Which layer of the skin - dermis or epidermis - is better nourished?

The dermis is connective tissue, which is vascular, so its cells would be better nourished than those of the epidermis, which is avasular epithelium.

While walking barefoot, Jeremy stepped on a rusty nail that penetrated the epidermis. Name the layers the nail pierced from the superficial skin surface to the junction with the dermis.

Since the sole of the foot has thick skin, the layers from most superficial to deepest would be the stratum corneum, stratum lucidum, stratum granulosum, stratum spinsosum, and stratum basale.

What is the major function of the stratum basale?

The stratum basale undergoes almost continuous mitosis to replace cells lost by abrasion.

Why are the desmosomes and tight junctions connecting the keratinocytes so important?

The skin is subjected to a lot of abrasion and physical trauma. The demosomes, which are connecting junctions, help to hold the cells together during such stress. The tight junction helps to reduce water movement through the skin.

Suppose that the dead cells of the stratum corneum did not shed from your body, but rather stuck to it and continued to accumulate. What problems might this cause?

Some possible answers to this question are:

1. You would either be unable to grow, or there would be big cracks in the stratum corneum as you grow.

2. The thickness of the skin would impede joint movement so it would be hard to move.

3. You could not be able to lose heat through your skin as effectively as you do now.

4. Your skin would be very heavy to carry around after a while.

What typoe of tissue makes up the papillary and reticular dermis?

The papillary dermis consist of areolar connective tissue, and the reticular dermis consist of dense irregular connective tissue.

You have just gotten a paper cut. It is very painful, but it doesn't bleed. Has the cut penetrated into the dermis or just the epidermis?

Because there is no bleeding, the cut has penetrated into the avascular epidermis only.

Stefan's front bike tire slipped on a patch of gravel as he road to work. He needed five stitches to close the cut above his left eye. The split skin ran along the cleavage line. Is Stephan likely to have a major scar or is the wound likely to heal cleanly? Explain

Since Stefan's wound runs along a cleavage line, it is likely to heal much more cleanly than it would if it ran perpendicular in the cleavage lines.

chart of dermis and epidermis labeled

Melanin and carotene are two pigments that contribute to skin color. What is the third and where is it found?

The third pigment that contributes to skin color is hemoglobin, the pigment contained in read blood cells found in blood vessels of the dermis.

Which alteration in skin color may indicate a liver disorder?

Jaundice, a yellow cast to the skin due to the deposit of yellow bile pigments in the body tissues, may indicate a liver disorder.

Why is having you hair cut painless?

There are no nerves in the hair, so cutting hair is painless.

Hair follicle diagram

What are the three concentric regions of the hair follicle?

Why is the lunule of the nail white instead of pink like the rest of the nail?

The lunule of the nail is white because the thick nail matrix that underlies it blocks the rosy color of the dermal blood supply from showing through.

Why are nails so hard?

Nails are hard because the keratin they contain is the hard keratin variety.

Which cutaneous glands are associated with hair follicles?

Sebaceous glands and apocrine glands are associated with hair follicles.

When Anthony returned home from a run in 85 degree weather, his face was dripping with sweat. Why?

His autonomic nervous system activated his eccrine sweat glands and caused heat-induced sweating in order to cool the body.

What is the difference between heat-induced sweating and "cold sweat", and which variety of sweat glands is involved?

Heat-induced sweating occurs all over the body when we are overheated. A cold sweat is emotionally induced sweating that begins on the palms, soles, and armpits and then spreads to other body areas. Both types of sweating are primarily produced by the eccrine sweat glands.

Sebaceous glands are not found in thick skin. Why is their absence in those body regions desirable?

The palms of the hands and soles of the feet are thick skin areas. It would be dangerous to have oily soles, and oily palms would decrease the ability of the hands to hang onto things.

What chemicals produced in the skin help provide barriers to bacteria? List at least 3 and explain how the chemicals are protective.

The low pH of the skin secretions (acid mantle) inhibits division of bacteria, and many bacteria are killed by dermcidin in sweat, bactericidal substances in sebum, or natural antibiotics called defensins produced by skin cells. Damaged skin secretes cathelicidins that are effective against a certain strain of strep bacteria.

Which epidermal cells play a role in body immunity?

The epidermal dendritic cells play a role in body immunity

How is sunlight important to bone health?

Sunlight causes the skin to produce a precursor of vitamin D from cholesterol. Vitamin D is essential for absorption of calcium from the diet, and calcium is a major component of bone.

When blood vessels in the dermis constrict or dilate to help maintain body temperature, which type of muscle tissue that you learned about in histology acts as the effector that causes blood vessel dilation or constriction?

The effector in this case is smooth muscle

Which type of skin cancer develops from the youngest epidermal cells?

Basal cell carcinoma develops from the youngest epidermal cells

What name is given to the rule for recognizing the signs of melanoma?

The ABCD rule helps one to recognize signs of melanoma

The healing of burns and epidermal regeneration is usually uneventful unless the burn is a third-degree burn. What accounts for this difference?

First and second degree burns can be healed uneventfully by regeneration of epidermal cells as long as infection does not occur. Third degree burns destroy the entire depth of skin and regeneration is usually not possible. Infection and loss of body fluid and proteins make recovery problematic.

Although the anterior head and face represent only a small percentage of the body surface, burns to this area are often more serious than those to the body trunk. Why?

Burns to the face are serious because damage to the respiratory passageways can occur in such burns.

Which epidermal cell type is most numerous?

keratinocyte

Which cell functions as part of the immune system?

dendritic cell

The epidermis provides a physical barrier due largely to the presence of?

keratin

Skin color is determined by?

a. the amount of blood

b. pigments

c. oxygenation level of blood

The sensations of touch and pressure are picked up by receptors located in?

the dermis

Which is not a true statement about the papillary dermis?

a. it is largely areolar connective tissue

b. it is most responsible for the toughness of the skin

c. it contains nerve endings that respond to stimuli

d. it is highly vascular

b. it is most responsible for the toughness of the skin

Which of the following is not an epidermal derivative?

a. hair

b. sweat gland

c. sensory receptor

d. sebaceous gland

c. sensory receptor

An arrector pili muscle?

can cause a hair to stand up straight

The product of this type of sweat gland includes protein and lipid substances that become odoriferous as a result of bacterial action?

apocrine gland

Sebum

a. lubricates the surface of the skin and hair

b. consists of cell fragments and fatty substances

c. in excess may cause seborrhea

The rule of nines is helpful clinically in?

estimating the extent of a burn

Distinguish clearly between first, second and third degree burns.

First degree burns damage only the epidermis, second degree burns damage the epidermis and the upper region of the dermis, and third degree burns damage the entire thickness of the skin (the entire epidermis and dermis)

Why does skin wrinkle and what accelerates the wrinkling process?

Wrinkling is due to the loss of the elasticity of the skin along with the loss of the subcutaneous tissue, and is hastened by exposure to the sun.

Which epidermal cells contain keratonhyaline and lamellar granules?

Stratum granulosum, 3-5 cell layers, contains diamond shaped cells with keratohyalin granules and lamellar granules.

Is a bald man really hairless? Explain

No, the follicular growth cycles become so short that many hairs never even emerge from their follicles before shedding.

Count Dracula, the most famous vampire, rumored to have killed at least 200k people, was based on a real person who lived in eastern Europe about 600 years ago. he was indeed a monster, although he was not a real vampire. The historical Count Dracula may have suffered from?

(a) Porphyria- Certain enzymes needed to form the heme of hemoglobin of blood are lacking. Without the enzymes, metabolic intermediates of the heme pathway called porphyrins build up, spill into the circulation, and eventually cause lesions throughout the body, especially when exposed to sunlight. The fingers, toes, and nose are disfigured, gums degenerate and teeth become prominent.

On an outline diagram of the human body, mark off various regions according to the rule of nines. What percentage of the total body surface is effected if the skin over the following body parts is burned?

Several methods are available to estimate the percentage of total body surface area burned. Rule of Nines - The head represents 9%, each arm is 9%, the anterior chest and abdomen are 18%, the posterior chest and back are 18%, each leg is 18%, and the perineum is 1%

Dean, a 40-year old aging beach boy, is complaining to you that although his suntan made him popular when he was young, now his face is all wrinkled, and he has several darkly pigmented moles that are growing rapidly and are as big as large coins. He shows you the moles, and immediately you think "ABCD". What does that mean and why should he be concerned?

ABCD the rule for melanoma recognition.

Patients with third-degree burns demonstrate the loss of vital functions performed by the skin. What are the two most important problems encountered clinically with such patients? Explain each in terms of the absence of skin.

The two most important problems encountered clinically with a victim of third-degree burns
are a loss of body fluids resulting in dehydration and an electrolyte imbalance, and the risk of
infection. Intact skin effectively blocks not only the diffusion of water and water-soluble
substances out of the body, but acts as a barrier limiting the invasion of various
microorganisms.

You go to the beach to swim on an extremely hot, sunny summer afternoon. Describe two ways in which your integumentary system acts to preserve homeostasis during your outing.

Chemical barriers of protection: Melanin provides a chemical pigment shield to prevent UV damage to skin cells.
Body temperature regulation: The body releases sweat (body heat) and as that evaporates off the skin it cools the body.

Describe the process of hair formation, and list several factors that may influence

a. growth cycles

b. hair texture

Each follicle goes through growth cycles. In the regressive phase, the hair matrix cells die and the follicle base and hair bulb shrivel somewhat, dragging the hair papilla upward to abut the region of the follicle that does not regress. The follicle enters a resting phase for one to three months. The cycling part of the follicle regenerates and the matrix proliferates again and forms a new hair to replace the old one that has fallen out or will be pushed out by the new hair.

Explain each of these familiar phenomena in terms of what you learned in this chapter.

a. pimples

b. dandruff

c. greasy hair and "skinny nose"

d. stretch marks from gaining weight

e. freckles

(a) Accumulated sebum blocks a sebaceous gland duct, a white head appears. If the material oxidizes and dries, it darkens to form a blackhead.
(b) Shingle-like cell remnants of the stratum corneum (cornified cells).
(c) The arrector pili muscle contracts to force sebum out of the hair follicles on to the skins surface (shiny nose), and the sebum directly on the hair shaft results in greasy hair.
(d) Silvery white scars (striae).
(e) Local accumulations of melanin.

Why are there no skin cancers that originate from stratum corneum cells?

Because the cells in the stratum corneum are dead.

A man got his finger caught in a machine at the factory. The damage was less serious than expected, but the entire nail was torn off his right index finger. The parts lost were the body, root, bed, matrix, and eponychium of the nail. First, define each of these parts. Then, tell if this nail is likely to grow back.

Body- visible attached portion
Root- embedded in the skin
Bed- extends beneath the nail
Matrix- thickened proximal portion of the nail bed
Eponychium- proximal nail fold projects onto the nail body

No, the nail is not likely to grow back because the matrix was lost.

Mrs. Gaucher received second-degree burns on her abdomen when she dropped a kettle of boiling water. She asked her doctor if she would need a skin graft. What do you think he told her?

Very serious deep second and full-thickness burns require skin graft surgery for quick healing and minimal scarring. In the case of large burn size, patients will need more than one operation during a hospital stay.

Integumentary System

Includes skin, nails, hair, glands (ceruminous = earwax; sebaceous = oil around hair follicles; sudoriferous = sweat glands)

Study of the integumenty system is

Dermatology

Integument is only made up of

epidermis and dermis

Functions of skin include

resist trauma; resist dehydration, vitamin D synthesis: protects from UV lights; participates in thermoregulation; involved in sensatoin of touch/temperature/pressure; useful in nonverbal communication.

Vitamin D synthesis

First state in production of vitamin D₃ called cholecalciferol is synthesized from a derivative of the steroid cholesterol in the skin

Thermoregulation

Lose excess heat from and keeps from loss of heat when needed to be retained.

Epidermis

Made up of keratinized stratified squamous epithelium

lakes blood vessels - avascular

Layers of Epidermis

Stratum basale, stratum spinosum, stratum granulosum, stratum lucidem, stratum corneum

Stratum Basale

contains stem cells which form all cells above them

Stratum Spinosum

named for the look in histology preps which is an artifact of preservation

Langerhans cells

Antigen presenting cells of immune system found in stratum spinosum

Stratum Granulosum

This layer is slowly replacing the cell contents with keratin as granules

Stratum Lucidem

Only found in thick skin!!!! Lucidem means clear

Stratum Corneum

the top layer of completely dead cells, completely filled with keratin. therefore, waterproof and dead... so can resist abraision

Dermis

Connective tissue

Contains: pressure sensors, i.e. Messiner's corpulsles and Merkel Discs: Blood vesselsL hair roots (but the hair lies in a follicle which is invagination of the epidermis into the dermis): contains Sudoriferous and sebaceous glandsL contains Erector Pili muscles to goosebumps

Broken collagen in this connective tissue layer cause Striae (stretch marks)

Hypodermis

Not part of the integument

is made up of connective tissue

Contains: Adipose tissue (fat) and largest blood vessels

is where you deliver injectables when they are given subcutaneously also termed hypodermal injection

Two types of normal pigments which contribute to color of a person's skin

Eumelanin

Pheomelanin

Eumelanin for skin

Eu means "true"; so its considered true melanin, therefore brownish black colored.

Pheomelanin for skin

which either contributes a reddish or a yellowish coloration to skin

Other normal factors affecting skin color include

Hemoglobin

Carotene

Hemoglobin for skin

gives pink undertones

Carotene for skin

found in yellow to orange vegatables which make skin orange like

Abnormal skin colors and their cause include

Cyanosis

Erythema

Pallor

Albinism

Jaundice

Hemotomia

Cyanosis is

due to a low oxygen carriage in the blood

Erythema is

abnormal redness, sunburn, anger, embarassment, exercise, etc.

Pallor is

a pale gray color termed "ashen" which normally means they are just about to pass out

Albinism is

a genetic inability to make pigment to color skin

Jaundice is

due to accumulation of unbrokendown hemoglobin because the liver isn't functioning properly

Hematomia is

a bruise which is blood outside of the blood vessels wrongfully

Friction Ridges

what we all call finger prints and these form in the womb before birth due to differences in temperature

Freckles

flat areas of skin which are intensely pigmented

Moles

More correctly termed Nevi ( one is a nevus) these are heaped up piles of pigmented cells of skin which can occur for several reasons including a tumor of skin or viral infection of skin cells

Hemogiomas

commonly called birth marks, these normally grow larger in children up till past the toddler stage of growth and then they normally start to shrink, therefore most of the time nothing is done about removal unless they block the eye being able to open. occlusion of sight for long periods of time can result in loss of vision so those birthmarks are considered for removal

Hair

hair is a pilus, several hair are pili

Lanugo

hair found on infants before time for birth

vellus hair

after birth we have soft hair on our body

Terminal hair

normally more pigmented, which is longer and coarser.

determinate hair

grows to certain lengths and stops growing

indeterminate hair

continues to grow, like the hair on our head or beard hair

Shaft hair

part of the hair above the skin surface

Root hair

the part of the hair below the skin surface

Bulb

beginning of the root closest to the skins dermis where blood vessels and nerve connect to the hair

The shape of the hair itself gives your hair it's texture

Round - straight

Oval - wavey

Nails

Just know the whiter crescent moon shape nearest your finger is the "lunule" and the pink nail bed is the "body" and the white tip is the "free edge" and that the nail has a root which is back up under the skin beside the lunula

Basal Cell Carcinoma

the most common skin cancer, seldom metastases, due to cell of stratum basale becoming cancerous often has a central depression and is pearly in appearance.

Squamous Cell Carcinoma

due to cells of stratum spinosum becoming cancerous, often raised and reddened and scaly, can metastasize over a long time

Melanoma

due to melanocytes becoming cancerous. Normally over 7mm wide (width of a No.2 pencil eraser) irregular bordered, and very dark in color. Often metastasizes and most people who find these do not survive but a few years. Like 2-5 years due to metastasis to major organs away from initial tumor before they even know the melanoma is there

Causes of burns

chemical, fire, sun

First Degree Burn

involves only the epidermis and appears red, swollen (edema) and is painful... like a sunburn

Second Degree Burn

involves the epidermis and part of the dermis... also known as a partial thickness burn... involves blistering and very painful, can be many colors, can scar

Third Degree Burn

involves epidermis and all the way through the dermis therefore called "full thickness burn" (which means it burns off the nerve endings therefore they don't feel the pain... which is a sign that the extent of damage is severe) and often cause of accidental death.... often requires skin grafts... if it goes to the bone they may refer to it as a 4th degree burn.

Skin Structure

Epidermal Cells and Layers of the Epidermis

Light micrograph of the dermis

Cleavage Lines

Flexure lines

Friction Ridges