Chapter 5 Flashcards
Skin
The first and foremost barrier
Functions: Protection, body temp regulation, cutaneous sensations, metabolic functions, blood reservoir, excretion of wastes
Skin
Epidermis
Dermis
2 layers of skin…
Superficial region
Consists of epithelial tissue (keratinized stratified squamous)
Avascular (no blood vessels)
Outer protective shield of body
Epidermis
Underlies epidermis
Mostly fibrous connective tissue
Bulk of skin
Contains nerves, blood vessels, and lymphatic vessels
Contains epidermal hair follicles, oil glands, and sweat glands
Dermis
Subcutaneous layer deep to skin
Not a part of the skin, but shares some functions
Mostly adipose tissue that absorbs shock and insulates
Anchors skin to underlying structures (mostly muscle)
Hypodermis
Keratinocytes
Melanocytes
Dendritic cells
Tactile (Merkel) cells
Four cell types found in epidermis…
Produce fibrous keratin
Keratinocytes
Spider-shaped cells, produce melanin
Melanocytes
Star shaped macrophages that patrol deep epidermis
Dendritic cells
Stratum corneum
Stratum lucidum
Stratum granulosum
Stratum spinosum
Stratum basale
Five skin layers
Deepest epidermal layer, one row of actively mitotic stem cells
Stratum basale
Several layers of keratinocytes unified by desmosomes
Stratum spinosum
Third portion in thin skin
Typically one to five layers of flattened cells, organelles deteriorating; cytoplasm full of lamella granules and keratohyalin
Stratum granulosum
Most superficial layer of epidermis, 20-30 layers of dead cells, essentially flat membranous sacs with keratin
Stratum corneum
Found only in thick skin; thin translucent band of dead keratinocytes; lies superficial to the stratum granulosum
Stratum lucidum
First layer in dermis
Thin, superficial layer made of areolar tissue
Interlacing collagen fibers form a loosely woven mat of small blood vessels
Includes dermal papillae
Papillary layer
Fingerlike projections that project into the epidermis
Dermal papillae
Mounds that dermal papillae rest on top of
Cause overlying epidermis to form epidermal ridges
Dermal ridges
Dermal ridges + Epidermal ridges
Enhance gripping ability
Create fingerprints
Friction ridges
Second layer in dermis
Most of dermal thickness and made up of dense irregular connective tissue
Collagen fibers provide strength and resiliency
Large networks of blood vessels
Reticular layer
Network of blood vessels between reticular layer and hypodermis
Dermal vascular plexus
Collagen fibers running parallel to skin surface
Externally invisible
Helps surgeons make incisions that will heal quickly
Tension lines
Dermal folds near joints
Where the dermis closely attached to the underlying structures
Flexure lines
Extreme stretching of skin causing dermal tears, leaving silver/white scars
“stretch marks”
Striae
Acute, short term traumas to skin creating fluid filled pockets that separate epidermal and dermal layers
Blisters
Melanin
Carotene
Hemoglobin
Three skin pigments:
Only pigment made in skin, made by melanocytes
Packages into melanosomes that are sent to shield DNA of keratinocytes from damaging UV sunlight
Freckles, and pigmented moles are local accumulations of melanin
Melanin
Clumping of elastic fibers, causing skin to become leathery
UV light destroys folic acid
Excessive sun exposure
Yellow to orange pigment
Most obvious in palms and soles
Accumulates in stratum corneum and hypodermis
Can be converted to vitamin A for vision and epidermal health
Carotene
Pinkish hue of fair skin is due to lower levels of melanin
Hemoglobin
Blueness in skin, low oxygenation of hemoglobin; sign of respiratory issues
Cyanosis
Emotional stress, low blood pressure, anemia
Pallor/Blanching
Yellowness, liver disorders
Jaundice
Redness, embarrassment
Erythema
Bruising; result of blood leakage from damaged blood vessel beneath skin
Red/Purple/Yellow marks
Hyperpigmentation, thickened skin in folds
Endocrine disorders
Brown or black patches
Consists of dead keratinized cells (hard)
Produces hair follicles
Warns of insects on skin
Guards against physical trauma
Protect from heat loss
Shield skin from sunlight
Hair
Sac that hair grows in, considered skin organ
Hair follicle
Where keratinization is still going on
Root
Where keratinization is complete
Projects from skin, extends halfway down portion of hair embedded in skin
Shaft
Protective covering for fingers and toes
Scale-like modifications of epidermis that contain hard keratin
3 parts - free edge, nail body, root
Nail
Epidermis underneath keratinized nail plate
Bed is the deepest layers of epidermis
Nail bed
Abundant on palms, soles, and forehead
Ducts connect to pores
Function in thermoregulation
Secrete sweat
Eccrine sweat glands
Ducts emptying into hair follicles
Function unknown but may act as sexual scent gland
Secrete viscous milky or yellowish sweat
Contains fatty substances and proteins
Bacteria break down sweat leading to BO
Apocrine sweat glands
Oil glands; Most develop from hair follicles and secrete into hair follicles
Secrete sebum
Sebaceous glands
Protection
Body temp regulation
Cutaneous sensations
Metabolic functions
Blood reservoir
Excretion of wastes
Skin functions:
Swelling caused by an abnormal growth of tissue
1. Benign - non cancerous, doesn’t spread
2. Malignant - cancerous, can spread
Tumor
Most common skin cancer, least likely to spread
Begins as a papule, enlarges and develops central crater
Cured by surgical excision
Basal cell carcinoma
Second most common type of skin cancer
Can spread to other organs
Usually reddened papule on scalp, ears, lower lip, or hands
Good prognosis if treated by radiation therapy or removed surgically
Squamous cell carcinoma
Cancer of melanocytes, most dangerous types
Can arise from a pre-existing mole or normal skin
Melanoma
Tissue damage caused by heat, electricity, radiation, or certain chemicals
Immediate threat is dehydration and electrolyte imbalance
Burns
Epidermal damage only; localized redness, swelling, pain
First-degree burn
Epidermal and upper dermal damage; blisters appear
Second-degree burn
Entire thickness of skin involved; Skin color turns gray-white, cherry red, or blackened
No swelling seen b/c nerves are destroyed
Third-degree burn
Involves deeper tissue, such as muscle or bone
4th-degree burn
