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Skin/Musculoskeletal: Anatomy/Dissection > Interstitia - Histology > Flashcards

Interstitia - Histology Flashcards

1
Q

What are the layers of the epidermis starting at the top of the skin?

A

stratum corneum

stratum granulosum

stratum spinosum

stratum generativum (basale)

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2
Q

Which epidermal layers are mitotically active and which are not?

A

the stratum generatibum and stratum spinosum are mitotically active.

the stratum granulosum and stratum corneum are not.

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3
Q

What are the two layers of the dermis starting below the epidermis?

A

the papillary dermis

the reticular dermis

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4
Q

what layer is below the reticular dermis?

A

the hypodermis

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5
Q

What are the 4 accessory structures found in the integument?

A

hair

nails

glands (sebaceous, sweat, mammary)

sensory structures

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6
Q

What are 8 functions of the integument?

A
  1. Protection (against injury; desiccation; invasion)
  2. Reception of stimuli (touch; pressure; pain; temperature; sunlight)
  3. Excretion (sweating)
  4. Secretion
  5. Thermoregulation
  6. Wound healing
  7. Fat-metabolism
  8. Vitamin D production
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7
Q

What are some characteristics of the stratum germinativum?

  • where is it?
  • what do the cells look like?
  • what junctions are involved?
  • are they mitotically active?
  • what does the cytoplasm of cells contain?
A

a. Single layer of cells adjacent to basal lamina
b. Cells are tall cuboidal or columnar
c. Hemidesmosomes along cell membrane adjacent to basement membrane;
other regions of cell membrane have typical desmosomes
d. Cells are mitotically active: cell proliferation is occurring in this layer
e. Cytoplasm of cells contains numerous polyribosomes and intermediate
filaments

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8
Q

What are some characteristics of the stratum spinosum?

  • what are these cells sometimes called?
  • how thick?
  • how are cells shapes?
  • mitotically active?
  • type of junctions?
  • what’s in the cytoplasm?
A

a. Variable thickness; can be several cell layers deep; immediately above
stratum germinativum
b. Cells are polygonally shaped
c. Some mitotic activity (but less than that found in stratum germinativum)
d. Numerous desmosomes; during fixation, cells frequently shrink slightly. Cell membranes pull back except at desmosomal contact points
Gives cell a “prickly” appearance

e. Cytoplasm contains many bundles of intermediate filaments (tonofibrils)
representing cytokeratins
f. Membrane-coating granules (keratinosomes) appear in cytoplasm
(1) Membrane-bound; contain lipid substance
(2) Tend to accumulate in superficial regions of cell beneath plasma membrane
(3) Thought to deposit a “toughening” layer on the surface of the cell membrane

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9
Q

What are some characteristics of the stratum granulosum?

  • how thick?
  • wat do cells look like?
  • mitotically active?
  • what’s in the cytoplasm?
  • what happens to the nucleus?
A

a. Three to five layers thick
b. Flattened polygonally-shaped cells (parallel to basement membrane)
c. No mitotic activity
d. Keratohyalin granules appear in cytoplasm
(1) Extremely basophilic
(2) Not membrane bound
(3) Probable precursor to keratin
e. Nucleus becomes pyknotic

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10
Q

What is the stratum lucidum? Characteristics?

A

a. Several layers of flattened, eosinophilic cells
b. Between stratum granulosum and stratum corneum
c. Cells appear “glassy”; contain a substance called eleidin

(1) May be transformation product of keratohyalin; we know little more about it
now than when it was first described in Ranvier in 1879

d. This layer is not always present
(1) Quite obvious in thick skin
(2) Lacking or inconspicuous in thin skin
e. Nuclei disappear

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11
Q

Describe the stratum corneum?

  • where is it
  • thickness?
  • what do cells look like?
  • what has happened to the cytoplasm?
A

a. Outermost layer of epidermis
b. Thickness and numbers of layers of cells varies considerably
c. Cells are clear; dead; flattened, fused

d. Cytoplasm has become completely “keratinized”
(1) Eleidin is apparently transformed to keratin

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12
Q

THe stratum lucidum may not actually exist, but if it does, wher eis it most apparent?

A

thick skin like the soles of feet and palms of hands

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13
Q

What is the thick skin vs. thin skin classification based on?

A

the thickness of the epidermis

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14
Q

WHat epidermal layer is particularly thick in “thick” sking?

A

the stratum corneum

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15
Q

WHat is keratin? What are the two major components?

A

keratin is a fibrous, proteinaceous material tha tis produced by epidermal cells.

it is composed of a filamentous component (intermediate filaments combined into tonofibrils).

it is also composed of an interfilamentous matrix

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16
Q

Describe the process of keratinization. What are the two phases?

A
  • *Synthetic phase**
    (1) Intermediate filaments, keratohyalin granules, membrane-coating granules and filaggrin and trichohyalin proteins are formed in large numbers
  • *Degradative stage**
    (1) Membrane-coating granule contents (lipid) discharged into intercellular spaces
    (a) Thickened cell envelope is result
    (2) Lysosomal enzymes degrade synthetic organelles
    (a) Filaments and keratohyalin remain unaffected
    (3) Filaments and keratohyalin consolidate into a fibrous-amorphous mass
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17
Q

Where is hard keratin located?

Where is soft keratin located?

A

Hard keratin is located in nails and hair.

Soft keratin is everywhere else - epidermis and internal root sheath

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18
Q

How is the production of hard keratin different from that of soft keratin?

A

hard keratin is produced without a morphological phase of granular cells

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19
Q

What are the 3 functions of keratin?

A
  1. water proofing
  2. protects underlying cells
  3. defense against bacterial invasion
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20
Q

What to melanocytes do?

A

they produce melanin granules called melanosomes

they then donate melanin granules to the cells in the stratum germinatibum and stratum spinosum

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21
Q

what enzyme is required for melanin production?

A

tyrosinase - it oxidizes the tyrosine to DOPA and then to melanin

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22
Q

What is the function of langerhands cells in the integument?

A

they are the monocytes of the integument for the immune response

they have Fc and C3 receptors, they phagocytose and process foreign antigens, and they can migrate to local lymph nodes to present epitopes to the T-lymphocytes

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23
Q

What are Merkel cells associated with and what are they probably involved in?

A

They are associated with unmyelinated sensory nerves and are probably involved in sensory reception

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24
Q

WHat causes psoriasis?

A

Results from an increase in the number of proliferating cells in the stratum basale and stratum spinosum

Also, there is an increase in the rate of cell turnover

Result: greater epidermal thickness and continuous turnover of the epidermis

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25
Q

What causes pemphigus vulgaris?

A

An autoimmune blistering disorder caused by disruption of desmosomes linking keratinocytes

Antibodies made against desmogleins

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26
Q

What causes bullous pemphigoid?

A

Autoimmune blistering disorder of the dermis-epidermis junction

IgG is directed against an antigen (BPA) in the dense plaque of the hemidesmosome

Blister occurs in the lamina lucida region of the basement membrane

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27
Q

Which skin will have more dermal ridges, the skin of the face or palm?

A

Skin on the palm will have more dermal ridges because it sees more trauma than the facial skin, so it needs a stronger adherence between the dermis and epidermis

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28
Q

What structure is responsible for fingerprints on the palm?

A

the furrows of the epidermis define ridges arranged in loops, whirls and spirals = fingerprints

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29
Q

When the primary ridges of the dermis separate into secondary dermal ridges/papillae, what is formed between them?

A

interpapillary pegs

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30
Q

What is the composition of the papillary layer of the dermis?

A

loose connective tissue - thin bundles fo collagen fibers, some reticular and elastic fibers

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31
Q

What is the difference between vascular papillae and nervous papillae in the papillary level of the dermis?

A

vascular papillae contain capillary loop projections, which is the only source of nourishment for epithelial cels. This is also important for thermoregulation.

Nervous papillae contain special nerve terminations, such as messner’s corpuscles and Krause end bulbs.

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32
Q

WWhat is the composition of the reticular layer of the dermis?

A

dense irregular connective tissue

coarse, dense, interfacing bundles of type 1 collagen

some reticular fibers and many elastic fibers

it’s less cellular than the papillary layer

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33
Q

What is the predominant direction of all the fibers in the reticular layer o the dermis?

A

parallel to the surface

this crease lines of skin tension called Langer lines

these are importnat to consider when making surgical incisions

34
Q

What are 6 cellular elements of the dermis?

A
  1. Fibroblasts
  2. Mast cells
  3. Macrophages
  4. Smooth muscle cells: arrector pili muscles; skin of nipple, scrotum, glans penis,
    and prepuce
  5. Skeletal muscle (in face and neck)
  6. Fat cells: singly or more often in groups
35
Q

What is the hypodermis composed of?

A

loose connective tissue

it frequently containes large accumulations of fat cells

somtimes continuous lobules of fat are present and form a fat pad called the panniculus adiposus

36
Q

What three factors are involved in the pigmentation of skin?

A
  1. Color of skin itself is yellow due to presence of carotene
  2. Blood in capillaries imparts a reddish hue
  3. Varying amounts of melanin pigment imparts shade(s) of brown
37
Q

Where are melanocytes located typically?

A

in the stratum basale layer of the epidermis.

they are highly branched dendritic cells that have processes that insuinuate themselves between other epidermal cells.

These processes contain many pigment granules called melanosomes

38
Q

What are the steps of melanin production?

A
  1. the TET forms enzymes with tyrosinase activity
  2. the golgi apparatus packages the tyrosinase in a membrane bound besicle called the pre-melanosome
  3. tyrosine is depositied in the pre-melanosomes and is oxidized by tyrosinase to DOPA, which is then acted on by tyroinase again to form melanin within the melanosome
  4. gradually the internal structur is obliterated as melanin is deposited
  5. tyrosinase activity declines as the melanosome matures.
39
Q

How are white people and black epople different in terms of melanin production?

A

they have the same relative number of melanocytes!

However, in white people the melanosomes are smaller, fewer, and closer to nucleus. they are degraded faster.

40
Q

What happens to melanosomes after they mature?

A

they are “donated” to adjacent epidermal cells and tend to reside on “sunward” sides of nuclei

41
Q

What are the two processes involves in sun[tanning?

A
  1. immediate darkening of existing melanin
  2. delayed - increase in tyrosinase activity
42
Q

What enzyme is lacking in albinism?

A

tyrosinase

43
Q

What is the purpose of melanin?

A

it protects the deep epidermal cells and dermal tissues against excessive UV radiation

44
Q

What is vitiligo?

A

it’s a disorder in which melanocytes are destroyed, probably due to an autoimune dysfunction, leading to depigmentation

45
Q

Where does most of the vascular supply of skin come from?

A

the largest arteries reside in subcutaneous tissue

these send branches superficially to form a horizontal network at the dermal hypodermal junctions called the rete cutaneum

the branches of the rete cutaneum go two directions: on one side they go down to supply the sweat glands and deeper portions of hair follicles. In the other direction they supply the dermis and form a secondarynetwork between the papillary and reticular layers called the rete subpapillare

46
Q

What does the rete subpapillare supply?

A

it ggives off small arteries up to supply the papillae

once in the papillae, they break up to form capillary networks to supply the papillae, sebaceous glands and intermediate portions of hair follicles

47
Q

What areas are not covered by hair?

A

palms, soles, anal and urogenital apertures

48
Q

What kind of hair covers a fetus?

A

lanugo hair

49
Q

How and when does hair form in the fetus?

A

At about the third month of fetal life, downgrowths occur in the epidermlal layer, down into the underlyin gdermis.

these become hair follicles and give rise to hair

50
Q

WHat is the hair root enclosed in?

A

the hair follicle

51
Q

in what layers is the hair follicle located?

A

part dermal and part epidermal

52
Q

WHat is the deepest end of the hair follicle called?

A

the hair bulb - it has an indentation called the connective tissue papilla

53
Q

What are three structures associated with the hair follicle?

A

sebaceous glands

arrector pili muscles

apocrine sweat glands

54
Q

What kind of hair covers the body of infants and remains into adulthood?

A

the vellus hair

55
Q

What are the coarse hairs of the scalp, eyebrows and thows that appear at puberty called?

A

terminal hairs

56
Q

what is the smooth muscle associated with hair follicles?

A

the arrector pili muscles

57
Q

What is the arrector pili muscle anchored to?

A

one end is anchored in the papillary layer of the dermis

the other is anchores to the connective tissue sheath of the follicle

58
Q

What does sympathetic activation of the arrector pili muscle lead to?

A

It contracts, pulling the hair straight

it also causes bumps in the skin - goose bumps

it compresses the sebaceous glands, squeezes out oil into the hair follicle

59
Q

What are the three main components that make up the nail?

A

1 . the nail plate composed to hard keratin in compacted horny scales

  1. the nail bed, called the stratum malpighian (stratum basale and stratum spinosum only)
  2. the natil matrix - at the most proximal portion of the nail bed where cells proliferate and push the nail plate distally
60
Q

What is the cuticle called in scientific terms?

what is the area under the distal end of the nail called?

what is the white crescent part called?

A

the eponychium

the hyponychium

the lunula

61
Q

What are sebaceous glands usually associated with?

A

hair follicles

62
Q

What type of gland is a sebaceous gland?

A

a simple, branched alveolar gland whose short duct empties into the hair follicle

63
Q

what type of secretion is associated with sebaceous glands?

A

holocrine secretion

this means the entire cell becomes part of the secretory product

the basal cells of the gland proliferate and get pushed toward the center of the gland. Inside, they synthesize and addumular lipids. The cells then die as they move farther from the blood supply and become part of the secretion itself.

64
Q

What is acne related to?

A

this is a substantial increase in sebum production that occurs at puberty due to male hormone.

this greately increases the mitotic activity in the cells of the gland and the cells can’t get out fast enough. This results in a bulge into adjacent skin - pimples

these are then prone to infection and you get the uncomfortable red, pussy zits.

Blackheads are similar - they are sebaceous glands plugged with melanin

65
Q

What are the two type sof sweat glands?

A

eccrine and apocrine

66
Q

Describe eccrine sweat glands?

A

they are simple coiled tubular glands

they are absent from nail beds, lips, glans, eardrum, and particularly numerous on palms and soles

they are comprised of a secretory portion located deep in the dermies or hypodermis. This is a highly coiled mass ot simple cuboidal or solumnar epithelial. There are dark and light cells.

They are associated with myoepithelial cells between the base of the cells and the basement membrane.

They also have excretory portions, which are the ducts that rise tot he epidermal surface by a slightly tortuous route that passes through the epidermal peg and spirals through the epidermis to open onto the epidermal ridge.These are made of stratified cuboidal epithelium and the cells appear darker. These reabsorbe potassium, sodium and chloride.

They produce a watery product

67
Q

Describe myoepithelial cells?

A

These are located between the base of the cells of secretory apocrine portions and the basement membrane

they are specialized smooth muscle cells

they help force materials out of the gland and into the duct

68
Q

Describe apocrine glands.

A

these are located only in axilla, areola of nipple, and anogenital region

they have a secretory portion that has a large lumen, comprised of simple cuboidal or simple columnar epithelium.

Myoepithelial cells are present.

The excretory portion has stratified cuboidal epithelial ducts that empty into the hair follicle

these secrete an odorless product that becomes odoriferous when acted on by cutaneous bacteria

these are probably pheromones in animals

69
Q

In general, what is a way to classify nerve endings into two categories?

A

naked or encapsulated

70
Q

Describe peritrichial nerve endings

A

they are free nerve endings that surround hair follicles and are sensitive to movement of the hair

71
Q

WHat are merkel cells?

A

The tactile cell of Merkel is cell that sits in the stratum basale of the epidermis

they are almost always associated with a sensory nerve fiber - likely sensitive to fine touch.

72
Q

Is the sensation of pain associated more with free or encapsulated nerve endings?

A

free

73
Q

WHat are two mechanoreceptors that have encapsulated nerve endings?

A

corpuscles of ruffini and krause’s end bulbs

74
Q

Describe Meissner’s corpuscle

A

It is a cell associated with nervous papilli in areas particularly sensitive t otouch - on the finger tips, toes, nipples, glans, etc.

they are sensitive to touch.

the sensory fiber lines up in nervous papilli of the papillary layer and will wind around surrounded by schwann-like cells of connective tissue

75
Q

Describe a pacinian corpuscle

A

they looked like sliced onions on histology

these are usually in deeper layers of dermis and hypodermis

they are sensitive to pressure.

the sensory nerve winds up around the eleonvated cells. as pressure pushes on the structure, the elongated cells push on the nerve and the message will be sent

76
Q

In generaly, what happens to the epidermis in wound healing?

A

After a cut, the epidermis cells will increase their mitotic rate and migrate down the walls of the sut, reepitheliarizin the surface. Then fibroblasts adjacent to the cut will start migrating up and producing collagen and ground substance. Gradually, the colagen will push the epidermal invagination uptwards and the epidermis is pushed back to the surface and the wound is healed

77
Q

What are the two types of skin grafts we talked about?

A

split skin grafts

full-thickness grafts

78
Q

Which is the preferred form of skin grafting and why?

A

split skin grafts - less likely to cause scarring at the donor site

79
Q

Describe a split skin graft

A

At the donor site, you cut through the dermis, but leave renmants of the hair follicles and eccrine sweat glands - you just take the top part off.

you put that slice of skin over the wound to help it heal, which leaves the donor site open. Because you only took the top layer, the cells will undergo divsion and reepitheliarize the donor site surface and return it to a reasonably normal area

80
Q

Describe full thickness grafts

A

If the wound is too deep, you’ll need to take a deeper graft

this means the donor site won’t be able to epitheliarize itself as well and you’ll get scarring

81
Q

What is the classification system for burns?

A

first degree - like sunburn

second degree - blistering involving the epidermis and dermis

third degree - horrible destruction of the epidermis and dermis

fourth degree - burn erodes into muscle and bone

82
Q
A

Skin/Musculoskeletal: Anatomy/Dissection (12 decks)

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