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Anatomy and Physiology
The Integumentary System
(Skin)
Skin
• Cutaneous Membrane
• With its derivatives they make up the
Integumentary System
– Sebacous glands
– Sweat glands
– Hair nails
Functions of the Integ. System
• Covers the body
• Waterproofs
• Protects from mechanical, chemical, and
bacterial damage
• Helps maintain body temperature
– Capillary network
– Sweat glands
More Functions
• Protects from UV radiation
– Melanin
• Produces Vitamin D
• Sensory Perception
– Pressure
– Pain
– temperature
Epidermis
• 5 Layers of avascular tissue
• Most of the cells are keratinocytes
• Deepest layer is Stratum Basale
• Most nourished
• Site of mitosis
• Melanocytes (freckles and moles)
• Cells move superficially through the next two
layers (flatten and keratiniized)
• Stratum Spinosum
• Stratum Granulosum
Epidermis Cont
• Dead cells form the outer two most layers
• Stratum Lucidum (palms and soles)
• Stratum Corneum
• 20-30 cells thick
• Shed on a continual basis (40lbs in lifetime)
• Replaced in 25-45 days
Dermis
• Dense Fibrous Connective Tissue
• Outer layer s the papillary layer
– Named for the papillae (peg-like projections)
– Many house capillaries that nourish the epi
– May contain nerve endings and touch
receptors (Meissner’s corpuscles
– Forms the fingerprints
Reticular Layer
• Blood vessels
– Help in maintaining temperature
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Sweat glands
Oil glands
Pressure sensors (pacinian corpuscles)
Collagen for tensile strength and elastic
fibers for elasticity
Homeostatic Imbalance
• Prolonged pressure
on the skin can cut off
blood supply
• Can result in cell
death
• Decubitus Ulcers
– Bedsores
• From not turning
patients
Skin Color
• Melanin
– Brown, black to yellow
• Carotene
– Yellow-Orange
• Hemoglobin
– Red from RBC’s picking up oxygen
– Gives Caucasian's their pink color
– Poor O2 causes cyanosis (blue)
Skin color variation
• Redness or erythema
– Blushing, fever, hypertension, inflammation, or allergy
• Palor (Pale)
– Stress, anemia, hypotension, ischemia
• Jaundice (yellowing)
– liver disorder
– Bile pigments circulating
• Bruises (black and blue)
– Blood into tissue (hematoma)
– Vitamin C deficiency or hemophilia?
Skin Appendages
• Exocrine Glands
– Release secretions to the skin via ducts
• Sebaceous glands (sebum)
– Open to hair follicle or to the surface
– Lubrication and anti-bacterial
– Increase in teenage years in response to testosterone
• Sweat Glands (sudoriferous)
– Eccerine produce sweat (pH 4-6) released via a duct/pore
» Heat regulation
– Apocrine produce a substance high in protein and fatty acid
» Found axillary and groin
» As bacteria break the substance down creates odor
Apocrine Glands
• Activated by stress and sexual arousal
Hair and Hair Follicles
• The body has 1,000,000’s of hairs
• Not much function
– Eyelashes and nose hairs filter
• Deepest part below the surface is the root
• Hair above the surface is called the shaft
– Most of it is dead keratinized cells
• None on hands, feet, nipples and lips
• Hormones determine growth of some areas
– Scalp, axillary, and groin regions
Hair Structure
• Central core is the
medulla
• Cortex is the middle layer
• Cuticle is outermost layer
– Most keratinized
– Wears away to cause split
ends
• Pigment from
melanocytes
• Shaft shape determines
hair texture
Hair Follicles
• Site of hair production
• Hair formed by division of
stratum basale in the
matrix
• As cells mature the
migrate outward, die and
become keratinized
• Dermal sheath outside an
epidermal sheath
– Dermal supplies nutrients to
the matrix
• Arrector pili stands hair up
Nails
Nails
• Scale like modification of the epidermis
– Body is exposed and root is hidden
• Nail bed is thickened stratum Basale
– Proximal end is the nail matrix site of nail growth
– Damage the matrix and nail regrowth is stunted
Homeostatic Imbalance
• Wide range of over 100 different ailments
– Very visible when something is wrong
• Allergies
• Infections
– Bacterial, viral or fungal
• Burns
• Cancer
Infections and Allergies
• Athletes foot (tinea pedius)
– Fungal infection
– Red peeling skin
• Boils and carbuncles
– Inflamed hair follice and sebaceous gland
– Bacterial infection
• Cold Sores
– Viral infection (herpes simplex) in cutaneous nerve
– Activated by emotion, fever, or sun
Infections and Allergies
• Contact dermatitis
– Allergic reaction to chemical
– Itching red skin
• Impetigo
– Pink weepy lesions that develop a crust and rupture
– Highly contagious staphlococcus infection
• Psoriasis
– Overpopulation of skin cells
– Red lesions with scaly skin that itches and burns
– Perhaps auto immune
Pictures
Burns
• Damage to the skin caused by heat,
electricity, UV, or chemical
• Very serious threat!
– Effects many systems
– Dehydration and electrolyte imbalance
• Kidney damage
• shock
– Infection
• Leading cause of death in burn victims
Burn Estimation
• To determine the
extent of fluid loss the
rule of 9’s is used
• 11 areas of 9% and
1% for genitals
Burn classification
• 1st Degree
– Epidermis only
– Heals in 2-3 days ex:
sunburn
• 2nd Degree
– Involves the epidermis and
dermis
– Blistering occurs
• 3rd Degree
– Full thickness of the skin is
destroyed
– Painless due to loss of
nerves
– Skin grafting must be done
•
Critical if any of the
following
1. 25% has 2nd degree
2. 10% 3rd degree
3. 3rd degree on hands, face or
feet
– Facial can hinder breathing
– Joint issues in hands and
feet
Burn Pictures
First Degree
Second Degree
Third Degree
Skin Cancer
• Tumors are referred to as neoplasms
– Benign do not spread
– Malignant invade other body tissues
• Skin cancer is the most common type of
cancer in humans
– 1/5 develop in lifetime
• Overexposure to UV is the greatest risk
factor
Skin Cancers
1. Basal Cell Carcinoma
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Least malignant and most common
Affects the stratum basale
Cells invade dermis and sub-q creating a
small raised nodule
Cure rate 99%
2. Squamous Cell Carcinoma
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Stratum Spinosum
Scaly papule turns into shallow ulcer with
raised border
Scalp, ears, hands, and lips
Sun induced?
Good chance with early detection and
treatment
3. Malignant Melanoma
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Cancer of the melanocytes
Only about 5% but increasing
Often develop from a mole
Rapid metastasis
50% survival rate with excision and immuno
Use ABCD rule in examination
ABCD Rule
A. Asymmetry
B. Border Irregularity
C. Color
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Spot contains different pigments
Black, brown, tan, red, blue
D. Diameter
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Greater than 6mm
(E. Elevation)
Developmental Aspects of Skin
• Prenatal to newborn
 Lanugo- hairs
 Vernix Caseous- cheese from seb gland
 Milia- baby pimples
• Adolescence
 Skin and hair oily ---- acne
• Old age
 Skin gets thinner and drier
 Colder and bruising
 Loss of elasticity leads to wrinkles (smoke, UV)
Developmental Aspects of Hair
• Hair looses luster
• Lose follicles over time
– Thinning hair is called alopecia
– May be male pattern baldness
• Hairs may become gray
– Delayed action gene shuts down melanin
production
• Stress, chemical, nutritional, radiation, and
fungi are all possible causes