CH5 Flashcards
(54 cards)
Function of skin
1) Maintains body’s temperature
2) Maintains body’s integrity
3) Converts inactive Vitamin D to active form
4) Provides sensory information
5) Maintains homeostasis
Epidermis
outer layer, superficial composed of epithelial cells.
- Avascular
- 5 distinct strata (layers) of cells
Dermis
inner layer, primarily composed of connective tissue. Vascular
- Contains hair, veins, arteries
- 2 layers; Papillary dermis and reticular dermis
Hypodermis
SQ underneath dermis, fatty layer that separates dermis from muscle tissue/organ
- Contains blood vessels that bring nutrients to and removes waste from the skin
Epidermis types of cells
Keratinocytes, intraepidermal macrophages, melanocytes, tactile epithelial cells
Keratinocytes
90%, Produces protein keratin which helps protect skin and underlying tissue from microbes (waterproof barrier and support)
- Made up of lamellar granules
- Keratin - tough fibrous protein that provides protection
Intraepidermal macrophages
Langerhan cells
- Comes from bone marrow and helps immune response by detecting invading cells
Melanocytes
8%, Found in stratum basale layer
- Produces pigment, contributing to skin color and absorbs UV light
- Form protective veil over nucleus, shield DNA from damage
Tactile epithelial cells
Merkel cells
- Sensory structure, tactile disc and gives you ‘sense of touch’. abundant on soles and palms
Layers of epidermis
- Stratum basale
- Stratum spinsosum
- Stratum granulosum
- Stratum lucidum
- Stratum corneum
Stratum basale
Basal cells (stem cell (simple cuboidal layer); single layer of stem cells that can regenerate and develop into keratinocytes of epidermis
+ As basal cells divide, they push up layers of cells; become five layers of epidermis
- Production site of melanin (melanocytes)
- Tactile epithelial cells (Merkel cells) found in layer
- Bottom layer
Stratum spinsosum
- Provides strength and flexibility to skin
- 8-10 layers of healthy keratinocytes (nucleus);
- intraepidermal macrophages (langerhan’s cells) are found in this layer.
Stratum granulosum
3-5 layers of keratinocytes; where breakdown of nucleu s occurs(apoptosis: nuclear degeneration). Due to epithelial cells moves further from blood supply, and cells begin to breakdown
Stratum lucidum
Found in thick skin only (palms, soles, digits)
- 3-5 layers of clear, flat, dead keratinocytes
Stratum corneum
outermost layer of skin exposed to outside environment, superficial
- 25-30 layers; dead keratinocytes
- Continuously shed
- Barrier to light, heat, water, chemical, bacteria (internal/external environment)
- Lamellar granules found in this layer - make skin waterproof
Thin skin
4 layers, hairy, covers the majority of the body. Has sebaceous, sweat glands and hair follicles
Thick skin
has all 5 layers of epidermis, hairless, only found on palms, digits, and soles of feet
- No sebaceous glands, but has sweat glands
Papillary dermis
areolar CT with collagen and elastic fibers (strength and stretch)
- dermal papillae (finger-like projections in the dermis that play a key role in hair growth)
- Meissner’s corpuscles (touch)
- nerve endings for sensation
Reticular dermis
deeper region
- Dense irregular connective tissue, containing collagen fibers and elastic fibers. Provides strength, extensibility and elasticity
- Pacinian corpuscles - deep touch/pressure
- Holds oil glands, sweat glands, fat and hair follicles
Hairs
pili
Shaft
above the surface
Root
penetrates the dermis and SQ layer
Cuticle
outermost layer of hair root cells; keratinized and shingle-like
Hair follicle
pore that surrounds hair root