Integumentary System Flashcards by Matthew Sarimos

Integumentary System

► Consists of:

Skin
Hair
Nails
Sweat Glands
Sebaceous (oil) Glands

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Superficial layer
-Consists of stratified squamous epithelial tissue and is avascular

Epidermis

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Underlies epidermis
-Mostly fibrous connective tissue, vascular

Dermis

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(Subcutaneous tissue)

-Subcutaneous layer deep to skin

-Not part of skin but shares some functions

-Mostly adipose tissue that absorbs shock and insulates

-anchors skin to underlying structures: mostly muscles

Hypodermis

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_______ - consists mostly of keratinized stratified squamous epithelium

Epidermis

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Produce fibrous keratin (protein that gives skin its protective properties) Major cells of epidermis, Tightly connected by desmosomes Millions slough off every day

Keratinocytes

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▸ Four cell types found in epidermis:

▸ Keratinocytes
▸ Melanocytes
▸ Dendritic (langerhans) cells
▸ Tactile (Merkel) cells

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▸ Five Layers of Epidermis Skin
(Only in thick skin)

Stratum Basale
Stratum Spinosum
Stratum Granulosum
Stratum lucidum
Stratum Corneum

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Spider-shaped cells located in deepest epidermis Produce pigment melanin, which is packaged into melanosomes

Melanosomes are transferred to keratinocytes, where they protect nucleus from UV damage

Melanocytes

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Star-shaped macrophages that patrol deep epidermis

Are key activators of immune system

Dendritic (langerhans) cells

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Sensory receptors that sense touch?

Tactile (Merkel) cells

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Deepest of all epidermal layers (base layer)

• Layer that is firmly attached to dermis

• Consists of a single row of stem cells that actively divide (mitotic), producing two daughter cells each time

One daughter cell journeys from basal layer to surface, taking 25-45 days to reach surface

Other daughter cell remains in stratum basale as stem cell

Layer also known as STRATUM GERMINATIVUM bec. of active mitosis

10 25% of layer also composed of melanocytes

Stratum Basale (basal layer)

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• Several Cell layers thick

• Cells contain weblike system of intermediate prekeratin filaments attached to desmosomes

• Allows them to resist tension and pulling

• Keratinocytes in this layer appear spikey, so they are called prickle cells

• Scattered among keratinocytes are abundant melanosomes and dendritic cells

Stratum Spinosum (prickly layer)

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• Four to six cells thick, but cells are flattened, so layer is thin

• Cell appearance changes; transitional stratum

Cells flatten, nuclei and organelles disintegrate

• Keratinization begins

Cells accumulate keratohyalin granules that help form keratin fibers in upper layers

Cells also accumulate lamellar granules, a water- resistant glycolipid that slows water loss Cells above this layer die

Too far from dermal capillaries to survive

Stratum Granulosum (granular layer)

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• Found only in thick skin

• Consists of thin, translucent band of two to three rows of clear, flat, dead keratinocytes

• Lies superficial to the stratum granulosum

Stratum lucidum (clear layer)

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• 20-30 rows of flat, anucleated, keratinized dead cells

• Accounts for three-quarters of epidermal thickness

• Though dead, cells still function to:

• Protect deeper cells from the environment

• Prevent water loss

• Protect from abrasion and penetration Act as a barrier against biological, chemical, and physical assaults

Stratum Corneum (horny layer)

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Strong, flexible connective tissue

▸ Cells include fibroblasts, macrophages, and occasionally mast cells and white blood cells

▸ Fibers in matrix bind body together

• Makes up the “hide” that is used to make leather

► Contains nerves, blood vessels, and lymphatic vessels

► Contains epidermal hair follicles, oil glands, and sweat glands

► Two layers
• Papillary
• Reticular

Dermis

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► Superficial layer of areolar connective tissue consisting of loose, interlacing collagen and elastic fibers and blood vessels

► Loose fibers allow phagocytes to patrol for microorganisms

Papillary Layer

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_________ : Superficial region of dermis that sends finger like projections up into epidermis

• Projections contains capillary loops, free nerve endings, and touch receptors (tactile corpuscles, also called Meissner’s corpuscles)

Dermal Papillae

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________ are small projections that provide blood supply to the epidermis.

Dermal papillae

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Papillary Layer

► In thick skin, dermal papillae lie on top of dermal ridges, which give rise to epidermal ridges

Collectively ridges are called _________.

•Enhance gripping ability
•Contribute to sense of touch
•Sweat pores in ridges leave unique fingerprint pattern

friction ridges

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_________ in reticular layer are caused by many collagen fibers running parallel to skin surface

• Externally invisible
• Important to surgeons because incisions parallel to cleavage lines heal more readily

Cleavage (tension) lines

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Reticular Layer (cont.)

► _______ of reticular layers are dermal folds at or near joints

• Dermis is tightly secured to deeper structures

• Skin’s inability to slide easily for joint movement causes deep creases

• Visible on hands, wrists, fingers, soles, toes

Flexure lines

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Clinical - Homeostatic Imbalance

▸ Extreme stretching of skin can cause dermal tears, leaving silvery white scars called ______.

• Also known as “stretch marks”

Striae

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▸ Acute, short-term traumas to skin can cause ______, fluid-filled pockets that separate epidermal and dermal layers

blisters

Give the 3 pigments contributes the skin color

- Melanin - Carotene - Hemoglobin

• Only pigment made in skin; made by melanocytes Packaged into melanosomes that are sent to keratinocytes to shield DNA from sunlight Sun exposure stimulates melanin production • Two forms; reddish yellow to brownish black • All humans have same number of keratinocytes, so color differences are due to amount and form of melanin Freckles and pigmented moles are local accumulations of melanin

MELANIN

• Yellow to orange pigment Most obvious in palms and soles • Accumulates in stratum corneum and hypodermis • Can be converted to vitamin A for vision and epidermal health

Carotene

Pinkish hue of fair skin is due to lower levels of melanin • Skin of Caucasians is more transparent, so color of hemoglobin shows through

Hemoglobin

Just Notes - no need to answer ▸ Excessive sun exposure damages skin • Elastic fibers clump, causing skin to become leathery • Can depress immune system and cause alterations in DNA that may lead to skin cancer • UV light destroys folic acid Necessary for DNA synthesis, so insufficient folic acid is especially dangerous for developing embryos • Photosensitivity is increased reaction to sun Some drugs (e.g., antibiotics, antihistamines) and perfumes cause photosensitivity, leading to skin rashes

Clinical - Homeostatic Imbalance

Alterations in skin color can indicate disease Blue skin color: low oxygenation of hemoglobin

Cyanosis

Alterations in skin color can indicate disease • (redness) Fever, hypertension, inflammation, allergy

Erythema

• (blanching or pale color) Anemia, low blood pressure, fear, anger

Pallor

• (yellow cast) Liver disorders

Jaundice

Alterations in skin color can indicate disease (cont.) • Inadequate steroid hormones (example:Addison's disease)

Bronzing

• (black-and-blue marks) Clotted blood beneath skinAlterations in skin color can indicate disease (cont.)

Bruises

▸ Consists of dead keratinized cells ► None located on palms, soles, lips, nipples, and portions of external genitalia

Hair

► what is the Functions of Hair?

•Warn of insects on skin •Hair on head guards against physical trauma • Protect from heat loss • Shield skin from sunlight

Hairs (also called ____): flexible strands of dead, keratinized cells ► Produced by hair follicles ► Contains hard keratin, not like soft keratin found in skin • Hard keratin is tougher and more durable, and cells do not flake off ► Regions: Shaft: area that extends above scalp, where keratinization is complete • Root: area within scalp, where keratinization is still going on

pili

______ is considered a sensory touch receptor.

Hair

Structure of a Hair (cont.) ► Hair pigments are made by __________ in hair follicles • Combinations of different melanins (yellow, rust, brown, black) create all the hair colors Red hairs has additional Pheomelanin pigment Gray/white hair results when melanin production decreases in air bubbles replace melanin in shaft

melanocytes

Structure of a Hair follicle ▸ Extends from epidermal surface to dermis ► ________: expanded area at deep end of follicle ► ________: (or root hair plexus): sensory nerve endings that wrap around bulb ► _________: actively dividing area of bulb that produces hair cells • As matrix makes new cells, it pushes older ones upward

- HAIR BULB - Hair follicle receptor - Hair Matrix

________ : small band of smooth muscle attached to follicle • Responsible for "goose bumps"

Arrector pili

• Dermal tissue containing a knot of capillaries that supplies nutrients to growing hair

Hair Papilla

Types and Growth of Hair ________: pale, fine body hair of children and adult females

Vellus hair

_______: Coarse long hair • Found on scalp and eyebrows • At puberty •Appear in axillary and pubic regions of both sexes • Also on face and neck of males ► Nutrition and hormones affect hair growth ► Follicles cycle between active and regressive phases • Average 2.25 mm growth per week Lose 90 scalp hairs daily

Terminal hair

Clinical - Homeostatic Imbalance › In women, ovaries and adrenal glands produce small amounts of androgens (male sex hormones), but tumors on these organs can cause abnormally large amounts of androgens ► Can result in excessive hairiness, called _______, as well as other signs of masculinization ▸ Treatment is surgical removal of tumors

Hirsutism

Hair Thinning and Baldness ▸ ________: hair thinning in both sexes after 40 ► True (frank) _______ • Genetically determined and sex-influenced condition • Male pattern baldness caused by follicular response to DHT (dihydrotestosterone -plays ang important role in sexual development of male)

- Alopecia - Baldness

Hair thinning can be induced by several factors:

• Acutely high fever • Surgery • Severe emotional trauma • Certain drugs (such as antidepressants, blood thinners, steroids, and chemotherapeutic drugs) • Protein-deficient diets • Alopecia areata: immune system attacks follicles • Some hair loss is reversible, but others (such as from burns or radiation) are permanent

▸ Scale-like modifications of epidermis that contain hard keratin ▸ Act as a protective cover for distal, dorsal surface of fingers and toes ► Consist of free edge, nail plate, and root

Nail

________: thickened portion of bed responsible for nail growth

Nail Matrix

________ is epidermis underneath keratinized nail plate

Nail bed

________: skin folds that overlap border of nail

Nail folds

________: nail fold that projects onto surface of nail body Also called cuticle

Eponychium

________: area under free edge of plate that accumulates dirt ▸ Nails normally appear pink because of underlying capillaries ▸ Abnormal color or shape can be an indicator of disease

Hyponychium

________: thickened nail matrix, appears white

Lunule

Also called sudoriferous glands

Sweat Glands

Sweat Glands Also called

sudoriferous glands

All skin surfaces except nipples and parts of external genitalia contain sweat glands • About __ million per person

what is the two main types of Sweat glands?

- Eccrine - Apocrine

The sweat glands Contain ______ cells, It Contract upon nervous system stimulation to force sweat into ducts.

myoepithelial

► Most numerous type ▸ Abundant on palms, soles, and forehead ▸ Ducts connect to pores ► Function in thermoregulation • Regulated by symphatetic nervous system ► Their secretion is sweat • 99% water, salts, vitamin C, antibodies, dermcidin (microbe-killing peptide), metabolic wastes

Eccrine (Merocrine) Sweat Glands

► Confined to axillary and anogenital areas ▸ Secrete viscous milky or yellowish sweat that contains fatty substances and proteins • Bacteria break down sweat, leading to body odor ▸ Larger than eccrine sweat glands with ducts emptying into hair follicles ► Begin functioning at puberty Function unknown but may act as sexual scent gland

Apocrine Sweat Glands

› Modified apocrine glands ________: Lining of external ear canal secrete cerumen (earwax) ________: secrete milk

- Ceruminous Glands - Mammary glands

► Widely distributed, except for thick skin of palms and soles ► Most develop from hair follicles and secrete into hair folliclles ► Relatively inactive until puberty Stimulated by hormones, especially androgens ▸ Secrete Sebum Oily holocrine secretion Bactericidal (bacteria-killing) properties Softens hair and skin

Sebaceous (Oil) Glands

_________ are blocked sebaceous glands. If secretion oxidizes, the whitehead becomes a blackhead.

Whiteheads

whitehead are blocked sebaceous glands. If secretion oxidizes, the whitehead becomes a _________.

blackhead

_______ is usually an infectious inflammation of the sebaceous glands, resulting in pimples(pustules)

Acne

▸ Overactive sebaceous glands in infants can lead to seborrhea, known as "_______" • Begins as pink, raised lesions on scalp that turn yellow/brown and flake off

cradle cap

▸ Overactive sebaceous glands in infants can lead to ________, known as "cradle cap" • Begins as pink, raised lesions on scalp that turn yellow/brown and flake off

seborrhea

Functions of Skin?

► Skin is first and foremost a barrier ► Its main functions include: • Protection • Body temperature regulation • Cutaneous sensations • Metabolic Functions • Blood reservoir • Excretion of wastes

Protection ► Skin is exposed to microorganisms, abrasions, temperature extremes, and harmful chemicals ► Constitutes 3 barriers:

• Chemical Barrier • Physical Barrier • Biological Barrier

• Skin secretes many chemicals, such as Sweat, which contains antimicrobial proteins, such as dermcidin. •Sebum also contains bactericidal substances • Cells also secrete antimicrobial defensins

► Chemical Barrier

_________: low pH of skin retards bacterial multiplication

▸ Acid Mantle

▸ ________ provides a chemical barrier against UV radiation damage

Melanin

• Flat, dead, keratinized cells of stratum corneum, surrounded by glycolipids, block most water and water-soluble substances - Some chemicals have limited penetration of skin: • Lipid-soluble substances • Organic solvents • Salts of heavy metals • Some drugs (Nitroglycerin) • Drug Agents (enhancers that help carry other drugs across skin)

Physical barrier

• Epidermis contains phagocytic cells Dendritic cells of epidermis engulf foreign antigens (invaders) and present to white blood cells, activating the immune response • Dermis contains macrophages Macrophages also activate immune system by presenting foreign antigens to WBC

Biological Barriers

Under normal, resting body temperature, sweat glands produce about 500 ml/day of unnoticeable sweat, Called ____________.

Insensible perspiration

► If body temperature rises, dilation of dermal vessels can increase sweat gland activity to produce 12 L (3 gallons) of noticeable sweat • Called _________; designed to cool body

Sensible perspiration

Metabolic Functions?

▸ Skin can synthesize vitamin D needed for calcium absorption in intestine ► Chemicals from keratinocytes can disarm some carcinogens ▸ Keratinocytes can activate some hormones • Example: convert cortisone into hydrocortisone ▸ Skin makes collagenase, which aids in natural turnover of collagen to prevent wrinkles

► Skin can hold up to 5% of the body's total blood volume ► Skin vessels can be constricted to shunt blood to other organs, such as an exercising muscle

Blood reservoir

► Skin can secrete limited amounts of nitrogenous wastes, such as ammonia, urea, and uric acid ▸ Sweating can cause salt and water loss

Excretion

▸ Skin can develop over 1000 different conditions and ailments ▸ Many internal diseases reveal themselves on skin ► Most common disorders are infections ► Less common, but more damaging, are: Skin cancer • Burns

Skin Cancer and Burns

► Risk factors • Overexposure to UV radiation • Frequent irritation of skin › Some skin lotions contain enzymes that can repair damaged DNA

Skin Cancer

Give the 3 Major types of skin cancer

• Basal cell Carcinoma • Squamous Cell Carcinoma •Melanoma

• Least malignant and most common • Stratum basale cells proliferate and slowly invade dermis and hypodermis • Cured by surgical excision in 99% of cases

► Basal Cell Carcinoma

▸ Second most common type; can metastasize ► Involves keratinocytes of stratum spinosum ▸ Usually is a scaly reddened papule on scalp, ears, lower lip, or hands ► Good prognosis if treated by radiation therapy or removed surgically

▸ Squamous cell carcinoma

Cancer of melanocytes; is most dangerous type because it is highly metastatic and resistant to chemotherapy Treated by wide surgical excision accompanied by immunotherapy • Key to survival is early detection: ABCD rule • A. Asymetry; the two sides of the pigmented area do not match B. border irregularity; exhibits indentations C. color; contains several colors (black, brown, tan, sometimes red or blue) D. diameter; larger than 6 mm (size of pencil eraser)

Melanoma

▸ Tissue damage caused by heat, electricity, radiation, or certain chemicals Damage caused by denaturation of proteins, which destroy cells > Immediate threat is dehydration and electrolyte imbalance Leads to renal shutdown and circulatory shock ► To evaluate burns, the Rule of Nines is used ▸ Body is broken into 11 sections, w/ each section representing 9% of body surface (except genitals which is 1%) ▸ Used to estimate volume of fluid loss

Burns

*Rules of Nines for Burns* Body Surface Area = Entire Head & Nick = Entire Right Am = Entire Left Arm = Entre Trunk = Groin = Entire Right Leg = Entire Left Leg =

9% 9% 9% 36% 1% 18% 18%

• Epidermal damage only -Localized redness, edema (swelling), and pain

• First-degree

• Epidermal and upper dermal damage - Blisters appear - First- and second-degree burns are referred to as partial- thickness burns because only the epidermis and upper dermis are involved

Second-degree

Entire thickness of skin involved (referred to as full- thickness burns) Skin color turns gray-white, cherry red, or blackened No edema is seen and area is not painful because nerve endings are destroyed Skin grafting usually necessary

Third-degree

Burns are considered critical if: • >___% of body has second-degree burns • >___% of body has third-degree burns • Face, hands, or feet bear third-degree burns

25% 10%

› Treatment in Burns includes:

• Debridement (removal) of burned skin • Antibiotics • Temporary covering • Skin grafts