Chp 5 Integumentary System Flashcards
Dermis
Deeper, thicker portion of the skin composed of dense irregular conn tissue, but upper thinner part is made of areolar tissue with plenty of nerve fibers, blood vessels and water
2 regions: Papillary layer (thinner) Reticular later (thicker)
Fibroblasts, macrophages, and adipocytes
Subcutaneous layer (Hypodermis)
Deep to the dermis, but not part of the skin
Consists of areolar and adipose tissues
Serves as a storage depot for fat and contains large blood vessels that supply the skin
Acts as heat insulation
Site for rapid and relatively pain free absorption of drugs (insulin or pelleted implants)
Keratinocytes
90% of epidermal cells
Produce keratin, which is a tough fibrous protein that helps protect the skin & underlying tissues from abrasions, heat, microbes, and chemicals
-also produce lamellar granules which release a water repellent sealant that decreases water entry & loss and inhibits entry of foreign material
Melanocytes
8% of epidermal cells
Develop from ectoderm of developing embryo and produce pigment melanin (a yellow-red or brown black pigment that contributes to skin color and absorbs damaging ultraviolet light)
-melanin granules protect keratinocytes but are susceptible to damage by UV light
Intra epidermal macrophages
Called Langerhans cells
- arise from red bone marrow
- participate in immune responses mounted against microbes that invade the skin, & are easily damaged by UV light
Tactile epithelial cells
Called Merkel cells (least numerous)
-detect touch sensations
Integumentary system function
Protection
Heat regulation
Synthesis of vitamin D- skin makes vitamin d (cholecalciferol) from cholesterol when exposed to sun light. Vitamin D is essential for the absorption and use of CA++ and P from food
Sensory reception
Dermoepidermal junction (DEJ)
Basement membrane that exists b/w epidermis & dermis
- special fibers & a unique polysaccharide gel or ‘glue’ strongly cement the 2 layers
- when ‘skin glue’ fails, blisters occur
Arrector pili muscles
Allows hair to stand on end during fright or cold; skin is raised causing goose bumps, cause nipple erection and elevation of testis
(In reticular layer of dermis)
Epidermis
Superficial thinner portion of skin, composed of epithelial tissue
Contains 4 primary types of cells: keratinocytes, melanocytes, intra epidermal macrophages, tactile epithelial
Papillary layer of dermis
Thin upper part. Loose conn tissue w network of collagen and elastic fibers containing dermal papillae
- Meissner corpuscles sensitive to touch
- nerve endings causing sensations of warmth, coolness, pain, tickling, and itching
- epidermal ridges leave finger prints
Reticular layer of dermis
Below papillary layer
Containing dense irregular conn tissue with plenty of collagen and elastic fibers
Spaces b/w fibers are occupied by adipose cells, hair follicles, nerves, sebaceous glands and sudoriferous glands
Acillary organs
Originate in basal layer of epidermis, but located in dermis
-Sudoriferous glands Apocrine or merocrine -sebacious glands -hair and nails -sensory receptors
Sudoriferous gland
- coiled tubular (exocrine) gland that opens into epidermis
- sweat is 99% water, some salts (mainly sodium chloride) and traces of urea
- 4.5 pH (acts as chemical barrier to microbial growth in skin
1) eccrine (merocrine) swear gland
- conc in palms, soles, forehead
- ducts open into pore of epidermis
- none in eyelids, lips, areola or nipple,or in labia
2) apocrine sweat gland
- larger and deeper in axillary and groin areas
- bacterial action causes BO
- ducts open at upper part of hair follicle
- sweat is more viscous and colored with fatty acids in it
- contain pheromones
Modified apocrine sweat glands A) ceruminois glands (wax)- earwax B) mammary glands (milk)-
Sebaceous glands
Halocrine
Produces oil or sebum;
Lubricates skin and hair, waterproofs skin
-acts as bactericidal & antifungal agent so considered chemical barrier to microbial skin growth
