Chapter Four
Skin and Body
Membranes
Classification of Membranes
• Epithelial
– Cutaneous
• Skin
• Stratified squamous
– Mucous (mucosa)
• Lines cavities
• Simple columnar
• Serous
– One layer
– Simple squamous
– Serous fluid
• Parietal & Visceral
–
–
–
–
Lines body cavities
Around organs
Pleura & Pericardium
Simple squamous
Functions of the Skin
• Protection
–
–
–
–
Against disease
Insulates & cushions
UV protection
Chemical protection
• Defense
– 1st line of defense
• Prevention of Dehydration
– Keratin
– Keeps H2O in & out
Functions of the Skin
• Maintenance of Body Temp.
– Heat loss – sweat
– Heat retention – blood flow
• Excretion of Wastes
– Salts
– Urea
– H2O
• Reception of Stimuli
– Touch, pressure, pain, cold, heat
• Vitamin D Synthesis
– Cholesterol molecules  Vitamin D (sunlight)
Layers of the Skin integumentary
• Epidermis
– Strata
• Stratum basale
– Closest to dermis
– Undergoes mitosis
– Nutrients from diffusion
• Stratum spinosum
– Flattened cells w/ spines
• Stratum granulosum
– Granules w/ keratin
• Stratum corneum
– “horny”
– 20-30 cell layers
– Soles. Palms, fingertips-stratum lucidum
Cell Types
• Keratinocytes
– Make keratin
• Melanocytes
– Make melanin
– Secretes melanin – basale layer
• Langerhans cell
– Macrophages-eat foreign substances
Skin Color – amount and kind
• Pigments
– Melanin
• Reddish brown, or black
– Carotenes
• yellow
– Hemoglobin
• rosy
• Emotional
– Redness (sympathetic)
•
•
•
•
Embarrassment
Anger
Fear
Allergies
Dermis – “hide” leather
• Thick connective tissue layer beneath stratum
basale.
– Collagen
– Elastin
• Papillary layer
– Upper, uneven
– Receptors (pain, touch)
– Dermal papillae
• Fingers-fingerprints
• Soles-footprints
Dermis cont…
• Reticular layer
– Deepest
– Blood vessels
– Sweat and oil glands
– Blood supply when restricted
• Degeneration
• Ulceration – bed sore
Appendages of the Skin
• Glands
– Sebaceous glands
•
•
•
•
Oil
Sebum: lubricant, bacteria killing
Whiteheads (blocked oil gland)  blackhead acne
Seborrhea – excess oil
– Sweat glands – 500 ml a day (25 million)
• Eccrine
–
–
–
–
–
Sweat
Clear
99% water
Salts, urea, lactic acid,
pH 4-6
• Apocrine
– Axillary & genital areas
– Fatty acids, proteins, sweat (yellowish)
– Empty into hair follicles
Appendages of the Skin cont..
• Nails
– Modified epidermal cells
– Keratin
• Hair
– 100,000 hairs scalp
– Follicle
• Keratinized cells
• Arrector Pili (goose bumps)– smooth muscles -Hairs
erect-increase blood flow to skin
– Cuticle
• Keep hairs separate
Infections and Allergies
1000 different conditions
• Fungi
– Athletes foot fungus
– Ringworm
• Bacterial
– Boils and carbuncles
• Staphylococcus into hair follicles
• Oil glands
– Impetigo
• Viruses
– Herpes “cold sores”
– Warts
• Allergies
– Eczema
– Contact dermatitis
– “rash”
• Unknown
– Eczema
– Psoriasis
– Hives
• Yeasts
Skin in Stress
• Wound Repair
– Wound
– Inflammatory reaction
• Blood flow
– Edema
• swelling
– Clots
• Stop bleeding
– WBC’s
• Fight bacteria
– Pus
• Dead blood cells
• Dead bacteria
– Scabs
• Burns
Skin in Stress cont…
– Thermal
• Heat
• Chemical – electrical - UV
– First degree
• Epidermis “red”
• Heal 2-3 days
– Second degree
• Epidermis & dermis
• Blisters
– Third degree
• Skin blackens
• Skin grafts
– Risk of death
• Fluid loss , imbalance of electrolytes
• Kidney failure
• Replace proteins , infection
Skin Cancer
• Basal Cell Carcinoma
– Most common
– Alters stratum basale cells
• Uncontrolled mitosis can’t form keratin
• Squamous Cell Carcinoma
– Stratum spinosum
– Scaly reddish papulae
– Spreads to lymph nodes
• Malignant Melanoma – (5%)
–
–
–
–
Brown black patches
Lymph & blood vessels
ABCD rule moles
Asymmetrical, border, color, diameter 76mm
Disease States
• Erythema
– Turns red
• Pallor, blanching
– Anemia
– Low blood pressure
• Jaundice
– Yellowing
– Liver disorder
• Porphyria
– purple
• Bruises
– Hematoma
– Broken capillaries
• Cyanosis
– “bluish”
– Low 02 in blood