Transcript The Integtumentary System

The
Integtumentary
System
Functions of the Integument
• Protection
• Excretion
• Sensory
• Water balance
• Thermoregulation
• Endocrine (Vitamin D)
Some facts about skin
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Largest organ of the Body
Approximately 2 square meters or 22 square feet
About 5 kg (11 pounds)
Ranges in thickness between 0.5 mm (genitals, lips,
eyelids) to 5 or 6 mm on the soles of the feet.
• Three layers, from superficial to deep:
1. Epidermis - outer layer of dead, keratinized cells
2. Dermis - dense irreg. c.t., nerves, vessels, etc.
3. Hypodermis - mostly subcutaneous adipose tissue
Slice o’ skin
Skin: Thick
Stratum granulosum
Stratum corneum
Stratum spinosum
Stratum Basale
Dermis
Thin skin: scalp
Human scalp
Scalp: deep
Human scalp
Organization of the Epidermis
Figure 5–2
The
Epidermis
Melanocytes
Figure 5–5
Skin Glands
There are two general types of skin glands:
1. Sudoriferous glands (sweat glands).
• Eccrine glands - produce watery sweat for
cooling, waste metabolite excretion & electrolyte
excretion. Found all over the body except nail
beds, genitals, & ear drums. Most dense on
palms, soles, forehead & chest.
• Apocrine glands - produce “stinky” sweat.
Secrete a thicker, protein and lipid rich fluid and
“pheromones”. Concentrated in arm pits, pubic
region, areolae. Activated by the stress
response or sexual arousal (sympathetic n.s.)
Skin Glands b.
• Mammary glands - Mammary glands are
specialized sudoriferous glands. They produce
milk. And yes, men have them too!
• Ceruminous glands - Modified sweat glands that
line the external auditory canal. They make
“cerumen”, also known as ear wax.
2. Sebaceous glands - produce oily secretion called
“sebum”. These glands open onto the hair follicles
and the oil keeps hair supple and skin water
resistant..
The Dermis: Glands
Sebaceous Glands
Figure 5–10
Apocrine Sweat Gland
Figure 5–11a
Merocrine
Sweat Gland
Other Integumentary Glands
• Mammary glands:
– produce milk
• Ceruminous glands:
– protect the eardrum
– produce cerumen (earwax)
Control of Glands
• Autonomic nervous system:
– controls sebaceous and apocrine sweat
glands
– works simultaneously over entire body
• Merocrine sweat glands:
– are controlled independently
– sweating occurs locally
Epidermal Appendages: Hair
Structure of a Hair
Figure 5–9d
Connective tissue
Root sheath
Follicle wall
Hair follicle: cross section
Internal root sheath
Cuticle
Cortex
Medulla
Hair follicle in cross section
Structures
of a
Follicle
Figure 5–9c
Epidermal
Appendages:
Nails
Ridges
and
Ducts
Figure 5–4
Repair of Localized Injuries
to the Skin: Step 1
• Bleeding occurs
• Mast cells trigger
inflammatory
response
Repair of Localized Injuries
to the Skin: Step 2
• A scab stabilizes
and protects the
area
The Inflammatory Response
• Germinative cells migrate around the
wound
• Macrophages clean the area
• Fibroblasts and endothelial cells move in,
producing granulation tissue
Repair of Localized Injuries
to the Skin: Step 3
• Fibroblasts
produce scar
tissue
• Inflammation
decreases, clot
disintegrates
Repair of Localized Injuries
to the Skin: Step 4
• Fibroblasts strengthen
scar tissue
• A raised keloid forms
Stages of wound healing
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Inflammatory
Migratory
Granulation
Maturation
– Fibrosis: scar tissue formation
• Hypertrophic scar is one that remains within the
boundaries of the original wound.
• Keloid scar is one that extends to surrounding
tissue beyond the original wound.
Burns
Rule of Nines
• To estimate
burn damage,
surface area is
divided into
multiples of 9
Figure 5–14
First degree (partial thickness)
Second Degree
First & second degree burns
Third degree (full thickness)
Third degree burns
Skin Cancer
• Basal cell carcinoma - 75%, arise from epidermal cells.
Rarely metastasize to other tissues. Easily removed.
• Squamous cell carcinoma - around 20%, may or may not
metastasize. Also from epidermal tissue.
• Malignant melanoma - remaining 5%, arise from
melanocytes. Often delayed reaction to sun exposure by 10 20 years. Poor prognosis, they metastasize very rapidly
once they begin to grow.
ABCDs of
skin cancer
detection
Risk factors for skin cancer
• Skin type - lighter skin pigmentation =
higher risk
• Sun exposure - lower latitude, more direct
sun. Longer time, greater exposure.
• Family history - Genetics nearly always
plays at least some role in susceptibility to
disease.
• Age - older = longer exposure.
• Immune system health - people with
compromised immune systems are at
greater risk.
Skin Cancer
Figure 5–6
Fungating Melanoma
Other skin pathologies
• Athlete’s foot - caused by a fungus
• Cold sore - herpes simplex virus type I. HSV II causes
genital herpes.
• Acne - inflamed sebaceous glands. Can be seriously
disfiguring. Accutane™ and Retin-A™ are prescription
treatments which are derived from vitamin A and have proven
helpful in severe cases. OTC treatments include salicylic acid
and benzoyl peroxide with variable efficacy.
• Impetigo - superficial infection caused by staphylcocci or
streptococci, two genera of bacteria very common to skin.
• Warts - raised lesions caused by papilloma virus. HPV
causes genital warts, a sexually transmitted infection, that is
often associated with cervical cancer in women.
Effects of Aging
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Epidermal thinning
Decreased numbers of Langerhans cells
Decreased vitamin D3 production
Decreased melanocyte activity
Decreased glandular activity (sweat and
oil glands)
Effects of Aging
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Reduced blood supply
Decreased function of hair follicles
Reduction of elastic fibers
Decreased hormone levels
Slower repair rate
Another
great use
for skin