A&P1 ch 5

The surface of the papillary layer where it contacts the epidermis is folded into projections referred to as dermal papillae

(provides oxygen to cells that dont have their own blood vessels) -The dermal papillae house tiny blood vessels called capillaries that are arranged into loops. These loops extend up into the superficial part of the dermal papillae, where oxygen and nutrients diffuse into the extracellular fluid of the dermis and up into the cells of the avascular epidermis.

tanning: immediate and delayed effects

***BOOK*** Its immediate action: - is to oxidize the melanin already formed within the keratinocytes, which causes the melanin to rapidly darken. UV radiation also damages the DNA of the melanocytes, which increases the production of additional melanin. These secondary effects: become visible about 72 hours after exposure but last longer than melanin oxidation. ***PWPT**** -Immediate response - oxidation of melanin already present in keratinocytes; causes melanin to quickly darken -Delayed or secondary effects - UV light causes DNA damage in melanocytes; stimulates melanin production; appears within 72 hours; lasts longer than melanin oxidation

sebaceous glands

- branched with clusters of secretory cells (acini) surrounded by small ducts; -converge to form central duct that empties into hair follicle or small pore; - make and secrete sebum -Everywhere on body except palms and soles; ----greatest number on face and scalp -Secretion is influenced by sex hormones, especially male hormone (testosterone) -Dramatic increase in sebum production occurs after puberty; Cell-Cell Communication Core Principle

vitiligo

- causes depigmentation patches in the skin; - - most likely combination of genetic factors coupled with disorder of immune system (autoimmune disease)

Melanocyte

- located in the stratum basale - produce the protein melanin -Melanin is a skin pigment ranging from orange-red to brown-black.

albinism

- melanocytes fail to manufacture tyrosinase; -results in lack of skin pigmentation and -greatly increased risk of keratinocyte DNA damage from UV radiation

how are glands important to protection in the skin?

- secrete antimicrobial substances; -sebaceous gland secretions give surface of skin slightly acidic pH (acid mantle); inhibits growth of many pathogens

Lamellated (Pacinian) corpuscles

- sensory receptors embedded within reticular layer; - respond mainly to changes in pressure and vibration

Dendritic cells

-?derived from macrophages? -?large mobile phagocytes? -in stratum spinosum; -phagocytes of immune system; protect skin and deeper tissues from pathogens

what is melanin composed of?

-Composed of two molecules of amino acid tyrosine; -chemically bonded by series of reactions catalyzed by enzyme tyrosinase; occurs in stepwise fashion within special vesicle (melanosome)

apocrine glands

-Found in specific regions of body such as axillae, anal area, and areola -Large glands; release protein-rich secretion into hair follicle -Secretions become odoriferous once skin bacteria metabolize contents -Influenced by sex hormones; become active after puberty

what happens to your skin if you're sitting in bath water or fresh water

-Fresh water is hypotonic to body fluids -Causes water to move into epidermis AKA: the bath is hypotonic because the bath water is moving into your dead keratinized cells to temporarily plump them up

hair has three visible regions. list them

-Inner medulla - soft core only found in thick hair (head); composed of soft keratin -Middle cortex - highly structured and organized with several layers of keratinocytes containing hard keratin; provides strengt -Outermost cuticle - single layer of overlapping keratinocytes containing hard keratin; provides mechanical strength

how does vitamin D synthesis work

-Modified cholesterol molecule (precursor) converted to cholecalciferol by exposure of epidermis to UV radiation -Cholecalciferol is released into blood; modified first by liver, then by kidneys, forming calcitriol (a hormone not an actual vitamin) (active form of vitamin D); required for calcium ion absorption from small intestine -Calcium ion - critical for nerve function, muscle contraction, building and maintaining bone tissue (many other physiological functions)

basal cell carcinoma

-Most common of all cancer types -Arises from keratinocytes in stratum basale of epidermis -Skin regularly exposed to UV radiation is at risk for developing these tumors -Appears as nodule with a central crater -Rarely metastasizes to other tissues -Can be resolved successfully with surgical removal

eccrine gland

-Most prevalent type -Simple coiled tubular glands in dermis -Sweat contains mostly water, waste products, and electrolytes -Exits from duct through sweat pore onto epidermal surface

Functions of hair

-Provides protection by preventing substances and organisms from entering eyes and nose -Protects underlying skin of scalp from UV radiation and mechanical trauma -Associated with small sensory neuron; plays role in detecting changes in environment

squamous cell carcinoma

-Second most common skin cancer -flakey flaps that bleed -Cancer of keratinocytes of stratum spinosum -Scaly plaques may ulcerate and bleed; -usually on head and neck -Tumors are more likely to metastasize than basal cell carcinoma; -surgical removal is still useful

two types of glands and where are they located

-Sweat (sudoriferous) glands - produce sweat -Sebaceous glands - produce oily sebum Located in: -derived from epithelial cells in the epidermis but are located in the dermis.

ceruminous glands

-The modified apocrine glands known as ceruminous glands -located in the ear, -they secrete a thick product called cerumen into hair follicles. Function: Cerumen (ear wax) lines the canal leading into the ear, where it lubricates the tympanic membrane and traps incoming particles before they reach the membrane.

third degree burns (full thickness burns)

-The most damaging burns are -involve the epidermis, dermis, hypodermis, and possibly deeper tissues including muscle and bone. -not generally painful at first because the nerves are destroyed too. - typically result in major tissue damage and significant scarring with loss of hair follicles and diminished or absent keratin production. Patients often have problems with dehydration due to massive fluid loss from the swelling that accompanies such burns -at great risk for infection. -Treatment: depends on the location and extent of the burn, -patients may require extensive skin grafting -These patients often face a prolonged and difficult recovery.

Characteristics of thick skin

-about as thick as paper towel; -hands and feet -has all five epidermal layers and very thick stratum corneum; -no hair follicles; -many sweat glands

what is a callus

-additional layers of stratum corneum; -forms in either thick or thin skin in response to repetitive pressure

Tactile (Meissner's) corpuscles

-also in dermal papillae; - sensory receptors; respond to light touch stimuli; -more numerous where sensation is primary function (skin of fingertips, lips, face, and external genitalia)

what can minimize skin wrinkles

-botox -cremes -filler

wounds

-common skin pathology; -defined as any disruption in skin's integrity; includes Lacerations (cuts) Burns Skin cancers

characteristics of thin skin

-covers areas of body not subjected to as much mechanical stress; -about as thick as sheet of printer paper; -only four layers (no stratum lucidum) -Each layer is thinner than those of thick skin -Numerous hairs, -numerous sweat glands numerous sebaceous glands

shaft

-dead -Most of the hair -Portion of hair projecting from skin's surface -Made of columns of dead keratinized epithelial cells that have completed keratinization process

stratum granulosum

-dead ish (50/50) - made of keratinocytes and keratin bundles -3 to 5 layers of cells -prominent cytoplasmic granules with keratin bundles or lipid-based substance; secreted by exocytosis -Hydrophobic lipids provide waterproofing; maintains internal fluid and electrolyte homeostasis; - leads to isolation and death of cells in layer and more superficial layers -this lipid coating acts as a water barrier and prevents the passage of hydrophilic molecules into or out of the skin

stratum basale (germinativum)

-deepest layer of epidermis -made of keratinocytes, stem cells, merkel cells, and melanocytes -layer that creates the other layers (if you destroy it your skin wont heal) - single layer of stem cells resting on basement membrane -Closest cells to dermal blood supply; -most metabolically and mitotically active strata -Responsible for Vitamin D synthesis and replacement of dead keratinocytes (lost from superficial layers)

four types of sweat glands: how do they secrete their products

-eccrine -appocrine -Ceruminous -Mammary glands -all secreted through exocytosis aka merocrine secretions

two main parts of skin (cutaneous membrane)

-epidermis -dermis

Growth stage (hair)

-hair grows about 1-1.5 cm per month not continuous - mitosis occurs in matrix (keratinocytes at base of root; actively divide) -As the cells divide, those above them are pushed farther away from the blood supply, keratinize, and die, in a similar manner to what takes place in the epidermis. -can last for a moth up to 6 yrs depending on where the hair is

what is different about the feedback loop when the body temp drops below normal range rather than above

-induces shivering (when the skeletal muscles contract) -the blood vessels in the dermis dont dilate instead the blood vessels narrow (vasoconstrict), reducing blood flow; heat lost to environment is limited

second degree burns (partial thickness)

-involve the epidermis and part or all of the dermis, - result in significant pain, blistering, and possibly scarring. - generally require medical intervention.

3 different types of hair

-lanugo -terminal hair -vellus hair

what cells compose the epidermis

-linked together by desmosomes keratinocytes -95% of the epidermis: -provide us with resistance to mechanical trauma (they make us tough) -they make kerotin (tough fibrous protein)

resting stage (hair)

-mitosis in matrix stops -follicles shorten -hair is pushed to surface where it remains dormant for a month or two -falls out or is pushed out by new hair in growth phase

first degree burn (superficial)

-only effects the epidermis -Erythema and minor pain are typically present, but -no blisters or permanent damage. -First-degree burns generally require no treatment. -An example is a minor sunburn.

stratum lucidum

-only in thick skin -all dead -made of keratinocytes - narrow layer of clear, dead keratinocytes; -found on palms of hands and soles of feet

stratum corneum

-outermost layer of epidermis -dead -made up of keratinocytes -several layers of dead, flattened keratinocytes with thickened plasma membranes -Filled with keratin bundles (little else) -Sloughed off or exfoliated mechanically as desmosomes holding cells together are lost

Merkel cell

-oval cells -scattered throughout stratum basale; -sensory receptors associated with small neurons in dermis: -Detect light touch and discriminate shapes and textures -Large numbers in regions specialized for touch: fingertips, lips, and at base of hairs

Flexure lines

-reticular layer Flexure lines - deep creases in areas of body (surrounding joints) where reticular layer is tightly anchored to deeper structures

reticular layer of dermis

-second (deeper) layer -made of dense irregular connective tissue -cells and fibers: collagen and elastic fibers -Function: separates dermis from the hypodermis -tears or excessive stretching in this region cause stretch marks -rich in proteoglycans that draw water into the ground substance and make skin appear firm Collagen bundles: strengthen dermis; prevent traumatic injuries from damaging deeper tissues Elastic fibers allow dermis to return to its original shape and size after stretching (young people have more so we look younger)

what are the two main parts of the hair and what are they made of

-shaft and root -stratified squamous keratinized epithelial cells

terminal hair

-thick - course - pigmented hair -located in eyelashes or scalp

stratum spinosum

-thickest layer; on top of stratum basale; -composed of keratinocytes and dendrytic cells -still close to blood supply; -metabolically and mitotically active (aka alive) - they too help produce vitamin D

vellus hair

-thin -nonpigmented -covers most of the body -after puberty much of this hair changes to terminal hair -more replacement in males

Lanugo hair

-thin, -nonpigmented hair -covering nearly entire body of fetus; -generally fall out around birth; -replaced with one of two hair types: vellus or terminal

What is the second function of vitamin D? Why is it so important?

-to decrease the synthesis of vitamin D in response to UV radiation. - The answer is that vitamin D levels must be kept within a specific range, as excess amounts can lead to calcium ion imbalance and kidney failure.

sebum

-waxy, oily mixture of mostly lipids; -released by holocrine secretion; secretory cells accumulate sebum until cell ruptures -Contains cellular fragments and debris in addition to lipids -Coats hair, providing it with hydrophobic barrier; inhibits water loss -Also inhibits growth of or kills certain bacteria

burns: what causes them and how are they classified?

-wounds caused by heat, extreme cold, electricity, chemicals, and radiation; -classified according to extent and depth of tissue damage:

take me through the steps if the body is overheating (feedback loop)

1) stimulus- body temp increases 2) receptor- thermo receptors (in brain) detect increase in skin and body temp 3) thermoregulatory center in brain receives signals from receptors 4) effector/response- blood vessels in dermis dilate and release heat/ sweat glands release sweat 5) as body temp returns to normal, feedback stops effector response

Which of the following would be found in the papillary layer but not the reticular layer of the dermis? a) capillary loops b) adipose cells c) lamellated corpuscles (pacinian corpuscles) d) the root of hair follicles e) sweat glands

A

malignant melanoma ABCDE rule

ABCDE rule: (A): Asymmetrical shape (two sides do not match) (B): Border irregularity (C): Color, usually blue-black or a variety of colors (D): Diameter generally larger than 6 mm (size of a pencil eraser) (E): Evolving (changing) shape and size

Along with sweating, which other responses by skin assists with thermoregulation?

ANSWER: A a) blood vessels near the skin can dilate, increasing blood flow and heat loss b) additional secretion of sebum coats the skin and protects it against the sun c) apocrine sweat glands add their sweat to eccrine glands to increase evaporative cooling d) as a response to cold, blood vessels dilate to bring more warmth to the skin's surface e) all of these occur

acne vulgaris

Acne vulgaris - affects 96% of adolescents and young adults to some degree what is it?: Accumulation of sebum and dead cells within sebaceous glands; produces ***comedone*** (blackhead); If it becomes infected?: -infected by Propionibacterium acnes; causes inflammation and formation of ***pustule (pimple)** -can cause permanent scarring Male sex hormones (testosterone) are the primary cause; tends to be more pronounced in males entering puberty; decreases and may disappear by age 20−25; may persist much longer in some individuals

Which feature(s) of the skin protect(s) us against microbes such as bacteria?

Answer: they all do! a) the many layers of keratinized cells form a barrier against microbes b) sebum contains compounds which kill bacteria c) sweat has an acidic pH which suppresses microbial growth d) Langerhans cells can alert the immune system should microbes invade

A freckle is a) Due to a local proliferation of melanocytes b) A small area of increased melanin production c) An area where melanocytes fail to manufacture melanin d) An area of skin that has depigmented e) An area of skin with increased blood flow

B

Which statement is NOT correct about the dermis? a) it is made up of dense, irregular connective tissue b) it is thinner than the epidermal layer c) it contains collagen and elastin fibers d) it provides the blood supply and many sensory receptors for the epidermis e) it has a smaller papillary layer, and a thicker reticular layer

B

what do these hair colors mean in terms of pigment blonde: black: red: gray:

Blond hair - little melanin Black hair - contains lots of melanin Red hair - special reddish pigment containing iron Melanocytes produce less melanin with aging so hair eventually turns gray or white and often contains bubbles

things present in reticular layer

Blood vessels, sweat glands, hairs, sebaceous glands, adipose tissue (small amount)

List the layers of the epidermis from deep to superficial

Brilliant studying gives loads of confidence -Stratum Basale -Stratum Spinosum -Stratum Granulosum -Stratum Lucidum -Stratum Corneum

Second degree burns a) Often associated with dehydration b) Always cause permanent damage c) Extend to dermal layer but no further d) Are not initially painful e) Only involve erythema

C

Which of the following is NOT a correct statement about melanin? a) granules of melanin are produced and exported by melanocytes b) melanin granules are the PRIMARY source of skin pigmentation c) melanin is necessary for the production of vitamin D by the skin d) melanin pigment protects DNA from damaging UV light e) melanin granules are taken up by keratinocytes

C

Which of the following may be treated with surgical removal, radiation therapy and chemotherapy? a) Acne vulgaris b) Squamous cell carcinoma c) Malignant melanoma d) Basal cell carcinoma e) None of these choices is correct

C

The active form of "vitamin" D is

Calcitriol

what does it mean if a tumor becomes cancerous? why is this bad

Cancerous tumors are able to metastasize; tumor cells spread through blood or lymphatic vessels to other tissues and continue to divide Damage caused by metastatic tumor cells alters function of invaded organs

Which of the following is LEAST important to normal skin color? a) Melanin production b) Carotene c) Hemoglobin d) Bilirubin e) Number of melanocytes

D

epidermal ridges

Dermal ridges indent overlying epidermis to create epidermal ridges; enhance gripping ability of hands and feet: Occur in characteristic patterns; loops, arches, and whorls; genetically determined and unique to each person Sweat pores open along ridges; leave thin film or fingerprint on things touched with fingers

Basal cell carcinomas a) Cannot be surgically removed b) Involve cells of the stratum spinosum c) Tend to spread to other tissues d) Are pigmented lesions e) Are the most common skin cancer

E

malignant melanoma

Early detection of melanoma is critical due to tendency to metastasize what happens: "Arms" of cancerous melanocytes extend down into dermis and access dermal blood vessels; enables cells to spread to other tissues via bloodstream How to treat: Treated with surgical removal; possibly radiation therapy and chemotherapy Prognosis depends on size of tumor, depth to which it extends into dermis, and whether it has metastasized to other tissues

The skin is composed of both a superficial epidermis and a deeper dermis. The epidermis is highly vascularized, while the dermis is avascular.

False

study pict on slide 70

GO NOW!

Hair (pili)

Hair (pili) - small filamentous structures; protrude from surface of skin over entire body except in regions with thick skin, lips, and parts of external genitalia

talk about how the kertinocyte life cycle works and what it has to do with a tan

Keratinocytes begin life in stratum basale or spinosum; pass through each epidermal layer; shed from stratum corneum -Migration from deepest strata to stratum corneum takes 40−50 days to complete TAN: -because you're shedding the tan cells and replacing them with new cells your tan fades

Name the cells of the Epidermis

Keratinocytes, Melanocytes, Dendritic cells (Langerhans' cells), and Merkel cells (tactile)

how does melanin get in the keratinocytes

Melanocyte's arm-like extensions contact or even pierce plasma membranes of keratinocytes in stratum basale and spinosum Melanosomes migrate to ends of extensions; released by exocytosis; taken into cytoplasm of keratinocytes

hemoglobin

Oxygen binds to iron in hemoglobin in oxidation reaction; same reaction causes iron to rust; oxidized hemoglobin changes color to bright orange-red; gives blood characteristic color THE BOOK: is an iron-containing protein found within our red blood cells that binds oxygen and transports it through the body. The interaction of hemoglobin with oxygen gives blood its characteristic red color. How does a blood protein affect the color of skin? The answer is that it doesn't affect the actual color, but, rather, the apparent skin color. Recall that the dermis is highly vascular, so a great deal of the body's blood resides in the dermis at any given time. In fair-skinned individuals, the epidermis is partly translucent, so we are able to look through the epidermis to see the blood in the vessels of the dermis. Under normal conditions, this gives the skin a faint pinkish hue. In regions where the stratum corneum is thinner, such as the lips, the pink is generally darker.

what is the primary function of melanin

Primary function - protecting keratinocyte DNA from mutations induced by UV radiation

how does skin protect from the sun

Provides protection from environmental hazards, including absorption of ultraviolet light (UV), before deeper tissues are damaged

what does thermoregulation rely on

Relies on negative feedback loops for maintenance of stable internal temperature

How does skin help maintain homeostasis?

Secretes hydrophobic lipid-based chemicals; repel ionic (salt) and polar covalent (water) molecules; keeps them from both leaving and entering body via skin; - critical for maintaining water and electrolyte homeostasis in wide range of weather conditions

talk about sensation in the integumentary system. what are they, why are they important, what does it detect?

Sensation - enables nervous system to perceive changes in body's internal or external surroundings; -critical to homeostasis: -Skin has numerous sensory receptors that detect changes in internal and/or external environment Receptors detect potentially harmful stimuli (heat, cold, and pain); could lead to tissue damage

what gives us a spectrum of skin tones (dont just say melanin)

Spectrum of human skin tones is due to differences in amount of tyrosinase activity and type (color) of melanin produced

The pigment-producing cells of the epidermis are located in which layer?

Stratum Basale

Which layer has stem cells that undergo cell division to continually produce new keratinocytes?

Stratum Basale

Which epidermal layer marks the transition between metabolically active cells of lower layers and the dead layers of keratinocytes of the upper layers?

Stratum Granulosum

This skin layer is only present in places subjected to high levels of mechanical wear-and-tear, and provide an additional protective layer where it occurs, such as in the soles of the feet, palms, and fingertips.

Stratum Lucidum

Langerhans cells are part of the skin's immune defenses and activate other immune cells when the skin is invaded by microbes. Which layer of the epidermis contains Langerhans cells? (Dendritic cells)

Stratum Spinosum

what happens to your skin when you swim in the ocean

Swimming in ocean - Ocean is a hypertonic solution Reverses direction of osmotic flow AKA: pulls a little bit of fluid from your epi cells

Tension (cleavage) lines (reticular layer)

Tension (cleavage) lines - indentations in epidermis from gaps between collagen bundles in dermis

Gaps found between collagen bundles in dermis create

Tension or Cleavage Lines

The majority of body hair of _________ is vellus rather than terminal hair.

adult females

mole or nevus

area of increased pigmentation; due to a local proliferation of melanocytes, not an increase in melanin production

Dermal ridges

areas where dermal papillae are more prominent due to presence of thick collagen bundles

why do we give shots in the hypodermis

because there are not a lot of important structures down there it is mostly just fat so nothing to worry about but there are still blood vessels so the substance injected into the layer can still travel quickly

pallor

blood floor to dermis decreases -extremely pale -epidermis takes on color of whitish collagen in dermis -normal: when body is cold and conserving heat -not normal: when nervous and endocrine systems alter blood flow to dermis; part of flight or fight response happens when there is something wrong with the nervous system or can happen when you get an emotional shock

erythema

blood flow to dermis increases making redness of the skin -can happen naturally through exercise (to control heat release) -can be bad and mean trauma, fever, infection

cyanosis

bluish discoloration of the skin -sign of needed immediate medical attention -hemoglobin has low levels of bound oxygen in the blood -makes blood turns reddish purple Occurs when: -difficulty breathing -hemoglobin or red blood cell level low -hemoglobin is unable to bind to oxygen

negative feedback loop steps

body temp goes above normal > sensory receptor -Sensory receptors (thermoreceptors) detect increase in temperature in skin and internal body fluids -Control center in hypothalamus acts as thermostat (thermoregulatory center); receives input from thermoreceptors; processes and responds to inputs -Control center stimulates sweating; sweat glands are stimulated to release sweat; water carries heat when it evaporates, so evaporating sweat produces cooling effect

hair pigment is determined by what?

by melanin produced in matrix by melanocytes;

what causes cellulite?

collagen bands forming around adipose tissue in the hypodermis -based on genetics, age, gender, weight

what are the functions of the skin?

critical for protecting underlying organs or maintaining homeostasis:

The skin is also known as a (the)_________.

cutaneous membrane

hypodermis

deep to the skin -not part of the skin -below the dermis -function is to connect/anchor skin to deeper structures ie muscle bone etc -made of loose connective and adipose tissue -has good blood supply

define accessory structures (give examples)

embedded in cutaneous membrane; sweat glands, sebaceous glands, hair, and nails

common variations of pigment

freckle, mole, or nevus

The amount and kind of melanin present in the cortex and medulla of a hair shaft determines hair color. When melanin is replaced by air bubbles in the shaft, which is the resulting hair color?

gray/white

mammary gland

highly specialized sweat glands; produce modified sweat (milk) BOOK: Milk contains proteins, lipids, sugars, and a variety of other substances to nourish a newborn infant.

The Dermis

highly vascular layer deep to epidermis Function: -It houses the blood supply of the epidermis, -contains sensory receptors, -anchors the epidermis in place

About 95% of the cells of the epidermis are of which type?

karatinocytes

Which type of epithelium makes up the epidermis?

keratinized stratified squamous

skin color is determined by

melanin

what produces melanin and where are they produced

melanocytes in the stratum basale

cancer

one of the most common diseases in the world; -caused by mutations in DNA; -induces cell to lose control of cell cycle -unchecked cell division leads to formation of large undifferentiated cells (tumor)

two layers of the dermis

papillary and reticular

freckle

pigment of melanin concentrated in one spot (increased melanin production)

two phases of growth

resting stage growth stage

talk about protection (integumentary) what gives it that protection (cell type)

skin protects from mechanical trauma, pathogens, and environment: -Provides continuous barrier to invasion by microorganisms or pathogens -cell type: Stratified squamous, keratinized epithelium provides durable but flexible surface; -protects body from mechanical trauma (stretching, pressure, or abrasions) Contains cells of immune system that destroy pathogens before they invade deeper tissues

Skin markings

small visible lines in epidermis created by interaction between dermis and epidermis; best seen in thick skin

what does the hypothalamus stimulate that happens in the dermis when temperatures rise above normal range

the hypothalamus (control center) is going to stimulate cutaneous vasodilation; - dermal blood vessels widen (dilate); - increased blood flow through vessels increases heat radiated from body

Skin contains sensory receptors and arrector pili muscles....

these help you be able to sense things on your skin -AP are (small bands of smooth muscle associated with hair) cause goose bumps

If the epidermis is avascular how does it get nutrients and oxygen. How does this relate to thick or thinness

they get it through diffusion which means the epidermis has to be thin in order for things to diffuse easily -Relies on diffusion of oxygen and nutrients from blood vessels in deeper dermis; -limits epidermal thickness; Gradients Core Principle -About 50% of epidermal cells are too far from adequate blood supply to sustain life; -superficial layers are made up entirely of dead cells

Papillary layer

tissue type- loose connective tissue (looks jumbled) -thinner of the two layers -top layer of dermis -contains fibroblasts, phagocytes, and collagen - Function: to anchor the epidermis to the dermis -Dermal papillae lay on the surface

hair -thermoregualtion

to sparse in humans to do so

what do polar and nonpolar have to do with topical medications

topical creams are polar and can't get into the skin (pass the epidermis)so we can use them on top of the skin - non polar can get into the skin (pass the epidermis) ex: birth control patch - downside there are bad things that are non polar too

carotene

yellow-orange pigment of skin -happens as a result of diet (orange vegis, eggs, etc..) Lipid-soluble molecule; accumulates in stratum corneum (*?also happens where adipose tissue is*?) Imparts slight yellow-orange color; particularly visible in stratum corneum of thick skin