Integumentary System Flashcards
Two components of the Integumentary System?
Skin and Associated Structures (hair; oil; sweat glands; sensory receptors; nails)
Skin
cutaneous membrane) [Largest organ in the body; covering the external surface]
Integumentary System Functions
- Regulates body temperature 2. Stores blood 3. Protects body fro external environment 4. Detects cutaneous sensations 5. Excretes and absorbs substances 6. Synthesis of vitamin D
Dermatology
The medical specialty that deals with structure; function and disorders of the integumentary system.
What are the 3 layes of integumentary system?
- Epidermis (part of the skin) 2. Dermis (part of the skin) 3. Subcutaneous tissue (not part of the skin)
Epidermis definition
Thinner; superficial portion composed of epithelial tissue; avascular
Layer composition of Epidermis
keratinized stratified squamous epithelium
4 Princle Types of Cells
Keratinocytes; Melanocytes; Intraepiderml macrophages; Merkel Cells
Keratinocytes
[90%; arranged in 4-5 layers; protein produced=keratin] Several distinct layers in various stages of development. 4 Strata (layers of the epidermis)-[most regions of the body; some exceptions] 1. Stratum Basale 2. stratum spinosum 3. stratum granulosum 4. stratum corneum (thin) 5 Strata (layers of the epidermis)-Exceptions [areas of greatest friction; fingertips; palms; soles] 1. Stratum Basale 2. stratum spinosum 3. stratum granulosum 4. stratum lucidium 5. stratum corneum
Keratin
tough; fibrous protein that helps protect the skin and underlying tissue from abrasions; heat; microbes & chemicals
Lamellar Granules
release a water repellent sealant
Function of Lamellar Granules
- decreases water entry and loss 2. Inhibits entry of foreign materials
Where do Melanocytes come from?
Develop from ectoderm of a developing embryo
Function of Melanocytes
Produce the pigment; melanin
Melanin
a yellow-red or brown-black pigment that contributes to skin color and absorbs damaging UV light.
Melanin Transfer
- Melanocytes have long slender projections that extend between keratinocytes and transfer melanin granules to them. 2. Once inside keratinocytes; melanin granules will cluster to form a protective veil over the nucleus on the side of the skin surface. 3. This is used to shield the DNA material; preventing UV damage from the sun 4. Note: melanocytes are susceptible to damage by UV light
Orgin of Intraepidermal macrophages
Red bone marrow
Function of Inraepidermal macrophages
migrate to the epidermis and participated in immune responses mounted against microbes that invade the skin and easily damaged by UV light.
Role of Intraepidermal macrophages
help other cells of the immune system recognize an invading microbe and destroy.
Merkel Cells (tactile cells)
Are least numerous; and are found in the deepest layer of the epidermis
Function of Merkel Cells
contact the flattened process of a sensory neuron (nerve cell) [aka: Merkel Disc or tactile disc]
What are the 5 Strata (Layers of Epidermis)
- Stratum Basale 2. stratum spinosum 3. stratum granulosum 4. stratum Lucidium 5. Stratum Corneum
Stratum Lucidum Location/Components
Present only in fingertips; palms; soles Components: Four to six rows of clear flat dead keratinocytes with large amounts of keratin
Stratum Granulosum
- 3-5 rows of flattened keratinocytes; organelles are beginning to degenerate 2. Keratohyalin protein (to convert keratin intermediate filaments to keratin) 3. Lamellar granules (release lipid-rich; water-repellent secretion)
Stratum Spinosum
- 8-10 rows of many-sided keratinocytes with bundles of keratin intermediate filaments 2. projections of Melanocytes 3. intradermal macrophages (Langerhan?s cells)
Stratum Basale
Components: 1. single row of cuboidal or columnar keratinocytes that contain scattered keratin intermediate filaments (tonofilaments) 2. stem cells which undergo cell division to produce new keratinocytes 3. Melanocytes 4. tactile epithelial cells associated with tactile disc; scattered among keratinocytes.
Stratum Corneum
Few to fifty or more rows of dead; flat keratinocytes; mostly containing keratin.
Steps in Keratinization
- Newly formed cells in the stratum basale; slowly push to the surface 2. Cells move from one layer of the epidermal layer to the next; accumulating more keratin 3. Nutrients and oxygen diffuse to the ?avascular? epithelium from the blood vessels in the dermis 4. Cells closer to the blood vessels receive more nutrients and oxygen; cells as they rise are farther from the blood vessels and begin to die
How long does Keratinization take?
appoximately 4-6 wees
When does the rate of cell division increase in the Stratum Basale?
increases when outer layers of the epidermis are stripped away (ie: abrasions; burns)
Dandruff
Excessive amount of keratinized cells shed from the skin of the scalp.
Dermis composition
dense irregular connective tissue; collagen and elastic fibers
Functions of Dermis
- Gives the skin great tensile strength 2. Stretch and recoil
Characteristics of Dermis
- Thicker than the epidermis (variable depending on where in the body)-Greatest at soles and palms 2. Blood vessels; nerves; glands and hair follicles
Cells of Dermis
- Fibroblasts 2. Macrophages (few) 3. Adipocytes (few; near the boundary of the subcutaneous layer)
Two principle layers of the dermis
- Papillary Region (thinner; superficial) 2. Reticular region (thicker; deep)
Papillary Region
- 1/5 of the total dermal layer 2. Contains: thin collagen + fine elastic fibers 3. Dermal papillae (small nipple shaped structures that project into the undersurface of the epidermis) 4. Contents of the Dermal Papillae: a. Capillary loops (blood vessels) b. Meissner corpuscles (touch/pressure nerve endings) c. Free nerve endings (temperature; light touch and itching)
Reticular Region
- 4/5 of the total dermal layer 2. Net-like layer attached to the subcutaneous layer 3. Contains: bundles of thick collagen fibers; scattered fibroblasts; wandering cells (macrophages); adipocytes in deepest part with coarse elastic fibers 4. Collagen fibers are more ?regular? in the reticular region and form a ?net-like? orientation. This orientation gives skin more resistance to stretching. 5. Spaces between fibers are filled with: blood vessels; nerves; hair follicles; sudoriferous sweat glands; sebaceous glands 6. Function: provides skin with strength; extensibility (the ability to stretch); elasticity (ability to return to pre-stretch shape)
Epidermal ridges (fingerprints) def.
Bond between the dermis and epidermis on the surfaces of the palms; soles and fingertips
Epidermal ridges function
- Increased surface area (increases number of corpuscles of touch and tactile sensitivity) 2. Increase grip; by increasing friction
Subcutaneous AKA: Hypodermis
(deep to the dermis; NOT part of the skin)
Hypodermis Layer composition
and adipose tissue; Fibers extend from the dermis and anchor the skin to this subcutaneous layer and CT (fascia) found around muscles and bones
Hypodermis Function
Storage for fat
Hypodermis associated structures
Nerve endings (aka: lamellated corpuscles) sensitive to pressure; large blood vessels
What are the three pigments that give skin color?
Melanin; Hemoglobin; Carotene
Melanin Def.
[varies skin color from pale yellow to reddish-brown] Two forms of melanin: 1. Pheomelanin [yellow to red] ? 2. Eumelanin [brown to black] ? hair
Melanocytes
melanin-producing cells; most numerous in epidermis of darker skinned area (penis; nipples; areolae); face; limbs; mucus membranes Number of melanocytes is about the same in all people; the difference in skin color is due to the amount of pigment these cells produce and transfer to keratinocytes
Melanin Orgin
synthesized from amino acid; tyrosine in the presence of tyrosinase
Melanin Organelle
melanosome synthesizes melanin
Hemoglobin
epidermis; skin color is pink to red depending on the oxygen content of the blood in the capillaries of the skin
Carotene
[yellow-orange pigment] Pre-curser to vitamin A; used to synthesize pigments for vision
Accessory structures of the skin
Hair; Glands; Nails
Hair Location
most skin surfaces; exception: palms; fingertips; soles; plantar surfaces of the feet
Hair Function
- Limited; but some protection from the sun rays 2. Decreases heat loss from scalp 3. Eyelashes/eyebrows protect the eyes from debris 4. Nostrils and hair in the ear protect structures from debris 5. Sensing light tough via hair root plexes
Composition of Hair
Dead; keratinized epidermal cells
Two parts of the hair
Hair root and hair shaft
Hair Root
(portion found penetrating into dermis and sometimes subQ tissue)
Hair Shaft
(portion found above the surface of the skin)
What are the three concentric layers of the hair?
Medulla; Cortex; and Cuticle of the hair
Medulla
inner layer; 2-3 rows of irregular cells contain pigment
Cortex
major part of the shaft; elongated cells
Cuticle of the hair
outermost; single layer; thin & flat and heavily keratinized
Hair Follicle
Surrounds the root of the hair
External Root Sheath
downward continuation of epidermis
Internal Root Sheath
[produced by the matrix; which forms a cellular; tubular sheath of epithelium between the external & internal root sheath.
Epithelial Root Sheath
External Root Sheath + Internal Root Sheath
Dermal Root Sheath
dermis surrounding the hair follicle
Bulb
?onion?shaped structure found at the base of each hair follicle and surrounding dermal root sheath.
Components of Buld
- Papilla of the hair 2. Hair matrix
Papilla of the Hair contents
Contents: areolar CT; many blood vessels
Hair matrix contensts
germinal layer of cells. Arise from Stratum basale (site of cell division)
Hair Matrix Functions
- Responsible for growth of existing hairs and generation of new hairs when old hairs are shed. (Occurs within the same follicle) 2. Gives rise to the cells of the internal root sheath
Structures associated with Hair
Sebaceous Oil Glands; Arrector Pilli Muscles; Hair Root Plexus
Sebaceous Oil Glands
[bundle of smooth muscle cells associated with hairs; secrete oil]
Arrector Pili Muscles
[smooth muscle which pulls hair shaft perpendicular; causing goose bumps]
Hair Root Plexus
[dendrites of neurons; surrounding each hair follicle]
Skin Glands
Sebaceous Oil Glands; Eccrine Sweat Glands; Apocine Sweat Glands; Ceruminous Glands
Sebaceous Oil Glands Described
- Distribution [largely-lips; glans penis; labia minora; tarsal glands; small-trunk; limbs; Absent: palms & soles] 2. Location of secretory portion [dermis] 3. Termination of excretory duct [mostly connected to hair follicle] 4. Secretion [sebum-a mixture of triglycerides; cholesterol; proteins & inorganic salts] 5. Functions 1. Prevent hairs from drying out 2. prevent water loss from skin 3. keep skin soft 4. inhibit growth of some bacteria 6. Onset of function: [relatively inactive throughout childhood; activated at puberty]
Eccrine Sweat Glands
- Distribution [throughout the skin/most regions of the body; especially skin of forehead; palms and soles] 2. Location of secretory portion [mostly; deep dermis; sometimes upper layer of SubQ] 3. Termination of excretory duct [surface of the epidermis] 4. Secretion [perspiration consisting of water; ions (Na+; Cl-); urea; uric acid; ammonia; amino acids; glucose; lactic acids] 5. Functions 1. regulation of body temperature 2. waste removal 3. stimulated during emotional stress 6. Onset of function: [soon after birth]
Apocrine Sweat Glands
- Distribution [skin of axillae; groin; areolae; bearded regions of face; clitoris & labia minora] 2. Location of secretory portion [mostly deep dermis & upper subcutaneous layer] 3. Termination of excretory duct [Hair follicles] 4. Secretion [perspiration; consisting of same components as eccrine sweat glands plus lipids and proteins] 5. Functions 1. stimulated during emotional stress 2. stimulated during sexual excitement 6. Onset of function: [Puberty]
Ceruminous Glands
- Distribution: [External auditory canal] 2. Location of secretory portion: [subcutaneous layer] 3. Termination of excretory duct: [surface of external auditory canal or into ducts of sebaceous glands] 4. Secretion [a waxy material known as cerumen] 5. Functions 1. impedes entrance of FB & insects into external ear canal 2. waterproof canal 3. prevent microbes from entering cells 6. Onset of function: [soon after birth
Nails
plates of tightly packed; hard; dead keratinized epidermal cells that form a clear; solid covering over the dorsal surfaces of the distal portions of the digits.
Compnents of Each Nail
Nail body plate); Free edge; nail root
Nail Body Plate
[visible portion of the nail] ? Comparable to stratum Corneum of the skin. ? Exception: flattened; keratinized cells fill with a harder type of keratin and cells are not shed. ? Mostly pink; due to vascularity of the tissue below
Free edge
[part of the nail that extends beyond the finger or toe] ? White region of the edge: white because there are no capillaries
Nail Root
[portion of the nail that is buried in a fold of skin and not visible]
Lunula
(little moon): moon-shaped; crescent-shaped area of the proximal end of the nail body; vascular tissue doesn?t show through due to thickened region of epithelium in the area.
Hyponychium
thickened region of stratum Corneum below the free edge. Function: secures nail to the fingertip
Eponychium (cuticle):
narrow band of epidermis that extends from & adheres to the margin of the nail wall; stratum corneum of the epidermis
Nail matrix
epithelium proximal to the nail root. Contains dividing cells which produce new nail cells
What is the rate of Nail Growth Determined By?
- Age 2. Health 3. Nutritional status 4. Season 5. Time of day 6. Environmental temperature
What is the average nail growth?
grows 1 mm/week Growth rate somewhat slower in toenails Longer the digit; the faster the nail grows
Functions of Nails
- Protect the ends of the digits 2. Provide support and counter pressure to palmar surface of the fingers; enhances touch perception and manipulation 3. Allow us to grasp and manipulate small objects; can be used to scratch and groom the body
What is the biggest contributor to epidermal thickniss?
Increased number of layers in the stratum Corneum (arises in response to greater mechanical stress in regions of thick skin).
Functions of Skin
- Thermoregulation 2. Blood reservoir 3. Protection 4. Cutaneous Sensations 5. Excretion & Absorption 6. Synthesis of Vitamin D
What two ways does skin participate in thermoregulation?
Liberating sweat at its surface; adjusting the flow of blood in the dermis
Blood reservoir
Dermis houses an extensive network of blood vessels; It holds 8-10% of total blood flow in a resting adult
Protection:
- Keratin protects underlying tissues from microbes; abrasion; heat and chemicals 2. Tightly interlocked keratinocytes resist invasion by microbes 3. Lipids released by lamellar granules inhibit evaporation of water; guarding against dehydration 4. Prevent entry of water across the skin surface during showering; bathing; swimming 5. oily sebum keeps skin and hairs from drying out; also contains bactericidal chemical 6. Acidic perspiration slows growth of mcirobes 7. Pigment melanin guards against UV light
What two types of cells carry out immunological protection functions?
Intraepidermal macrophages (Langerham’s cell and macrophages in the dermis
Intraepidermal macrophages (Langerhan?s cells)
[alert immune system to presence of potentially harmful microbe invaders; recognize and processes them
Macrophages in the dermis
phagocytize bacteria and viruses that manage to bypass the intraepidermal macrophages of the epidermis]
Cutaneous Sensations
sensations that arise in the skin; including tactile sensations (touch; pressure; vibration; tickling; thermal); Pain [sensation that is an indication of impeding or actual tissue damage] Variety of nerve endings and receptors distributed throughout the skin. Examples: 1. Tactile discs of the epidermis 2. Corpuscles of touch in the epidermis 3. Hair root plexuses around each hair follicle
Does skin have a role in exretion and absorption?
Skin has a small role in excretion and absorption
Excretion
elimination of substances from the body 1. Approximately 400 ml of H20 is excreted each day 2. Salts 3. CO2 4. Two organic molecules resulting from the break down of proteins (ammonia; urea)
Absorption
passage of materials from the external surface of the body; inside; negligible amount but it does occur Lipid-soluble materials [Fat-soluble vitamins ADEK; certain drugs; gases like oxygen and CO2; toxic materials; salts of heavy metals such as lead mercury; arsenic; poison ivy/oak] Drugs placed on the skin/dermis [steroids such as cortisone are lipid soluble and they move into the papillary region of the dermis] ? Anti-inflammatory properties; inhibit histamine production by mast cells Other drugs can be placed on the skin; varying effect in the form of patches [nitroglycerine; fentanyl]
What are the requirments for the synthesis of Vitamin D?
- Activation of a precursor molecule in the skin by UV rays of sunlight 2. Enzymes in the liver and kidney modify the activated molecule 3. Produces calcitriol [most active form of vitamin D] Only a small amount (10-15 min; twice a week) is necessary for vitamin D synthesis.
Who is at risk of vitamin D deficiency?
- Those who live in colder; northern climates 2. Those who always use sunscreen
What are the two types of wound healing?
Epidermal wound healing and Deep wound healing
Epidermal Wound healing
Common types of wounds: Abrasions; minor burns Response to an epidermal wound: 1. Basal cells of the epidermis surrounding the wound; break contact with the basement membrane 2. Cells enlarge and migrate across the wound as a sheet; until advancing cells from opposite sides of the wound meet. 3. Upon encountering each other; the cells stop migrating due to a cellular response (aka: contact inhibition) 4. Epidermal Growth Factor (EGF) stimulates basal cells to divide and replace the ones that have moved into the wound 5. Relocated basal epidermal cells divide to build new strata; thus thickening the new epidermis
Deep wound healing
Wounds that extend into the dermis
What are the 4 phases of deep wounds
Inflammatory; Migratory; Proliferatie; Maturation Phase
Inflammatory Phase
[blood clot unites the wound edges?epithelial cells migrate across the wound ? vasodilation & increased permeability of BV enhance phagocytes ? mesenchymal cells develop into fibroblasts]
Migratory Phase
[fibroblasts migrate along fibrin threads and begin synthesizing collagen fibers & glycoproteins]
Proliferative Phase
[epithelial cells grow extensively]
Maturation Phase
[scab sloughs off ? epidermis is restored to normal thickness ? collagen fibers become more organized ? fibroblasts begin to disappear ? BV restored to normal]
Embryology of the Integumentary System
- Epidermis is derived from: Embryonic Ectoderm; [hair; nails; skin glands are epidermal derivatives] 2. Dermis is derived from [mesodermal cells]
Aging and the Integumentary System
- Effects start around 40?s 2. Specific effects of aging on the Integumentary system: a. Wrinkling b. Loss of subcutaneous adipose tissue c. Atrophy or sebaceous glands d. Decrease in number of melanocytes e. Decrease in number of intraepidermal macrophages
Skin Grafts
Transfer of a patch of healthy skin taken from a donor site to cover a wound. New skin is unable to regenerate if the injury has damaged a large area of the stratum basale and its stem cells.
Benefits of Skin Grafts
- Protects against fluid loss and infection 2. Promotes tissue healing 3. Reduce scar formation 4. Prevent loss of function 5. Cosmetic
Complications of Skin Grafts
Tissue rejection
Skin taken from the same person
Autograft
Skin taken from an idenitical twin
Isograft
Autologous Skin Transplantation
small amounts of a person?s epidermis are removed; keratinocytes are cultured in the lab and grown to produce thin sheets of skin; which will be transplanted
Psoriasis Definition
common/chronic skin disorder in which keratinocytes divide and move more quickly than normal from the stratum basale to the stratum corneum and will be shed prematurely (7-10 days).
Psoriasis Pathology
Pathology: immature keratinocytes make an abnormal keratin; which forms flaky; silvery scales at the skin surface; most often on the knees; elbows and scalp.
Psoriasis Treatment
topical ointments and UV phototherapy; Anything that will suppress cell division; decrease the rate of cell growth or inhibit keratinization
Albinism Definition
The inherited inability of an individual to produce melanin
Albinism Pathology
most have melanocytes; but they are unable to synthesize tyrosinase. Melanin will be missing from their skin; eyes & hair.
Albinism Manifestations
problems with night vision & tendency of the skin to burn with over-exposure to sun.
Vitiligo
the partial or complete loss of melanocytes from patches of skin; producing irregular white spots
Cyanotic
(blue)-blood does not pick up adequate oxygen from the lungs (most apparent in the mucous membranes; nail beds and skin)
Jaundice
(yellowish)-build-up of the yellow pigment; known as bilirubin in the skin; yellowish skin and sclera; likely indicates liver disease
Erythema
(redness)-engorgement of the capillaries in the dermis with blood due to skin injury; exposure to heat; infection; inflammation or allergic reactions
Pallor
(paleness)-may occur in conditions such as shock or anemia.
How do you diagnosis when the individual has darker skin?
These changes may be difficult to diagnose in individuals with darker skin; therefore looking at the nail beds; gums; mucous membranes and conjunctiva are helpful.
Transdermal drug administration
Alternative Route for drug administration
Transdermal
enables a drug contained within an adhesive skin patch to pass across the epidermis and into the blood vessels of the dermis. The drug has a controlled release over a period of one to several days.
Benefits of Transdermal
Effective for drugs that are quickly eliminated from the body; they don?t have to be taken as frequently
Examples of Transdermals
- Nitroglycerine (prevention of angina pectoralis) 2. Scopolamine (motion sickness) 3. Estradiol (post-menopausal estrogen replacement therapy) 4. Contraceptive patches: (birth control) 5. Nicotine: (stop smoking ) 6. Fentanyl: relieves severe pain in cancer patients.
