Download File

DO NOW
1.
2.
3.
4.
Take out your homework from the weekend.
Summarize the reading from yesterday!
What’s the point of skin?
We are going to watch a video on artificial
skin- get ready to summarize!
INTEGUMENTARY
SYSTEM
Unit 3
PURPOSE OF SKIN
Protection
Sensation
Temperature Regulation
Vitamin D production
Excretion
PROTECTION
Defends the body from the external
environment
From mechanical damage
Prevents of microorganisms from entering
body
Melanin: protects from ultraviolet light
Hair, Nails: heat insulator, keeps out
unwanted objects
Reducing water loss
SENSATION
Receptors to detect pain, heat, cold, pressure
SENSATION
TEMPERATURE REGULATION
 Maintain Homeostasis!
 If HOT:
 Blood vessels dilate
(vasodilation), heat goes to the
surface of the skin
 Heat OUT
 If COLD:
 Blood vessels constrict
(vasoconstriction), less blood
goes to surface, so less heat is
lost
 HEAT STAYS
 Frostbite
VITAMIN D PRODUCTION
Vitamin D:
 Hormone that gathers calcium (Ca) and
phosphate (P)
 Helpful for nerve and muscle function
IF YOU DON’T HAVE ENOUGH VITAMIN D…
Possible to get Rickets
(Osteomalacia)
Skeletal and dental
deformities
Often from malnutrition
EXCRETION
Sweat: removes some waste products from
the body
 Urea
 Uric acid
 Ammonia
Insignificant amounts: most from urinary
system
2 LAYERS OF SKIN
Two main layers of skin:
Epidermis: most superficial layer of skin
 Resists abrasion on skin’s surface
 Reduces water loss through the skin
Dermis: connective tissue
 Responsible for the structural strength of skin
Subcutaneous Layer (Hypodermis):
 Connects skin to muscle or bone
 Not part of the integumentary system
EPIDERMIS
DERMIS
SUBCUTANEOUS LAYER
QUESTIONS
How does skin provide protection?
How does the skin help regulate body
temperature?
What substances are excreted in sweat? Is
skin an important site of excretion?
EPIDERMIS
What is the epidermis?
Superficial layer of the skin
Resists abrasion to the skin’s surface, reduces
water loss
Not as thick as the dermis
Contains no blood vessels
CELLS IN THE EPIDERMIS
*Keratinocytes: make
keratin (a protein),
makes cells durable
*Melanocytes: make
skin color
Langerhans cells:
part of the immune
system
Merkel cells: cells
with nerve endings
for touch
THICK V. THIN SKIN
 Based on the structure of the epidermis
 Thick: where areas of pressure, friction are
constantly applied, all five layers
 Examples: palms of hands, soles of feet, fingertips
 Thin: rest of skin; more flexible than thick skin
 Hair found in thin skin!
SKIN COLOR
Three main factors:
 Pigments in skin
 Blood circulating in the skin
 Thickness of the stratum corneum
Melanin: Group of pigments
Differs for different areas of the body
Melanocytes: cells that produce melanin
Melanosomes: vesicles released by
melanocytes filled with melanin
DIFFERENCES OF SKIN COLOR
Production: dependent on genetic
factors, exposure to light, hormones
All races have = number of melanocytes
Racial variations in skin color
from amount & type of melanin
Also from size, number, and distribution of
melanosomes
DO NOW
1. What are the different layers of the
skin?
2. Why do people have different skin
color?
3. What are the four different cells in the
epidermis?
ALBINISM
Deficiency or absent
of pigment in skin,
hair, and irises of the
eye
KERATINIZATION
Cells divide at bottom
layer and get pushed up
Cells change shape and
composition as they move
up
Keratinization: when
keratinocytes change
shape and fill with keratin
(protein) as they move
towards the surface of the
skin
PSORIASIS
Process of keratinization occurs too fast
Causes thick, red skin, flaky silver-white
patches: scales
Not contagious
Can be triggered by infection, injury, stress
5 LAYERS
Strata: the regions of the different cells of the
epidermis
LAYERS
STRATUM BASALE
 Lowest Layer
 Attached to the basal
membrane
 Separates epidermis from
loose connective tissue
 Basal Cells: stem cells
that replace the cells in
the surface of the skin
(keratinocytes)
 Melanocytes: spread
throughout to give the
skin it’s color
STRATUM SPINOSUM
Spiny Layer
Second lowest layer
Several layers thick
Melanocytes are
common in this layer
Langerhans cellscommon here
STRATUM GRANULOSUM
 All cells still have a nucleus
 Cells are making:
 Keratohyalin
 Keratin
 Make cells water resistantprotecting our epidermis
 Synthesis: can be affected by
the environment
 Callus: thickening of skin,
increasing the rate of synthesis
STRATUM LUCIDUM
Only found in THICK skin
Doesn’t stain all the time
Lack organelles/nucleus
STRATUM CORNEUM
 Most superficial layer
 15-30 layer of
dead/flattened cells
 Lack organelles/nucleus
 Long fibers of keratin
filaments
 Normally dry to help
protect against
microorganisms
 Rate: 15-30 days from
Basale to Corneum
5 LAYERS
Part
Structure
Function
Stratum Corneum
Most superficial layer
of epidermis
Provides structural strength from
keratin, prevents water loss
Disperses keratohyalin
Stratum Lucidum
3 -5 layers of dead
cells, seems
transparent, mostly in
thick skin
2-5 layers of flattened,
diamond-shaped cells
Produces keratonhyalin granules;
lamellar bodies release lipids,
cells die
8- 10 layers of manysided cells
Produces keratin fibers, lamellar
bodies form inside keratinocytes
Deepest stratum of
epidermis
Produces cells, also holds
melanocytes
Stratum Granulosum
Stratum Spinosum
Stratum basale
QUESTIONS
 In which stratum are new cells formed by mitosis?
 Which strata have living cells? Which strata have
dead cells?
 Compare the structure and location of thick and thin
skin. Does hair grow out of thick or thin skin?
 Which cells produce melanin? What happens to the
melanin once produced?
 How do genetic factors, exposure to sunlight, and
hormones determine the amount of melanin in the
skin?
DERMIS
Connective tissue: made of collagen
(main connective tissue fiber)
Two layers:
Reticular Layer
Papillary Layer
Dermal papillae
FINGERPRINTS
LANGER LINES
Reticular layers: dense irregular connective
tissue
Langer lines: elastic and collagen fibers are
orientated more in certain directions
(Cleavage lines, tension lines)
Important for surgeons:
 cut with the lines, less likely to gap, leave scars
 Cut across lines, increases time for healing and scar
tissue
STRETCH MARKS
If skin is overstretched, dermis can
rupture and leave lines visible through
epidermis
Often during pregnancy, intense weight
gain (athletes)
QUESTIONS
What are the two layers of the dermis?
Which layer is responsible for most of
the structural strength?
What are formed by the dermal papillae
in thick skin? What is their purpose?
What are cleavage lines and how are
they related to the healing of a cut?
SUBCUTANEOUS TISSUE
NOT part of the skin!
Loose connective tissue with collagen
and elastic fibers
Three main types of cells:
Fibroblasts: synthesizes collagen
Adipocytes: cells that store fat
Macrophages: cells that eat/engulf others
FIBROBLASTS
ADIPOCY TE
MACROPHAGE
SUBCUTANEOUS TISSUE
Stores lipids (~½ of the body’s!)
Function as insulation, padding, and
source of energy
Used to estimate body fat
INJECTIONS
Intradermal Injections
Subcutaneous Injections
Intramuscular injections
DO NOW
What are you doing this weekend?
What is your favorite animal and why?
What is your favorite type of candy and
why?
OTHER CONDITIONS
 Erythema: blood flowing through the skin, causing a
reddish hue
 Infections
 Sunburn
 Allergic reactions
 Exposure to cold
 Blushing
 Cyanosis: decrease in blood flow  pale skin
 Bluish skin color
 Carotene: yellow pigment in plants
 Using for vitamin A
 If large amounts are consumed, excess accumulates in stratum
corneum, so skin can become yellow
DO NOW
Take out your skin model
Write down your homework!
There will be a vocabulary quiz on Friday.
How does melanin affect your skin color?
What is the purpose of the subcutaneous
tissue?
ACCESSORY SKIN STRUCTURES
Three main parts:
Hair
Sebaceous & sweat
glands
Nails
HAIR
Two main types:
 Terminal: long, coarse, pigmented (scalp, eye lids,
and eyebrows)
 Vellus: short, fine, unpigmented
HAIR
What’s its purpose?
Protection from UV light
Cushioning blow to head
Insulation
Detects/keeps out entry of foreign particles
HAIR STRUCTURE
Hair Shaft v. Hair Root
Hair:
Medulla (soft keratin)
Cortex (hard keratin)
Cuticle (hard keratin)
HAIR FOLLICLE
Where hair
develops!
Dermal root
sheath
Epidermal root
sheath
Hair Bulb
HAIR GROWTH
Two stages:
Growth
Cells differentiate, keratinize, die
Hair grows longer as cells are added on
Hair will stop growing, follicle shortens to hold
hair in place
Resting
Old hair falls out, new cycle begins
HAIR COLOR
 From melanin!
 Different types of melanin cause different color sof
hair
 Age: causes amount of melanin to decrease (white,
faded)
 Hair color: controlled by several genes
ARRECTOR PILI MUSCLE
With each hair follicle
Smooth muscle cell
From dermal root sheath to papillary layer of
dermis
When contract, pulls follicle into
perpendicular position
Goose bumps!
DRUG TESTING
 Hair fed by bloodstream, drugs go into the blood
stream
 Drug testing tests for use of: cocaine, marijuana,
opiates (codeine, morphine), methamphetamine, PCP
 Covers 30-90 days, cut about 100-120 strands of
hair and test the most recent portion
 Color does not matter
 In comparison to traditional tests:
 Wider window of detection
 Harder to tamper with the test
GLANDS
Sebaceous Glands:
 In dermis
 Produce sebum oily white
substance with lots of lipids
 Oils the hair and skin surface
 Prevents drying and protects
against some bacteria
Sweat Glands:
 Produce sweat
 Evaporates to cool the body
LIE DETECTOR
Polygraph
You sweat when you are emotionally
stressed!
Salt in skin conducts electricity and
lowers the electrical resistance of the
skin
National Academy of Sciences do NOT
think this is a reliable measure
NAILS
Nail: Thin plate with dead stratum
corneum cells + really hard keratin
Nail Root v. Nail body
Nail matrix: stratum basale gives rise to
cells that form the nail
QUESTION
 While trying to fix some loose boards on his deck,
Bob hit his left thumb with his hammer. The hammer
struck his thumbnail distal to the lunula in the nail
body. After a short period, a dark area appeared in
the area of the nail bed. The injury was very painful
until a physician drilled a small hole through Bob’s
nail, releasing bloody fluid. After nearly 2 months,
the dark area moved to the free edge of the nail.
Explain why a dark area developed in the nail and
why it moved distally. What caused Bob’s pain, and
why did drilling a hole in his nail relieve it?
SKIN GUN
 https://www.youtube.com/watch?v=eXO_ApjKPaI&feature=rel
mfu