Name the three major regions of the skin or integument system.

List them in order from superficial to deep.

Epidermis

Dermis

Hypodermis

note: epi meands above; hypo means below

Name the layers of the integument that correlate with letters A & B?

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A- epidermis

B - dermis

note: the adipose cells at the bottom of the section bracketed as B are the beginning of the hypodermis

Keratinized stratified squamous epithelium

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keratinocytes

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What percentage of the epidermis is composed of melanocytes?

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Darker

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3

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(these British babies are twins whose mother is of Nigerian and English heritage)

 Langerhans* cells, a type of Epidermal Dendritic cell 

* named after the 21 yr old German medical student who discovered them

bacteria

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birth begins the colonization of the baby by bacteria. 

stratum corneum 

(this layer contains dead cells, flat membranous sacs filled with keratin)

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What layer of skin is indicated by line #1?

What does the layer contain?

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• It is the Stratum Corneum (horny layer, apparently because its cells are toughened like an animal horn)
• It contains dead skin cells, flat membranous sacs filled with keratin 

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• What layer of skin is indicated by #2?
• (note: this is thick skin)
• What is the layer composed of?

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• Layer 2 is the Stratum Lucidum (clear layer, as in lucid)
• It is composed of a few layers of flat dead keratinocytes.
• NOTE: It is present only in thick skin and may not be on diagrams we are asked to label.

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What layer does line #3 point to?

What is this layer composed of?

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• The layer labelled 3 is the stratum granulosum (grainy layer)
• This layer is composed of 3-5 layers of dying cells whose organelles are deteriorating and whose cytoplasm is full of granules. 

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What is the layer labelled #4 and what is it composed of?

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• Layer 4 is the Stratum Spinosum (spiny layer).
• It is composed of several layers of keratinocytes united by desmosomes (which keep the cells tightly interlocked and prevent water loss)[image]

What is the layer labelled #5 and what is it composed of?

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• Layer 5 is the deepest layer of the skin. It is the stratum basale. 
• It contains one row of actively mitotic (capable of dividing) stem cells, occassional melanocytes are also present. 

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Desmosomes are in the stratum spinosum or spiny layer. They enable the cells to interlock creating a barrier that prevents water loss. 

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4-5

(not including the basement membrane)

stratum basale (basal layer)  

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What layers correspond with each letter in this thick skin?

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A. Stratum Corneum 

B. Stratum Lucidum

C. Stratum Granulosum

D. Stratum Spinosum

E. Stratum Basale

Here is one mneumotic used to remember the layers, top to bottom: Cora Lucille's Granny Spins Baseballs [image]

• How long does skin cell turnover takes?
• Note: this is a range of days

• In class, our professor indicated that it takes about 14 days (presumably that's the journey from basale to corneum.)
• He also included a PowerPoint note that stated 25- 45 days for that process. Perhaps this fact includes the cell's time on the surface once there.
• Complete cell turnover occurs every 28 to 30 days in young adults, while the same process takes 45 to 50 days in elderly adults. (U.S. National Institude of Health)

What kind of skin includes the stratum lucidum (clear layer)?

What are two prominant places where it is found on the body?

Thick skin.

It is found on the palms and soles of the feet. 

stratum granulosum

(Mnemonic: Cora Lucille's Granny Spins Baseballs)

• Stratum Basale
• Stratum Spinosum
• Stratum Granulosum (dying but not quite dead)

What fraction of the entire width of the epidermis is composed of the Stratum Corneum or Horny Layer?

note: top layer

3/4 three quarters (roughly)

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Which layer of skin provides all of the following?

1. Protection from abrasions and penetration
2. Water resistance (waterproof accrd. to notes)
3. Barrier against biological, chemical and physical assaults 

Papillary layer

Reticular layer

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• Which kind of tissue predominates in the papillary layer of the dermis?
• Which 2 kinds of fibers are seen in the layer?
• Is the papillary layer vascular or avascular?

• Tissue type: Areolar connective tissue 
• Fibers: Collagen and elastic fibers (for strength and flexibility)
• Vascular: red blood vessels are present. 

Papillae, for which the papillary layer of the dermis is named, means "nipple like extension", the uppermost part of which extends into the epidermis.

What 3 things do these dermal papillae contain and what function does each fulfill ?

Capillary loops - allow thermal regulation

Meissner's Corposcles & Free nerve endings - both of which are sensory receptors

connective tissue

papillary layer - loose connective tissue (areolar)

reticular layer- dense connective tissue (irregular)

Most commonly:

Fibroblasts

Macrophages

Less commonly:

Mast cells

White blood cells

Reticular layer

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What forms the epidermal ridges visible on our finger tips and why is each person's supposedly unique?

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• Dermal ridges (formed by the raised "nipple like" papilla in the papillary layer) form the basis of epidermal ridges. See illustration below.
• These ridges alter as, in utero, babies press their hands against the embryonic sac and explore their environment.
• This, apparently, modifies them, making even those of identical twins different. 

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Sweat, from sweat glands on the friction ridges.

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What is the anatomical basis for the cleavage (or tension) lines on our bodies?

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melanin

carotene

hemoglobin

What produces melanin?

Where does melanin go once it's produced?

• melanocytes produce melanin
• once produced, melanin migrates, or is fed into, keratinocytes.

UV light

freckles and pigmented moles

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Melanocytes produces different colored melanin based on ones genetic makup. What colors are possible?

yellow to reddish brown to black

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Yes!

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Carotene is yellow to orange and is abundant in certain vegetables, notably carrots. Apparently people even use beta carotene pills to give themselves tans. 

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What is responsible for the blanching or "whitening" of compresed skin?

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Why do some people "grow pale" with fear?

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The blood leaves the surface of the body to assist the rest of the body in the flight or fight response. Because there is less blood at the surface of the body, the person appears pale. 

What are the two main types of sweat glands?

Where is each located?

Eccrine and apocrine sweat glands 

• Eccrine sweat glands: everywhere, especially abundant on the palms, soles, forehead
• Apocrine sweat glands: underarms (axillary) and anogenital areas

1. water
2. NaCl (sodium chloride or salt)
3. vitamin C
4. antibodies
5. dermicidin (a kind of natural antibiotic)
6. metabolic wastes (urea)

Look at this picture and identify the means by which eccrine sweat and apocrine sweat access the surface of the skin. 

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Eccrine sweat accesses the surface of the skin via sweat pores

Apocrine sweat accesses the surface of the skin via fair follicles

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What appendage of the integumentary system is pictured in microscopic view below?

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Eccrine sweat glands

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It is composed of sweat, fatty substances and proteins 

• (note: our notes say that the apocrine glands produce sebum but this may not be correct. other sources only note sebacous glands as a source of sebum.)

When do the apocrine glands become active?

What is one theory of their evolutionary purpose?

Apocrine glands become active at puperty.

They are theorized to be a sexual scent gland.

• What are the two types of modified apocrine glands we learned about?
• Where are they located?
• What does each produce?

Ceruminous glands - in external ear - produce ear wax

Mammary glands- in breast tissue - produce milk

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Sebaceous (oil) glands

blackheads and/or whiteheads

(sources differ on the cause of each)

What appendages of the skin is shown in the microscope slide below?

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HF- hair follicle

SG - Sebacous (oil) gland

sebum is bactericidal, meaning it kills bacteria. 

• Alerting the body to the presence of insects
• Guarding the scalp against:
• physical trauma
• heat loss
• sunlight

dead keratinized cell contain:

hard keratin and the hair pigment melanin. 

decreased production of melanin 

increased air bubbles in shaft blocking the melanin

Alopecia

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nope.

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What type of hair loss generally starts in front and works towards the back of the skull?

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True (frank) baldness

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1. Chemical protection
2. Physical/mechanical barriers
3. Biological barriers

In what two ways does the skin offers chemical protection?

What does chemical protection protect from?

acid mantle

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apparently one can also purchase a product that claims to restore such a mantle

• Dendritic cells (a kind of immune cell)
• Macrophages (defense cells)
• DNA

• plant oleoresins (such as poison ivy)
• organic solvents
• salts of heavy metal (such as mercury) &
• some drugs (such as nicotine administered by patch, or testosterone by gel)

What occurs to dermal vessels when body temperature increases?

What is the usual result?

vasodilation (blood vessels dilate)

and temperature goes down

sensible perperation via increased sweat gland activity

temperature regulation via vasodilation 

temperature 

touch 

pain

wet/dry

texture

• Synthesis of vitamin D precursor (we discussed this the most)
• Synthesis of collagenase
• Chemical conversion of carcinogens
• Cheminal conversion of some hormones

Overexposure to UV radiation

Frequent irritation of the skin

enzymes in liposomes

(the liposomes deliver the enzymes because they can get through the skin)

• Basal cell carcinoma
• Squamous cell carcinoma
• Melanoma 

Which cells are affected in squamous cell carcinoma? 

Which layer are they on?

• The keratinocytes of the stratum spinososum layer
• note: stratum spinosum is directly above the stratum basal (aka stratum germinativum) where basal cell carcinoma is found

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What type of skin cancer is seen in each of the following images?

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• On areas of frequent sun exposure:
• scalp
• ears
• lower lip
• hands

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• What  are the 2 general courses of treatment for squamous cell carcinoma?
• What is the prognosis?

• General course of treatment is either radiation or surgical removal.
• Prognosis is good.

What is the general, two part, course of treatment for melanoma?

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• Asymmetry: the two sides of the pigmented area do not match
• Border: exhibits indentations
• Color: black, brown, tan sometimes red or blue. Two toned is not good
• Diameter: larger tan 6mm or the size of an eraser

• Heat
• Electricity
• Radiation 
• Chemical

Heat burn

(e.g. fire)

What are the two most immediate threats with burns?

What is the danger of these threats, i.e. what might they lead to?

dehydration and electrolyte imbalance

They lead to renal (kidney) shut down and circulatory shock

• tissue damage
• denatured proteins
• cell death

To estimate volume of fluid loss from burns

(and to understand the spread of the burns)

• Note what % of the total body area is indicated by each letter. Assume both the anterior and posterior areas are indicated.
• a. anterior and posterior of head and neck
• b. anterior and posterior of a single arm
• c. anterior and posterior of trunk
• d. genital region
• e. anterior and posterior of a single leg

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• a. anterior and posterior of head and neck - 9%
• b. anterior and posterior of a single upper limb - 9%
• c. anterior and posterior of trunk - 36% (9 x 4)
• d. genital region - 1%
• e. anterior and posterior of a single lower limb - 18%
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What layer(s) of the skin are damaged with a first degree burn?

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Second degree burn

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Infection from bacteria or viruses. 

There is no protection because there is no epidermis. 

skin grafts

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1. scar tissue
2. sensation loss
3. thermoregulation imbalance
4. fluid retention