Ant205 Skin And Appendages

Front 1

The epidermis is ____ in origin.

Back 1

ectodermal

Front 2

The epidermis has what epithelial characteristics?

Back 2

stratified squamous, keratinized epithelium

Front 3

What are 5 types of layers found in the epidermis?

Back 3

Layers (strata)
1. Stratum germinativum
2. Stratum spinosum
3. Stratum granulosum
4. Stratum lucidum
5. Stratum corneum (comes off on keyboards)

Front 4

Stratum Germinativum
also called stratum basale
is a single layer of ___ or ____ which rest on the basal lamina.

Back 4

cuboidal or columnar

Front 5

How are the basal cells of the straum germinativum attached to the basal lamina? How are these cells attached to adjacent cells?

Back 5

by hemidesmosomes; then to other cells by desmosomes.

Front 6

This cell layer is made up of polygonal cells that have spiny projections that form “intercellular bridges”. These bridges were once believed to represent sites of cytoplasmic continuity between cells. They are now known to be locations of desmosomes that contribute to the cohesiveness of the epidermis. Mitoses seen in this layer as well

Back 6

epidermis - straum spinosum

Front 7

The stratum germinativum and stratum spinosum are frequently referred to as the____.

Back 7

malpighian layer. This region of keratinocyte proliferation is named after the Italian histologist Marcello Malphigi.

Front 8

This layer is characterized by basophilic granules, keratohyaline granules, which are not membrane bound. There are also membrane bound granules called membrane-coating granules. These granules contain glycosaminoglycans and phospholipids that are extruded out into the extracellular space to form a barrier to micro-organisms, foreign substances and most importantly water.

Back 8

Stratum Granulosum

Front 9

It is most prominent in thick skin. In thin skin, this layer is often not identifiable. It is a translucent layer of normally very acidophilic cells that are devoid of nuclei and organelles.

Back 9

Stratum Lucidum

Front 10

What is the name of the epidermal layer that contains flattened keratin-filled cells devoid of any organelles including the nucleus? (They are also called horny cells or squams.)

Back 10

Stratum Corneum

Front 11

What is the characteristic of a 1st degree burn?

Back 11

Damage to superficial epidermis
Cells of stratum germinativum remain viable and regenerate epidermis

Front 12

What is the characteristic of a 2nd degree burn?

Back 12

Epidermis completely destroyed
Remnants of sweat glands and hair follicles in the dermis are able to regenerate the epidermis

Front 13

What is the characteristic of a 3rd degree burn?

Back 13

Full-thickness burn
Destroys epidermis and dermis
Skin grafts are typically necessary
Loss of body fluids can cause hypovolemia and shock - With 15% of body area in adults - With 10% of body area in children

Front 14

what are four Cells types Found in Epidermis?

Back 14

Keratinocytes
Melanocytes
Langerhans cells
Merkel Cells

Front 15

What is the origin of Melanocytes?

Back 15

neural crest

Front 16

what is the origin of keratinocytes?

Back 16

ectodermal origin

Front 17

What are Langerhan's cells?

Back 17

Dendritic, antigen presenting cells

Front 18

What are Merkel Cells? and what is their origin?

Back 18

Specialized keratinocyte that is involved in touch.
must be ectodermal if it is a keratinocyte deriviative.

Front 19

what do keratinocytes produce?

Back 19

the protective dead cell layer, the stratum corneum.

Front 20

What are 70% of skin cancers?

Back 20

Basal Cell Carcinoma

Front 21

Where do basal cell carcinomas arise?

Back 21

arise in regions of skin containing sebaceous glands.
typically on eyelids and bridge of nose in fair-skinned 40-yr-olds.

Front 22

True /False: Basal Cell carcinomas typically metastasize.

Back 22

false, they rarely do this.

Front 23

in basal cell carcinoma - what is different about the basal cell?

Back 23

Histologically basal cell carcinoma cells form discrete nests or islands of cells that resemble normal basal cells

Front 24

What makes up 20% of skin cancers?

Back 24

squamous cell carcinoma

Front 25

Fair-skinned blonds with outdoor occupations are particularly prone to this form of cancer

Back 25

what is squamous cell carcinoma

Front 26

in squamous cell carcinoma, Histologically, there is a complete replacement of normal epithelium with ____ cells.

Back 26

pleomorphic (capable of assuming different shapes )

Front 27

What is the metastasis rate of squamous cell carcinomas?

Back 27

Relatively few squamous cell carcinomas (2-5%) metastasize to regional lymph nodes.

Front 28

These dendritic cells are mainly found in the stratum spinosum.
They are NOT attached to adjacent keratinocytes by desmosomes.
They are similar to dendritic cells seen in lymphoid tissues.
They are responsible for engulfing invading micro-organisms in the epidermis and presenting antigens to lymphoid cells.

Back 28

langerhans cells

Front 29

How are langerhans cell samples prepared?

Back 29

Langerhans cells cannot be distinguished easily in H and E stained tissue. One must use gold impregnation techniques to visualize Langerhans cells.

Front 30

What type of cell can act as a resevoir for HIV that is found in the epidermis?

Back 30

langerhans cells

Front 31

What type of cell can migrate out of the epidermis, enter lymphatics in the underlying dermis and travel to local lymph nodes.

Back 31

langerhans cell

Front 32

Where are melanocytes located?

Back 32

stratum germinativum

Front 33

True/False: Melanocytes cannot replicate.

Back 33

false. Melanocytes can replicate slowly throughout life, thereby maintaining epidermal-melanin units (one melanocyte associates with a fixed number of keratinocytes).

Front 34

What is not determined by race or gender?

Back 34

among other things, Epidermal-melanin units

Front 35

Melanocytes have which, hemidesmosome or desmosomes?

Back 35

Melanocytes are NOT connected to surrounding keratinocytes by desmosomes, but can be attached to the basal lamina by hemidesmosomes

Front 36

melanocytes contain a large amount of what substance, and what does it do?

Back 36

Melanocytes contain large amount of the enzyme, tyrosinase. Tyrosinase is responsible for conversion of tyrosine through a series of steps to melanin.

Front 37

What is cytocrine secretion?

Back 37

A process in which Melanin granules are injected into keratinocytes.

Front 38

Melanin granules take position above the nuclei of keratinocytes in the ____ and ____.

Back 38

strata germinativum
spinosum

Front 39

Melanin granules eventually fuse with lysosomes in the keratinocytes and are degraded by the time the keratinocytes reach the ____.

Back 39

stratum granulosum

Front 40

______ of melanin granules is slower in darker-skinned races and melanin granules may be evident in the upper strata of the epidermis.

Back 40

Lysosomal degradation

Front 41

What are 2% of skin cancers?

Back 41

malignant melanomas

Front 42

what type of skin cancer, Because of the neural crest origin (i.e. highly migratory cells), are very metastatic?

Back 42

malignant melanoma; Melanoma appears as nests of pigmented melanocytes that penetrate the epidermis.

Front 43

Melanoma appears as nests of pigmented melanocytes that penetrate the epidermis. The cells also invade the dermis where they have access to ____ and ____.

Back 43

blood vessels and lymphatics.

Front 44

Where are merkel cells typically found?

Back 44

They are primarily found in thick skin where touch is acute.

Front 45

What type of cell in the epidermis contain 80nm neurosecretory granules?

Back 45

merkel cells

Front 46

What type of cell cannot be distinguished from keratinocytes in H and E preparations?

Back 46

merkel cells, a specialized keratinocyte.

Front 47

What are two distinc cell layers in the dermis?

Back 47

papillary and reticular

Front 48

which layer of the dermis has loose CT containing fibroblasts, mast cells and macrophages as well as some leukocytes - major part of the dermal papillae or pegs

Back 48

papillary

Front 49

which layer has dense irregular CT - composed of collagen fibers (type I) and fewer cells than the papillary layer

Back 49

reticular layer

Front 50

Where can you find thick (glaborous) skin?

Back 50

Found in areas exposed to greater wear and abrasion.
The palms of the hands and the soles of the feet have classic examples of thick skin.

Front 51

What layers does thick skin have?

Back 51

Thick skin has all five epidermal layers with a prominent stratum lucidum and a thick stratum corneum.

Front 52

Does thick skin have sebaceous glands?

Back 52

Thick skin is hairless and, as such, has no sebaceous glands.

Front 53

Where can you find thin (hairy) skin?

Back 53

Anywhere but the palms of hands and soles of feet.

Front 54

thin hairy skin is missing what epidermal layer, and which layer is especially thin?

Back 54

It typically has no distinct stratum lucidum and a thin stratum corneum

Front 55

What lies deep to the dermis, but not considered part of the skin?

Back 55

hypodermis;It is also called superficial fascia or subcutaneous CT.

Front 56

What does the hypodermis contain?

Back 56

loose CT with varying numbers of fat cells. The fat cells vary in size according to the degree of obesity of the individual

Front 57

what are five appendages of the skin?

Back 57

Hair follicles
Sweat glands
Sebaceous glands
Mammary glands
nails

Front 58

Hair follicles are invaginations of epidermis which during periods of growth have what?

Back 58

bulbous terminal dilations -the hair bulb.

Front 59

the hair bulb of a hair follicle rests upon a dermal papilla that contains what?

Back 59

the capillaries that nourish the hair follicle.

Front 60

The cells of the hair bulb are like those of which epidermal cell layer?

Back 60

the stratum germinativum.

Front 61

Apocrine or Eccrine?
simple, coiled tubular glands - secrete a non-viscous fluid. Evaporation of the fluid cools skin. Sweat glands are also excretory. Sweat contains catabolites.

Back 61

Eccrine

Front 62

Apocrine or Eccrine?
have lightly staining, simple cuboidal secretory acini (arrows) and darker staining, stratified cuboidal ducts (arrowheads)

Back 62

eccrine

Front 63

What are myoepithelial cells?

Back 63

specialized cells that squeeze the secretions from the sweat acini.
They are epithelial, not smooth muscle cells.
They are acidophilic because they contain actin filaments.

Front 64

why are myoepithelial cells acidophilic?

Back 64

they contain actin

Front 65

Apocrine or Eccrine?
Specialized glands located in the axillary, areolar and anal regions.

Back 65

apocrine

Front 66

Apocrine or Eccrine?
The ducts open into hair follicles and secrete a viscous, odorless fluid. The secretion attains a distinctive odor by the action of bacteria that reside on the skin.

Back 66

apocrine

Front 67

The mammary gland is believed to be a highly modified what?

Back 67

apocrine sweat gland

Front 68

What do sebaceous glands develop in association with?

Back 68

hair follicles; They are not found, therefore, on the palms of the hands or soles of the feet. (thick skin)

Front 69

What locations do sebaceous glands exist without hair follicles?

Back 69

They are found, however, in the skin of the lips, the glans penis and the clitoris where they are not associated with hair follicles.

Front 70

what secrete sebum by holocrine secretion.

Back 70

sebaceous glands

Front 71

what sweat gland makes for good pimples? especially at puberty?

Back 71

sebaceous glands

Front 72

The cells at the base of a sebaceous gland are germinal cells. what happens to these cells As the cells fill with sebum?

Back 72

their nuclei become pyknotic (irreversibly condensed) and eventually are lost.

Front 73

blue nails indicate what?

Back 73

Blue indicates poor oxygenation (cyanosis).

Front 74

nails are plates of what?

Back 74

keratinized epithelial cells

Front 75

which part has the stratum germinativum and stratum spinosum only (the malpighian layer) ?

Back 75

nail bed; this layer does not contribute to the nail plate.

Front 76

Case Presentation: A 24-year-old blond, blue eyed woman has moved to Sarasota from Alaska. She finds Siesta Beach irresistible and spends 4-5 hours per day sunbathing using only coconut butter to get a deep, dark tan.
One year later, a darkly-pigmented, irregular lesion appears on her right upper pectoral region. On a visit to her dermatologist, the lesion was surgically excised and sent to a pathologist. The pathology report came back 4 days later and the lesion is malignant.

What type of cancer does she have?

What is the embryological origin of the cells that gave rise to the cancer?

Is the risk of metastases high or low?

Back 76

melanoma;
neural crest;
high

Front 77

Describe free nerve endings in the skin.

Back 77

Unmyelinated axons that penetrate the basal lamina of the epidermis to enter the stratum germinativum and spinosum.
Ramify among the epithelial cells.
Involved in temperature and pain perception.
May also function in crude touch as evidenced by the fact that they are the only type of receptor found in the cornea.

Front 78

What are meissner's corpuscles?

Back 78

most abundant in thick (glabrous) skin as well as in the skin of the lips and nipples.
These specialized encapsulated receptors can be found within the dermal papillae of thick skin.
Involved in discriminative touch, ability to discriminate two points.

Front 79

What are Pacinian Corpuscles?

Back 79

This encapsulated receptor is found in the dermis and often, the hypodermis, of both thick and thin skin.
Pacinian corpuscles are especially abundant in the skin of the fingertips.
The corpuscle is traditionally described as a pressure sensor, but its rapid adaptation has lead some to believe the pacinian corpuscle signals a vibratory sense, i.e. it responds to a tuning fork placed against the skin.