CH5 Flashcards
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
Bulb
base of the hair follicle, near blood vessels and germinal cell layer
- New hairs develop from cell division in the bulb
Arrector pili
smooth muscle in dermis contracts forming goosebumps
Hair root plexus
nerves surrounding hair follicles
Sebaceous (oil) glands
connected to hair follicles, produce sebum; moistens hair, waterproofs and softens skin, inhibits growth of bacteria and fungi
- Acne - bacterial inflammation of glands
Sudoriferous (Sweat) glands
Eccrine and apocrine
Eccrine
most areas of skin, coiled glands deep in the dermis; pore opens on surface of skin
- Regulate body temperature through evaporation
- Eliminates waste such as urea
Apocrine
limited to armpits, pubic and areolae
- Duct that opens onto hair follicle
- Secretions are more viscous and odorous
- pinches off top part of gland during secretion
Ceruminous glands (ear wax)
modified sudoriferous glands
- Secretions of oil and wax called cerumen
- Barrier for entrance of foreign bodies
Nail plate
tightly packed keratinized cells
Nail body
visible portion pink due to underlying capillaries, free edge appears white (whites of nails)
Nail roots
buried under skin layers
- Lunula is white due to thickened stratum basale
half moon on nail bed
Eponychium (cuticle)
stratum corneum layer
Skin cancers
Caused by excessive exposure to sunlight, skin type, family history, age, and immune system
3 common forms of skin cancer
1) Basal cell carcinoma (rarely metastasizes)
- Most common form of skin cancer, occurs in basal layer
- Can be removed
2) Malignant Melanoma (metastasize rapidly)
- Arises from melanocytes
- New unusual growth or change in existing mole
- High risk, metastasizes rapidly, life threatening
3) Squamous cell carcinoma (may metastasize)
to check for skin cancer
ABCDE
- Asymmetrical skin lesion. (want symmetry in a normal mole)
- Border : edges are ragged, notched, uneven, or blurred
- Color: have multiple colors
- Diameter: moles greater than 6mm (pencil eraser) more likely to be melanoma.
- Evolving: change of a mole may be a sign that it is malignant.
Burns
tissue damage from heat, electricity, radioactivity, or corrosive chemicals
Systemic effects of a burn
Loss of water, plasma, and plasma proteins
Bacterial infection
Reduced blood circulation
Reduced urine output
Diminished immune responses
- Seriousness of a burn is determined by its depth, extent, area, age, and general health. When the burn area exceeds 70%, over half of the victims die
First degree
Only epidermis (sunburn)
Second degree burn
- Destroy entire epidermis and part of dermis
- Fluid-filled blisters separate epidermis and dermis
- Heals within 3-4 weeks
Third-degree burns or full-thickness
- Destroys epidermis, dermis and stem cells
- Damaged area is numb due to loss of sensory nerves
Pressure ulcers (decubitus ulcers)
deficiency of blood to tissues overlying a bony projection over prolonged pressure
Rosacea
A condition that causes redness and often small, red, pus-filled bumps on the face
Vitiligo
a loss of pigment of the skin that is displayed in patches
Xerosis
dry, rough patches of skin with cracks, flaking and peeling
Alopecia
partial or complete hair loss
Hyperhidrosis
excessive sweating unrelated to temperature or exercise
Hirsutism
Excessive hair growth on unexpected areas of the body, such as on the face, chest, and back
Dermatitis
inflammation of the skin
Psoriasis
A condition in which skin cells build up and form scales and itchy, dry patches
Acne
a skin condition that occurs when your hair follicles become plugged with oil and dead skin cells. Common in teenagers
Eczema
patches of skin become rough and inflamed, with blisters that cause itching and bleeding
