Kim Ingteumentary System
Terms
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- Two primary components of the Skin
- Cutaneous layers & accessory structures
- Cutaneous: 2 layers
- Epidermis & Dermis
- Epidermis is...
- ...avascular & relies on dermis for diffusion of nutrients, etc.
- Cells of the Epidermis
- Keratinocyte Melanocyte Langerhans or dendritic cells Merkel cells
- Keratinocyte
- primary cell of epidermis lives for 25-45 days produces keratin
- Melanocyte
- "orange octopus" produces "melanin" creates melanosomes that end up in keratinocytes
- Langerhans or dendritic cells
- stimulate immune response to microorganisms & surface skin cancers
- Merkel cells
- found in hairless areas of skin--act as sensory receptors
- Layers of the epidermis (deep to superficial)
- Stratum germantivum or basale Stratum spinosum Stratum granulosm Stratum lucidum Stratum corneum
- Stratum basale
- Is attached to dermis 1 cell thick stems cells called basal cells new cells get pushed up into next layer melanocytes & Merkel cells among them
- Stratum spinosum
- "spiny layer" 8-10 cells thick cells interconnected by desmosomes Langerhans or dendritic cells in this layer
- Stratum granulosum
- grainy layer last layer of living cells:transitional layer 3-5 cells thick keratin production rapid here Cells thinner & flatter--dehydration of cells starting
- Stratum lucidum
- "glassy" layer thick skin only 1 cell thick cells flatttend & filled with keratin
- Stratum corneum
- 75% of thickness 15-30 cells thick Cells dead, but connections still tight
- Dermis: definition
- the hide strong flexible cutaneous layer deep to the epidermis filled with elastic & collagen fibers
- Structures in the dermis
- 1. Blood vessesls in the cutaneous plexus: branches that run to the top of dermis & form "papillary plexus" supplies blood to epidermis, hair follicles, sweat glands 2. Nerve receptors: a)Meissner's or tactile corpuscles: light touch b)Lamellated corpuscles: deep pressure & vibration
- Layers of the dermis: superficial to deep
- 1)Papillary: dermal papillae, Meissner's corpuscles, epidermal ridges (fingerprints for friction). 2. Retcular layer: 80% of thickness; lamellated corpuscles, elastic & collagen fibers woven together to bind dermis to sub Q & epidermis a)cleavage lines--collagen arranged: areas of typical stress b)flexure lines--extra skin for joints
- Homeostatic imbalances of the Dermis
- Striae:strectch marks Wrinkles: loss of collagen & elastin with age UV hornmones Blisters: separation of dermis & epidermis & interstitial fluid or blood fills gap Dermatitis: inflammation of skin, primarily papillary layer
- Subcutaneous/Hypodermis layer
- NOT PART OF SKIN stabilizes skin very elastic fat cushion no major organs & only some blood vessels--good for shots!
- Melanin is produced by...
- melanocytes, which then go into the keratinocytes via melanosomes
- Racial differences in melanin production
- NOT DUE TO # OF MELANOCYTES due to: size of melanosome where it enters keratinoctye type of pigment
- Effect of UV light on melanin
- stimulates melanocytes & creates darkening for PROTECTION
- Carotene
- yel to org pigment collects in corneum most observable in lt. skinned
- Hemoglobin
- blood pigment when oxygenated is red; blushing, exertion
- Cyanosis
- bluish tint due to poorly oxygenated blood. Respiratory disorders or COPD
- Pallor
- reduced color: lack of blood flow to area
- Jaundice
- liver cannot excrete bile, so bilorubin collects in skin & schlera of eyes UV light can break down bilorubin in babies
- Bronzing
- Addison's disease or tumors of pituitary gland Excess stimulation of melanocytes
- Accessory structures of the skin
- Hair & hair follicles Sweat glands Sebaceous glands Nails
- Hair & hair follicles--Function
- Sensory Protection Filters
- Structure of a follicle
- Embedded in dermis Produced by epidermal tissue Outer layer: epidermal sheath Inner layer: connective tissue from dermis Hair bulb: papilla & matrix Arrector pilli muscle Root hair plexus
- Type of hair
- Vellus: peach fuzz Terminal: heavy deeply pigmented hairs: Hormones can change hair types
- Club hair
- hair being pushed out of follicle: no longer growing
- Hair thinning & baldness
- Alopecia: coarse to vellus: hair stops Male pattern baldness is genetic Changes in circulating hormones Other: fever,surgery, emotional trauma, protein deficiency, lactating
- Hair color is...
- ...produced by melanocytes. When there is less production, we go grey
- Sweat glands
- Merocrine or eccrine Apocrine Mammary glands Ceruminous
- Merocrine or eccrine
- excretes thru pore palms soles & forehead sensible perspiration secretion is 99% water with solutes of salt, antibodies, lactic acid & waste: acidic Func: Thermoregulation/evaporation hot: you sweat from top down
- Apocrine sweat glands
- excrete from hair follicle armpits & groin sticky cloudy secretion with fatty materials in it which bacteria eat hence odor Func: sexual??
- Mammary glands
- modified apocrine gland got milk?
- Ceruminous glands
- earwax
- Sebaceous glands & follicles
- Everywhere but palms & soles produce sebum, which softens skin & hair, prevents water loss, bacteriocidal Glands release sebum into hair follicle Seb. follicles into skin: face, chest,upper back
- Homeostatic imbalance of sebaceous glands...
- Cradle cap Dandruff
- Nails
- Nails are a modified stratum corneum with these parts Nail bed/nail body/nail root Lunula Eponychium--cuticle
- Functions of Integumentary system
- Sensation Protection Thermoregulation Vitamin D3 synthesis Excretion Storage of Lipids
- Homeostatic Imbalance: Injuries to Skin
- Stem cells cause regeneration a)Germinative cells from basale to replace lost epidermis b)Mesenchymal cells replace lost dermal cells Small area vs. abrasion
- Four stages of skin regeneration
- Bleeding occurs: Mast cells intiate immune response Scab forms: temporary protection; stratum germ. makes new epi; macrophages clean up; fibroblasts & mesenchymal cells make new dermis Replacing the clot: deep portions dissolve & fibroblasts disintegrating New dermis: scar: new collagen; no sweat, hair or nerves replaced Keloid: excess new dermis