Ch. 5: The Integumentary System Flashcards
What does the Integumentary System consist of?
Skin, hair, nails, sweat glands, sebaceous (oil) glands
Describe the Epidermis
Superficial region; consist of epithelial tissue, avascular
Describe the Dermis
Underlies epidermis; mostly fibrous connective tissue, vascular
Describe the Hypodermis (superficial fascia)
- Subcutaneous layer deep to skin
- Not part of skin but shares some functions
- Mostly adipose tissue (absorbs shock & insulates)
- Anchors skin to underlying structures (mostly muscles)
Where are the 4 cell types found in epidermis?
- Keratinocytes: produce fibrous keratin (protein that gives skin protective properties); major cells of epidermis
- Melanocytes: spider-shaped cells located in deepest epidermis; product melanin
- Dendritic (Langerhans) cells: star-shaped macrophages that patrol deep epidermis; key activators of immune system
- Tactile (Merkel) cells: sensory receptors that sense touch
How many layers is the epidermis made up of?
4 or 5 layers
- Thick skin contains 5 layers (strata), found in high-abrasion areas (hands, feet)
- Thin skin contains only 4 strata
Describe Stratum Basale (basal layer)
- Deepest (base layer)
- Single row of stem cells that actively divide (mitotic), producing 2 daughter cells each time
- 10-25% of layer also composed of melanocytes
Describe Stratum Spinosum (prickly layer)
- Cells contain weblike system of intermediate prekeratin filaments attached to desmosomes
- Keratinocytes appear spikey (prickle cells)
Describe Stratum Granulosum (granular layer)
Keratinization begins; cells gather keratohyaline granules that help form keratin fibers in upper layers
Describe Stratum Lucidum (clear layer)
- Found only in thick skin
- Consists of thin, translucent band of two to 3 rows of clear, flat, dead keratinocytes
Describe Stratum Corneum (horny layer)
- 20-30 rows of flat, anucleated, keratinized dead cells
- Though dead, cells still function to protect deeper cells from environment
Describe the Dermis
- Strong, flexible connective tissue
- Cells include fibroblasts, macrophages, occasionally mast cells & WBC
- Contains nerves, blood vessels, & lymphatic vessels
- Contain epidermal hair follicles, oil glands, sweat glands
- 2 layers: papillary & reticular
Describe the Dermal Papillae
Superficial region of dermis that sends fingerlike projections up into epidermis
- Projections contains capillary loops, free nerve ending, touch receptors
Describe the Reticular Layer
- Makes up ~80% of dermal thickness
- Consists of coarse, dense fibrous connective tissue
- Many elastic fibers provide stretch-recoil properties
- Collagen fibers provide strength & resiliency
- Cutaneous plexus: network of blood vessels between reticular layer & hypodermis
- Extracellular matrix contain pockets of adipose cells
Explain “stretch marks”
Extreme stretching of skin can cause dermal tears, leaving silvery white scars (striae)
Explain “blisters”
Fluid-filled pockets that separate epidermal & dermal layers
Define Hemoglobin
Red pigment in RBC
Define Carotene
Yellow-orange pigment stored in the stratum corneum & adipose tissue
Define Hairs (pili)
Flexible strands of dead keratinized cells
Describe the structure of hair
- Produced by hair follicles
- Contains hard keratin (tougher, durable)
- Located in shaft (area that extends above scalp, where keratinization is complete) & root (area within scalp, where keratinization is still going
Define Hair Matrix
Actively dividing area of bulb that produces hair cells (as matrix makes new cells, pushes older ones up)
Define Arrector Pili
Small band of smooth muscle attached to follicle (goose bumps)
Define Hair Papilla
Dermal tissue containing a knot of capillaries that supplies nutrients to growing hair
Define Alopecia
Hair thinning in both sexes after age 40
Describe True (frank) Baldness
- Genetically determined & sex-influenced condition
- Male pattern baldness caused by follicular response to DHT (dihydrotestosterone)
Describe the Structure of a Nail
- Scale-like modifications of epidermis that contain hard keratin
- Act as a protective cover for sitar dorsal surface of fingers & toes
- Consist of free edge, nail plate, & root
- Nail bed is epidermis underneath keratinized nail plate
- Nail matrix: thickened portion of bed responsible for nail growth
What are the 4 types of glands?
- Sebaceous (oil) glands: connected to hair follicles
- Eccrine sweat gland: most numerous; function in thermoregulation
- Apocrine sweat glands: located mainly in hairy skin areas (begin functioning at puberty)
- Ceruminous glands: modified sweat glands located in ear canal
What are the skin’s main functions?
- Protection: chemical, physical, biological barriers
- Body temperature regulation: sweat, blood flow to dermis
- Cutaneous sensations: tactile, thermal, pain sensations, blood reservoir
- Metabolic functions: vitamin D for calcium absorption in intestine
- Blood reservoir: skin hold up to 5% of body’s total blood volume
- Excretion of wastes: elimination of substances from the body
What are the ABCDEs of Detecting Melanoma
Asymmetry, Border, Color, Diameter, Evolving
Describe the Skin & Old Age
- Epidermal replacement of cells slows (skin thins)
- Subcutaneous fat layer diminishes
- Decreased elasticity & loss of subcutaneous tissue wrinkles
