Term | Definition |
integument | the skin covering the body, also known as the cutaneous membrane. scientific study and treatment is termed dermatology
- Body's largest organ
- Protects internal bodystructures
- Account for 7~8% of body weight
- Surface area ranges between 1.5-2.0m2 |
Integument composed all tissue type | - Surface - epithelium
- Underlying: connective tissue, provides strength and resilience
- Smooth muscle tissue associated/w hair follicles
- Nervous tissue: touch, pressure, temperature and pain |
Two Layers | Epidermis - Top layer
Dermis - Deeper Layer |
Epidermis | Epi = above, Derma = Skin
Consists of Keratinized, startified squamous epithelium,
Specific layers, or strata |
Layers of the epidermis from deep to superficial | - Stratum Basale
- Stratum Spinosum
- Stratum Granulosum
- Stratum Lucidum
- Stratum Corneum |
Stratum basale | Three cell types
- Keratinocytes
- Melanocytes
- Tactile cells |
Keratinocytes | - Most abundant cells in epidermis
- all layers
- divide to regenerate neww cell, replace old cells shed at the surface
- synthesis of keratin(the protein that strengthens the epidermis) |
Melanocytes | - Scattered among the keratinocytes of the stratum basale
- Spider-shaped epithlial cells
- produce the pigment(melanin) in response to UV |
Melanosomes | Melanocytes manufacture melanin from the amino acid tyrosin, and apckage it in membrane bound granules |
Melanosomes | Transferred from melanocytes into Keratinocyes
- Accumulate on the superficial(Sunny side) of the Keratinocyte nucleus
- Shield nuclear DNA from UVradiation
- Responsible for the darker tones of skins |
Tactile cell | - Know as Merkel cells
- Few in number
- Sensitive to touch
- When compressed, release chemicals: stimuulate sensor nerve ending |
Stratum Spinosum | - Several layers of polygonal keratinocytes
- Know as spiny layer |
Spinosum | Daughter cells from stratum basale are pushed into this layer
Non-dividing keratinocytes
attached by intercellular Junction called desmosomes |
Epidermal Dendritic cells(Langerhans cells) | - often present in stratum spinosum and granulosum
- Immune cells that help initiate immune response to fight infection in the epidermis
- Responsive to pathogens and epidermal cancer cells |
Stratum Granulosum | - Three to five layers of Keratinocytes
- Known as granular layer
- Keratinization begins within it: process where keratinocytes fill with keratin
casue nucleus and organelles to disintegrate
fully keratinized cells are dead but struturlly strong |
stratum lucidum | - Two to three layers of keratinocytes
- Clear layer
- Found only Thick skin within the palms and soles
- Filled with a translucent protein Eleidin
- Helps protect skin from UV light |
Stratum Corneum | - 20-30 layers of dead keratinized cells ( anucleate/without a nucleus), tightly packed, plasma membrane enclosing keratin protein
- Known as the hornlike layer
- Most superficial layer of epidermis
- Secretions of exocrine gladns, helping prevent grow |
Variations in the epidermis | - its thickness, coloration, and skin markings
- the epidermis exhibits variation: between different body regions within one individual and between individuals |
Hemoglobin | - Oxygen binding compound present in red blood cells
- bright red color upon binding oxygen
- Gives blood vessels in dermis a reddish tint
- Seen most easily in fair skinned individuals and more visible if blood vessels dilate |
Melanin | -Pigment produced and stored in melanocytes
- Occurs in blak, brown, tan, yellow-brown shades
- Amount in skin varies according to heredity and light exposure
- All ppl same # of melanocytes
- darker skinned producing more and darker colored melanin |
Carotene | - Yellow-orange pigment
- Acquired from yellow-orange vegetables
- Accumulates inside subutaneous fat and keratinocytes of stratum corneum
- Converted to Vitamin A within the body |
Nevus | - Common called a mole
- Harmless ovdrgrowth of melanin forming cells
- Rarely may become malignant, typically as a consequence of excessive UV light exposure - should be monitored for changes that my suggest malignancy |
Freckles | - Yellowish or brown spots
- Represent localized areas of increased melanocyte activity
- Degree of pigmentation based on sun exposure and heredity |
Hemangioma | - Skin discoloration due to blood vessels that proliferate to fom a benign tumor |
Capillary hemangiomas | - appear in skin a sbright red to deep purple nodules
- usally present at birth and disappear in childhood
- known as strawberry-coloredd birthmarks |
Cavernous hemangiomas | - involve larger dermal blood vessels
- may last a lifetime
- known as prot-wine stains |
friction Ridge | - Complex arches and whorls on fingers, aplms, soles, and toes
- Formed from large folds and valleys of dermis and epidermis
- each individual with a unique pattern of friction ridges
- Allows for persnoal identification |
Dermis | -Deep to the epiderrmis
- Composed of connectve tissue |
Component of the Dermis | - Collagen with elastic and reticular fibers
- motile dentritic cells serving an immun function
- blood vessels, sweat, sebaceous glands
- Hair follicles, nail roots, sensory nerve ending, arrector pili muscles
- Papillary layer&deeper reticular layer |
Papillary layer of the dermis | - Superficial region of the dermis
- Directly adjacent to epidermis
- Composed of areolar connertive tissue |
Layer of the dermis | - Dermal papille
- contain capillaries and sensory nerve endings
- projections of epidermis interdigitating with papillae
termed epidermal ridges |
Reticular layer of the dermis | - Deeper, major protion of the dermis
- Extends from papillary layer to subcutaneous layer
- consists primarily of dense irregular CT
- Contains large bundles of collage fibers |
Stretch marks | - Some collagen fibers are torn causing stretch marks |
Dermal blood vessels | - Supply nutrients to epidermis and dermis
- Large vessels along reticular and subcutaneous border
- Smaller vesses branching into dermis and dermal papillae
- Play an important role in body temperature and blood pressure regulation |
Subcutaneous Layer | - Deep to dermis
- Layer of areolar & adipose connective tissue
- termed hopodermis
- Not part of the integumentary system
- Pads and protects the body |
subcutaneous Layer | - Acts as energy reservoir
- Provides thermal insulation
- Drgus often infected here
- Woment, generally thicker : primarily in breasts, buttocks, hips, and thighs
- Men, thinner : neck, upper arms, abdomen, lower back, buttocks |
Nails, hair, exocrine glands | - Know as epidermal derivatives or appendages, of the integuments
- Both nails and hair are composed primarily of dead keratinized epithelial cells
- exocrine glands are composed of living epithelial cells |
Structure of nails | - Scalelike modifications of the stratum corneum
- form on the dorsal edges of fingers and toes
- protect that distal tips of the digits
- assist in grasping objects |
Hair composition | - Single hair, termed Pilus, with shape of a slender filament
- Composed of keratinized cells growing from hair follicles |
Three types of hair | - Lanugo
- Vellus
-Terminal hair |
Lanugo | Fine, unpigmented, downy hair,
appears in last trimester |
Vellus | Fine, unpigmented or lightly pigmented hair
replaces lanugo at birth
found in children and adult females |
Terminal hair | Coarser, pigmented longer
on scalp, eyebrows, and eyelashes men's beards
duiring puberty replaces vellus hair in axillary and pubic regions |
Hair bulb | Swelling at the base in the dermis
surronds hair papilla that is composed of connectivetissue containin tiny blood vessels and verves |
Root | portion of hair deep to skin surface |
Shaft | portion of hair that projects rom the skin & extends up to where the hairshaft loses its connetion with the follicle
both root and shaft consists of dead epithelial cells |
Hair components | - Hair Matrix
- Medulla
- Cortex
- Cuticle
- Hair follicel
- arrector pili muscle |
Hair matrix | structure at the base of the hair bulb
epithelial cells are dividing here to elongate the hair |
Medulla | Inner layer of hair
contains loosely arranged cells and air spaces
contains flexible, soft keratin
absent in fine hair |
Cortex | Middle layer of hair |
Cuticle | single layer of overlapping cells around cortex which coats the hair |
Hair follicle | oblique tube surrounding hair root
extends into dermis and sometimes subcutaneous layer
has an outer connective tissue root sheath originating in dermis
has inner epithelial tissue root sheath orginating from epidermis |
Arrector pili muscle | thin ribbons of smooth muscle
extend from hair follicle to the dermal papillae
elevates hair with contraction, producing "goosebumps" |
Functions of hair | Protection - scalp form sunburn and injury
within ears protecting from foreign matter
eyebrowns keeping sweat out of eyes
heat retention- prevents loos of heat from scalp to air
senesory reception-
visual identification
chemical signal disperal |
Hair color | - Results from synthesis of melanin in the matrix adjacent to hair papillae
- Relects genetic, enviornmental, and hormonal factors
- Becomes lighter with age as pigment production decreases |
Hair growth rate | one-third mm per day in the scalp for 2 to 5 years
enters dormant phase of 3 to 4 monts
eventually pushed out and replaced by new hair
Hair growth rate and the duratiom of the hair growth cycle varies |
Hair loss | Normal sclp loss o 10 to 100 hairs per day: may be result of drugs, dietary factors, radiation, high fever, stress
Thinning of hair termed alopecia : usually as a result of aging |
Diffuse hair loss | hair shed from all parts of salp
primarily in women |
male pattern baldness | loss of hair from only some regions of scalp
combination of genetic and hormonal factors
baldness allele dominant in male
Recessive in females
expressed only in the presence of high testosterone |
Eocrine glands of the skin | many types of exocrine glands
Two most common: Sweat glands, Sebaceous glands |
Sweat glands | merocrine
apocrine |
sweat gland duct | carrying secretions |
sweat pore | opening of the gland duct on epidermal surface termed |
Merocrine sweat glands | Most numerous and widely distributed sweat glands
simple, coiled tubular glands
discharge their secretions onto skin surface
secrete sweat composed of 99% water&1% other chemicals |
Major function of thermoregulation | Regulation of body temperature by fluid evaporation
loss of water and electorlytes
some protection from environmental hazards both by : diluting harmful chemiclas, preventing the growht of microorganisms
produce secretions by exocytosis |
Apocrine sweat glands | Coiled tubular glands
Dischargesecretions into hair follicles
Produces secretions by exoytosis |
Apocrine sweat glands found | axillae, around nipples,pubic and anal region
contain proteins & lipids, produce odor acted on by bacteria
Start producing secretions during puberty |
Sebaceous gland | Produce oily secretion called sebum
acts as a lubricant for skin and hair
has bactericidal properties
discharged into a hair follicle
holocrine glands
Secretion stimulated by hormones, especially androgens
Active during puberty |
Ceruminous glands | - Modified apocrine sweat glands
- Located only in the external acoustic meatus
- Secretions form waterproof earwax, cerumen
help trap foreign material
help lubricate acoustic meatus and eardrum |
Mammary galnds | - Modified aprocrine sweat glands of the breast
- Found in both males and females
- only function in pregnant and lactating females
- Produce milk |
Epidermis functions | metabolic rgulation
Secretion and absorption
Immune function |
Metabolic regulation | Vitamin D : termed cholecalcifero
Synthesized from a steroid precursor by keratinocytes
ocuurs upon UV exposure
Released into blood and transported to the liver
condidered a hormone
increases absorption of calcium and phosphate |
Vitamin D synthesis | important in regulating blood levels of calcium and phosphate
Skin able to convert some compounds to slightly different forms
UV rays stimulating melanocytes to produce melanin |
Dermis function | Temperature regulation: influenced by capillaries and sweat glands here
Blood vessel dilation and sweating when body too warm
blood vessel constriction when body too cold |
Sensory reception | detectors mostly in dermis
detect heat, cold, touch, pressure, and vibration |
Repair and Regeneration | Response to repetitive mechanical stress
mitosis is stimulated in stratum basale resultin in : Thickening off the epidermis to provide more protection |
Regeneration | replacement of damaged cells with same cell type
restores organ funciton |
Fibrosis | gap filled with scar tissue
composed primarily of collagen produced by fibroblasts
functional activities not restoredd
if organ too damaged or cells lacks ability |
Stage wond healing | 1) cut blood vessels bleed into wound
2) Blood clot forms and leukocytes clean wond - clot a temporary barrier for pathogens
3)Blood vessels regrow and granulation tissue forms
4) Epithelium regenerated and connective tissue fibrosis occurs |
Wond healing | - Not rapid
- Longer for wider and deeper surfaces
- With severe damages : less likely to return to original condition
hair follicles, exocrine glands, nerves, and arrector pili muscle cells not repaired |
ASYMMETRY | moles that, if ided in half are not the same on both side |
Border | moles with edges that are jagged like a coastline |
Colour | Moles gainning or losing colour, or multicoloured |
Diameter | Moles more than 1/2 cm in diameter(especially if uneven colour) |
Evolution | Moles that have changed size, shape, colour or risen |