Chapter 5 Review (12 questions) Flashcards
• What are the 2 major components of the integumentary system?
- Outer epidermis
¥ Superficial epithelium - Inner dermis
¥ Connective tissues
• All membranes are composed of an epithelium and connective tissue. What is the relationship between the dermis, epidermis, and this general membrane structure?
¥ Originate in the dermis ¥ Extend through the epidermis to skin surface ¥ Hair ¥ Nails ¥ Multicellular exocrine glands
• Which body systems have important connections with the integumentary system?
¥ Cardiovascular system
¥ Blood vessels in the dermis
¥ Nervous system
¥ Sensory receptors for pain, touch, and temperature
• What is the relationship between the hypodermis and the cutaneous membrane?
Hypodermis (Superficial Fascia or Subcutaneous Layer)
¥ Loose connective tissue
¥ Below the dermis
• What are the functions of skin?
¥ Protection of underlying tissues and organs
¥ Excretion of salts, water, and organic wastes (glands)
¥ Maintenance of body temperature (insulation and evaporation)
¥ Production of melanin
¥ Production of keratin
¥ Synthesis of vitamin D3 ¥ Storage of lipids
¥ Detection of touch, pressure, pain, and temperature
• What cell type is most abundant in the epidermis? How are these cells organized?
¥ Keratinocytes contain large amounts of keratin
¥ Are the most abundant cells in the epidermis
• What is the difference between thin skin and thick skin?
o What is the relationship between structure, function, and location for these two types of skin?
Thin Skin ¥ Covers most of the body ¥ Has four layers of keratinocytes Thick Skin ¥ Covers the palms of the hands and soles of the feet ¥ Has five layers of keratinocytes
• How are the 5 strata of keratinocytes organized in thick skin?
o What structures/functions are associated with the cells of each layer?
o Which layers include actively dividing cells? non-dividing cells? dead cells?
Stratum Basale
¥ Innermost epidermal layer attached to basement membrane by hemidesmosomes
¥ Forms a strong bond between epidermis and dermis
¥ Forms epidermal ridges (e.g., fingerprints)
¥ Has many basal cells (stem cells or germinative cells)
¥ Dermal papillae (tiny mounds)
¥ Increase the area of basement membrane
¥ Strengthen attachment between epidermis and dermis
Specialized Cells of Stratum Basale
¥ Merkel cells (tactile cells) respond to light touch trigger nervous system
¥ Found in hairless skin
¥ Melanocytes contain the pigment melanin
¥ Scattered throughout stratum basale
Stratum Spinosum the “spiny layer”
¥ Produced by division of stratum basale
¥ Eight to ten layers of keratinocytes bound by desmosomes
¥ Cells shrink until cytoskeleton sticks out (spiny appearance)
¥ Continue to divide, increasing the thickness of epithelium
¥ Contain dendritic (Langerhans) cells that are active in immune responses
Stratum Granulosum the “grainy layer”
¥ 3 to 5 layers of keratinocytes derived from stratum spinosum
¥ Cells stop dividing and start producing keratin
¥ A tough, fibrous protein that makes up hair and nails
¥ Dense granules of keratohyalin cross-link keratin fibers
¥ Cells ultimately dehydrate and die, leaving behind a tightly interlocked layer of cells that are packed with keratin/keratohyalin
Stratum Lucidum the “clear layer”
¥ Found only in thick skin
¥ Covers stratum granulosum
¥ Cells are flat, densely packed, and filled with keratin
Stratum Corneum the “horn layer”
¥ Exposed surface of skin
¥ 15 to 30 layers of keratinized cells
¥ Water resistant (NOT waterproof)
¥ It takes 7 to 10 days for a cell to move from the stratum basale to the stratum corneum
¥ Dead cells generally remain in the stratum corneum for 2 weeks before they are shed away
• How does water move across the cutaneous membrane?
Dehydration
¥ Insensible perspiration goes undetected
¥ Interstitial fluid lost by evaporation through the stratum corneum 500ml per day
¥ Sensible perspiration can see/feel water loss
¥ Water excreted by sweat glands
¥ Immersion in hypertonic solution swimming in the ocean
Hydration
¥ Immersion in hypotonic solution taking a bath
¥ Cells of the stratum corneum may swell to 4 times their normal volume
• What influences skin color?
o How are the 2 major skin pigments synthesized or absorbed into the body?
- Carotene
¥ Orange-yellow pigment found in orange vegetables
¥ Can be converted to vitamin A maintenance of epithelia and synthesis of photoreceptor pigments - Melanin
¥ Yellow-brown or black pigment produced by melanocytes in the stratum basale
• What is required for epidermal cells to produce vitamin D3?
¥ Epidermal cells produce vitamin D3 (cholecalciferol)
¥ In the presence of UV radiation
o How is vitamin D3 connected to the structure and function of the skeletal system?
¥ Liver and kidneys convert vitamin D3 into calcitriol
¥ Facilitates absorption of calcium and phosphorus along digestive tract
• What are the functions of epidermal growth factor?
¥ Promotes division of basal cells
¥ Accelerates keratin production
¥ Stimulates epidermal repair
¥ Stimulates glandular secretion
• What are the 2 major layers of the dermis?
o What structures/functions are associated with each layer?
The Papillary Layer
¥ Consists of areolar CT
¥ Contains smaller capillaries, lymphatics, and sensory neurons
¥ Has dermal papillae projecting between epidermal ridges
The Reticular Layer
¥ Consists of dense irregular connective tissue
¥ Contains larger blood vessels, lymphatic vessels, and nerve fibers
¥ Contains collagen and elastic fibers
¥ Contains connective tissue proper
• How can skin be damaged?
Dermal Strength and Elasticity
¥ Presence of two types of fibers
1. Collagen fibers
¥ Very strong, resist stretching but bend easily
¥ Provide flexibility
2. Elastic fibers
¥ Permit stretching and then recoil to original length
¥ Skin turgor describes the properties of flexibility and resilience, also a marker of dehydration
