Chapter 5 Flashcards
Cells of the Epidermis
- Keratinocytes
- Langerhans Cells
- Merkel Cells
- Melanocytes
Keratinocytes
- Composes more than 90% of epidermal cells
- Makes keratin
Keratin
-Gives skin its strength and flexibility
Langerhans Cells
- Immune cells
- Phagocytose foreign particle, and initiates an immune response if necessary
Merkel Cells
-Touch receptors
Melanocytes
- Make melanin
- Protects us from UV rays
Epidermal Layers
- Stratum Basale
- Stratum Spinosum
- Stratum Granulosum
- Stratum Lucidum
- Stratum Corneum
Stratum Basale
- Deepest epidermal layer
- Mitotic layer
- Melanocytes and Merkel cells found in this layer
Stratum Spinosum
- Some mitosis
- Langerhans cells found in this layer
Stratum Granulosum
-Keratinization occurs here
Keratinization
-Granules containing keratin begin to form
Stratum Lucidum
- Only in thick skin
- Thin clear layer of dead keratinocytes between the stratum corneum and the stratum granulosum
Stratum Corneum
- Most superficial layer of the skin
- 20-30 layers of dead keratinocytes
- Protects from abrasion, outside environment, water loss
Layers of the Dermis
- Papillary Layer
- Reticular Layer
Papillary Layer
- Most superficial layer (20% total thickness)
- Areolar tissue
- Dermal Papillae (fingerprints)
- Meissner Corpuscle (light touch receptor)
Reticular Layer
- Deep layer (80% total Dermis thickness)
- Dense irregular
Cleavage Lines
-Natural separations in the dermis caused by bundling collagen fibers i the reticular layer
What determines our skin color?
- Melanocytes
- Melanin
Melanocytes
-Make melanin
Melanin
- The pigment that dictates our skin color, and protects us from UV radiation
- Production is determined by genetics and UV exposure
Albino
-Lack the enzyme responsible for melanin production
Why is UV radiation bad?
- Causes DNA damage (Leads to skin cancer)
- Breaks down elastin (Leads to wrinkles)
- Depresses the immune system (More susceptible to infection)
Other skin pigments
- Carotene
- Hemoglobin
Carotene
- Found in stratum corneum
- Yellowish pigment
Hemoglobin
- Found in red blood cells
- Gives skin a pinkish color when it is oxygenated
Skin color changes
- Redness
- Pallor (whitening of skin)
- Cyanosis
- Jaundice
Redness of the skin
- Dilation of superficial blood vessels
- Caused by blushing, drinking, fever, inflammation, allergy, high blood pressure
Pallor
- Whitening of the skin
- Caused by fear, anger, anemia, low blood pressure
Cyanosis
- Bluish tinged skin
- Caused by lack of oxygen in skin
- Could indicate abnormal heart or lung function
Jaundice
- Yellow tinged skin
- Caused by bilirubin in the blood (breakdown product of RBC)
- Could indicate liver function
Appendages of the skin
- Hair
- Sweat glands
- Oil glands
Hair
- Arrector pili-smooth muscle (contracts in response to chilled body surfaces or fear)
- Germinal matrix
- Papilla
Germinal matrix
- Epithelial cells undergoing mitosis
- Responsible for new hair growth
Papilla
- Dermal tissue
- Provides nourishment
Growth Cycle of Hair
- Active Growth Phase
- Resting Phase
Active Growth Phase
- Hair matrix cells undergo mitosis
- Scalp: 6-10 Years
- Eyebrows: 3-4 months
Resting Phase
- Hair matrix cells die, follicle shrivels
- Scalp: 2-3 months
What affects hair growth?
- Hormones
- Nutrition
- Smoking
Hormones
- Testosterone
- Estrogen (Increases growth period)
Nutrition
- Proteins, Vitamins, Omega-3 fatty acids promote hair growth
- Soft drinks, processed foods, and sugar impedes hair growth
Hair Thinning
- After 40 folicular atrophy
- Hairs are shed faster than they are replaced
Male pattern baldness (MPB)
- Extremely shortened hair
- Inherited
Rogaine
Minoxidil
Sudoriferous (Sweat) Glands
Two types
- Eccrine
- Apocrine
Eccrine Gland
- Most numerous
- Found all over the body
- High expression on palms, soles of feet, forehead
- Secrete sweat:
- 99% water
- NaCl, Antibodies, Urea, Uric Acid, Lactic Acid
Thermoregulation
- Eccrine glands are important for this
- Regulation of body temp
Evaporation
-Cooling process
Convection
-Increases evaporation by movement of air
Conduction
-Transfer of heat to substances in contact with the body
Apocrine (Sweat) Gland
-Found in axillary regions and anogenital areas
-Larger than eccrine glands and found deeper in dermis or hypodermis
-Secrete sweat into a hair follicle
-Begins functions at puberty
Activated by estrogen and testosterone
Difference between Apocrine glands and eccrine glands
- Apocrine sweat also contains fat and proteins
- Odorless
Sebacous Gland
-Found all over the body Except palms and soles -Usually attached to hair follicle -Secretes sebum (oil) -Softens/lubricates hair and skin -Bactericidal Properties
Whitehead
- Pore is clogged and sebum accumulates
- Pore clogged with sebum and dead skin cells
Blackhead
- Pore is clogged and sebum accumulates
- Sebum becomes oxidized
Infection
- Papules (Zits)
- Inflamed Acne
Papules (Zits)
-Bacteria grows, pores become irritated
Inflamed acne
-Irritation causes further inflammation and infection
Ceruminous Glands
- Located in the external ear canal
- Make earwax
Mammary Glands
-Secrete milk
Functions of the Integumentary
- Protection
- Excretion
- Thermoregulation
- Sensation
- Vitamin D Synthesis
Protection
-Biological Langerhans Cells -Physical Waterproofing glycolipids in the epidermis Melanin protects from UV layers -Chemical Acid Mantle (low pH) Sebum-Bactericidal
Excretion
- Water loss through sweat
- Waste (Urea, Uric Acid, Lactic acid) loss also through sweat
Thermoregulation
-Evaporation of sweat from the skin dissipates heat, cooling the body
-Insensible perspiration (500mL/day)
-Sensible perspiration
Occurs when body temp rises. Up to 12L/day
Prevents overheating
Sensation
- Meissner Corpuscle (light pressure)
- Pacinian Corpuscle (Deep pressure)
- Free Nerve Endings (pain, temperature)
Vitamin D Synthesis
- Vitamin D increases calcium absorption in intestines
- Increases bone mineralization
