Ch. 5: The Integumentary System Flashcards
(30 cards)
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
