Week 3 Quiz

Why do teenagers often experience acne?

Acne results from a blockage of sebaceous glands by sebum. The blockage causes blackheads to form, which are susceptible to infection. The infected tissue then becomes red and inflamed. Teenagers experience this at high rates because the sebaceous glands become active during puberty. Hormones that are especially active during puberty stimulate the release of sebum, leading in many cases to blockages.

Cells of the epidermis derive from stem cells of the stratum basale. Describe how the cells change as they become integrated into the different layers of the epidermis.

As the cells move into the stratum spinosum, they begin the synthesis of keratin and extend cell processes, desmosomes, which link the cells. As the stratum basale continues to produce new cells, the keratinocytes of the stratum spinosum are pushed into the stratum granulosum. The cells become flatter, their cell membranes thicken, and they generate large amounts of the proteins keratin and keratohyalin. The nuclei and other cell organelles disintegrate as the cells die, leaving behind the keratin, keratohyalin, and cell membranes that form the stratum lucidum and the stratum corneum. The keratinocytes in these layers are mostly dead and flattened. Cells in the stratum corneum are periodically shed.

In addition to sweating, arterioles in the dermis dilate so that excess heat carried by the blood can dissipate through the skin and into the surrounding environment (Figureb). This accounts for the skin redness that many people experience when exercising.

During strenuous physical activities, such as skiing (a) or running (c), the dermal blood vessels dilate and sweat secretion increases (b). These mechanisms prevent the body from overheating. In contrast, the dermal blood vessels constrict to minimize heat loss in response to low temperatures (b). (credit a: "Trysil"/flickr; credit c: Ralph Daily)

Figure If you zoom on the cells at the outermost layer of this section of skin, what do you notice about the cells?

Figure These cells do not have nuclei, so you can deduce that they are dead. They appear to be sloughing off.

Tattoos and Piercings

For any form of armor, a breach in the protective barrier poses a danger. The skin can be breached when a child skins a knee or an adult has blood drawn—one is accidental and the other medically necessary. However, you also breach this barrier when you choose to "accessorize" your skin with a tattoo or body piercing. Because the needles involved in producing body art and piercings must penetrate the skin, there are dangers associated with the practice. These include allergic reactions; skin infections; blood-borne diseases, such as tetanus, hepatitis C, and hepatitis D; and the growth of scar tissue. Despite the risk, the practice of piercing the skin for decorative purposes has become increasingly popular. According to the American Academy of Dermatology, 24 percent of people from ages 18 to 50 have a tattoo.

If you cut yourself and bacteria enter the wound, which of the following cells would help get rid of the bacteria?

Langerhans cells

Describe the structure and composition of nails.

Nails are composed of densely packed dead keratinocytes. They protect the fingers and toes from mechanical stress. The nail body is formed on the nail bed, which is at the nail root. Nail folds, folds of skin that overlap the nail on its side, secure the nail to the body. The crescent-shaped region at the base of the nail is the lunula.

Why do people sweat excessively when exercising outside on a hot day?

Sweating cools the body when it becomes warm. When the body temperature rises, such as when exercising on a hot day, the dermal blood vessels dilate, and the sweat glands begin to secrete more sweat. The evaporation of the sweat from the surface of the skin cools the body by dissipating heat.

The skin consists of two layers and a closely associated layer. View this animation to learn more about layers of the skin. What are the basic functions of each of these layers?

The epidermis provides protection, the dermis provides support and flexibility, and the hypodermis (fat layer) provides insulation and padding.

Integumentary System

The first thing a clinician sees is the skin, and so the examination of the skin should be part of any thorough physical examination. Most skin disorders are relatively benign, but a few, including melanomas, can be fatal if untreated. A couple of the more noticeable disorders, albinism and vitiligo, affect the appearance of the skin and its accessory organs. Although neither is fatal, it would be hard to claim that they are benign, at least to the individuals so afflicted.

What determines the color of skin, and what is the process that darkens skin when it is exposed to UV light?

The pigment melanin, produced by melanocytes, is primarily responsible for skin color. Melanin comes in different shades of brown and black. Individuals with darker skin have darker, more abundant melanin, whereas fair-skinned individuals have a lighter shade of skin and less melanin. Exposure to UV irradiation stimulates the melanocytes to produce and secrete more melanin.

Explain your skin's response to a drop in body core temperature.

When the core body temperature drops, the body switches to heat-conservation mode. This can include an inhibition to excessive sweating and a decrease of blood flow to the papillary layers of the skin. This reduction of blood flow helps conserve body heat.

The hair matrix contains ________.

a layer of basal cells

keratohyalikn

accumluats lamellar granulles within cells - nuclei an other cell organelles disintegrate as cells die leave beyhind keratin, keratohyalin and cell membranes

men

accumrate fat in differen areas- abdomen, neck, arms and lower back

anagen

active phase of the hair growth cycle - shed replced by new hair -- rapid cell divide root of hair, pushes hair shaft up and out --- 2 to 7 years.

`Eccrine sweat glands ________.

are present in the skin throughout the body and produce watery sweat

Bedsores ________.

are preventable by eliminating pressure points

In response to stimuli from the sympathetic nervous system, the arrector pili ________.

are responsible for goose bumps

lunula

basal part of the nail body that consists of a crescent-shaped layer of thick epithelium - little moon -

skin

belongs to one of the body's most essential and dymain systems: integumentary system

women

breats hip thighs buttock

In general, skin cancers ________.

can be reduced by limiting exposure to the sun

hair follicle

cavity or sac from which hair originates

melanocyte

cell found in the stratum basale of the epidermis that produces the pigment melanin -

keratinocyte

cell that produces keratin and is the most predominant type of cell found in the epidermis - manufactures and stores protein keratin --- stratum corneum area dead and regularly slough away and gets replaced by cells from deeper layers

eleiden

clear protein-bound lipid found in the stratum lucidum that is derived from keratohyalin and helps to prevent water loss- clean protein rich in lipids

scar

collagen-rich skin formed after the process of wound healing that is different from normal skin

beneath the dermis lies the hypodermis

composed mainly of loose connective and fatty tissues

epidermis

composed of keratnized, stratified squamous epithelium- made of four or five layers of epithelial cells depending on its location in the body - does not have any blood vessels within it - it is AVASCULAR

vitamin D

compound that aids absorption of calcium and phosphates in the intestine to improve bone health - our epidermal layer synthesizes vitamen d when exposed to UV radiation- sunlight.

The papillary and reticular layers of the dermis are composed mainly of ________.

connective tissue

hypodermis

connective tissue connecting the integument to the underlying bone and muscle - subcutaneous layer or superficial fascia - below dermis and serves to connect skin to underlying fascia (fibrous tissue) of bones and muscles - not part of skin border between hypodermia dn dermis

dermis

core of integumentary system - distinct from epidermis, hypodermis - contains blood and lymph vessels, nerves and other structures such as hair follcles and sweat glands

reticular layer

deeper layer of the dermis; it has a reticulated appearance due to the presence of abundant collagen and elastin fibers -- irregular connective tissue - well vascularized and has rich sensory and sympathetic nerve supplies -- tight meshwork of fibers

stratum basale (stratum germinativum)

deepest layer of the epidermis, made of epidermal stem cells- attached epidermis to basal lamina- below lie layers of the dermis

hair texture (sraight/curly)

determinated by shape and strcture of structure of the cortex

fat

distribution changes when we mature and age

unstained epidermis

do not exhibit characteristic appearance

stratum spinosum

eight to 10 layers of keratinocytes

stratum granulosum

grainy appearance due to changes to karetinocytes pushed from strum spinosum - three to five layers - become flatter their cell membranes thicken, generate large amoutn of proterin keratin

kertohyalin

granulated protein found in the strtum granulosum

hair root ends deep in the dermis - layer of mitotically active basal cells

hair bulb

Which protein makes hair, skin and nails hard and water resistant?

keratin

Squamous cell carcinomas are the second most common of the skin cancers and are capable of metastasizing if not treated. This cancer affects which cells?

keratinocytes of the stratum spinosum

hair

keratinous filament growing out of the epidermis- made of dead, keratinized cells

skin

made of tissues

nail body

main keratinous plate that forms the nail--- formed on the nail bed protecting our toes and fingers --

melanin

pigment that determines the color of hair and skin - protects living cells of epidermis from ultraviolet radiation damage --- Eumelanin exists as black and brown, pheomelanin- red color. dark skinned produce more melanin than pale skin. UV rays - sun or tanning salons causes melanin to built up keratinocystes. Melanin protects DNA damager from UV rays -- 10 days after initial sun exposure for melanin synthesis to peak- why pale skinned suffer from sunburns. Dark skinned are more proteted.

What is the basic role of the epidermis?

protection

skin

protects inner organs and daily care and protects maintaining it's health

Which of the following is not a function of the hypodermis?

source of blood vessels in the epidermis

langerhans cell

specialized dentritic cell found in the stratum spinosum that functions as a macrophage - engulfs bateria , foreign particles and damged cells that occur in this layer

metastasis

spread of cancer cells from a source to other parts of the body. In general, cancers result from an accumulation of DNA mutations. These mutations can result in cell populations that do not die when they should and uncontrolled cell proliferation that leads to tumors. Although many tumors are benign (harmless), some produce cells that can mobilize and establish tumors in other organs of the body; this process is referred to as

Which layer attaches the epidermis to the basal lamina?

stratum basale

Pacinian corpuscle

(also, lamellated corpuscle) receptor in the skin that responds to vibration , MERKET CELL scattered in stratum basale, touch repectors

Meissner corpuscle

(also, tactile corpuscle) receptor in the skin that responds to light touch ---

sweats

500 ml of sweat are secreted a day

animals

pattern of storing excess calories as fats- food is not readily availabe

skin

protects inner organs and needs daily care and protection to maintain it's health

Merkel cell

receptor cell in the stratum basale of the epidermis that responds to the sense of touch - sensory nerves that the brain perceives as touch -- ex hands and feet are abundant

human body

skin makes up 16% of body weight and covers an area og 1.5 to 2 m2

Collagen lends ________ to the skin.

structure

fingerprints

unique to each individual - patterns do not change with growth and aging process

deeper layer of skin

vascularized (has numerous blood vessels)

In humans, exposure of the skin to sunlight is required for ________.

vitamin D synthesis `

elastin fibers

fibers made of the protein elastin that increase the elasticity of the dermis -- enables movement

epidermis

outermost tissue layer of the skin

integumentary system

refers to skin and its accessory structures, responsible for much more than simply lending to your outward appearance

The papillary layer of the dermis is most closely associated with which layer of the epidermis?

stratum basale

Doctors often give their patients the following ABCDE mnemonic to help with the diagnosis of early-stage melanoma. If you observe a mole on your body displaying these signs, consult a doctor.

Asymmetry - the two sides are not symmetrical Borders - the edges are irregular in shape Color - the color is varied shades of brown or black Diameter - it is larger than 6 mm (0.24 in) Evolving - its shape has changed Some specialists cite the following additional signs for the most serious form, nodular melanoma: Elevated - it is raised on the skin surface Firm - it feels hard to the touch Growing - it is getting larger

Explain the differences between eccrine and apocrine sweat glands.

Eccrine sweat glands are all over the body, especially the forehead and palms of the hand. They release a watery sweat, mixed with some metabolic waste and antibodies. Apocrine glands are associated with hair follicles. They are larger than eccrine sweat glands and lie deeper in the dermis, sometimes even reaching the hypodermis. They release a thicker sweat that is often decomposed by bacteria on the skin, resulting in an unpleasant odor.

The accessory structures also have lowered activity, generating thinner hair and nails, and reduced amounts of sebum and sweat. A reduced sweating ability can cause some elderly to be intolerant to extreme heat. Other cells in the skin, such as melanocytes and dendritic cells, also become less active, leading to a paler skin tone and lowered immunity. Wrinkling of the skin occurs due to breakdown of its structure, which results from decreased collagen and elastin production in the dermis, weakening of muscles lying under the skin, and the inability of the skin to retain adequate

Many anti-aging products can be found in stores today. In general, these products try to rehydrate the skin and thereby fill out the wrinkles, and some stimulate skin growth using hormones and growth factors. Additionally, invasive techniques include collagen injections to plump the tissue and injections of BOTOX® (the name brand of the botulinum neurotoxin) that paralyze the muscles that crease the skin and cause wrinkling.

Why do scars look different from surrounding skin?

Scars are made of collagen and do not have the cellular structure of normal skin. The tissue is fibrous and does not allow for the regeneration of accessory structures, such as hair follicles, and sweat or sebaceous glands.Scarring occurs in cases in which there is repair of skin damage, but the skin fails to regenerate the original skin structure. Fibroblasts generate scar tissue in the form of collagen, and the bulk of repair is due to the basket-weave pattern generated by collagen fibers and does not result in regeneration of the typical cellular structure of skin. Instead, the tissue is fibrous in nature and does not allow for the regeneration of accessory structures, such as hair follicles, sweat glands, or sebaceous glands.

This ABC video follows the story of a pair of fraternal African-American twins, one of whom is albino. Watch this video to learn about the challenges these children and their family face. Which ethnicities do you think are exempt from the possibility of albinism?

There are none.

Sebaceous glands ________.

are associated with hair follicles

fourth-degree burn

burn in which full thickness of the skin and underlying muscle and bone is damaged ddly, third and fourth-degree burns are usually not as painful because the nerve endings themselves are damaged. Full-thickness burns cannot be repaired by the body, because the local tissues used for repair are damaged and require excision (debridement), or amputation in severe cases, followed by grafting of the skin from an unaffected part of the body, or from skin grown in tissue culture for grafting purposes.

third-degree burn

burn that penetrates and destroys the full thickness of the skin (epidermis and dermis)These are serious burns that may appear white, red, or black; they require medical attention and will heal slowly without it

basal cell carcinoma

cancer that originates from basal cells in the epidermis of the skin--- form of cancer that affects mitotically active stem cells in the stratum basale of the epidermis -- common on head, neck, arms and back --- ex onset of puberty due to associated hormonal changes, but can also occur in infants and continue into adulthood. Hormones, such as androgens, stimulate the release of sebum. An overproduction and accumulation of sebum along with keratin can block hair follicles. This plug is initially white. The sebum, when oxidized by exposure to air, turns black. Acne results from infection by acne-causing bacteria (Propionibacterium and Staphylococcus), which can lead to redness and potential scarring due to the natural wound healing proces

rickets

disease in children caused by vitamin D deficiency, which leads to the weakening of bones--- painful condition in children bones are misshapen due to lack of calcium, causing bowleggedness (who suffer from vitamin D deficiency can develop a condition called osteomalacia, a softening of the bones. In present day society, vitamin D is added as a supplement to many foods, including milk and orange juice, compensating for the need for sun exposure.

An individual has spent too much time sun bathing. Not only is his skin painful to touch, but small blisters have appeared in the affected area. This indicates that he has damaged which layers of his skin?

epidermis and dermis

skin is composed of two main layers

epidermis, made of closely packed epithelial cells, and the dermis made of dense irregular connective tissues that house blood vessels, hair follicles, sweat glands, and other structures.

dermal papilla

extenion of the papillary layer of the dermis that increases surface contact between the epidermis and dermis - finger like projection/fold- strength of connection

fetus

fingerprints form where cells of stratum basale meet papillae of underlying dermal layer - formation of ridges on fingers

nail fold

fold of epithelium at that extend over the sides of the nail body, holding it in place -- overalps nail on sides helping anchor nail body

nail cuticle

fold of epithelium that extends over the nail bed, also called the eponychium --- proximal end of nail body

one of the functions of the integumentary system is protection. Which of the following does not directly contribute to that function?

folic acid synthesis

medulla

forms central core of the hair surrounded by cortex

Thick skin

found on palms of hands and soles of the feet - fifth layer is strtum lucidum - located between strtum corneum and stratum granulosum

albinism

genetic disorder that affects the skin, in which there is no melanin production. ex: Individuals with albinism tend to appear white or very pale due to the lack of melanin in their skin and hair. Recall that melanin helps protect the skin from the harmful effects of UV radiation. Individuals with albinism tend to need more protection from UV radiation, as they are more prone to sunburns and skin cancer. They also tend to be more sensitive to light and have vision problems due to the lack of pigmentation on the retinal wall. Treatment of this disorder usually involves addressing the symptoms, such as limiting UV light exposure to the skin and eyes.

strands of hair originate in an epidermal penetration of the dermis- three concentric layers of cells

hair follicle

includes layer of mitotically active basal cells referred to active basal cells

hair matrix

hair bulb, made of connective tissue and contains blood capillaries and nerve endings from the dermis

hair papila

lipid storage example

hypodermis is to maintain weight under control. adipose tissue consits of fat storing cells store energy reserve, insulate body to prevent heat loss, and act as cushion to protect underlying structures from trauma

Similar to the hair, nails grow continuously throughout our lives. Which of the following is furthest from the nail growth center?

hyponychium

medulla

in hair, the innermost layer of keratinocytes originating from the hair matrix

cuticle

in hair, the outermost layer of keratinocytes originating from the hair matrix, as seen in a cross-section of the hair bulb

cortex

in hair, the second or middle layer of keratinocytes originating from the hair matrix, as seen in a cross-section of the hair bulb

After a skin injury, the body initiates a wound-healing response. The first step of this response is the formation of a blood clot to stop bleeding. Which of the following would be the next response?

increased production of connective tissue

internal root sheath

innermost layer of keratinocytes in the hair follicle that surround the hair root up to the hair shaft - extend up to hair shaft and derived from hair matrix

melanosome

intercellular vesicle that transfers melanin from melanocytes into keratinocytes of the epidermis -- pigments (melanin, carotene, hemoglobin) -- scattered throughout stratum basale of epidermis via cellular vesicle -- temporary structures that are destroyed by fusion with lysosomes-- when tanning impermannet

hair

keratinous filament growing out of the epidermis - protects sensory input, thermoregularion, and communication- helps with skull from sin. Hair in nose and eas, eyelashes- defends body by trapping exclusing dust particles that contain allergens and microbes. Hair eyesbrows prevents sweat and other particles from dripping into bothering eyes. Hair is sensitive to air movemnt and other distubrances in environment.

skin

largest organ system in the human body

hair matrix

layer of basal cells from which a strand of hair grows

cortex

layer of compressed keratinized cells that is covered by an outer layer of very yhard keratinized cells ---> cuticle

glassy membrane

layer of connective tissue that surrounds the base of the hair follicle, connecting it to the dermis - thick, clear connetive tissue sheath covering hair rooth, connects tissue of dermis

nail bed

layer of epidermis upon which the nail body forms - tips of fingers and toes - pink pigment except at base

dermis

layer of skin between the epidermis and hypodermis, composed mainly of connective tissue and containing blood vessels, hair follicles, sweat glands, and other structures

stratum lucidum

layer of the epidermis between the stratum granulosum and stratum corneum, found only in thick skin covering the palms, soles of the feet, and digits -- Smooth- translucent layer located above stratum granulosum and below stratum corneum - thin layer found only in thick skin of palms , soles and digits

stratum spinosum

layer of the epidermis superficial to the stratum basale, characterized by the presence of desmosomes - spiny apperance due to protuding cell process that join the cells via structure

stratum granulosum

layer of the epidermis superficial to the stratum spinosum

Deep to superficial

layers are stratum basale, stratum spinosum, stratum ganulosum, and stratum corneum

layers are

longitudinal cross section of hair folicle

stretch mark

mark formed on the skin due to a sudden growth spurt and expansion of the dermis beyond its elastic limits. a cancer that affects the keratinocytes of the stratum spinosum and presents as lesions commonly found on the scalp, ears, and hands (Figure). It is the second most common skin cancer. as the skin stretches to accommodate the excess pressure. Stretch marks usually accompany rapid weight gain during puberty and pregnancy. They initially have a reddish hue, but lighten over time. Other than for cosmetic reasons, treatment of stretch marks is not required. They occur most commonly over the hips and abdomen.

hair papilla

mass of connective tissue, blood capillaries, and nerve endings at the base of the hair follicle

body max index BMI

measure of fat,

dermatologists

medical doctors who specialize in diagnosing and treating skin disorders.

stratum corneum

most superficial layer of the epidermis layer is also exposed outside environment ---- 15 to 30 layers of cell - dry dead layer prevent penetration of microbes and drhydration of underlying tissues provides protection again abrasion more delicate underlying layers - sheds periodically and replaced pushed up stratum ganulosum -- replacing takes 4 weeks ... to loook fresh

skin

multiple layers of cells and tissues underlying structures by connective tissue

eponychium

nail fold that meets the proximal end of the nail body, also called the cuticle

sebum

oily substance that is composed of a mixture of lipids that lubricates the skin and hair - lkepps it pliable

Skin belongs

one of the body's most essential and dynamic systems - integumentary system

external root sheath

outer layer of the hair follicle that is an extension of the epidermis, which encloses the hair root

An individual using a sharp knife notices a small amount of blood where he just cut himself. Which of the following layers of skin did he have to cut into in order to bleed?

papillary dermis

hair shaft

part of hair that is above the epidermis but is not anchored to the follicle

hair root

part of hair that is below the epidermis anchored to the follicle

hair shaft

part of the hair not anchored to the follicle, and much of this is exposed at the skin's surface

nail root

part of the nail that is lodged deep in the epidermis from which the nail grows - matrix of proliferating cells from the stratum bvasle that enables nail to grow continuously

second-degree burn

partial-thickness burn that injures the epidermis and a portion of the dermis-- These burns result in swelling and a painful blistering of the skin. It is important to keep the burn site clean and sterile to prevent infection. If this is done, the burn will heal within several weeks

hair root

rest of the hair, anchored in the follicle, lies below the surface of the skin

telogen

resting phase of the hair growth cycle initiated with catagen and terminated by the beginning of a new anagen phase of hair growth -- hair follicle is at rest and no new groth occurs -- end of phase lasts about 2 to 4 months, angen phase begins --- hair grows at .3 mm perday during anagen phase.. 50 hairs are lost and replaced per day

burn

results when the skin is damaged by intense heat, radiation, electricity, or chemicals. The damage results in the death of skin cells, which can lead to a massive loss of fluid. Dehydration, electrolyte imbalance, and renal and circulatory failure follow, which can be fatal. Burn patients are treated with intravenous fluids to offset dehydration, as well as intravenous nutrients that enable the body to repair tissues and replace lost proteins. Another serious threat to the lives of burn patients is infection. Burned skin is extremely susceptible to bacteria and other pathogens, due to the loss of protection by intact layers of skin.

integumentary system

skin - accessory stuctures = provides protection

integumentary system

skin and its accessory structures

eczema

skin condition due to an allergic reaction, which resembles a rash--- Acne involves the clogging of pores, which can lead to infection and inflammation, and is often seen in adolescents. Other disorders, not discussed here, include seborrheic dermatitis (on the scalp), psoriasis, cold sores, impetigo, scabies, hives, and warts. It may be accompanied by swelling of the skin, flaking, and in severe cases, bleeding. Many who suffer from eczema have antibodies against dust mites in their blood, but the link between eczema and allergy to dust mites has not been proven. Symptoms are usually managed with moisturizers, corticosteroid creams, and

acne

skin condition due to infected sebaceous glands

vitiligo

skin condition in which melanocytes in certain areas lose the ability to produce melanin, possibly due an autoimmune reaction that leads to loss of color in patches

adult human body

skin makes up 16% of the bodies weight and covers an area of 1.5 to 2 m2

thin skin

skin that has FOUR layers of cells

arrector pili

smooth muscle that is activated in response to external stimuli that pull on hair follicles and make the hair "stand up" --- contracts response to nerve signals from sympathetic nervous system making external hair stand up -- trap air add insulation-- such as goose bumps or cat raises fur

bedsore

sore on the skin that develops when regions of the body start necrotizing due to constant pressure and lack of blood supply; also called decubitis ulcers. , long-term, unrelieved pressure on certain body parts that are bony, reducing blood flow to the area and leading to necrosis (tissue death). Bedsores are most common in elderly patients who have debilitating conditions that cause them to be immobile. Most hospitals and long-term care facilities have the practice of turning the patients every few hours to prevent the incidence of bedsores. If left untreated by removal of necrotized tissue, bedsores can be fatal if they become infected.

As you are walking down the beach, you see a dead, dry, shriveled-up fish. Which layer of your epidermis keeps you from drying out?

stratum corneum

Langerhans cells are commonly found in the ________.

stratum spinosum

hair bulb

structure at the base of the hair root that surrounds the dermal papilla

desmosome

structure that forms an impermeable junction between cells - interlock with each other and strengthen bond between cells - spiny nature staining process

first-degree burn

superficial burn that injures only the epidermis-- may be painful and swollen, these burns typically heal on their own within a few days. Mild sunburn fits into the category of a first-degree burn.

papillary layer

superficial layer of the dermis, made of loose, areolar connective tissue - collagen and elastin fibers ofthis layer form a loose mesh - contains phagocytes, defensive cells help fight bacteria or other infections that breach the skin -- could also be called lymphatic capillaries, nerve fibers, touch receptors-- Meissner corpuscles

sudoriferous gland

sweat gland cool the body -- merocrine glands secretions are excreted by exocytosis through a duct without affect cells of gland

high temperatures

sweat glands are stimulated by sympaththetic nervous sysstem produces large amounts of sweat .7 to 1.5 L per hour for an active person . sweat evaporates from skin to surfrace of the body and body is cooled as body heat is dissipated

fat deposited and accumluated with hypodermis depends on hormones

testosterone, estrogen, insulin, glycagon, leptin and others - genetic factors

body temperatures drop

the arterioles constrict to minimize heat loss, particularly in the ends of the digits and tip of the nose. This reduced circulation can result in the skin taking on a whitish hue. Although the temperature of the skin drops as a result, passive heat loss is prevented, and internal organs and structures remain warm. If the temperature of the skin drops too much (such as environmental temperatures below freezing), the conservation of body core heat can result in the skin actually freezing, a condition called frostbite.

callus

thickened area of skin that arises due to constant abrasion. This occurs because the basal stem cells in the stratum basale are triggered to divide more often to increase the thickness of the skin at the point of abrasion to protect the rest of the body from further damage. This is an example of a minor or local injury, and the skin manages to react and treat the problem independent of the rest of the body. Calluses can also form on your fingers if they are subject to constant mechanical stress, such as long periods of writing, playing string instruments, or video games.

hyponychium

thickened layer of stratum corneum that lies below the free edge of the nail -

thermoregulation

tight association with sympathetic nervous system and division of nervous system associated with fight or flight responses . sympathetic nervous system monitors body temperature and initiates appropriate motor responses.

integumentary system

to the skin and its accessory structures- provides body with overall protection

catagen

transitional phase marking the end of the anagen phase of the hair growth cycle - 2 to 3 weeks marks transition from hair follicles active growth

dermis -

two layers of connective tissue- interconnects elastin and colagenous fibers - produced by fibroblasts

corn

type of callus that is named for its shape and the elliptical motion of the abrasive force

sebaceous gland

type of oil gland found in the dermis all over the body and helps to lubricate and waterproof the skin and hair by secreting sebum

keloid

type of scar that has layers raised above the skin surface. overproduction of scar tissue, because the process of collagen formation does not stop when the wound is healed;In contrast, scars that result from acne and chickenpox have a sunken appearance and are called atrophic scars.

melanoma

type of skin cancer that originates from the melanocytes of the skin.. Typically, a melanoma develops from a mole. It is the most fatal of all skin cancers, as it is highly metastatic and can be difficult to detect before it has spread to other organs. Melanomas usually appear as asymmetrical brown and black patches with uneven borders and a raised surface (Figure). Treatment typically involves surgical excision and immunotherapy.

squamous cell carcinoma

type of skin cancer that originates from the stratum spinosum of the epidermis

basal cell

type of stem cell found in the stratum basale and in the hair matrix that continually undergoes cell division, producing the keratinocytes of the epidermis - it's cuboidal shaped stem cell - precursor of keratincocytes of epidermis

keratin

type of structural protein that gives skin, hair and nails its hard, water-resistant properties - intracellular fibrous protein that gives hardness

apocrine sweat gland

type of sweat gland that is associated with hair follicles in the armpits and genital regions --- lie deep in dermis- reached hypodermis, duct empties hair follicle . water and salts- smell and bace4rial decomposition. both nervous and hormonal control- it is poorly misunderstood as human pheromone respohnse

eccrine sweat gland

type of sweat gland that is common throughout the skin surface; it produces a hypotonic sweat for thermoregulation -- glands are found all over skins surface such as palsm of hand, soles of feet, and forehead where sweat is releadest. coiled glands laying deep inside dermis- duct rising up pore on skin surface where sweat is released. sweat released by exocytosis hypotonic and coposed mostly of water, salt, antibodies, metabolic wates, dermicidin, antimicrobial peptide