Transcript Integumentary System

Integumentary System
Chapter 6
The Skin, etc.
Test is Oct. 8th!!!!
Note Cards Due September 29th!!!
Integumentary System
• Consists of…
– Skin
– Sweat glands (sudoriferous glands)
– Oil glands (sebaceous glands)
– Hair
– Nails
Functions of Integumentary
System
• Protection from injury
– Mechanical (punctures, pricks, etc.)
– Pathogen entry
• Physically stops pathogens
• Chemically stops pathogens
• Sensation
– Feeling
• Metabolic Functions
• Temperature Regulation
• Looks
Skin Structure
• Epidermis
– Superficial
– avascular
– Consists of 4 -5 layers of epithelial cells
• Dermis
– Deep
– Vascular
– Fibrous connective tissue
– Accessory appendages
http://missinglink.ucsf.edu/lm/DermatologyGlossary/img/Dermatology%20Glossary/Glossary%20Histo%20Images/Epidermis_20x-210.jpg
Epidermis
• Keratinized stratified
squamous epithelium
• Avascular
• Consists of 4-5 cell
types
http://missinglink.ucsf.edu/lm/DermatologyGlossary/i
mg/Dermatology%20Glossary/Glossary%20Histo%20
Images/Epidermis_20x-210.jpg
4 types of cells
• Keratinocytes
– structure
• Melanocytes
– pigment
• Merkel cells
– sensation
• Langerhans’ cells
– phagocytes
Keratinocytes
• 95% of all cells in epidermis are keratinocytes
• Found in all layers of epidermis
• Produces keratin
– Tough, fibrous structural protein
– Protects underlying layers from environmental
factors (heat, UV radiation, water loss)
– Key component of hair and nails
• Connected to each other by desmosomes
(cell structure that is used for cell to cell
adhesion)
Keratinocytes
• New skin is made deep and “pushed” up
• Keratin is made in the journey up from the
bottom of the skin.
• By the time they reach the upper layer of
skin keratinocytes are just scale-like
“bags” of keratin
http://download.videohelp.
com/vitualis/med/thick_ski
n_epidermis_w.jpg
Melanocytes
• Produce the pigment melanin
• Found in the deepest layer of the
epidermis
• Spider shaped
• Package melanin into granules called
melanosomes and then transfer those
melanosomes to the keratinocytes
http://www.ccs.k12.in.us/chsBS/kons/kons/images/Skin_tws_16_02.jpg
Melanocytes
• Melanin granules protect the DNA in the
nucleus from UV damage
Thick skin
• Found on soles of feet and palms of hands,
also found on fingers and toes
• Contains 5 epidermal sheets
– Stratum basale
– Stratum spinosum
– Stratum granulosum
– Stratum lucidum
– Stratum corneum
http://download.videohelp.com/vitua
lis/med/thick_skin_epidermis_w.jpg
Thin Skin
• Found everywhere else
• 4 layers
– Stratum basale
– Stratum spinosum
– Stratum granulosum
– Stratum corneum
• The layers themselves are thinner than
thick skin
http://missinglink.ucsf.edu/lm/DermatologyGlossary/img/Dermatology%20Glossary/Glossary%20Histo%20Images/Epidermis_20x-210.jpg
Stratum Corneum
• Outermost stratum
• 20-30 layers of squamous dead cells that
contain high amounts of keratin
• Helps in water absorption and retention
• Protection
• Sloughs off (ashy skin)
Stratum Lucidum
• Occurs only where skin is thick and
hairless
• 3 to 5 layers of dead, flattened
keratinocytes
• Appears clear under a microscope
because the cells have no nuclei
Stratum Granulosum
• 2 – 4 cell layers thick
• Cells continue to flatten (nuclei and
organelles disintegrate)
• Filled with keratohyalin (staining granules
required for keratin formation)
• Keratinization begins here
Stratum spinosum
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8 to 10 layers thick
Irregular shaped cells
Spinous or prickle cell
Rich in RNA (needed for protein synthesis)
Some cells can still be mitotic
Cells shrink, exposing desmosomes (causes
spiny appearance)
• Lipids present create a hydrophobic barrier
Stratum basale
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Deepest layer
Firmly attached to the dermis
Single layer of cells
Cells undergo mitosis
Contain melanocytes
Stratum germinativum
• “growth” layer
• Describes strata spinosum and basale
together
***this term’s definition varies based on the
source***
• ..\Desktop\Videos\The_Skin.wmv
Dermis
• Layer between the epidermis and
subcutaneous
• Strong, flexible fibrous tissue
• Composed of 2 layers
–Papillary layer
–Reticular layer
Papillary Layer
• Upper 1/5
• Intertwined with rete ridges (Epidermal
thickenings that extend downward
between dermal papillae) in the epidermis
• Composed of loose (areolar) CT
• Contains lots of blood vessels that
constrict in cold weather and dilate in hot
weather
Reticular Layer
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•
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Lower 4/5 of the dermis
Dense irregular CT
Primary location for elastic fibers
Most skin appendages are found here
http://missinglink.ucsf.edu/lm/DermatologyGlossary/img/Dermatology%20Glossa
ry/Glossary%20Histo%20Images/Papillary_vs_Reticular_Dermis_10x-208.jpg
Dermal Growth & Repair
• Dermis does not continually regenerate
• If it is not repaired with new skin, a scar
will form
• Where an incision has been made plays a
role in whether or not it will heal quickly.
• Stretch marks – elastic fibers are stretched
too quickly or for too long
Langer’s Cleavage Lines
• Dense
bundles of
white
collagenous
fibers that
make up the
reticular layer
of the dermis
orient
themselves in
a pattern
Langer’s Cleavage Lines
• Incisions made across Langer’s cleavage
lines heal more slowly than cuts made
along or parallel to Langer’s cleavage lines
What color is your skin?
• Well, that depends on your…
–Melanin
–Carotene
–Hemoglobin
• Only melanin is actually skin
Skin Color
• Melanin
– Polymer of tyrosine – synthesis is
catalyzed by tyrosinase (Albinos lack this
enzyme)
– Range in color from yellow, reddish brown
to black
– All people have the same # of melanocytes
– Skin color variation depends on how much
and what type of melanin is made
– Freckles and moles are local spots of
melanin
Skin Color
• Carotene
–Yellow to orange pigment found in
food
–Eat too much and it is temporarily
deposited in the stratum corneum of
thick skin
• Hemoglobin
–Causes a somewhat pink color in
caucasians
http://media.photobucket.com/image/skin%20color/Yoshi1684/04-skin-color-map_cl.png
Skin Appendages
•
•
•
•
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Sebaceous glands
Sudoriferous glands
Ceruminous glands
Hair
Nails
Sebaceous Glands
• Alveolar glands found everywhere but
palms of hands and soles of feet
• Secrete oil (sebum) for the hair and skin
• Reduces fungal activity on the skin surface
• Oxidation can cause sebum to darken,
forming a blackhead.
Sudoriferous Glands
• Sweat glands
– Classified as
either
eccrine
(merocrine)
or apocrine
Eccrine (Merocrine) glands
• Distributed all over the body
• Simple, coiled, tubular glands
• Produce sweat
– Contains salts, ammonia, uric acid, urea
– Eliminates waste
– Maintains constant core temperature
– pH of sweat is 4-6, creating an “acid shield”
on the body
Apocrine glands
– Deep in subcutaneous layer (armpit, areola of
the breast, pigmented anus)
– Larger than eccrine sweat glands
– Sweat is thicker than eccrine sweat
– Odor is often associated with theses glands
– Become active at puberty
Ceruminous Glands
• Modification or variety of apocrine sweat
glands
• Excretory ducts that open onto the ear
canal and/or with skin hair follicle on the
neck area
What else is attached to the
skin????
http://assets.babycenter.com/ims/2008/03mar/20080
327/april_2008_hair_new_mamma21.jpg
http://blogs.smarter.com/blogs/long%20nails.jpg
Hair
• Hair is a flexible strand made of highly
keratinized dead cells.
• Cells do not flake off individually like they
do on the skin.
• Made by the living hair follicle
Hair follicle
• Hair has a shaft
that protrudes
from the skin.
• Root gets wider
at the base
• Made of 3
concentric rings
– Medulla
– Cortex
– Cuticle
Medulla
http://shs.westport.k12.ct.us/forensics/09-trace_evidence/splitting_hairs.htm
• The innermost layer of the hair.
• It is made of cells that form a shaft through
the middle of the hair.
• Different amounts of medulla may be
present in the hair.
• Medulla
Cortex
http://shs.westport.k12.ct.us/forensics/09-trace_evidence/splitting_hairs.htm
• The intervening layer of the hair (i.e.,
between the cuticle and the medulla).
• It is made of spindle shaped cell and
pigment granules (these give color to the
hair).
• You may also find ovoid bodies (look like
large pigment granules) and cortical fusi
(small bubble-like structures) in the cortex.
Cuticle
http://shs.westport.k12.ct.us/forensics/09-trace_evidence/splitting_hairs.htm
• The outermost layer
of the hair.
• It is made of keratin.
• The cuticle is really a
series of overlapping
scales - very resistant
to chemical
decomposition
http://www.answersingenesis.org/assets/images
/articles/am/v2/n3/Human_Hair3.jpg
http://academic.pgcc.edu/~aimholtz/AandP/LectureNotes/ANP1_Lec/205Lec.html
Hair and Hair Follicles
• The hair follicle surrounds
much of the hair root.
• It contains an outer
connective tissue sheath and
an inner epithelial root
sheath.
• At the base of the hair follicle
is a single layer of mitotic
cells derived from the
stratum basale. This is the
hair matrix.
• All the cells of the hair are
derived from the hair matrix.
Just beneath the hair matrix
is an obvious dermal papilla
called the hair papilla. It
contains the blood vessels
that nourish the matrix and
the cells of the hair follicle.
http://academic.pgcc.edu/~aimholtz/AandP/LectureNotes/ANP1_
Lec/205Lec.html
Notice the hair shaft, hair follicle, papilla,
and the multiple sebaceous glands.
http://academic.pgcc.edu/~aimholtz/AandP/LectureNotes/ANP1_Lec/205Lec.html
Hair and Hair Follicles
http://academic.pgcc.edu/~aimholtz/AandP/LectureNotes/ANP1_Lec/205Lec.html
• Wrapped around the bulb of the
follicle is a network of sensory
nerve endings known as the hair
root plexus. Allow the hairs to
serve a sensory function.
• Attached to each hair is a bundle
of smooth muscle known as an
arrector pili muscle. In times of
fright or cold, these muscles
contract and cause the hair to
stand on end – and produces
goose bumps.
– Increases airflow in mammals with
significant hair (i.e., not humans) and
increases the apparent size of an
animal with significant hair. Vestigial
in humans.
The arrow indicates an arrector pili muscle. In this picture, you
should also try to identify the shaft, root, follicle, hair papilla, and
sebaceous gland.
http://academic.pgcc.edu/~aimholtz/AandP/LectureNotes/ANP1_Lec/205Lec.html
Nails
• Nail body – visible part
of the nail
• Nail Root – hidden
under the cuticle
• Cuticle – fold of skin
• Lunula – crescent
shaped white area
• Nail bed – appears pink
because of the number
of blood vessels, under
the nail body
• Free edge – the “white”
part that hangs over
http://4.bp.blogspot.com/_TGR8TxUfiIw/RmtdbrJUuTI
/AAAAAAAAAF0/78AjZ0Jmdbg/s400/14.jpg
Cell Cycle
• Interphase
• Cell growth, where cell spends most of its time
• Mitosis
– Prophase
– Metaphase
– Anaphase
– Telophase
• Cytokinesis
http://www.biologycorner.com/resources/cell_cycle.jpg
A schematic representation of the mammalian cell cycle.
Collins K et al. PNAS 1997;94:2776-2778
©1997 by The National Academy of Sciences of the USA
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•
•
S = Synthesis (DNA replication)
G1 and G2 = growth and reorganization
G0 = state of quiet (cells stop cycling)
Cell checkpoints = quality control
Cell Cycle and Cancer
• Two things happen…
• Checkpoint doesn’t register that something
is wrong and allows the “bad” cell to
continue through the cell cycle
• “bad” cells are insensitive to the signals
that tell the cell what to do (i.e. die)
What type of cancers do I need
to know about?
• Basal cell carcinoma
• Squamous cell carcinoma
• Melanoma
Skin Disorders
• Impetigo – bacterial infections
• Tinea – fungal infection (ringworms, jock
itch, athelete’s foot)
• Warts – viral infection
• Boils – Staph infections of hair follicles
Vascular and Inflammatory
• Bed sores
• Hives
• Scleroderma – autoimmune diseases
• Psoriasis
• Eczema
Body Temperature….ooops
• The skin helps sense changes in the
external temperature and then allows the
body to maintain homeostasis.
• Sometimes though, there are problems in
the body temperature
• Fever
– unusually high body temperature
– Pyrogens (“fire-makers”) cause the body to
produce a fever
– Is thought best to let the fever “run its course”
• Malignant hyperthermia
– Genetic condition
– Abnormally high body temp
– Muscles become rigid when exposed to
certain muscle relaxers or anesthetics
• Heat exhaustion
– Body loses too much fluid from heat-loss
mechanisms
– Normal body temperature is maintained
– Treated with rest in a cool area and fluid
replacement
• Heat Stroke
– Body cannot maintain normal temperature
– Age, disease, drugs, heat play a role
– 105 degrees or higher
– Immediate cooling down and fluid
replacement required
• Hypothermia
– Cannot maintain normal body temperature in
cold conditions
– Body temperature is 95 degrees or lower
– Slowly warm the person back up
– ..\..\Desktop\Videos\Hypothermia.asf
• Frostbite
– Localized damage
– Necrosis and gangrene can occur
– ..\..\Desktop\Videos\Frostbite.asf