• Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off
Reading...
Front

Card Range To Study

through

image

Play button

image

Play button

image

Progress

1/332

Click to flip

Use LEFT and RIGHT arrow keys to navigate between flashcards;

Use UP and DOWN arrow keys to flip the card;

H to show hint;

A reads text to speech;

332 Cards in this Set

  • Front
  • Back
  • 3rd side (hint)
Keratinocytes
Produce a tough fibrous protein that gives the epidermis its protective qualities
Melanocytes
Responsible for skin pigmentation
Merkel cells
Sensory receptor for touch
Langerhans' cells
Present antigens to killer T lymphocytes
Stratum basale
The deepest layer of the epidermis, the stratum basale, is a single layer of cells resting on a basement membrane (layer between the dermis and epidermis). The stratum basale cells divide continuously. As new cells form, older ones are pushed toward the skin surface.

The epidermis does not have a direct blood supply; all nutrients that feed these cells come from the dermis. Only the deepest cells of the stratum basale receive nourishment. The cells that are pushed away from this layer die. When the cells reach the skin surface, they are sloughed off in a process called desquamation.
Single row of cells composed of keratinocyte stem cells, melanocytes, and Merkel cells
Stratum spinosum
The next layer, the stratum spinosum, consists of spiny prickle cells that interlock to support the skin.

During desquamation, keratinocytes are pushed toward the surface. These cells begin to produce the keratin that eventually will dominate their contents. When these cells reach the epidermis outer layer, they are little more than keratin-filled sacs. Millions of these dead cells are worn off daily, creating a new epidermis every 35 to 45 days.
Several cell layers thick, with intermediate filaments, keratinocytes and Langerhans' cells
Stratum granulosum
Three to five layers of flattened keratinocytes possessing filaments and keratohyaline and lamellated granules

The stratum granulosum, the thin middle layer, initiates keratinization (production of keratin). This process starts the death of epithelial cells (the cell type that makes up skin).
Stratum lucidum
The stratum lucidum protects against sun ultraviolet-ray damage. This thick layer appears only in frequently used areas such as palms of the hands and soles of the feet. Thick skin epidermis has all five strata. Thin skin covers thinner epidermal areas such as eyelids. Thin skin has three or four of the five strata; it never has stratum lucidum
Stratum corneum
Many cell layers of dead keratinocytes filled with keratin (outermost layer of skin)

The stratum corneum, the fifth, outermost layer is thick with rows of dead cells. These cells contain soft keratin, which keeps the skin elastic and protects underlying cells from drying out.
Epidermis
Keratinized stratified squamous epithelium
Hypodermis
Adipose connective tissue
Papillary layer of dermis
Areolar connective tissue
Reticular layer of dermis
Dense irregular connective tissue
Protection
Provides a chemical barrier and a mechanical barrier to ward off bacterial invasion and to provide "waterproofing"
Body temperature regulation
Dilation of blood vessels and secretion of sweat that evaporates from body surface
Cutaneous sensation
Activation of numerous receptors that are part of the nervous system
Metabolic functions
Synthesis of vitamin D; destruction of cancer-causing chemicals; activation of some steroid hormones
Blood reservoir
Potential to hold about 5% of the body's blood volume in numerous blood vessels
Hemoglobin
Red
Carotene
Yellow to orange
Cyanosis
Blue
Melanin
Ranges from yellow to reddish to brown to black
Root
The portion of the hair that is embedded in the skin
Cuticle
Superficial covering of a hair consisting of a single layer of cells that overlap one another
Shaft
Region of a hair that projects above the skin surface
Medulla
The central core of a hair, consisting of large cells and air spaces
Cortex
The intermediate layer of a hair composed of several layers of flattened cells
Hair matrix
Actively dividing cellular area of the bulb that produces the hair
Connective tissue root sheath
Superficial wall of the hair follicle which is derived from the dermis
Hair bulb
The expanded, deep region of a hair follicle
Root hair plexus
A knot of sensory nerve endings wrapped around the base of a hair follicle
Arrector pili
Bundle of smooth muscle tissue running from the superficial dermis to the hair follicle; responsible for producing goose bumps
Sebaceous glands
Found all over the body except the palms and soles
Eccrine sudoriferous glands
Most abundant on the palms, soles, and forehead
Apocrine sudoriferous glands
Axillary, anal, and genital regions
Ceruminous glands
Line the external ear canal
Mammary glands
Pectoral region
Sebaceous gland
Oil
Eccrine sudoriferous gland
Sweat
Apocrine sudoriferous gland
Components of sweat plus fatty substances and proteins
Ceruminous gland
Components of earwax
Mammary gland
Milk
Body
Visible, attached part of the nail
Nail bed
Epidermis on which the nail rests
Root
Proximal region of the nail, embedded in the skin
Free edge
Distal edge of the nail
Nail matrix
Actively growing part of the nail
Lunula
White, crescent-shaped area under the nail's proximal region
First-degree burn
Damage to only the epidermis that results in redness, swelling, and pain
Second-degree burn
Injury to the epidermis and the superficial region of the dermis resulting in redness, swelling, pain, and blisters
Third-degree burn
The entire thickness of the skin is consumed, resulting in the burned area appearing white, red, or blackened.
Basal cell carcinoma
Least malignant form of skin cancer in which the stratum basale cells proliferate and invade the dermis and hypodermis, causing tissue destruction
Squamous cell carcinoma
Arises from the keratinocytes of the stratum spinosum with lesions appearing as scaly, irregular, reddened small, rounded elevations that tend to grow rapidly and metastasize if NOT removed
Melanoma
The "most dangerous form" of skin cancer because it is highly metastatic; can originate wherever there is pigment, but often arises from existing moles, metastasizing rapidly into surrounding circulatory vessels
Asymmetry
The two halves of a spot or a mole do NOT match
Border irregularity
Pigmented spot possesses notches and indentations
Color
Inconsistent pigmentation
Diameter
Larger than 6 mm
Elevation
Rises above the skin surface
Alopecia areata
A rare condition where hair follicles are attacked by the immune system, causing the hair to fall out in patches
Impetigo
Fluid-filled, raised lesions, common around the mouth and nose, that develop a yellow crust and eventually rupture; contagious
Keloid
Large, unsightly mass of scar tissue at the skin surface produced by excessive and prolonged proliferation of connective tissue during the healing of skin wounds
Psoriasis
Chronic inflammatory condition, resulting from an over proliferation of the epidermis, characterized by reddened epidermal papules covered with dry, silvery scales
Too much carotene
Causes yellowing of skin, especially in palms and soles from accumulation in stratum corneum when consumed in large amounts
Tanning
Increased production of melanin due to increased exposure to the sun
Jaundice
Yellowish to pale-green coloring of skin caused by an accumulation of bile pigments in blood
Cyanosis
Possible heart failure; possible respiratory disorders
Redness or erythema
Fever, hypertension, polycythemia, inflammation, allergy
Pallor or blanching
Fear, anger, stress, anemia, low blood pressure
Jaundice
Liver disorder
Bronzing
Addison's disease; hypofunction of adrenal cortex
Black and blue marks or bruises
Blood clots beneath the skin
Eccrine sweat glands
Secrete a hypotonic filtrate of the blood (99% water with traces of salt, vitamin C, antibodies, metabolic wastes and lactic acid)
Apocrine sweat glands
Contains same secretions as true sweat, plus fatty substances and proteins. When these organic molecules decompose by bacterial action there is an associated unpleasant odor
Ceruminous glands
Modified apocrine glands that secrete earwax
Mammary glands
Modified sweat glands that secrete milk
Sebaceous glands
Holocrine glands that secrete an oily substance called sebum to lubricate skin and hair
Black hair
Maximum production of melanin
Blonde hair
No production of melanin; no iron-containing pigment
Red hair
Absence of melanin; presence of iron-containing pigment
White hair
Replacement of melanin with air bubbles in the hair shaft as melanin production decreases
Newborn baby
Presence of vernix caseosa produced by sebaceous glands
Infancy and childhood
Skin thickens and more subcutaneous fat is deposited
Adolescence
Skin and hair become oilier as sebaceous glands are activated; dermatitis becomes more common
Old age
Epidermal cell replacement declines; skin thins; sebaceous gland activity diminishes
Vellus hair
Body hair of children and adult females
Terminal hairs
Coarser, long, darker hairs
Alopecia
Loss of hair
Male pattern baldness
Genetically predetermined balding
A hypodermic needle is injected into the skin. Identify the first integumentary structure through which the needle will pass.
Epidermis
A hypodermic needle would first pass through the superficial layer of the skin, the epidermis, then the two layers of the dermis, the papillary layer and the reticular layer, before penetrating the hypodermis.
Sebaceous glands are located in all of the following areas, except the:
palmar region.

Sebaceous glands occur over the entire body, with the exception of the palms and soles of the feet.
Sebaceous glands belong to which of the following classes?
Simple branched alveolar

Sebaceous glands are simple alveolar glands with several alveoli opening into a single duct.
Terminal hair is located in all of the following areas, except the:
body hair of females.

The body hair of women and children is the fine, short, vellus variety, while the adult male's body hair is the terminal variety.
The dermis is primarily composed of which tissue type?
Dense irregular connective tissue

The deeper reticular layer, which accounts for about 80% of the thickness of the dermis, is composed of dense irregular connective tissue.
The epidermis is composed of which of the following tissues?
Keratinized stratified squamous epithelial tissue

The superficial layer of the skin, the epidermis, is composed of thick keratinized stratified squamous epithelium.
What is the primary function of melanin?
Provides protection against the sun's UV rays

Melanin forms a protective layer that screens out a portion of the sun's cancer-causing UV rays.
Which is the correct sequence of epidermal layers of thick skin, deep to superficial?
Stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum

In thick skin, the cell layers, ordered from deep to superficial, are: stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, and stratum corneum.
Which of the following are NOT derivatives of the epidermis?
Dermal papillae

Dermal papillae are fingerlike projections found on the superficial surface of the dermis.
Which of the following cells would one NOT expect to find in the dermis?
Keratinocytes

The dermis possesses all the cells that one would expect to find in connective tissue: mast cells, fibroblasts, macrophages, and scattered white blood cells.
Which of the following epidermis components possesses a waterproofing glycolipid that functions in preventing water loss?
Lamellated granules

The lamellated granules contain a waterproofing glycolipid that is secreted into the intercellular space and is the major factor for slowing water loss across the epidermis.
Which of the following human integumentary system glands is believed to be analogous to the sexual scent glands of an animal?
Apocrine sudoriferous gland

Apocrine glands start to function at puberty under the influence of androgens, their activity is increased by sexual foreplay, and they enlarge and recede with the phases of a women's menstrual cycle.
Which of the following is most important in determining skin coloration?


.
Melanin

Melanin, the most important contributor to skin coloration, is present in several varieties, ranging from yellow to reddish to brown to black
Which of the following is NOT a component of the integumentary system?
Hypodermis

The hypodermis, deep to the skin, shares some of the skin's functions, but it is not a part of the integumentary system.
Which of the following is NOT a function of the skin?
Respiratory gas exchange
Although the skin functions in protection and insulation, excretion, preventing unnecessary water loss, and the regulation of body temperature, respiratory gas exchange is a function of the respiratory system.
Which of the following is NOT considered a critical burn?
Thirty percent of the body has first degree burns

First-degree burns are not considered critical because they typically heal in a few days without any special attention.
Which of the following is the most immediate threat to life from a serious burn?
Loss of body fluids

The immediate threat to life from serious burns is a catastrophic loss of body fluids, which, in turn, can lead to fatal circulatory shock.
Which of the following strata is absent in thin skin?
Stratum lucidum

The stratum lucidum appears in thick skin but not in thin skin.
Which of the following structures are primarily responsible for fingerprints?
Epidermal ridges and sweat pores

Sweat pores open along the crests of the epidermal ridges, leaving distinct fingerprints on anything that is touched.
Which of the following thick skin strata is the thickest?
Stratum corneum

The superficial stratum corneum is many cell layers thick, much thicker than any other epidermal layer.
A person who experiences sudden flushing of the skin, especially on the nose and cheeks, may be in the early stages of:
rosacea.

Sudden flushing of the skin may indicate rosacea, especially when it appears to worsen in conjunction with intake of alcohol, spicy foods, or after a hot bath or sun exposure.
Which of the following layers of the skin relies on capillaries in the underlying connective tissue in the dermis for its nutrients?
Epidermis

This layer is dead and does not require nutrients.
A possible cause of rosacea is:
the same bacterium that causes peptic ulcers.

Many people with rosacea are helped by antibiotic therapy.
Which of the following cells is part of the immune system?
Langerhans' cell

The Langerhans' cell is a fixed macrophage.
Which of the following cells function as sensory receptors for touch?
Merkel cells

Merkel cells function as sensory receptors for touch.
Keratinocytes in the stratum spinosum are known as:
prickle cells.

Keratinocytes in the stratum spinosum are known as prickle cells because of their spiny appearance under the microscope from an artifact produced by staining procedures.
All of the following are true about our fingerprints, except that:
they represent the sweat patterns left by dermal ridges.

This is an incorrect statement.
Striae in the skin are caused by:
dermal tears.

Striae in the skin are due to dermal tears.
Which of the following conditions would not be seen from overexposure to UV light?
Activation of the immune system

Overexposure to UV light will lead to an increase in the melanin pigment production by melanocytes, which causes an increased pigmentation of the skin in fair people, or a "tan."
A hematoma in the skin appears as:
black and blue marks.

A hematoma caused by clotting of blood under the skin appears as black and blue marks or bruises.
Wounded skin releases large quantities of protective peptides that help prevent some infections.
True

These peptides (cathelicidins) are particularly effective in preventing infection by group A streptococcus bacteria.
A surgical incision performed on the forearm will heal more readily if the incision is made along a longitudinal plane rather than along a transverse plane.
True

Because lines of cleavage run longitudinally in the skin of the limbs, an incision made parallel to these lines will result in the skin gaping less and healing more readily than when an incision is made along a transverse plane across cleavage lines.
Because of the great thickness of the epidermis, it is very vascular.
False

Like all epithelia, the epidermis is avascular and relies on capillaries in the underlying connective tissue for its nutrients.
Dermal blood vessels hold 2% of the body's blood.
False

Dermal blood vessels account for 5% of all the blood in the body.
Sweat is produced as a holocrine secretion, in which the cells themselves break up to form the product.
False

Sweat is produced as secretions pass through the secretory cells of the sweat glands by the process of exocytosis, leaving the secretory cells intact.
The dermis functions in helping to control body temperature.
True

Dermal blood vessels not only contract, reducing heat loss, but engorge with blood as well, allowing heat to radiate from the body.
The body produces carotene when exposed to sunlight.
False

Carotene is found in certain plant products. We obtain it by eating plants containing this pigment
The hypodermis is also known as the subcutaneous layer as well as the deep fascia.
False

The hypodermis can correctly be referred to as the subcutaneous layer as well as the superficial fascia.
The main function of our body hair is to prevent heat loss.
False

The main function of our sparse body hair is to sense things that lightly touch our skin.
The melanocytes are the most abundant cells in the epidermis.
False

Keratinocytes, by far the most abundant epidermal cells, produce keratin, a tough fibrous protein that gives the epidermis its protective properties.
The skin functions in synthesizing vitamin D.
True

Vitamin D, important in the uptake of calcium, is produced in the skin from modified cholesterol molecules.
The sebaceous and sweat glands, located in the dermis, are derived from the epidermis.
True

The appendages, including hair and hair follicles, sebaceous glands, oil glands, and nails, extend into the dermis, but are derived from the epidermis.
The superficial region of the skin is called the epidermis.
True

The epidermis is the superficial region of the skin, overlaying the deeper dermis.
Thick skin is composed of four strata of cells.
False

Thick skin, which covers the palms and soles, consists of five layers, or strata, of cells.
A cyanotic appearance in Caucasians is a symptom of liver disease.
False

Cyanosis indicates lack of oxygen.
A child who has been playing in the dirt will often accumulate dirt in the lunula of the nail.
False

The dirt accumulates in the hyponychium of the nail.
Blood vessels in the dermis constrict when the external environment is cold, minimizing heat loss from the skin.
True

Constriction causes warm blood to bypass the skin temporarily, thereby conserving body heat.
Melanin functions as an effective "sunscreen."
True

Melanin is able to convert potentially destructive radiation into harmless heat.
New skin lotions have been developed that can "fix" damaged DNA before the cells develop into cancer cells.
True

These lotions contain liposomes filled with enzymes that initiate repair of damaged DNA.
The dermis contains two histologically separate areas.
True

The dermis contains the papillary and reticular layers.
Arrector pili muscles cause "goosebumps."
True

Arrector pili muscles elevate hair follicles, causing them to bulge on the surface of the skin.
The correct order of the layers of the epidermis from deep to superficial is:
stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum.
Tactile cells
Sensory detection
Hypodermis
Skin anchoring
Melanin
Protection from UV radiation
Langerhans cells
Activate the immune system
Keratinocytes
Make a fibrous protein for skin protection
Keratin protects the skin from the damaging effects of ultraviolet (UV) radiation.
False
The role of ceruminous glands is to:
produce earwax.
If an individual was unable to produce sebum, what problem would they most likely develop?
They would be more prone to water loss when exposed to low humidity.
Apocrine glands:
are not functional until puberty

See pages 155-156. Both apocrine and eccrine glands use exocytosis to make their secretions. Eccrine glands function throughout life while apocrine sweat glands begin to function at puberty. Apocrine sweat glands are located deeper in the dermis than eccrine glands. Compared to the watery secretions of eccrine glands, apocrine sweat glands have secretions that are enriched with fats and proteins.
For humans, food is the only source of vitamin D.
False
The region deep to the skin is the:
hypodermis.
If dermal papillae were missing then:
friction ridges would be absent.
One main difference between thin skin and thick skin is that:
in thin skin the stratum lucidum appears to be absent.
Keratin is found in hair and nails.
True

See pages 157-160. The primary component of hair and nails is hard keratin.
Sebaceous glands
Sebum
Mammary glands
Milk
Sudoriferous glands
Sweat
Ceruminous glands
Cerumen
Hirsutism is a condition that is characterized by:
excessive hairiness.

See page 159. Hirsutism is a condition resulting in excessive hair growth. This is usually a result of excessive androgen production in women.
Follicles that give rise to eyelashes remain active longer than follicles of the scalp.
False

See page 159. The follicles of the scalp remain active for up to ten years while those of the eyebrow are only active for up to 4 months. Because of this difference in follicle activity, the hair on your head can grow longer than the hair of your eyelashes.
Choose the false statement.
See pages 160-161. Skin acts as a chemical, physical and biological barrier. Defensins, cathelicidins, sebum, salt, and an acidic pH limit bacterial growth on the skin. Also, skin acts as a means to regulate body temperature.
Melanoma is particularly dangerous because:
it readily metastasizes.
What type of mole or pigmented spot on the skin would be the most concerning?
A spot with varying colors and irregular borders.
A sunburn is generally classified as being:
a first-degree burn.
Which of the following is not composed of hyaline cartilage?
Intervertebral cartilage
Appositional growth:
occurs when cartilage-forming cells secrete new matrix against the external face of the existing cartilage tissue.
The appendicular skeleton includes the upper and lower limb bones.
True
Which of the following bones belong to the axial skeleton?
Ribs
Which of the following is classified as a short bone?
Wrist bone

See page 174. Examples of short bones are bones of the wrist and ankle. Short bones are roughly cube-shaped
Bones serve as an important reservoir of:
calcium.
Fossa are:
bone depressions.
Yellow marrow is useful as:
a fat reserve.
Bone is broken down by:
osteoclasts.
Yellow marrow can revert to red marrow if more red blood cells are needed by the body.
True
The structural unit of compact bone is:
the Haversian system.

See page 179. The osteon (also called the Haversian system) is the structural unit of compact bone.
Spongy bone contains osteons.
False

See pages 179-180. Osteons are in compact bone, not in spongy bone.
Collagen fibers do not:
provide for bone hardness.

See page 180. The exceptional hardness of bone, giving it the ability to resist compression, is attributed to the presence of inorganic hydroxyapatites. Hydroxyapatites such as calcium phosphates are particularly important for bone hardness. Organic substances such as collagen fibers contribute to tensile strength, not hardness. Collagen fibers help to prevent bone fractures by allowing for flexibility of the bone as well as resistance to stretching and twisting.
Most bones below the base of the skull form by endochondral ossification.
True
At the end of secondary ossification, hyaline cartilage can be found:
at epiphyseal plates.
In adolescence, the "growth spurt" that is observed is mainly attributed to an increase in:
sex hormones.

See page 185. During infancy and childhood the single most important stimulus for bone growth (epiphyseal plate activity) is growth hormone. The action of growth hormone is modulated by thyroid hormones. In adolescents, sex hormones (testosterone and estrogen) spur bone growth. Later in life, sex hormones actually end longitudinal bone growth.
When Ca2+ concentration in the blood becomes lower than normal:
parathyroid hormone is released
A patient is brought to the emergency room with a broken bone. According to the x-ray, the bone is fragmented into three pieces. This would be considered a:
comminuted fracture.

See pages 188 and 190. When a bone fragments into three or more pieces, the bone is said to have a comminuted fracture.
The final step in fracture repair is:
bone remodeling.
What are the 4 stages of fracture repair?
1. Blood escapes from ruptured blood vessels and forms a hematoma.

2. Spongy bone forms in regions close to developing blood vessels, and fibrocartilage forms in more distant regions.

3. A bony callus replaces the fibrocartilage.

4. Osteoclasts remove excess bony tissue, restoring bone structure much like the original.
Rickets can be caused by:
a deficiency of vitamin D.
What do Langerhans cells do? Where are they found? What do they look like? How does their morpholgy help in their function? What is their origin?
Langerhans cells are cells of the immune system. They are found scattered throughout the stratum spinosum. They are stellate shaped with many branches and hence are also called dendritic cells. Their cytoplasm is clear or light staining. They DO not have desmosomes so they can move. They arise from monocytes or macrophages.
Give a short description of Keratinocytes. What do they do? What are they derived from?
Keratinocytes are the principal cell type of the epidermis. They are mostly all cells of the epidermis. They produce keratin and are derived from ectoderm.
How do Langerhan's cells participate in the immune response? What is an example of such a reaction?
Langerhan's cells participate in immune responses by presenting antigens to T-helper cells during hypersensitivity reactions such as contact dermatitis.
Give a short description of Melanocytes. What is their function? What layer are they found in? What is their origin?
Melanocytes are pigmented cells of the epidermis. They give skin part of its color. They are found in the stratum basale and are neural crest in origin.
What are Merkel cells? Where are they found? What do they look like? What do they contain? What function do they serve?
Merkel cells are a small clear cell in the stratum basale they contain dense core vesicles like cells in the adrenal medulla. They do NOT contain catecholamines. Each cell is innervated by a single axon. They are slow adapting cutaneous mechanoreceptors. They are responsible for light touch and constancy of it (still know somthing is there).
How does the epidermis create a protective barrier?
It does this by producing a layer of dense impenetrable, dead cells. This layer of dense cells prevents the passage of substances through epidermis.
What is Keratin made up of?
A family of fibrous proteins that make up intermediate filaments. (40-70,000 mw protein)
What are the two different phases cells can be in? What layers are undergoing what phase?
Degeneration phase (stratum corneum, stratum lucidum, stratum granulosum) or degeneration phase (Stratum spinosum, stratum basale)
How does stratum basale participate in the process of keratinization? Describe its morphology.
It is where keratin first appears. There are numerous desmosomes for mechanical attachement to adjacent cells and hemidesmosomes for attachement to the extracellular matrix. IT principal function is proliferation.
What is the process whereby cells undergo differentiation and maturation as they migrate to the surface? How long does this take?
The process is called cytomprphosis. This takes approximately 3-4 weeks for cells to migrate from bottom to top.
What is Filaggrin?
A protein that cross links tonofilaments, first found in the stratum granulosum.
What is involucrin? What does it do? Where is it found? What other protein is it associated with?
A protein first produced in the stratum spinosum. It is associated with increased levelss of tranglutaminase (creates cross linking of involucrin onto cell mebrane). This creates a water impermeable cell membrane that causes cell death.
How is the stratum lucidum associated with cytomorphosis? What are its characteristics? What do its cells look like?
In the stratum lucidum the keratinocytes are dead, there are no nuclei present and losts of waterproofing. Cells are also full of keratin in more complex forms.
What is eliden? Where is it found?
Eliden is a transformed keratohyalin granule found in the stratum lucidum.
How does the stratum corneum participate in cytomorphisis? What do the cells of this layer look like? What about granules?
The stratum corneum consists of flattened squamous cells called squames. The nuclei of the cells are gone and all the cells are dead. The cells must be dead to form a proper watertight barrier. The plasma membrane is packed with keratin. The plasma membrane is thickened with non-keratinous material. NO keratohalin granules or lamellar granules are remaining.
What is a bundle of keratin called? What type of filament is it?
tonofilaments of cytokeratin. It is intermediate filament.
What are lamellar granules? What are they rich in?
First found in the stratum spinosum, they are membrane bound packets of light and dark bands that are extruded as the cells move toward the stratum granulosum. They are rich in glycolipids.
How does the stratum granulosum participate in cytomorphisis? What type of granules appear in this layer? What do these granules do?
Keratohalin granules appear in this layer. Also secretes lamellar granules (rich in glycolipids) that form a waterproof substance between the cells. Also intercellular space increases 30x. Cells also begin to die in this layer.
What are keratohyalin granules?
Dark irregular shaped granules/cytoplasmic inclusions that are not membrane bound and are found in the stratum granulosum.
What happens in the stratum spinosum during keratinziation and cytomorphisis? What two types of structures appear within the cell.
In the stratum spinosum more keratin is produced and fills the cytoplasm. Tonofilaments increase in quantity as cells move toward the stratum granulosum. As the cell moves upward keratin formes bundles called tonofibrils. Lamellar granules appear in the cytoplasm.
What is Epidermal growth factor?
Epidermal growth factor stimulates the proliferation of keratinocytes.
Describe Psoriasis. What is its cause? How does it occur? What are the characteristics of the epidermis of a person with psoriasis?
Psoriasis is a chronic skin condition characterized by patches of red-brown area with whitish scales. It is due to excessive proliferation of keratinocytes. It is caused because it takes cells 1 week to reach th surface instead of 4 weeks. The epidermis is not fully differentiated: cells not fully keratinized, large spaces between cells because lamellar granules are not secreted, the integrity of the epidermis is compromised.
Describe eczema. What layers does it affect? What is it characterized by? What is the origin of the disease?
Eczema effects the epidermis and the dermis. It is characerized by edema, exudation, crusting and severe itching (pruritus). Dermis also affected: edema and infiltration of lymphocytes moncytes and eosinophils. Cause thought to be immunological in origin.
What is Phemphigus? How serious is it? What is its cause? What sort of symptoms does it display?
Phemphigus is a potentially fatal skin disease that is an autoimmune disease against desmosome proteins (cadherins) in epidermis. It causes severe blistering and loss of fluids, as well as entrance of infections.
Describe basal cell carcinoma. How common is it? What cells in what layer does it effect? What does it do? Does it metastasize often?
Basal cell carcinoma is the most common of all skin cancers, it affects the keratinocytes in the basal layer. It destoys local tissue but does not metastasize readily.
Describe Squamous cell carcinoma. How common is it? What are some of its causes? Does it metastasize often?
Squamous cell carcinoma is the 2nd most common skin cancer. IT has avariety of causes such as UV, X-rays, chemical agents, and arsenic
What is an epidermal proliferation unit (EPU)? Why does it exist?
Vertical stacks of cells that interlock with adjacent squames. It is the most efficient way to pack cells together.
Describe the process of how an EPU (epidermal proliferation unit) is formed and how long this process takes.
In an EPU a single stem cell is located in the center. This stem cell gives rise to 10-11 basal cells that migrate to the periphery. They differentiate as they move laterally. As the proliferation occurs, cells move upward as a group. They move up about one cell a day. It takes 1 month to move from bottom to top of the epidermis.
What is fibronectin? Where is it found?
Fibronectin is an adhesion glycoprotein in the basement membrane that regulates the rate of keratinization.
What is DMSO? WHat does it do? What is it used as an unofficail remedy for?
Dimethyl sulfoxide is a penetrating agent of skin, it carries other substances with it. The elderly use it as an unofficial remedy for arthritis because it soothes pain.
What 3 pigments are responsible for skin color?
Melanin, Carotene, and oxyhemaglobin.
Describe carotene. Where is it deposited? What is it obtained from?
Carotene is an exogenous plant pigment depositited in stratum corneum or adipose cells. (yellow). Eat lots of carrots and you will turn orange.
Describe melanin. What color is it? What is it produced by?
It is a brown pigment produced by the skin.
Describe oxyhemaglobin. WHat color is it?
Oxyhemaglobin is located in RBC's of blood vessels of the dermis (red).
What cells produce melanin pigment? Where are they located?
Melanocytes are the only cell in the epidermis that produces melanin pigment and it is located in the stratum basale.
What are melanocytes also known as? Why? What are they derived from? Describe their morphology.
Melanocytes are also known as clear cells because they have no desmosomes attaching it to surrounding cells so it is able to shrink and form a clear region around it. It is highly branched. It is derived from the neural crest.
What is melanocyte's distribution in normal and pigmented skin? What about ratio of melanocyte/epidermal cell? Where is pigmented skin located?
In normal skin there are about 1000 melanocytes per square mm. 1/every 10 epidermal cells. In pigmented skin there are 2000 melanocytes/square mm and 1/every 4 epidermal cells. Pigmented skin is located on the face, forhead, areolae of the nipple and genital skin.
What is the difference in skin color based on?
The difference in skin color is due to the rate and number of melanin granules produced and transferred to the keratinocytes.
What is a melanin epidermal unit composed of? Where is it located?
A melanin epidermal unit is composed of melanocyte and associated keratinocytes. It is located in the stratum basale and spinosum.
What is tyrosinase? Where is it located? What does it do?
Tyrosinase is in melanocytes and converts tyrosine into melanin within vesicles.
How do melanocytes produce melanin? What kind of secretion is it?
They use tyrosinase to convert tyrosine into melanin within vesicles. The vesicles first form premelanosomes in the melanocyte(elongated particles with fibrillar substructure that arise from golgi). Next, melanosomes are formed by producing more melanin. This continues until melanin granules are formed. These migrate lout to the ends of branches, the end of the process in pinched off into the cytoplasm of keratinocytes. (cytocrine secretion)
What happens to melanin granules in keratinocytes? What do darker skinned races have that others do not?
The melanin granules fuse with lysosomes to form a melanosome complex which forms a cap of complexes over the nucleus. The complexes slowly degenerate. The dark skinned races have increased number of melanosomes, longer lasting melanosomes, and granules in all layers.
What two types of ultraviolet light are people commonly exposed to? What effects do these have?
UVA (320 nm) causes wrinkling and sagging of skin, also increases cancer risk, it does not burn the skin, and is most used by tanning salons.

UVB (370 nm)
Induces inflammation of BV's in dermis, casue of sunburning and most block this wavelength.
What is wrong with albino's?
They have no tyrosinase but same number of melanocytes.
What is Vitiligo? What symptoms does it have? What sort of treatment can one recieve?
Vitiligo is a depigmentation disorder which is a genetically inherited defect in skin and hair. It is characterized by scattered patches of white skin and white hair where the melanocytes have been destroyed. Treatment is cosmetic or hydroquione treatment to reduce the formation of melanin in normal areas of skin.
What is a freckle due to?
Slightly higher concentration of melanin granules.
What is a nevus?
A mole or benign localized overgrowth of melanocytes arising during early life.
What is a malignant melanoma?
Carcinoma of melanocytes. Extremely malignant.
What is tanning and what is it due to?
It is due to immediate darkening of melanin. It as also an increase in tyrosinase activity over several days of continued exposure.
What is the purpose of melanin?
Protection against UV rays from reaching and damaging chromosomes in keratinocytes undergoing mitosis.
What two layers does the dermis have?
The papillary and reticular layers.
Describe the papillary layer. Where is it located? What type of tissue does it contain? What type of structures does it contain?
The papillary layer is the thinner of the 2 layers and is located subjacent to the epidermis. It is composed of modified areolar CT> IT contains dermal papillae which are finger like projections of connective tissue.
Describe the shape of papille in thick skin. How do these features help in function?
In thick skin the interpapillary peg of the epidermis divides primary dermal ridge into 2 secondary ridges, the primary dermal ridges correspond to the epidermal ridge (friction ridges). These ridges improve grip.
Describe the epidermal-dermal junction. What is its purpose?
The epidermal dermal junction is irregular due to dermal papillae, the dermal papillae interdigitate with the epidermal pegs or ridges and it helps to prevent shearing forces from seperating the two layers.
Describe the papille of thin skin.
Thin skin simply has rounded bumps or mounts of connective tissue.
Describe the reticular layer, what kind of tissue is it composed of? What types of fibers is it rich in?
The reticular layer is the thickest layer of the dermis, it is composed of dense irregular irregular CT. It is rich in collagen and elastic fibers.
What are the cleavage Lines of Langer? Why are they important?
The cleavage lines of langer are the predominant direction of bundles of collagen fibers in a region of the body. They are important for surgery so that incisions made parallel to the the LL do not gape open. If you cut across them, a large scar will form.
What are striae? Why do they occur?
Straie are stretch marks where the skin is pulled too tight and the dermis slowly tears but the epidermis is not broken. The gap is repaired with scar tissue. It occurs in pregnancy, obesity and weight lifters.
Where is the blood supply of the skin derived from?
IT is derived from the subcutaneous plexus and from arteries in subcutaneous fascia.
What are decubitus ulcers and what are they caused by?
They are bedsores caused by compromised circulation to an area of skin.
WHat is a contusion?
A bruise.
What is an erythema?
A redness of the skin due to engorged capillaries.
What is capillary hemangioma? WHen does it appear?
Capillary hemangioma is a benign vascular tumor of dermal capillaries. It appears soon after birth as a "strawberry mark" or "port wine stain".
Describe what hair is made of.
IT is a hard keratinous epithelial fiber that is composed of keratinocytes.
Describe hair follicle. What layers is it in? What is its structure?
This is a tubular invagination of the epidermis. It extends down through the dermis into the hypodermis. Each follicle is surrounded by connective tissue called the dermal sheath.
What two types of sheaths does the hair follicle contain? Where are they located?
The external root sheath is an extension of strata basale and spinosum downward. The internal root sheath goes halfway up follicle from root of hair.
What is the state of AV shunts during high temperatures?
Passive dialation of arterioles and veins allows blood to flow to surface and irradiate heat.
What happens during low temperature to AV shunts?
AV shunts are clamped closed and blood is kept from heading towards the surface.
Are there AV shunts in Apical skin? (Finger/toe tips, nail beds, nose, lips eyses)
Yes but not in the rest of the body. They regulate via sympathetic release of norepinephrine that causes vasoconstriction of arterioles. It also releases acetylcholene which usually causes vasodilatation.
What are the 3 layers or plexuses of vessels associated with the skin in order of deepest to most superficial?
The subcutaeneous plexus, the cutaneous plexus, and the subpapillary plexus.
Describe the subcutaneous plexus. Where is it located?
Subcutaneous plexus is the deepest plexus and is located in the hypodermis (subcutaneous fascia).
Where is the cutaneous plexus located?
It is located at the dermal-subcutaneous or dermal-hypodermal junction.
WHere is the subpapilary plexus located?
It is located in the papillary layer and capillaries loops run up into the dermal papillae.
Why is vasculature uniquely important in the skin?
It plays a key role in temperature regulation of the body.
What are AV shunts?
Glomulos or a bunch of small blood cells that run parrallel to the skin and are a coil of small vessels that run from the arteriol to the vein.
What is the state of AV shunts during normal temperature?
They are partially closed so blood runs to the surface.
What are the three regions the hair follicle is subdivided into? Where are they located?
The three regions are the hair shaft (the part of the hair that protrudes above the surface), the root of hair (reaches from the centor of hte follicle down to the bulb), and the bulb (an enlargement at the deep end of the hair follicle it contains the dermal papillae composed of connective tissue)
What is the Matrix or germativum zone?
Where the proliferation of keratinocytes occurs at the base of the follicle, it is the equivalent of the stratum basale in the epidermis. The keratinocytes move upward and differentiate by keratinaization process.
What is the Keratogenous zone?
This is where the cells become fully keratinized as they move upward, in the hair hard keratin is formed (not soft keratin like in the epidermis)
What is the difference between hard and soft keratin?
Hard keritin contains more sulfer and more cross links that soft keratin and is found in hair as opposed to in the epidermis.
What is the internal root sheath? What is it derived frome? What does the layer contain?
It is derived from outside the region of the matrix as cells move upward. The layer contains soft keratin. The layer disappears halfway up the follicle near the opening of the sebaceous gland duct into the follicle.
What are the 3 layers of the hair shaft? Where are they located? What type of keratin do they contain?
Cuticle of hair- on outside of hair shaft (hard keratin)
Cortex - makes up bulk of shaft (hard keratin)
Medulla - located in the center (soft keratin)
How is pigment in hair produced?
Melanocytes in hair produce pigment which is transferred to keratinocytes.
What does hair color depend on?

Match the various types of hair color with their morpholgy.
Pheomelnin = yellow and develops from tryptophan.

Eumelanin = brown and black, develops from tyrosine.

Grey hair = melanocytes lack tyrosinase to produce melanin.

White hair = pigment lacking but air pockets in hair reflect white light.
What do the arrector pili muscles do? What kind of muscle are they?
They are smooth muscle that stands hair erect, creates goose bumps due to insertion on to dermal papille and dermal sheath.
What are sebacious glands? What kind of secretion do they produce? Where in the hair shaft do they produce this?
Sebacious glands are an oil gland in the angle of the hair shaft. It empties into the upper part of the follicle.
What are the 3 phases of hair growth? Does it grow continually?
1. Growth Phase = anagen phase

2. Transitional phase = catagen phase

3. Resting phase = telogen phase

No hair growth is cyclic in that hair is lost and replaced periodically.
What occurs during the growth or anagen phase?
Matrix proliferates (soft keratin), hair grows in length at rate of 0.4-0.5 mm/day. There is a different length of growth phase in different arease of the body. (Scalp hair has longer growth phase than eyebrow hair)
What occurs during the transitional phase or catagen phase?
Growth stops and the hair remains in the follicle (short period of time).
What occurs during the resting phase or telogen phase?
During the telogen phase the hair shaft falls out. Normally there i always some hair falling our. Approximately 100/day.
Name the 3 types of glands in skin.
Eccrine sweat glands, apocrine sweat glands and sebaceous glands.
Describe the sebaceous glands. What are they associated with? What type of morphology do they have? What do they secrete? What is their mode of secretion? What pathology do they give rise to? How does this pathology occur?
Sebaceous glands are associated with hair follicles and are simple or branched alveolar. THey have a single duct that empties into the hair follicle about mid follicle. They secrete sebum, an oily substance. The mode of secretion is holocrine (whole cell). These are the glands that give rise to acne when infected by bacteria. Sex hormones at puberty increase secretion so they bulge and become more prone to infection.
What are sudiferous glands?
They are any sweat gland.
Describe eccrine sweat gland. Where are they located on the body? What type of morphology do they have? What type of secretion do they have? Where on the body do they commonly secrete? What mode of secretion do they have?
Eccrine sweat glands are the most common type of sweat gland and are located all over the body. Morphologically they are simple coiled tublular glands. Their type of secretion is merocrine and thier ducts open at the top of friction ridges in the hands and feet.
What 3 types of cells do eccrine sweat glands contain? What is the nature/function of each?
Clear cells are serous in nature.
Dark cells are mucous.
Myoepithelial cells help expel the secretions.
What are the major functions of eccrine sweat glands?
Temperature regulation by evaporation and excretion of ions (Na, PO) water, ammonia and urea.
Describe apocrine sweat glands. Whare are they located on the body? Describe their morphology in relation to eccrine sweat glands. What is their secretion mode/type? When do they start functioning? What pathology are they associated with?
Apocrine sweat glands are located in axilla, mons pubis and circumanal regions. The duct opens into the hair follicle above the sebaceous gland. Morphologically they are simple coiled tubular glands. They secrete a serous product via merocrine secretion. They don't start producing untill puberty. Bacteria invades these glands to give rise to armpit odor.
What are the 3 other types of glands in the skin that are modifications of sweat glands? Describe each.
Meibomian glands (tarsal glands) are modified sebacous glands which produce an oily substance and are located on the inner surface of eyelids.

Ceruminous glands are on the external auditory canal. They are modifate apocrine sweat glands that secrete a wax (cerumen).

Mammary glands are modified apocrine sweat glands.
What is the nail plate? What type of cells compose it? What does it replace in the epidermis?
The nail plate is the main body of the nail, it is composed of keratinocytes containing hard keratin. It replaces stratum corneum of the epidermis.
What is the lunula? What does it demarkate?
The lunula is characterized as the whitich crescent at root of nail. It marks the extent of the underlying nail matrix.
What is the lateral nail groove?
It is the lateral edges of the nail plate.
What is the nail root?
It is the proximal portion where the nail starts.
What is the nail bed? What is it composed of and continuous with?
The nail bed is the portion of the epidermis over which nail plate lies. It is composed of and continuous with the strata basale and spinosum of epidermis.
What is the nail matrix? What happens here?
The portion of the nail root where keratinocytes proliferate. Proliferation in this region shoves cells outward towards the free end of the nail.
What is the eponychium?
It is the cuticle of the nail at the root (the flap of skin that grows over the nail).
What is the hyponychium?
The excess stratum corneum under the free edge of nail.
What is a receptor?
A transducer that changes an energy stimulus into an afferent nerve impulse that the brain can interpret. Each type of receptor is basically an afferent nerve ending with associated cells of surrounding tissue.
What are the three functional classifications of receptors? What do they respond to?
Mechanoreceptor - respond to displacement by touch, pressure or stretch

Thermoreceptor - respond to temperature changes.

Nociceptor - respond to pain, itch and injurious agents
What are the two morphological general classifictions? What are they called?
Morphologically simple - free nerve endings that end without associated structures.

Morphologically complex - encapsulated receptors that have associated cells (identified by structure)
Morphologically simple
- free nerve endings that end without associated structures.
Morphologically complex
encapsulated receptors that have associated cells (identified by structure)
What are the six types of morphological receptors?









A encapsulated receptor that are elongated and lie parallel to epidermal-dermal junction. Typically they are located deep in dermis or hypodermis. They are mechanoreceptors for tension of collagen fiber that run through surrounding capsules.
What are Krause capsules? What do they look like? Where are they found in the body?
Krause capsules ahve a delicate capsule where axon branches lie within the capsule like tree branches. THey are located in a layer of the conjunctiva of the eye, oral cavity mucosa, and tongue. They have an unknown function.
Free nerve endings, Merkel cell ending, pacinian corpuscle, meissner's corpuscle, ruffini corpuscle, Krause capsule.
Describe free nerve endings. What types of sensation are they usually?
Free nerve endings lack schwann cells and myelin at their terminal end. They are naked nerve fibers lying between epidermal cells. They are thought to be thermoreceptors and nociceptors.
Describe Merkel cell endings. Where are they usually found? What stimumulus do they usually respond to?
Merkel cells are located between keratinocytes in stratum basale. There is an unmyelinated nerve fiber that forms a disc terminal on the cell. It is thought to be a mechanoreceptor for touch.
Describe pacinian corpuscles. What do they appear like? What do they usually detect? Where are they located.
Pacinian corpuscles are an encapsulated receptor that appears as an onion-like oval deep in lower dermis and hypodermis. They are very large and are mechanoreceptors for pressure and vibration.
What are Meissner's corpuscles? Where are they located. What to they usually detect?
Meissner's corpuscules are an ecapsulated receptor (flattened cells with horizontal nuclei surrounding it). They are located in dermal papillae of papillary layer (thick skin). They are mechanoreceptors for light touch.
What are Ruffini corpuscles? Where are they located? What do they look like? What do they detect?
A encapsulated receptor that are elongated and lie parallel to epidermal-dermal junction. Typically they are located deep in dermis or hypodermis. They are mechanoreceptors for tension of collagen fiber that run through surrounding capsules.
What are Krause capsules? What do they look like? Where are they found in the body?
Krause capsules ahve a delicate capsule where axon branches lie within the capsule like tree branches. They are located in a layer of the conjunctiva of the eye, oral cavity mucosa, and tongue. They have an unknown function.
What is the mucocutaneous junction? Describe it.
Where the skin meets the mucous membranes, it is reddish due to blood in capillaries, you can see blood due to a lack of keratin in cells.
What are the appendages of the skin?
These are structures derived from epidermis and associated with the skin. They include nails, hair, and glands (sweat, sebaceous ceruminous).
Desribe the Epidermis, what type of epithelium is it? What is it derived from? How many layers does it have?
It is stratisfied squamous keratinized type epithelium. It is derived from ectoderm, it is avascular and consists of 5 well defined layers.
Describe the dermis. What type of tissue is it? What is it derived from?
The dermis is the thickest layer of skin, it consists of dense irregular connective tissue. It is derived from mesenchyme and is vascular (supplies nutrients to the epidermis).
What is the papillary layer? Where does it lie? What does it contain?
Part of the dermis. The Papillary layer is superficial, and is immediately underneath the epidermis, it contains the dermal papille which are finger like projections.
What is the Reticular layer? What does it contain? Describe it.
The reticular layer is the deepest and thickest layero f the dermis, it contains appendages.
What is the Hypodermis? Describe it. What are some other names for it?
The lowest layer. NOT part of the skin. It is made up of areolar connective tissue. It is a layer of underlying loose CT. It is also called the subcutaneous fascia or superficial fascia.
What does the hypodermis consist of?
Primarily fat and is called the panniculus adiposus in the region of the abdomen.
What are dimples?
Where the dermis is tightly attached to the underlying deep fascia or bone.
List 8 functions of the skin.
Mechanical protection, Maintenance of body fluids, maintenance of body temperature, synthesis of vitamin D, immunity, reception of sensory stimuli, organ of communication, repair
Describe specifics of the mechanical protection that skin provides.
Physically protects against mechanical trauma, creates a physical barrier to bacteria etc., blocks U.V. rays.
Describe the specifics of maintenance of body fluids.
Prevents dessication (prevents body from losing or gaining fluids), carries out excretion (sweat glands excrete water, ions, urea, and ammonia)
Describe the specifics of the synthesis of vitamin D.
Works with 4 other organs to produce vitamin D. Precursor of vitamin D is converted by UV rays to cholecalciferol (another precursor. Liver further processes it to 25-hydroxy cholecalciferol. Kidney converts this to vitamin D.
Describe the maintenance of body temperature.
Sweat glands secrete serous fluid that cools the body. Blood vessels bring heat to the surface via vascular plexuses. Adipose serves as insulation.
Describe the specifics of immunity and skin's role.
Skin contains wandering cells of immunity system.
Describe the specifics of reception of sensory stimuli.
Lots of sensory receptors are found in the skin. pain, touch, pressure, temperature
Describe the organ of communication function of the skin.
Can tell when someone is embarrassed or nervous. Can tell about the functioning of the body via skin appearance. Cyanosis (blue), jaundice, age, nerve damage (due to loss in dermatome patterns).
Describe the specifics of the skin repair function of skin.
Skin repairs itself to prevent loss of functions. It also forms scars.
Describe the structure of the epidermis. What kind of tissue is it made of? Where does it get its nurients from?
It is composed of stratified squamous keratinized epithelium. It is avascular so all nutrients must diffuse up from dermis.
List the 5 layers of the epidermis starting from deepest toward most superficial.
Stratum Basale (Germinativum)
Stratum Spinosum
Stratum Granulosum
Stratum Lucidum
Stratum Corneum
What is the Stratum Malphigi? What does it consist of?
It consists of two layers the stratum basale and spinosum.
Describe the stratum basale (germinativum) what is its diagnostic characteristic? Describe the morphology of the cells. What processes go on here?
Deepest layer, diagnostic is a single layer of cells that sit on basement membrane. Cells are cuboidal and columnar in shape. Serves as a site for germinitivum (makes more epidermis cells via mitosis).
Describe the Stratum Spinosum. What do its cells look like? What is its diagnostic characteristic? Why does this diagnostic characteristic form?
Stratum Spinosum consists of several layers of cells. The cells are irregulary shaped. The diagnostic characteristic of this layer is that the cells are separated by narrow space or cleft which is crossed by intercellular bridges or spins (hence spiny appearance). The spines are where desmosomes attach and hold the cells together. The gaps form due to shrinkage during tissue processing.
Describe the Stratum Granulusom. What do its cells look like? What is its diagnostic characteristic?
Stratum Granulosum consists of a narrow layer that is 3-5 layers thick. The cells are flattened and nuclei are disappearing. Its diagnostic is darker staining due to prescence of numerous keratohyalin granules.
Describe the stratum lucidum. What is its diagnostic characteristic? What other layer is it considered part of?
Stratum lucidum is thin layer 2-3 cells thick. The cells and nuclei are not visible (diagnostic characteristic) b/c the cells are dead. It is considered part of the stratum corneum.
Describe the stratum corneum. What do its cells look like? What is in the cells? What is the most superfical part of this laye called?
The stratum corneum has numerous layers of dead cells, it has no nuclei visible (diagnostic characteristic) and its cells are filled with keratin (membrane bound bags called squames). Most superficial cells sloughing off that is called stratum disjunctivum.
Describe thick skin. What is another name for it? What layer is it actually the thickening of? What is its diagnostic characteristic? Where is the skin thickest?
Thick skin also known as glabrous skin. It lacks hair and sebaceous glands (diagnostic). IT is the thickening of the epidermis only. The skin is thickest on the soles of the feet and on the palms. 1 mm thick
Describe the thin skin. What is it also known as? What are its diagnostic characteristics? (2) What layer is lacking? Where on the body is it located?
Thin skin is also known as hairy or nonglabrous skin. It has the diagnostic characteristics of presence of hair and sebaceous glands and has a reduced thickness of stratum corneum, granulosum spinosum. The stratum lucidum is absent. It is located on the rest of the body that does not have thick skin. (Eyelids are thinnest)
What are the 4 types of cells found in the epidermis?
Keratinocyte, Melanocytes, Langerhans cells, and Merkel cells.