Ch 5 - Integument Flashcards
6 Primary Functions of the Skin
1) Protection - Chemical, Physical, and Biological
2) Temperature Regulation - (in)sensible perspiration
3) Sensation - Exteroceptors: cutaneous sensory receptors
4) Metabolic functions - vitamin D production
5) Blood Reservoir
6) Excretion/waste elimination - sweat out some nitrogenous wastes
Chemical Protection - secretions kill bacteria, melanin prevents damage caused by UV light
Physical Protection - skin prevents enterance of bacteria/viruses
Biological Protection - Dendritic cells and Macrophages prevent infection
Exteroceptors - can be nociceptors, thermoreceptors, mechanoreceptors, etc.
Blood Reservoir - ~5% of total blood volume - can be “moved”
Nitrogenous wastes - urea, ammonia, uric acid
Layers of the skin:
1) Epidermis - unvascularized outermost portion
2) Dermis - vascularized, most of ingtegument
Hypodermis - At the base of the dermis, not a true structure
Cell types found in Epidermis
1) Keratinocytes - produce keratin protein; linked by desmosomes + tight junctions
2) Melanocytes - produce contain melanosomes (produce melanin)
3) Dendritic cells (Langerhans cells) - “presenting cells” - from bone marrow
4) Tactile cells (Merkel cells) - present in epidermal-dermal junction; sensory receptor function
Keratin protein - gives epidermis its tough and dry protective qualities
Melanocytes - produce melanin which is then transferred to shallow side of keratinocyte for protection
Layers of the Epidermis
1) Stratum basale (base layer)
2) Stratum spinosum (spiny layer)
3) Stratum granulosum (granular layer)
4) Stratum lucidum (clear layer)
5) Stratum corneum (horny layer) - outermost
3 basic characteristics of the stratum basale
1) Innermost layer
2) Simple layer of stem cells - rapid division
3) 10-25% melanocytes; most keratinocytes
3 basic characteristics of the stratum spinosum
1) stratified
2) contains pre-keratin protein (filaments that resist tension)
3) Dendritic cells most abundant
4 characteristics of the stratum granulosum
1) Keratinization begins
2) Keratohyaline granule: elps with formation of keratin in upper layers of epidermis
3) Lammelar granules: contains water-resistant glycolipid (makes skin waterproof)
4) Cells are especially tough and water resistant ^^^
3 Characteristics of Stratum Lucidum
1) “clear”
2) not living cells
3) not found in thin skin
5 characteristics of stratum corneum
1) outermost layer
2) not living
3) makes up most of epidermal thickness
4) Glycolipids between cells help waterproof
5) Keratin inside cells protects from friction/abraision
Layers of the dermis
1) Papillary dermis
2) Reticular dermis
Filled mostly with fibroblasts and macrophages, lots of fibers
What kind of tissue makes up the papillary dermis
Thin areolar connective tissue
The fibers are thin so that defensive cells can wander freely
What are the projections (bumps) found in the papillary dermis and what is their function?
Dermal papillae - can have pain receptors or tactile corpuscles
These projections form “Friction Ridges” - AKA: fingerprints
What kind of tissue makes up the reticular dermis
Dense irregular connective tissue
Definition
Lines in skin formed by alternating dense & less dense regions of fibers
Not Visible Externally
Cleavage lines in reticular dermis
Definition
Area where dermis is tightly anchored, not as flexible, and is forced to fold
Flexure lines (at/near joints) in reticular dermis
Three pigments that determine skin color
1) Melanin: polymer that comes in two forms (reddish yellow/brownish black)
2) Carotene: yellow-orange pigment (accumulates in stratum corneum and adipose tissue)
3) Hemoglobin: pink/red pigment (oxygenated)
What protein synthesizes melanin
Tyrosinase
Exposure to sun - DNA in cells damaged by sun - repair is first signal to produce melanin — keratinocytes release chemical to “activate” melanocytes
Where is carotene stored and why?
In stratum corneum & adipose tissue; can be used by the body to proudce vitamin A
Vitamin A is useful for vision and epideral health
4 homeostatic imbalances of skin color
- Jaundice (liver failure)
- Cyanosis (low oxygenated blood/hemoglobin)
- Argyria (silver buildup)
- Albinism/melanism (genetic mutations cause no melanin or too much melanin)
Regions of a Hair (pili)
- Root: part of hair imbedded in skin (from follicle)
- Shaft: part of hair projecting out of skin
** all cells are dead and keratinized
Functions of Hair
1) Sensory structures: nerves associated with hair follicles
2) Protection: scalp, eyes, nose
Layers of each hair
1) Medulla: central core composed of large cells and air space - absent in fine hairs
2) Cortex: several layers of flattened cells
3) Cuticle: outermost layer (most heavily keratinized) - shingled
** all cells are dead and keratinized
Structures associated with hair:
1) Hair follicle - growing part of hair (results from fold of epidermis entering dermis)
2) Root hair plexus - hair bulb (contains nerve endings)
3) Dermal papilla - provides capillaries to follicle
4) Arrector pili - muscle attached to hair follicle
Layers of a hair follicle
1) Peripheral sheath: outermost layer composed of dermis
2) Glassy membrane: “basement membrane” joining the peripheral sheath to root sheath
3) Root sheath: innermost layer derived from epidermis
hair matrix at bulb
Hair shape = follicle shape
Round follicle = 1)
Oval follicle = 2)
Flattened follicle = 3)
1) Round
2) Wavy/slightly curly
3) Very curly/coiled
How does hair grow
- Rapidly dividing cells from hair bulb of follicle
- Pushes cells up and out
- Growth is cyclical
Cyclic hair growth: anagen (growth), catagen (transition), and telogen (rest)
Types of hair
1) Vellus hair: thin/fine hairs
2) Terminal hair: thick/coarse hairs (darker)
What makes up a nail
Hard keratin
1) root
2) nail plate
3) free edge
Nail matrix responsible for nail growth
Function of a nail
protective covering for distal portions of fingers, contributes to dexterity
Glands of the skin
1) Sweat glands - myoepithelial (eccrine or apocrine)
2) Sebaceous glands (oil glands)
Types of sweat glands
1) Eccrine sweat glands: simple tubular glands that open directly to skin surface at pore (mostly water)
2) Apocrine sweat glands: release sweat into hair folicles, has added fatty substances & proteins (react to sex hormones)
Sweat glands are myoepithelial - contract when stimulated
Modified Versions of Apocrine glands: ceruminous glands and mammary glands
Functions of Sebaceous Glands
- Secretes sebum (oily substance, largely lipid based, some cells)
- Lubricant for skin/hair
- Slows water loss from epidermal surface
- Kills bacteria
Forms of skin cancer:
In US - 9500 people diagnosed each day
1) Basal cell carcinoma - most common, least malignant
2) Squamous cell carcinoma - second most common - fast
3) Melanoma - lowest amount of overall skin cancer cases, causes most death
Cancer caused from statum basale with colorless “rolled” edges
Basal cell carcinoma
Slow-growing, mostly on face
Cancer started from statum spinosum with scaly, red lesions on skin
Squamous cell carcinoma (keratinocytes)
Cancer that starts in melanocytes, black/brown blotches
Melanoma
Use ABCDE
