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What are the 2 parts of the integument?
- 1. The cutaneous membrane: the superficial epidermis and the deep dermis
- 2. Accessory structures: originate in the dermis and extend through the epidermis to the skin surface (hair, nail, exocrine glands)
What are the 2 parts of the cutaneous membrane?
- 1. The epidermis: contains 4 or 5 layers from deep to superficial stratum basale, stratum spinosum, stratum granulosum, stratum lucidum (thick skin only), and stratum corneum
- 2. The dermis: contains 2 layers from superficial to deep are the papillary layer and the reticular layer
What are the functions of the integument?
- 1. Protection of the underlying tissues and organs
- 2. Excretion of salts, water, and organic wastes
- 3. Maintenance of body temperatures
- 4. Production of melanin and keratin
- 5. Synthesis of vitamin D3
- 6. Storage of lipids
- 7. Detection of touch, pressure, pain and temperature
What are the structures and functions of the stratum basale?
- 1. Basal stem cells divide to produce daughter keratinocytes
- 2. Attached to the basement membrane by hemidesmosomes
- 3. Forms epidermal ridges that couple with the dermal papillae to give us fingerprints
- 4. Melanocytes contain melanin
- 5. Merkel cells are found in hairless skin that respond to touch
What are the structures and functions of the stratum spinosum?
- 1. Called the "spiny layer" because cells start to lose water which makes the cytoskeleton stick out
- 2. Cells deeper continue to divide and push other cells more superficial which increases the thickness of the epithelium
- 3. Dendritic "Langerhans" cells are active in the immune response
What are the structures and functions of the stratum granulosum?
- 1. Called the "grainy layer" because keratinocytes stop dividing and start producing keratin
- 2. Produces protein fibers
- 3. The dehydrated keratinocytes form a water resistant barrier
What are the structures and functions of the stratum lucidum?
- 1. Lucid = thinking clearly; lucidum = clear layer
- 2. Found only in thick skin
- 3. Covers the granulosum
What are the structures and functions of the stratum corneum?
- 1. Called the "horn layer"
- 2. Contains the exposed surface of the cell
- 3. All keratinocytes are dead and completely filled with keratin
- 4. Water resistant
- 5. Cells are shed and replaced every 2-4 weeks
What is keratinization?
- 1. It is the formation of a dead, protective layer of skin filled with keratin
- 2. It is the skin life cycle
- 3. Takes approximately 2-4 weeks
- 4. Psoriasis: when keratinization happens too fast
Is the integument water proof?
No, the integument is not water proof, but it is water resistant. The keratinized cells of the stratum corneum resist water. When the integument is submersed in a hypotonic solution water moves into the cells through the process of osmosis. The cells swell which looks like pruned skin.
What is the difference between sensible and insensible perspiration?
- 1. Sensible perspiration: water excreted by gland cells which results in dehydration
- 2. Insensible perspiration: interstitial fluid lost by evaporation through the stratum corneum (we are not aware it is happening)
What controls the pigment of our skin?
- 1. Carotene - orange/red color
- 2. Melanin - brownish/yellow color
- 3. Blood circulation - red blood cells
What are the functions of carotene?
- 1. Produces the orange/yellow pigment in our skin
- 2. Found in orange vegetables
- 3. Accumulates in the epidermal cells and fatty tissues of the dermis
- 4. Can be converted into vitamin A
What are the functions of melanin?
- 1. Yellow/brown pigment produced by melanocytes in stratum basale
- 2. Stored in transport vesicles and transferred to keratinocytes
- 3. Protects skin from sun damage; limited UV exposure can stimulate melanocytes to produce more melanin that acts as a shield
How to capillaries effect skin color?
- 1. Blood vessels dilate from heat which reddens the skin (especially pale skin)
- 2. Blood flow decreases, skin pales
- 3. Cyanosis: bluish tint skin caused by severe reduction in blood flow or oxygenation
What are the functions of the 2 layers of the dermis?
- 1. Papillary layer: Superficial to the reticular layer; consists of areolar tissue; has dermal papillae; contains small capillaries and sensory neurons
- 2. Reticular layer: dense irregular connective tissue; collagen and elastic fibers; contains large blood vessels and nerve fibers
What are cleavage lines?
- 1. Follow the pattern of collagen fiber bundles in the dermis.
- 2. Typically run parallel to other fibers
- 3. Patterns direct surgeons to cut in between or along the fiber lines, if possible; reduces noticeability of scar tissue, and allows scars to heal faster
How is blood delivered to the epidermis?
- 1. Cutaneous plexus: a network of arteries in the hypodermis
- 2. Tributaries of these arteries supply adipose tissue in the subcutaneous membrane and the tissues of the integument
- 3. Papillary plexus: the small arteries form another branching network in the papillary layer of the dermis
What glands are found in the integument?
- 1. Sebaceous glands: oil glands, or holocrine glands, secrete oil with hair follicles
- 2. Apocrine glands: smelly sweat glands found in armpits, around nipples and groin
- 3. Merocrine glands: odorless sweat glands concentrated mostly on the palms and soles of the feet
How is hair produced?
- 1. Hair is produced in hair follicles
- 2. Follicles are located deep in the dermis
- 3. The follicle is wrapped in a dense connective tissue sheath
- 4. The base of the follicle is surrounded by sensory nerves called the root hair plexus
- 5. Arrector pili: a smooth muscle bundle that causes hair to stand up (goose bumps)
How are nails produced?
- 1. Nail root: a deep epidermal fold near the bone where nails are produced
- 2. Nails are designed to protect the fingers and toes
- 3. Nails are made of dead cells packed with keratin
- 4. metabolic disorders can change the nail structure
Ouch! You got cut. How does the wound get repaired?
- 1. Bleeding occurs and mast cells trigger an inflammatory response.
- 2. A scab forms and cells of the stratum basale migrate along the edges of the wound to close it from deep to superficial; macrophages remove the clotted blood so fibroblasts can move in to make scar tissue
- 3. A week after the injury, scab is undermined by epidermal cells migrating over meshwork produced by fibroblast activity
- 4. After several weeks, the scab is shed; a shallow depression remains, but fibroblasts work to create scar tissue that will level the epidermis