer in men and polycystic ovary syndrome in
women
 Terminal hair replaced by vellus hair progresses posteriorly
 Treatment: drugs that inhibit testosterone
production (Rogaine, Propecia)

FYI: Polycystic Ovarian Syndrome
More on these topics
when we study the
Endocrine System
Imbalance: FYI
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Thinning hair can be caused by an abundance
of factors.
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Heterozygous traits
Nutrition
Medications
Stress (affects nutrition & hormones)
Hormones
Physical factors
Appendages of the Skin
 Nails: Just know diagram & these imp.
facts – add to diagram:
 Scale-like modifications of the epidermis
 Heavily keratinized
 Stratum basale extends beneath the nail
bed to form nail matrix
 Which is responsible for growth
 Lack of pigment makes them colorless
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Nail Structure
Nail Structure

Know all parts labeled on diagram

Why is lunula white?

What happens if matrix is damaged?
Sweat Glands
 Sudoriferous (sweat) glands
 Three types
 Eccrine glands
 Widely distributed in skin: abundant on
palms, soles, forehead
 Open via duct to pore on skin surface
 Sweat composition: mostly water with
a slightly acidic 4-6 pH
 Function: thermoregulation
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Sweat Glands
• Apocrine glands (also sudoriferous)
 Ducts empty into hair follicles
 Found mainly in anogenital & axillary region
 Begin to function at puberty due to
hormones
 Organic contents: Fatty acids and proteins
– can have a yellowish color that stains
clothes
 Odor is from associated bacteria
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4.17
Sweat Glands
Ceruminous glands
 Modified apocrine gland
 Found in outer 1/3 of ear canal
 Produce ear wax to trap “invaders”
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Appendages of the Skin
 Sebaceous glands (all over except palms
and soles of feet)
 Produce oil for waterproofing
 Lubricant for skin & kills bacteria
 Most with ducts that empty into hair follicles
 Glands are activated at puberty: stimulated
by hormones
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Imbalances
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Upper right hand box in notes;
Acne – active infection of sebaceous glands
Whitehead - Sebaceous gland duct blocked
by sebum
Blackhead – sebum oxidizes, dries, and
darkens
Seborrhea – “cradle cap” – Over activity of
sebaceous glands in infants
Integumentary Functions
Protection - biological

Biological – cells – macrophages &
Langerhan’s cells engulf invaders.
Protection - mechanical
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Mechanical – physical
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Continuity – skin is made impermeable through
the tight junctions & desmosomes
Keratin – physically blocks the passage of water
and water soluble substances
FYI: Molecules that can pass through your skin:
 Lipid soluble – O2, CO2, ADEK, steroids,
nicotine, & other transdermal medications
 Oleoresins – poison ivy & poison oak, etc – you
have less than 10 min to wash it off!
Protection - Chemical
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Chemical
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Skin secretions: tears, sweat, oil lower pH and
contain lysozyme (chemical that lyses cells)
Melanin – pigment shield against UV radiation
Excretion
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Limited amounts of nitrogen containing
wastes (most is excreted in urine unless you
have a kidney disorder in which case urea will
be excreted in small amounts through skin)
Sodium chloride through sweat
Water through sweat
Heat through sweat
Homeostasis of Body Temperature
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Heat production – chief determinant is muscle
activity
Heat loss/gain
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80% of heat transfer is through the skin – the rest
is through the mucosa (dogs are opposite!)
Regulated by vasoconstriction & vasodilation
since heat is carried primarily in the water content
of the blood (reminder: on page 1 of notes)
Understand what is
happening in these
diagrams!!
Vitamin D Production

Vitamin D is important
in the uptake of Calcium
from the food you eat.
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Ca has to be absorbed
from your stomach into
the blood to go anywhere
Cholesterol molecules
when exposed to UV
light become a Vitamin
D precurser
Precurser becomes active
in the liver & kidneys
Sensation – skin receptors
Don’t need to memorize
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Free nerve ending = pain
Meissner’s corpuscles = discriminating touch,
light pressure (think fly on your arm)
Krause’s – cold
Ruffini’s – heat
Merkel Disc – Medium pressure
Pacinian corpuscle – Deep pressure
See diagram in notes
End of Quiz 2 Material
Now Study!