The Skin

Hair Thinning

Advanced Age Decrease mitotic rates leads to epidermal thinning Slower repair rate of epidermis Lose of dermal papillae cause increase tends for tears and blisters In addition, reduction of collagen &elastic fibers (weaker & less resilient skin leads to wrinkling Decreased numbers of epidermal dendritic cells Decreased melanocyte activity Paler skin, less UV protection, white hairs Decreased glandular activity (sweat and oil glands) Drier, scalier skin Decrease heat tolerance Lose of sensory endings - decrease pain and temperature sensitivity Reduced blood supply Skin is cooler (skin thermoreceptors may make a person "feel" cold in a warm room) Decreased function of hair follicles leads to _____

Puberty

Age Related Changes in Skin Children Few active sweat glands (eccrine type) More rapid wound healing; more keratinocytes enter mitosis daily compared to adults ________- rise in sex hormones, esp. androgens Development and activation of sebaceous and apocrine sweat glands Increase sweat & sebum production

Stratum granulosum Stratum basale and spinosum

Darker skin individuals produce larger melanosome and the transfer to epithelial cells may occur in higher regions (_______) compared to lighter individuals (transfer occurs _____ and ______). In addition, pigment tends to be lost from the cells in the more superficial layers of lighter skinned individuals.Freckles and moles are localized accumulations of melanin.

25-35 desquamated stratum corneum

Epidermal Growth and Repair Turnover time: Migration from basal layer to the surface takes about ______ days on average Cells remain on surface for additional 2 weeks before being shed (______) Friction or abrasions will shorten turnover time Callus formation, a thickening of the _______, occurs because of persistent friction stimulates mitosis and shortens migration rate leading to an increase accumulation of cell at the skin surface

Epidermal Growth Factor

Epidermal Growth and Repair _______: Stimulates basal cell division Accelerates keratin production Stimulates exocrine gland activity of epidermis

Keratinocytes Melanocytes Tactile (Merkel) cells Epidermal dendritic cells

Epidermis contains 4 distinct cells types: 1) 2) 3) 4)

Reticular layer

This layer is a part of the dermis. It has about 80% thickness. Consists of dense irregular connective tissue as well as: collagen -strength & retains moisture elastin - flexibility Contains: larger blood vessels, lymph vessels, nerve fibers, muscle, and accessory structures

Thin Skin Thick Skin

Two Types of Skin 1) _______: Covers most of body surface Haired 2) _______: Found only on soles and palms Hairless Friction ridges ("prints")

Epidermis Dermis Hypodermis

Two main components: 1) Skin or Cutaneous Membrane __________: keratinized stratified squamous epithelium __________: areolar and dense connective tissues _________ (subcutaneous layer of superficial fascia) -not part of integument 2) Accessory structures Hair Nails Exocrine glands (sweat and sebaceous)

Fibroblast

UV radiation stimulated melanin production - but not in time to prevent sunburn. UV radiation is harmful to DNA and over time will impair proper _______ activity, which results in faulty maintenance of the dermis and premature aging.

Hydration

Water can be gained through skin - _______: results from immersion in hypotonic solution, (e.g., freshwater) this is not a significant source for gaining water (since our skin is not water proof). (we don't live in water environment)

Hormones

______ causes the distribution of subcutaneous fat deposit to shift. In males, the fat accumulates at the neck, arms, lower back and buttocks. In females, SQ fat accumulates at breasts, buttocks, hips and thighs. Few fat cells on the back of the hands or dorsum of the feet.

Striae Flexure lines

______ or stretch marks are tearing and scarring of the dermal layer ______: deep creases in the skin usually near joints where the dermis is tightly secured to underlying structures and does not freely move.

Nail matrix Lunula Nail bed Pitting

_______ (or germinal matrix) - epidermal growth region located deep in the skin fold at the eponychium at the root and extents distally to the end of the lunula ______ -the pale crescent at the base of the nail; appears white because of the thickness of the matrix in this area ______: continuation of the nail matrix beneath the nail body from the lunula to the free edge The nail bed appears pink because of the visibility of the rich capillary supply in the dermal layer beneath the nail bed Changes of the nail appearance can be associated with disease. Yellowing may occur with some chronic respiratory disease, AIDS or thyroid disorders. _____ occurs with psoriasis or damage to nail root. Some blood disorders cause the nail to have a concave appearance.

Stratum granulosum Cornified

_______ is named for the abundant granules found in and around the cells. The granules contain keratin or glycolipids. The glycolipids function as waterproofing around cells. ______ cells refer to the shingle-like cell remnants of the keratinocytes that are found in the upper most layer of skin. Normal loss of water across the epidermis is about 500 ml /day. Burns and abrasions can greatly increase this form of insensible water loss.

Insensible perspiration Sensible perspiration

________ - interstitial fluid lost by evaporation through the stratum corneum ________ -water excreted by sweat glands

1st Degree Burns 2nd Degree Burns 3rd Degree Burns 4th Degree Burns

________ - only epidermis is damaged area inflammed heals in 2-3 days _________ - injury extends down to the top region of the dermis area inflammed and blistering occurs healing 2-3 weeks; generally with some scarring __________ - full thickness burns skin appears white, cherry red or blackened (eschar) extensive scarring may require skin grafts may not be painful because of destruction of nerve endings ____________ - if burning includes tissues deeper than the dermis (muscles, fasciase or bone).

The Dermis

_________: General Characteristics Forms the bulk of the thickness of skin Strong, flexible CT layer between epidermis and hypodermis. Anchors the accessory structures of the integument (hair follicles, sweat and sebaceous glands) Blood supply Nourish epithelia Temperature regulation Composed of two layers: Papillary layer (superficial) Reticular layer (deep)

Eccrine Apocrine

2 Types of Sweat Glands ______ (also called merocrine sweat glands): Most common; found everywhere except lips, ear canals, glans penis Highest density on palms and soles Open directly onto skin (not via hair follicle) Involved in thermoregulation Secretion is regulated by the sympathetic nervous system ________: (secretion is merocrine mode, not apocrine) Found in armpits, around nipples, and groin and are associated with hair follicles Produce sticky, cloudy secretions; bacterial activity causes odor (under arm sweat) Do not function in thermoregulation; involved in emotional sweating Influence by sex hormone Active during sexual foreplay Olfactory communication (phermones)

Merocrine Apocrine Eccrine Myoepithelial

Both types of sweat glands release sweat via the _______ mode of secretion (i.e. exocytosis) ________ sweat glands are involved in emotional sweating at armpits (but emotional sweating also occurs in thick skin)and ______ sweat glands are involved in thermoregulation ________ cells squeeze apocrine sweat gland secretions onto the skin. The so-called pores on your skin are openings for hair follicles (not opening for eccrine sweat glands)

Bilirubin Jaundice

Bruising can cause a rainbow of different colors as hemoglobin is degraded to _______ Bile pigments (bilirubin) accumulate with liver disease and increase levels occur in the blood and adipose tissue causing the condition called ______

Dehydration

Burns are tissue damage due to excessive heat, electricity, radiation or certain chemicals _________ is the most immediate threat to life The volume of fluid loss can be estimated by the Rule of Nines; this method divides the body into 11 regions which each represent 9% of the total body surface. Infections

Sebaceous glands Holocrine Sebum Sebum accumulation Vernix caseosa

Exocrine Glands in the Skin _______ (oil glands): found in all area except thick skin (palms and soles); usually associated with hair follicles. Mode of secretion: _____ _________ - is a mixture of triglycerides, cholesterol, proteins and electrolytes. Sebum production is stimulated by androgens. Secretion is facilitated by the arrector pili muscles. It conditions the hair and skin, has some antibacterial properties, and reduces water loss from the skin. Sebaceous follicles are large sebaceous glands not associated with hair follicles (face, back, chest, genitalia)- can become affected with bacteria which produces acne. _________ - whiteheads/blackheads (whitehead oxidized blackhead) During fetal development the sebaceous glands produce a cheesy-looking substance, _______, that protects the skin from constant exposure to amniotic fluid.

Lentigos Albinism Vitiligo

Freckles and ______ (similar to freckles but with irregular borders) are regions of larger-than-normal melanin production. ______ is a genetic disorder involving lack of active tyrosinase enzyme that is needed to convert tyrosine into melanin. ______ - loss of melanocytes. Can be the result of a immune disorder or certain diseases (Addison, thyroid disease)

Stratum corneum

Function of Skin 2. Role of Skin in Water Balance Evaporative loss of water directly through the skin Damage to _______ such as by burns and blisters will greatly increase water loss

Excretion

Function of Skin 3. _______ Sweat contains salts and metabolic wastes (urea, ammonia, uric acid)

Protection

Functions of Skin 1. _________ Physical barrier Keratin protects against abrasion Waterproofing by glyolipids Melanin reduces UV exposure Surface film - emulsion of sebum, sweat and epithelial elements Antibacterial and antifungal properties Low pH retards bacterial growth Natural antibiotics (human defensin and cathelicidins) Reduces water loss

Thermoregulation

Functions of Skin 4. _________ 80% of heat loss occurs from skin - heat loss is enhanced by dilating blood vessels at the superficial regions of the dermis where heat can be dissipated by radiation, conduction and convection Sweating enhances heat loss by evaporative cooling Sweating can result in a significant loss of body water

Papillary Layer

This layer is a part of the dermis. It has 20% thickness. Consists of loose areolar connective tissue Forms dermal papillae - interdigitating fingers that prevent the epidermis from sliding over the dermis,

Hormone Production Sensation Immunity

Functions of Skin 5. __________ (Vitamin D3- steroid based hormone ) UV exposure converts 7-dehydrocholesterol to cholecalciferol (a Vit. D3 precursor). Cholecalciferol is converted to 25-hydroxychoelcalciferol at the liver and this compound is converted to the active form of Vit. D3 1,25 hydroxycholecalciferol(calcitriol) by the kidney. Calcitriol is needed by the GI system to promote absorption of calcium. 6. _________ - sensory receptors in dermis 7. __________ Phagocytic cells Epidermal dendritic cells

Mitotic division

Growth of Nails The bulk of the nail is produced by _______ of the epidermal cells of the nail matrix at the nail root. New cell push older cells distally. The nail bed adds additional material to the nail body as it grows over the nail bed. Fingernail grow 0.1-.2 mm/day (about 6 mm/month); toenails grow at a slower rate.

Lanugo Villus Terminal

Hair _______: downy fur usually lost before birth _______: ("peach-fuzz")- stronger, fine hair with little pigmentation that replaces the lanugo. Covers most of the body surface ________: course, pigmented hair that replaces villus on scalp, eyebrows, axillary and pubic regions (and chest & extremities of males) Irritation can cause changes to vellus hair to terminal hair (shaving legs, bricklayers shoulders)

Anagen Catalan Telogen

Hair Growth Cycle ________ - active phase - hair grows about 0.33mm/day or about 11 cm/year Scalp hairs continue to grow for 6 to 10 years; eyelashes are only active for a few months _______- regressivel phase - the epithelial root sheath shrinks and separates from connective-tissue root sheath. The hair is termed a club hair and is destined to be shed. _______ - Resting phase which last about 100 days. When a new growth cycle starts (anagen) a new hair is produced and pushes the club hair out of the shaft. Average loss of 50-100 hairs/day

Age Air Bubbles

Hair color is due to pigments of yellow, brown, or red color. Pigmentation decrease with _____ and hair lightens. White hairs result from loss of pigment and the presence of ______ in the shaft of hair. Hair colorants must penetrate the hair cortex and medulla, in doing so they damage the cuticle and weaken the hair and dehydrating it.

Hair papilla Hair matrix

Hair growth The _______ is a mound of dermal tissue (similar to dermal papillae) The _______ (layer epidermal tissue covering the hair papilla) produces the hair keratinocytes Cells become organized into concentric layers to for the hair: medulla, cortex, and cuticle Melanocytes near the hair matrix transfer pigments to the hair cells Continuous cycles of mitosis pushes the hair cells up and out of skin

Medulla Cortex Cuticle

Hair shaft is composed of 3 concentric rings of keratinized cells: The hair cells are keratinocytes, that produce hard keratin. Hard keratin which is found in hair and nails is more durable than soft keratin of skin and does not allow individual cells to flake off. Core of the hair contains some soft keratin as well. _______ - central core that consists of large cells and air spaces _______ - consist of several layers of flattened cells ________ - outer layer composed of a single layer of overlapping cells; provides strength and compresses the inner layers.

Embryonic epidermis Skin surface

Integumentary Accessory Structures: Hair follicles, sebaceous glands, sweat glands, and nails: All are derived from _________ All are located in dermis but project through the _______

Parallel Across

Lines of Cleavage Collagen and elastic fibers in the dermis: are arranged in parallel bundles resist force in a specific direction. Lines of cleavage establish important patterns: a ______ cut gape less, heals well a cut _____ (right angle) pulls open and is more likely to scar

Surface Dermal papillae Sclera

Lips and nail beds show changes in hemoglobin saturation best because the dermis is closest to the ______ (thinner epidermis) Caucasians with very little pigment have a pinkish hue to their skin because of the reflection of oxygenated hemoglobin through the capillary beds in the _________. Jaundice can be distinguished from excess carotene consumption by examining the whites of the eyes. Jaundice will cause yellowing of the ______, but carotenemia will not.

Melanosomes Activity

Melanocytes release melanin in packets called ______ which are ingested by surrounding keratinocytes. The number of melanocytes to germinative cells varies in different regions of the body. The cheeks, nipples, forehead and genital region have a higher concentration than other regions of the body. Individuals of different skin color do not differ in the number of melanocytes, rather the ______ of the melanocytes is greater in darker skin individuals.

Ceruminous Mammary glands

Modified Apocrine Sweat Glands _______ glands in ear canal are modified apocrine sweat gland that produce a secretion that mixes with sebum from nearby sebaceous gland to make cerumen (ear wax) _________ are considered modified sweat glands

Tretinoin

Much of the damaging affects of UV radiation of the skin is due activation of an enzyme that degrades collagen and other dermal components leading to loss of dermal elasticity and strength. _______, a derivative of Vit A, inhibits these enzymes and slows the aging process

Modified epidermis Nail Body Hyponychium Nail root

Nail ________ - thick sheets of hard keratin Nails protect the dorsal surface of the digits and prevent distortion when the end of the digit is compressed. Nail Structure: Body and Root ________: visible plate of hard keratin ________: free margin of the nail body ________: proximal end of the nail embedded in the skin; extends several mm into the skin pass the cuticle (eponychium)

Stratum spinosum Stratum basale

Only the cells in _____ & _______ receive adequate nourishment via diffusion from the dermis.

Beta carotene Hemoglobin Cyanosis

Other pigments that alter skin color _______ (group of yellowish pigments from food) that tends to accumulate in epidermal cells & fatty tissues of the dermis and hypodermis- can cause yellow colouration of the skin in young kids/infants. _________—color changes also occur as a result of changes in blood flow Redder skin color when blood flow to skin increases; paling when blood flow is decreased ________ —bluish color caused by darkening of hemoglobin when it loses oxygen and gains carbon dioxide (blue lips)- most significant where skin is thinnest ie//lips

Elastin and collagen Scar tissue

Over stretching of the skin will cause breakdown of the _____ & ______ fibers and the skin will lose its resiliency. Excessive stretching will cause the breakdown of the dermal tissue that will be replaced by _____ (striae or stretch marks). Retention of fluids by the dermal collagen is used to access hydration status in patients. The collagen fibers normally retain moisture, but when dehydration occurs the water is moved back into capillary beds. When the skin is pinch - it remains tented in a person who is dehydrated, but a hydrated individual the skin will flatten out immediately.

Puberty Whitehead Blackhead Pimple Seborrhea

Sebaceous glands are relatively inactive until _____. ______ is an accumulation of sebum within a blocked duct. ______ occurs when oxidation causes the sebum in the blocked duct to turn black. An infected sebaceous gland is a ______. Staphylococcus is the most common bacterial infection resulting in pimples ______ is a condition associated with overactive secretion of sebaceous glands.

Eumelanin Pheomelanin

Skin Color Melanin product of melanocytes - only pigment produced in the skin. ______—group of dark brown (almost black) melanins ______—group of reddish and orange melanins

Metals

Some materials can penetrate skin: Lipid-soluble compounds and organic solvents Salts of heavy _____ like mercury and lead

Keratin

Structure of Hair Dead tissue composed of three concentric layers of cells containing hard _______: Medulla Cortex Cuticle

Dermicidin Cools

Sweat Composition: Hypotonic filtrate of blood composed of 99% water Salts (mostly NaCl) Antibodies Metabolic waste (urea, uric acid, ammonia) ______ - antimicrobial peptide May contain small amounts of ingested drugs Apocrine secretion also contains small amounts of fat and protein. Bacterial action changes these components into body odor. Function of Sweat: _______ skin Excretes water and electrolytes Flushes microorganisms and harmful chemicals from skin

Hair follicle

Temporary increase in hair loss can occur with disease dietary deficiency, drug, radiation, excess vit A., stress, high fever and hormonal factors. Hair will regrow if the condition is corrected as long as the _______ is intact.

Arrector pili muscles

The Hair Follicle Base is deep in dermis Dense connective-tissue sheath derived from the dermis Sebaceous gland ________ - causes the hair to stand up and produces "goosebumps" Surrounded by sensory nerves (root hair plexus)

Stratum spinosum

This is one of the 5 layers. This is also known as the spiny layer - it is several cell layers thick. In prepared slides the cytoplasm shrinks giving cells spiney appearance due to the desmosome attachment between keratinocytes Few of the keratinocytes cells remain mitotically active Epidermal dendritic cells are also found in this area.

hair papilla

The _______ is equivalent to the dermal papillae in the rest of skin. The walls of the hair follicle is made up of a dermal layer (CT root sheath) and epidermal component (epithelial root sheath). The epithelial root sheath tapers to a single layer of epithelial cells covering the hair papilla.

Fibrous elements polysaccharides Dense fibrous Dermal tissue Dermal ridges

The junction of the dermis and epidermis is normally well glued together by _______ & _________ which can act as a barrier to movement of substances. Excessive friction can cause the junction to separate and cause blister formation. The _____ connective tissue gives the skin strength and flexibility. This is the layer that becomes leather when animal skin is tanned. The _____ is also the attachment point for smooth and skeletal muscles that move the skin of the face and scalp. On the palms and soles large mounds called ______ are found. Epidermal ridges overlie the dermal ridges and produce the swirls and whorls that are associated with fingerprints. Sweat gland pores open upon the crest of the epidermal ridges causing the film of moisture to be left behind when "leaving fingerprints".

7 Dermis Areolar Dense Fibrous Hypodermis

The skin makes up about _____% of the total body mass; 4 to 5 kilograms in an adult; about 1.2 to 2.2 square meters The ______ makes up the bulk of the skin thickness. It is composed of superficial ______ CT layer and deeper _____ CT layer. The deeper layer makes up 80% of the dermis. ______ consist mostly of adipose tissue - provides a loose anchor to underlying tissue, allows for mobility of the skin and also acts as a layer of cushioning and insulation.

Hypodermis Reticular

The subcutaneous layer or _______: Lies below the dermis; helps anchor the dermis to underlying structures Connected to the _____ layer of the dermis by connective tissue fibers Consists of elastic areolar and adipose tissues that provide cushioning and insulation Allows separate movement of skin and underlying tissues Site for SQ (subcutaneous) injections (few large vessel & no vital structures).

Stratum lucidum Stratum basale Stratum granulosum

There are 5 microscopic layers of the epidermis which include: Stratum basale Stratum spinosum Stratum granulosum Stratum lucidum -thick skin Stratum corneum In thin skin, not only is the ____ absent the other layers are all thinner. The ______ is sometimes referred to as the Stratum germinativum - single row of mitotically active cells **By the time you get to the _____ the cells are no longer mitotically active and these cells start to die. They accumulate keratin.

Melanocytes

These are pigment (melanin) producing cells. Melanin is transferred to keratinocytes where it accumulates over the nucleus to provide protection against UV radiation Moles (nevus) is a localized area where melanocytes have accumulated.

Epidermal Dendritic Cells

These cells (A.K.A Langerhans' cells) have immune function (antigen presenting cells) and are produced in bone marrow, but migrate to the deeper layers of the epidermis

Tactile Cells

These cells (A.K.A. Merkel cells) are specialized sensory receptors for touch sensation

Keratinocytes

These type of cells are connected by desmosome and produce keratin (fibrous protein). Keratin is a fibrous protein that is responsible for many of the protective properties of skin. Constitutes 90% of cells in the epidermis; continually produced by basal layer of the epidermis; eroded away from surface (epidermis is regenerated every 25-35 days to migrate up + 2 weeks on surface)

Dermal papilla

Thick skin has large dermal ridges (and corresponding epidermal ridges) that form the foundation for fingerprints. _______ are the egg-carton bumps that help entwine the epidermis with the dermis (keeps the two layers from sliding across each other). Found in both thick and thin skin. ie//Checking temperature by feeling the forehead is done with the back of the hand instead of the palm because the skin is thinner on the back of the hand.

Stratum basale or germinativum

This is one of the 5 layers. It is a single layer of columnar cells. Consists mostly of stem cells, that are constantly regenerating new keratinocytes 10-25% cells are melanocytes and is attached to basal lamina by hemidesmosomes that form strong bonds between epidermis and dermis.

Stratum granulosum

This is one of the 5 layers. This is the granular layer. It is 3-5 cell layers thick. Keratinocytes become thin and flattened as organelles disintegrate and cell cytosol dehydrates Accummulation of keratin and keratohyalin granules starts to destroy the cells ability to function, but adds protection against penetration and abrasion. Accumulation of glycolipid granules that when released when the cells dies will slow water loss across the epidermis

Stratum lucidum

This is one of the 5 layers. It is a clear layer but it is only present in thick skin. Dead cells that are flattened, densely packed & filled with keratin

Stratum corneum

This is one of the 5 layers. It is the horny layer and the thickest layer of the epidermis The most superficial 20-30 cell layers of squashed, scale-like cells. These dead cells are referred to as cornified cells, and are shed continuously (e.g. dandruff). They protect against abrasion. Relatively dry and water resistant (but not waterproof) Secretions of sebaceous gland coats the skin with lipids increasing water resistance