A&P Chapter 5: Integumentary System

Hirsutism

Excessive body hair / body hair in areas that are usually not hairy. Caused by tumor in adrenal glands, testes, or ovaries that produces an excessive amount of androgens.

Hair growth cycle- the 3 stages

Growth stage Regression stage Resting stage

White hair

Results from lack of melanin and accumulation of air bubbles in shaft

What makes up the system?

Skin, hair, oil and sweat glands, nails and sensory receptors

Arrector pilli muscle

Smooth muscle that contracts with fear or cold

Tatooing

pigment injected into dermis (does not shed)

Jaundice

-Due to buildup of yellow bilirubin in skin (liver disease) -Yellowish appearance to skin and whites of eyes

Hair colour

-Due primarily to amount and type of melanin in its keratinized cells -Melanin is synthesized by melanocytes scattered in matrix of the bulb and passes into cells of the cortex and medulla of the hair

Deep wound healing phase 1

*Inflammatory phase* - a blood clot forms in wound and loosely unites the wound edges. Involves inflammation, a vascular cellular response that helps eliminate microbes, foreign material, dying tissue. Vasodilation and increased permeability of blood vessels associated with inflammation enhance delivery of helpful cells (phagocytic white blood cells (neutrophils); monocytes (develop into macrophages); mesenchymal cells (develop into fibroblasts)

Deep wound healing phase 4

*Maturation phase* - the scab sloughs off once epidermis has been restored to normal thickness. Collagen fibers become more organized, fibroblasts decrease in number, blood vessels are restored to normal.

Deep wound healing phase 2

*Migratory phase* - the clot becomes a scab and epithelial cells migrate beneath the scab to bridge the wound. Fibroblastst migrate along fibrin threads and begin synthesizing scart issue (collagen fibers and glycoproteins) and damaged blood vessels begin to regrow. -Tissue filling the wound is called *granulation tissue*

Deep wound healing phase 3

*Proliferative phase* - characterized by extensive growth of epithelial cells beneath the scab, deposition by fibroblasts of collagen fibers in random patterns, and continued growth of blood vessels.

Epidermis -Composed of ____________ ________________ ________________ _________________ -Four principal types of cells: _______________, __________________, ___________________ ________________ (_______________ ______________) + _________________ __________________ _________________ (_______________ _________________)

- Composed of kearatinized stratified squamous epithelium -Four principal types of cells: keratinocytes, melanocytes, intraepidermal macrophages (langerhans cells), and tactile epithelial cells (Merkel cells)

Hair Anatomy

-*Shaft* = superficial portion of hair that projects above sfc of skin -*Root* = deep to shaft, penetrates into dermis, sometimes sub-Q -Surrounding root = *hair follicle* (external root sheath + internal root sheath produced by matrix) -Around hair follicle = *dermal root sheath*, dense dermis -base of each hair follicle and surrounding dermal root sheath = onion-shaped structure called the *bulb* -structure that houses each hair follicle = *papillae of the hair*, contains aereolar CT + many blood vessels to nourish growing hair follicle -Bulb also contains germinal layer of cells called the *hair matirx* that arises from stratum basale (responsible for growth of hairs)

Types of sweat (4)

-*Thermoregulatory sweating* (cools body; as sweat evaporates large qty of heat energy leave body sfc) -small role in excretion of wastes such as urea, uric acid, ammonia from body -*Insensible perspiration* = sweat that evaporates from skin before it is perceived -*Sensible perspiration* = sweat that is excreted in larger amounts, seen as moisture on skin -*Emotional sweating* = in response to emotional stress such as fear or embarrassment

Skin in adults: -Surface area -Weight -Thickness

-2 meters squared -4.5-5kg (7% of total body weight) -0.5 mm to 4.0 mm thick (usually 1-2 mm)

Stratum Corneum -_____ - ______ layers of ____________ ______________ ____________ (can range in thickness from a ________ dead cells in thin skin to ____ or more cell layers in thick skin) -They are __________, ___________ _____________-membrane enclosed packages of ______________ (no longer have ____________ or ______________; _____________ product of differentiation of keratinocytes) -Cells continuously ______________ and replaced by cells from ______________ strata -______________ deeper layers from _____________ and _____________

-25-30 layers of flattened dead keratinocyes (but can range in thickness from a few dead cells in thin skin to 50 or more cell layers in thick skin) -Thin, flat plasma-membrane enclosed packages of keratin (no longer have organelles or nucleus; final product of differentiation of keratinocytes) -Cells continually shed and replaced by cells from deeper strata. -Protects deeper layers from injury and microbes

Sudiferous glands -How many? -What are they? -Release ____________ into _______________ ______________ or onto _____________ _____________ through _____________ -What are the two main types?

-3-4 million *suderifrous (sweat) glands* -Release perspiration into hair follicles or onto skin surface through pores -Divided into two main types: eccrine and apocrine, based on structure and type of secretion

Excretion and abosorption

-400 mL water evaporates through skin daily + 200 mL water lost via sweat (if you're sedentary) -Excretion of small amounts of salts, CO2, urea and ammonia -Water soluble substances barely absorb via skin, but lipid-soluble materials DO penetrate the skin (vitamins A, D, E, K, drugs, gasses O2 and CO2) -Toxic materials can be absorbed via skin including acetone, carbon tetrachloride (dry-cleaning fluid), salts of heavy metals like lead, mercury, and arsenic, poison ivy & poison oak substances

Melanocyets -_________% of epidermal cells -Produce a ______________ called _______________ -Their long, slender _______________ extend between ____________________ and transfer _______________ granules to them -Once inside the ____________________ the __________________ granules cluster to form a _______________ __________________ over nucleus on side toward __________________ _________________, shielding _______________ __________________ from UV damage. -_________________ contributes to skin __________________ and ______________ damaging UV light

-8% of epidermal cells -Produce pigment called *melanin* -Their long, slender projections extend between keratinocytes and transfer melanin granules to them. -Once inside the keratinocyte the melanin granules cluster to form a protective veil over nucleus on side toward skin surface, shielding nuclear DNA from UV damage -Melanin contributes to skin colour and absorbs damaging UV light.

Keratinocytes -___________ % epidermal cells -Arranged in _____-_____ layers -Produce a protein called _________________ (what does it do?) -Produce _____________ ______________ which release ____________-________________ _________________ (helps mitigate ________________ entry and loss)

-90% of epidermal cells -Arranged in 4-5 layers -Produce a protein called *keratin* (tough, fibrous protein that protects skin and underlying tissue from heat, microbes, chemicals) -Produce *lamellar granules* which release water-repellent sealant (helps mitigate water entry and loss)

Epidermal wound healing

-Abrasions, minor burns 1. Basal cells of epidermis surrounding wound break contact with basement membrane 2. The cells enlarge and migrate across the wound (migrate as a sheet until advancing cells from opposite sides of wound meet) 3. When epidermal cells encounter each other, they stop migrating due to cellular response called *contact inhibition* 4. As basal epidermal cells migrate they secrete a hormone called *epidermal growth factor* which stimulates basal stem cells to divide and replace the ones that have moved into the wound. 5. The relocated basal epidermal cells divide to build new strata, thickening the new epidermis

Resting stage

-After regression stage, hair follicle enters resting stage, after which a new growth cycle begins. -Scalp hair is in resting stage for about 3 months

What do dermal papillae contain? -All contain ____________ ___________ -Some contain ____________ of ___________(______________ ____________) nn endings sensitive to ___________ -Some contain free ____________ _______________ (___________- initiate signals of ________________, _____________, ______________, _____________, _____________)

-All contain capillary loops -Some contain corpuscles of touch (Meissner corpuscles) nn endings sensitive to touch -Some contain free nerve endings (dendrites - initiate signals of warmth, coolness, pain, tickle, itch)

Melanin -___________ of melanin causes skin colour to vary from __________ ____________ to ______________-_____________ to ____________ -2 kinds of melanin? -# of _____________ same in everyone, but amount of ______________ ______________ produce and transfer to ____________ varies -_______________ synthesize _____________ from ____________ ___________ ______________ via enzyme ___________. Occurs in ____________ called _____________ -Exposure to ___________ ___________ increases ____________ activity in ______________, increasing ____________ production (protects body from ____________ _______________ ________________)

-Amount of melanin causes skin colour to vary from pale yellow to reddish-brown to black -2 kinds of melanin - yellow to red (pheomelanin) + brown to black (eumelanin) - most apparent in hair -# melanocytes same in everyone, but amount of pigment melanocytes produce and transfer to keratinocytes varies. -Melanocytes synthesize melanin from amino acid tyrosine via enzyme tyrosinase. Occurs in organelle called melanosome -Exposure to UV light increases enzymatic activity in melanosomes, increasing melanin production (protects body from further UV radiation)

Thick (hairless) skin

-Areas such as palms and soles -0.6-4.5 mm thick, mostly due to thicker stratum corneum -Stratum lucidum present; thicker strata spinosum and corneum -Epidermal ridges present due to well-developed and more numerous dermal papillae organized in parallel rows -Hair follicles and arrector pilli mm absent -Sebaceous glands absent -Sudiferous glands more numerous -Sensory receptors denser

Reticular region of the dermis -Attached to ________________ layer -Bundles of _____________ ________________ fibers, scattered ______________, various ________________ cells (like _____________) -Some _____________ cells at ________________ part -Contains some ________________ ____________, ______________ and _______________ glands

-Attached to subcutaneous layer -Bundles of thick collagen fibers, scattered fibroblasts, various wandering cells (like macrophages) -Some adipose cells at deepest part -Contains hair follicles, sebaceous glands, sudiferous glands

Growth stage

-Cells of hair matrix divide to produce length -while cells of hair are pushed upward, become keratanized and die -Scalp hair is in the growth stage for 2-6 years

Regression stage

-Cells of hair matrix stop dividing, hair follicle atrophies, hair stops growing -Scalp hair is in regression stage for 2-3 weeks

Psoriasis -______________ _____________ skin disorder in which ________________ divide and move more ___________ than normal from stratum _________________ to stratum ___________________ and are shed _____________ (as little as _________-_________ days) -_____________ keratinocytes make ______________ keratin (what is seen at sfc of skin?) -Most often found where (3)

-Common chronic skin disorder in which keratinocytes divide and move more quickly than normal from stratum basale to stratum corneum and are shed prematurely (as little as 7-10 days) -Immature keratinocytes make abnormal keratin (flaky, silvery scales at sfc of skin) -Most often at knees, elbows, scalp.

Nail structure - the 3 parts

-Consists of nail body, a free edge, nail root -*Nail body* = visible portion of the nail, comparable to startum corneum of general epidermis except that its flattened, keratinized cells fill with harder type of keratin and cells are not shed. Appears pink due to blood capillaries in underlying derms -*Free edge* = part of nail body that may extend past distal end of digit; white b/c no underlying capillaries -*Nail root* = portion of nail buried in fold of skin. Whiteish crescent-shaped area is the *lunula* (little moon). Whiteish b/c vascularized tissue does not show due to thickened region of epithelium here.

Hemoglobin

-Darker skinned people = large amounts of melanin in epidermis. -Lighter skinned people = little melanin in epidermis; appears translucent, skin colour pink to red depending on oxygen content of blood moving in capillaries in dermis (due to hemoglobin)

Dermis -_____________ part of skin -Composed of _______________ _______________ __________________ tissue containing _______________ and _______________ fibers -______________ fibers provide tensile strength -_________________ fibers provide extensibility and elasticity -Few cells are present: _______________, ________________, and _____________ near subQ layer -________________ ____________, _________________, _________ ____________ embedded in dermal layer

-Deeper part of skin -Composed of dense irregular connective tissue containing collagen and elastic fibers -*collagen fibers* provide tensile strength (resist pushing and pulling) -*elastic fibers* provide extensibility (ability to stretch) and elasticity (return to original shape) -Few cells present: fibroblasts, macrophages, adipocytes near subcutaneous layer -Blood vessels, nerves, glands, hair follicles embedded in dermal layer

Which hormonelike protein regulates the growth of skin?

-Epidermal growth factor (EGF) (NOTE the rate of cell division in stratum basale increases when outer layers of epidermis stripped away as in abrasions and burns)

Epidermal ridges -Found in ___________, _____________, ______________, _______________ -Series of _____________ and ______________ -Produced during _________ month of fetal development (___________ projections of _____________ into ______________ between dermal ______________ and ________________ region of dermis) -Create a ____________ ____________ between dermis and epidermis in region of ___________ _______________ _______________ -Increase ___________ ___________ which ______________ the _____________ of _______________ of ___________ (______________ _____________) to _____________ ________________ sensitivity.

-Found on palms, fingers, soles, toes -Series of ridges and grooves -Produced during 3rd month of fetal development (downward projections of epidermis into dermis between dermal papillae and papillary region of the dermis) -Create strong bond between dermis and epidermis in region of high mechanical stress -Increase surface area which increases the number of corpuscles of touch (Meissner's corpuscles) to increase tactile sensitivity

Melanin quirks

-Freckles - patches where melanin accumulates -Age (liver) spots - accumulation of melanin, appear as person ages -Nevus (mole) - round, flat, raised area represents benign localized overgrowth of melaoncytes

Lanugo hair

-Hair follicles develop at about 12 weeks after fertilization -By 5th month of development the follicles produce fine, nonpigmented, downy hairs called *lanugo* that covers the fetus' body

Accessory structures of the skin

-Hair, skin glands, nails -*All develop from embryonic epidermis*

Albanism -Inherited inability of person to produce _______________ -Most albinos have _______________ that are unable to synthesize _________________ -Melanin missing from ___________, _______________, ___________ -Problems with ____________, tendency to __________________ easily on overexposure to sunlight

-Inherited inability of a person to produce melanin -Most albinos have melanocytes that are not able to synthesize tyrosinase. -Melanin missing from hair, eyes, skin -Problems with vision, tendency of skin to burn easily on overexposure to sunlight

Protection from external environment

-Keratin protects from microbes, abrasion, heat, chemicals -Tightly interlocking keratinocytes resist microbe invasion -Lipids released by lamellar granules inhibit evaporation of water from skin sfc and retard entry during showers, swimming -Oily sebum from sebacious glands keeps skin and hairs from drying out and contains bactericideal chemicals -Acidic pH of perspiration retards growth of some microbes -Pigment melanin helps shield against damaging effects of UV light -*Intraepidermal macrophages (Langerhans cells)* alert immune system to presence of potentially harmful microbial invaders & *dermal macrophages* phagocytize bacteria and viruses that manage to bypass intraepidermal macrophages of epidermis

Thermoregulation

-Liberation of sweat to sfc - high environmental heat or exercise, sweat production in eccrine sweat glands increases; evaoporation of sweat from skin lowers body temp. -Adjustment of flow of blood to dermis - blood vessels in dermis dilate, more heat loss from body.

Types of skin

-Local variations related to thickenss of epidermis, strength, flexibility, degree of keratinization, distribution and type of hair, density and types of glands, pigmentation, vascularity (blood supply), and innervation (nerve supply) -*thin (hairy) skin* -*thick (hairless) skin*

Which 3 pigments is skin colour based on?

-Melanin -Hemoglobin -Carotene

Ceruminous glands

-Modified sweat glands in external autiditory meatus -Produce waxy lubricating secretion -Excretory ducts open either directly onto sfc of external auditory canal or into ducts of sebaceous glands; secretory portion in subcutaneous layer -*cerumen* = ear wax -Cerumen + hairs on external auditory canal provide sticky barrier that impedes the entrance of foreign bodies and insects -Cerumen also waterproofs and prevents bacteria and fungi from entering cells

Epidermal keratinization -Newly formed cells in ________________ ______________ slowly pushed to _________________. As they move from one epidermal layer to the next, they accumulate more _________________ = "_______________", then undergo _______________. -Eventually they ________________ ______ and are replaced by ______________ ____________ -The whole process takes ____-_____ weeks in epidermis of _____ mm thick (average) -_____________ and __________ diffuse to ____________ ________________ from blood vessels in _____________ (so stratum basalis is _______________ to nutrients, O2)

-Newly formed cells in stratum basale slowly pushed to surface. As they move from one epidermal layer to the next, they accumulate more keratin = *keratinization*, then undergo apoptosis -Eventually they slough off and are replaced by underlying cells -The whole process takes 4-6 weeks in epidermis of 0.1 mm thick (average) -Nutrients and O2 diffuse to avascular epidermis from blood vessels in dermis (so stratum basalis closest to nutrients, O2)

Subcutaneous layer -Not part of the _________, deep to the __________ -AKA ______________ -Fibers which extend from ______________ anchor skin to the ___________ layer, which in turn attach to underlying _____________ -Serves as ______________ _______________ for fat and contains large __________________ ________________ that supply the ____________________ -Contains _________________ (_______________) __________________ (sensitive to pressure)

-Not part of the skin, deep to the dermis -AKA hypodermis -Aereolar and adipose tissue. -Fibers which extend from dermis anchor skin to "subQ" layer, which in turn attaches to underlying fascia (the connective tissue between mm and bones) -Serves as storage depot for fat and contains large blood vessels that supply skin. -Contains *pancinian (lamellated) corpuscles* (sensitive to pressure)

Deep wound healing

-Occurs when injury extends to dermis and subQ layer -Scar tissue formed, healed tissue loses some if its normal function -Four phases: inflammatory phase, migratory phase, proliferative phase, maturation phase

Synthesis of vitamin D

-Vitamin D synthesis requires activation of precursor molecule (7-dehydrocholesterol) in skin by UV light. -Enzymes in liver and kidney modify the activated molecule, eventually producing *calcitrol* (hormone that aids in absorption of calcium from foods in GI tract into blood).

Stratum Lucidum -Only present in ________________ _________________ of areas such as ___________, ________________, ______________ -____-_____ layers of __________, ___________________ ________________ keratinocytes that contain large amounts of __________________ and _____________ plasma membranes -It is an "_____________ layer of _______________"

-Only present in thick skin of areas such as fingertips, palms, and soles -4-6 layers of flattened clear dead keratinocytes that contain large amounts of keratin and thickened plasma membranes -Additional layer of toughness

Vitiglio -Partial or complete loss of ______________ from patches of _______________ produces irregular ____________ spots -May be related to ____________ _____________ malfunction in which antibodies attack _________________

-Partial or complete loss of melanocytes from patches of skin produces irregular white spots -may be related to immune system malfunction in which antibodies attack melanocytes

Nails

-Plates of tightly packed, hard, dead, keratinized epidermal cells that form a clear, solid covering over dorsal sfcs of distal portions of digits -Clear, solid covering over dorsal sfcs of distal ends of digits

Terminal hairs

-Prior to birth lanugo of eyebrows, eyelashes, scalp shed and replaced by long, coarse, heavily pigmented hair called *terminal hairs*

Vellus hairs

-Prior to birth the laguno on the rest of the body replaced by *vellus hairs*, ("peach fuzz"), which are short, fine pale hairs that are barely visible to the naked eye

Nail functions

-Protect distal end of digits -Counter-pressure to palmar sfcs of fingers -Enhance touch perception and manipulations -Allow grasping and manipulation of small objects -Scratch and groom body

Nail matrix

-Proximal portion of epithlium deep to nail root -Superficial nail matrix cells divide mitotically to produce new nail cells -Rate of nail growth influenced by age, health, nutritional status, season, time of day, environmental temperature

Which exocrine glands are associated with the skin?

-Sebaceous (oil) glands -Sudiferous (sweat) glands -Ceruminous (ear wax) glands -Mammary glands (specialized sudiferous glands) (discussed in chapter on reproductive)

Functions of hair

-Senses light touch (hair root plexus) -Prevents heat loss (scalp) -Protection (scalp fro sun, eyelashes and browns protect eyes from foreign particles)

Layers of epidermis -Several distinct layers of ________________ in various stages of ______________ form ____________ -Most regions of body it has _____________ strata (____________) (list them) -Where exposure to ______________ is the greatest (3 places) epidermis has _______ layers (list them)

-Several distinct layers of keratinocytes in various stages of development form epidermis -Most regions of body it has four strata (layers): statum basale, stratum spinosum, stratum granulosum, and thin stratum corneum (thin skin) -Where exposure to friction is greatest (fingertips, palms, soles) epidermis has five layers: staratum basale, stratum spinosum, stratum granulosum, *stratum lucidum*, and *thick* stratum corneum

Eccrine sweat glands

-Simple, coiled tubular glands -More common than apocrine -Not associated with hair follicles -Found throughout skin of most regions of body, esp. forehead, palms, soles. -Located mostly in deep dermis (sometimes upper subQ layer). Secretory part projects through dermis and epidermis and ends as a pore at sfc of epidermis -Sweat consists of water, ions (Na+ & Cl-), urea, uric acid, ammonia, amino acids, glucose, lactic acid

Apocrine sweat glands

-Simple, coiled tubular glands (like eccrine sweat glands) -Associated with hair follicles -Found mainly in skin of axilla, groin, areolae (pigmented area around nipples), bearded region of face in males. -Previously believed that secretions released in apocrine manner (i.e. pinching off portion of the cell). However, now we know that it is by exocytosis (which is how eccrine glands work too) -Secretory portion is loacted in lower dermis or upper subQ layer, excretory portion opens into hair follicles -Apocrine sweat appears milky/yellowish; contains same components as eccrine sweat + lipids and proteins -Odourless but when interacts with bacteria on skin sfc = musky odour -Start to function at puberty -Active during emotional sweating including sexual activity. Not active during thermoregulatory sweating

Layers of the dermis

-Superficial papillary region -Thick deeper reticular region

Stratum Spinosum -Superficial to ________________ _______________ -Mostly ________-___________ layers of ______________ -______________ here produce ________________ bundles of ________________ in ________________ filaments than in basal layer (reason for name?) -@ each _____________ projection bundles of _________________ __________________ ________________ insert into ______________ (tightly _____________ cells ______________) = provides both ____________ and _______________ -__________________ ____________________ (___________________ cells) + projections of _________________ also present in stratum spinosum

-Superficial to stratum basale -Mostly 8-10 layers of keratinocytes -Keratinocytes here produce coarser bundles of keratin in intermediate filaments than in basal layer (NOTE: though they are rounded in living tissue, they shrink and pull apart when prepared for microscopic examination; appear to be covered in thornlike spines which is the reason for their name) -@ each spinelike projection bundles of keratin intermediate filmanets insert into desmosomes (tightly join cells together) = provides both strength and flexibility -intraepidermal macrophages (langerhans cells) + projections of melanocytes also present in stratum spinosum

Sebum

-The oily substance that sebacious glands secrete -A mixture of triglycerides, cholesterol, proteins, inorganic salts -Coats the surface of hairs and helps keep them from drying/becoming brittle -Prevents excessive evaporation of water from skin, keeps skin soft and pliable, inhibits the growth of some (but not all) bacteria + fungi

Fibrosis

-The process of scar tissue formation -scar tissue differs from normal skin - collagen fibers more densely arranged, decreased elasticity, fewer blood vessels, may not contain same # hairs, skin glands, sensory structures.

Skin's Functions

-Thermoregulation -Blood storage -Protects body from external environment -Detects cutaneous sensations and provides sensory info about environment -Excretes and absorbs substances -Synthesizes vitamin D

Thin (hairy) skin

-all parts except palms, soles -epidermal thickness: 0.1 - 0.15 mm -Stratum lucidum lacking; thinner stratum spinosum and corneum -Epidermal ridges lacking due to poorly developed, less well-organized dermal papillae -Hair follicles and arrector pilli mm present -Sebacious glands present -Fewer sudiferous glands -Sensory receptors sparser than in thick skin

Cyanosis

-bluish colour to nail beds and skin -hemoglobin depelted of oxygen looks blue-purple

What factors may influence rate of growth and replacement of hair?

-illness, diet, fever, radiation/chemo, surgery, blood loss, severe emotional stress, gender

Cutaneous sensations

-include tactile (touch, pressure, vibration, tickle) + thermal sensations (warmth, coolness) -pain = indication of impending or actual tissue damage -Various nerve endings and receptors distributed throughout the skin including tactile discs of epidermis, corpuscles of touch in dermis, hair root plexuses around each hair follicle

Stratum Granulosum -where is it located? -_____-_____ layers of ________________ keratinocytes that are undergoing _______________ -Though keratin ______________ _______________ no longer produced by cells here, they become more ____________ because ____________ in cells are ______________ -Distinctive feature = ________________, which ____________ keratin _______________ ______________ into ____________ -Also in __________________ are _____________-________________ _______________ ___________________ which fuse with ______________ ________________ and release ______________-_________________ secretion -The _______________-_______________ secretion is deposited in spaces between cells of 3 strata (which ones?) - (acts as _________________-__________________ _________________) -As _______________ break down during _________________ the cells ________________ - the stratum granulosum marks _______________ between deeper ____________________ __________________ strata and dead cells in more superficial layer

-located approximately at middle of epidermis -3-5 layers of flattened keratinocytes that are undergoing apoptosis -Though keratin intermediate filaments no longer being produced by cells here, they become more aparent b/c organelles in cells are regressing -Distinctive feature = *keratohyalin*, which assembles keratin intermediate filaments into *keratin* -Also in keratinocytes are membrane-encolosed *lamellar granules* which fuse with the plasma membrane and a release lipid-rich secretion. -The lipid-rich secretion is deposited in spaces between cells of stratum granulosum, stratum lucidum, and stratum corneum (acts as water-repellent sealant) -As nuclei break down during apoptosis the cells die - the stratum granulosum marks transition between deeper metabolically active strata and dead cells in more superficial layer

Erythema -______________ of skin caused by ________________ of __________________ in _______________ with ________________ due to skin _______________, exposure to _______________, _____________, _______________, ______________ reaction)

-redness of skin caused by engorgement of capillaries in dermis with blood due to skin injury, exposure to heat, infection, inflammation, allergic reaction

Hypertrophic scar vs keloid scar

-so much scar tissue formed during deep wound healing that raised scar elevated above normal epidermal surface results. -If remains within boundaries of original wound, it is a *hypertrophic scar*. -If it extends beyond boundaries into normal surrounding tissues, it is a *keloid scar*

Papillary region of the dermis -_________________ ____% of the dermis -Made up of ___________ ___________ and ______________ __________ fibers -Surface area is greatly __________ by _____________ ________________, small ____________-___________ structures that _______________ into _______________ of epidermis (___________ dermis to epidermis)

-upper 20% of the dermis -thin collagen and fine elastic fibers -surface area greatly increased by *dermal papillae*, small nipple-shaped structures that project into undersurface of epidermis (anchor dermis to epidermis)

Carotene -colour pigment? -precursor to what? needed for what? -Excessive consumption causes it to be stored in ____________ _____________ and __________ ___________ of _________________ and _____________ layer = yellow tinge to sking

-yellow-orange pigment -precursor for vitamin A (makes pigments needed for vision) -Excessive consumption of carotene causes it to be stored in the stratum corneum and fatty areas of dermis and subcutaneous layer = yellow tinge to skin.

The two main parts of the skin

1. *Epidermis* = superficial, thinner portion composed of epithelial tissue (avascular - dead and dying cells) 2. *Dermis* = deeper, thicker connective tissue portion (vascular)

Functions of the integumentary system (6)

1. Regulates body temperature 2. Stores blood 3. Protects body from external environment 4. Detects cutaneous sensations 5. Excretes and absorbs substances 6. Synthesizes vitamin D

Daily hair loss

70-100 hairs per day

How much of scalp hairs are in growth stage at any one time?

85%

Intraepidermal macrophages -AKA -How many of epidermal cells? -Arise from _______________ ______________ _______________, migrate to _______________ -Participate in ________________ _____________________ mounted against ________________ that invade the skin (i.e they help __________________ immune cells _________________ invading _______________ and ___________ it) -Easily ________________ by ___________ ______________

AKA Langerhans cells -Small fraction of epidermal cells -Arise from red bone marrow, migrate to epidermis -Participate in immune response mounted against microbes that invade the skin (i.e. they help other immune cells to recognize invading microbe and destroy it) -Easily damaged by UV light

Tactile epithelial cells -AKA -How many? -Located at _____________ layer of epidermis where they contact the ______________ ______________ of a _______________ __________________ called a _________________ (____________________) __________________ -Tactile epithelial cells + associated discs detect ______________ _________________.

AKA Merkel cells -Least numerous of the epidermal cells -Located at deepest layer of epidermis where they contact the flattened process of a sensory neuron called a *tactile (Merkel) disc* -Tactile epithelial cells + associated discs detect touch sensations

Eponychium

AKA cuticle A narrow band of epidermis that extends from and adheres to the margin (lateral border) of the nail wall and proximal border of nail. Made of stratum corneum

Androgenic Alopecia

AKA male pattern baldnes -In genetically predisposed adults, androgens inhibit hair growth

Hyponychium

AKA nail bed Thickened region of stratum corneum beneath the free edge that secures the nail to the fingertip

Hairs

AKA pili -composed of columns of dead, keratinized epidermal cells bonded by extracelluar proteins -present on most skin sfc except palmar and plantar sfcs. -genetics and hormones determine thickness and pattern of distribution

Stratum Basale -AKA -___________ layer of epidermis -Single row of _______________ or ______________ _______________ -Some cells in this layer are ____________ ______________ that undergo ______________ ________________ continually to produce new _______________ -In stratum basale, the ___________________s' cytoskeleton includes scattered ___________________ ___________________ (__________________) -keratin __________________ _______________________ attach to __________________ which bind cells of stratum basale to each other and to cells of _______________ stratum spinosum and to _________________, which bind ___________________ to ______________ ______________ between epidermis and dermis. -______________ and ________________ _________________ cells (___________ ________________) with their associated _______________ ______________ are scattered among keratinocytes here

AKA stratum germinativum -Deepest layer of epidermis -Single row of cuboidal or columnar keratinocytes -Some cells in this layer are stem cells that undergo cell division continually to produce new keratinocytes -In stratum basale, the keratinocytes' cytoskeleton includes scattered intermediate filaments (tonofilaments) -(keratin intermediate filaments form a tough protein keratin in more superficial epidermal layers, protecting deeper layers from injury) -In stratum basale, keratin intermediate filaments attach to desmosomes, which bind cells of stratum basale to each other and to the cells of adjacent stratum spinosum and to hemidesmosomes, which bind keratinocytes to basement membrane between epidermis and dermis. -Melanocytes and tactile epithelial cells (Merkel cells) with their associated Merkel discs are scattered among keratinocytes here

Impacted cerumen

Abnormal amount of cerumen in external auditory meatus; can prevent sound from reaching eardrum

Sebacious (oil) glands

Associated with hair follicles

Acne

Bacterial inflammation of sebaceous glands

Gray hair

Becomes gray because of a progressive decline in melanin production; contains only a few melanin granules. here is a decrease in the number of functioning melanocytes (due to decrease in tyrosinase), resulting in gray hair and atypical skin pigmentation.

Tension lines -______________ ________________ in ______________ region (of dermis) orient in one _____________. Surgery along _______________ of _____________ decreases _________________

Collagen fibres in reticular region orient in one direction. Surgery along direction of fibers decreases scarring.

Blond and red hair

Contain variants of *pheomelanin* (yellow/red)

Dark coloured hair

Contains mostly *eumelanin* (brown/black) ("eu" = true, good in Latin)

Skin AKA

Cutaneous membrane

What happens when an excessive amount of keratanized cells are shed from the skin of the scalp?

Dandruff

What are stretch marks?

Dermal tears from extreme stretching

Blood storage

Dermis houses extensive network of blood vessels that carry 8-10% of total blood flow in resting adult. Blood reservoir

Chemotherapy

Drugs kill rapidly dividing cells such as hair matrix cells. The 15% of hairs in resting stage are not affected.

Glands

Epithelial cells that secrete a substance

What does constant exposure of skin to friction stimulate? -Increase in _____________ ____________ and ________________ ______________ that results in formation of a ____________________ (............... of ________________ ______________)

Increase in cell production and keratin production that results in formation of a callus (abnormal thickening of stratum corneum)

What % of male / female hair is terminal and what % is vellus (in adults)

Males: -Terminal: 95% -Vellus: 5% Females: -Terminal: 35% -Vellus: 65%

Can skin regenerate if an injury destroys a large area of the stratum basale and its stem cells?

No, a skin graft is required.

Sebacious glands

Oil glands -Simple, branched acinar (rounded) glands -Connected to hair follicles (with a few exceptions) -Secreting portion lies in dermis and usually opens into the neck of a hair follicle -In some locations like lips, glans penis, labia minora, and tarsal glands of eyelids sebaceous glands open directly into surface of skin -absent in palms and soles -small in most areas of trunk and limbs -large in skin of breasts, face, neck, superior chest

Pallor

Paleness of skin, may be due to shock, anemia

Alopecia

Partial or complete loss of hair. May be caused by genes, aging, endocrine disorders, chemotherapy, skin disease

What happens to vellus hair at which specific areas during puberty?

They are replaced by terminal hairs in response to hormones (androgens) secreted at puberty -Axillae, pubic regions + face, limbs and chest of boys