Layers of the Dermis

how does excessive sun exposure physical effect the skin ?

causes elastic fibers to clump which results in leathery skin

which direction around the neck and the trunk ?

circular

what can carotene be converted into in the body ?

vitamin A, essential for normal vision and epidermal health

what is "pallor or blanching"

when people become pale due to fear, anger, or emotional distress. Pale skin may also signify anemia or low blood pressure

what are stretch marks actually called ?

"striae" meaning streaks

What percent of the dermis does the reticular layer account for ?

80%

What about the dermis binds the entire body together ? Making it like your "hide"

A semi fluid matrix embedded with fibers creates a body stocking

Dermis tissue is typical of ?

Any connective tissue proper

What kind of tissue makes up the papillary layer ?

Areole connective tissue

Where does the cutaneous plexus lie ?

Between the Reticular layer and the Hypodermis

What do dermal papillae contain ?

Capillary loops and others house free nerve endings (pain receptors) and touch receptors called tactile or Meissener's corpuscles

What does the reticular layer consist of ?

Coarse, dense irregular connective tissue

What are the network of blood vessels that nourishes this layer ?

Cutaneous plexus

What are peg like projections from the papillary layer ?

Dermal papillae

What are the function of friction ridges ?

Enhancing the gripping ability of fingers and feet like tire tread

List examples of the cells of connective tissue proper

Fibroblasts, macrophages, and occasional mast cells and white blood cells

Explain the makeup of papillary tissue ...

Fine interlocking collagen and elastic fibers form a loosely woven mat that is heavily invested in small blood vessels

What are these skin ridges known as collectively

Friction ridges

What are friction ridge patterns determined by ?

Genetics

Is the papillary layer thick or thin ?

It is a thin superficial layer (to the reticular layer)

In thick skin such as the soles of the feet and palms of the hands what do these papillae lie on top of ?

Larger mounds called "dermal ridges"

What wanders around this loose connective tissue layer looking for bacteria and other offenders that may have penetrated the skin ?

Phagocytes

The dermis has a rich supply of what ?

Nerve fiber, blood vessels, and lymphatic vessels

What are the two layers of the dermis ?

Papillary layer and Reticular layer that lie next to each other along and indistinct boundary

Collagen fibers run in various planes but most run which way ?

Parallel to the skin surface

What does the extra cellular matrix of the reticular layer contain ?

Pockets of adipose cells and thick bundles of interlacing collagen fibers

What else do they contribute to ?

Sense of touch, amplifying vibrations detected by the large lamellar corpuscles (receptors) in the dermis

What is the Dermis made of ?

Strong flexible connective tissue

How are finger prints created ?

Sweat pores open along the crests of friction ridges leaving identifying films of sweat called fingerprints

Is the Reticular layer thick or thin ?

THICK

The major portions of hair follicles, oil and sweat glands derive feom epidermal tissue but actually reside where ?

The dermis

What do dermal ridges cause ?

They cause the epidermis to form epidermal ridges

what is "bronzing"

a bronze metallic appearance in the skin, a sign of addison's disease, where the adrenal cortex produces inadequate amounts of it's steroid hormones , also a sign of pituitary gland tumors that inappropriately secrete melanocyte stimulating hormone (MSH)

what is cyanosis ?

a condition in caucasians where the hemoglobin is poorly oxygenated and the blood and skin appears blue

why are cleavage lines important to surgeons ?

because when an incision is made parallel to these lines the skin gapes less and heals more readily

what is melanin ?

a polymer made of tyrosine amino acids, it's two forms range in reddish yellow to brownish black

what is "jaundice or yellow cast"

a yellow skin tone that signifies a liver disorder, yellow bile pigments accumulate in the blood and are deposited in the body tissues

what is carotene ?

a yellow to orange pigment found in certain plant products such as carrots

what chemicals tend to induce skins sensitivity to UV radiation ?

antibiotics, antihistamine drugs, and chemicals in perfumes and detergents

where do people with light skin tend to evolve from ?

closer to the poles

what consequences does ultraviolet radiation have ?

destroys the bodies folic acid that is necessary for DNA synthesis, this could effect pregnant women because folic acid is necessary for the embryos nervous system to develop

when does skin become cyanotic ?

during heart failure and severe respiratory disorders

name appendages of the skin...

hair follicles, hair, nails, sweat glands, and sebaceous glands

where is melanin pigment only found ?

in the deeper layers of the epidermis

since the masking effects of melanin do not show signs of cyanosis in dark skinned people how would you physically be able to tell that it is occurring ?

in the mucous membranes and nail beds

where is carotenes color most obvious ?

in the palms and soles of the feet where the stratum corneum is thickest, it is most intense when large amounts of carotene filled foods are eaten

where does carotene accumulate ?

in the stratum corner in the fatty tissues of the hypodermis

what is hemoglobin?

it is the oxygenated pigment in the red blood cells circulating through the dermal capillaries, it is the crimson color that is reflected as the pinkish hue that fair skin reflects

since all humans have the same relative number of melanocytes why are there differences in skin coloring ?

it reflects the kind and amount of melanin made and retained

melanin synthesis depends on an enzyme in melanocytes called tyrosinase it passes from melanocytes to where?

keratinocytes

what are freckles and pigmented nevi (moles) ?

local accumulations of melanin

which way do these externally invisible lines run on the head and the limbs ?

longitudinally

what do these appendages help do for the body ?

maintain homestasis

which of the three is made in the skin?

melanin

dark skinned people get skin cancer less often than light skinned people and when they do it is on the souls of their feet, an nail beds ....what does this attest to ?

melanin's effectiveness as a natural sunscreen

what determines skin color ?

melanin, carotene and hemoglobin

melanocytes of black or brown skinned individuals produce many more what than light skinned people ?

melanosomes

where are people with darker people skin usually found ?

nearer the equator where greater protection from the sun is needed

describe "redness, or erythema"

reddened skin that may indicate embarrassment , fever, or hypertension, inflammation or allergy

what are cleavage lines ?

seperations or less dense regions between interlacing collagen fiber bundles form cleavage tension lines

what happens in theses reactions ?

small blisters that that peel off in sheets

what do collagen fibers of the dermis give skin ?

strength and resiliency that prevent minor jabs and scrapes from penetrating the dermis. It also binds water helping to keep skin hydrated

what do elastic fibers provide ?

stretch and recoil properties of skin

we all have the same number of keratinocytes but what happens in darker skinned individuals ?

their keratinocytes retain longer

what is "black and blue marks or bruises"

these reveal where blood has escaped from circulation and clotted beneath the skin, these blood clots are known as homatomas (meaning blood swelling)

when we expose our skin to sunlight how does that effect keratinocytes ?

they secrete chemicals that stimulate melanocytes, prolonged sun exposure causes melanin build up which helps protect the DNA of viable skin cells from UV radiation by absorbing the rays and dissipating the the energy as heat