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sum: histology 1 > Integumentary System > Flashcards

Integumentary System Flashcards

1
Q

Skin

A

The LARGEST single organ of the body

Accounting for 15 to 20%

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2
Q

Skin is also known as

A

Integument or Cutaneous Layer

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3
Q

What is Skin composed of

A

Epidermis (epithelial layer)
Dermis
Subcutaneous Layer

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4
Q

What are the specific functions of the Skin

A

Protective: provides physical barrier agains thermal & mechanical insults such as friction and against most potential pathogens or materials

Sensory: sensory receptors allow skins o constantly monitor the environment

Thermoregulatory: body temprerature is easily maintained due to skins insulating components (fatty layer, hair)

Metabolic: cells of skin synthesize vitamin D3 needed in calcium metabolism and proper bone formation

Sexual signaling: sex pheromones produced by the apocrine sweat glands and other skin glands

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5
Q

Epidermis consists of what type of tissue

A

Stratified squamous keratinized epithelium

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6
Q

Epidermis is composed of what type of cells

A

Keratinocytes

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7
Q

What are the Three much less abundant epidermal cell types

A
  1. Melanocytes (antigen-presenting cell)
  2. Langerhans cells
  3. Markell cells (tactile epithelial cells)
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8
Q

What is the distinction between thick or thin epidermal layer?

A

The size varies according to the site of the body part ex: back, scalp, foot

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9
Q

If epithelia, stratified squamous epidermis lacks microvasculature, how are they receiving nutrients

A

It’s cells receive nutrient and O2 by diffusion form the dermis

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10
Q

How many layers does the Epidermis layer consist of and what are they

A

4 layers: from the bottom

  1. Stratum Bisale (cytoskeletal keratin)
  2. Stratum Spinosum (thickest layer, polyhedral cells having central nuclei with nucleoli & cytoplasm actively synthesizing Karatins)
  3. Stratum Granulosum (general layer, 3-5 flatten cells undergoing terminal differentiation process of keratinization)
  4. Stratum Lucidum (
  5. Stratum Corneum (Dead keratonicytes)
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11
Q

Human epidermis is renewed about

A

15 to 30 days depending on age and region of body

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12
Q

Example of a cornified layer on hands

A

Calluses from working out with free weights

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13
Q

Skin is considered to be what type of tissue:

A

Consists mainly of superficial stratified Squamous Epithelium

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14
Q

What is the external skin layer called:

A

-Epidermis

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15
Q

What is the thick layer of connective tissue called:

A

-Dermis

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16
Q

What does epidermis consists of ?

A

-Keratonicytes

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17
Q

What overlies a subcutaneous hypodermis?

A

-Dermis

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18
Q

Keratonicytes under go a teminal differentiation process which is series of steps that form distinct epidermal strata or layers called:

A

Keratinization

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19
Q

What is one layer of mitotically active cuboidal

cells called?

A

-stratum basale

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20
Q

How is stratum basale attached to the basement membrane and to each other

A
  1. hemidesmosomes and integrins to the basement
    membrane
  2. and to each other by desmosomes .
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21
Q

stratum spinosum has several layers of ………… attached to eachother and by ………………….? At the tips of short projections containg bundled ……………. Or ………………..?

A
  • polyhedral cells
  • attached to each other by desmosomes
  • containing bundled keratin or tonofibrils .
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22
Q

What tye of tissue is stratum granulosum?

A

thinner layer of keratinocytes

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23
Q

What is Stratum Granulosum filled with?

A

flattened and filled densely with keratohyaline granules containing
filaggrin and other proteins binding the tonofibrils.

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24
Q

What are tonofibrils?

A

A structural cytoplasmic protein, of a class known as intermediate filaments, bundles of which together form a tonofibril

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25
Q

What does superficial stratum consist of?

A

consists of flattened, terminally differentiated cells, or squames , which are slowly lost.

26
Q

What is the epidermis-dermis interface streangthened by?

A

enlarged and strengthened by interdigitating epidermal ridges or pegs and dermal papillae in which microvasculature also supplies nutrients and O 2 for the epidermis.

27
Q

Where are Melanocytes found?

A
  • basal epidermis
28
Q

What are melanocytes responsible for?

A

They synthesize dark melanin pigment in melanosomes and transport these to adjacent keratinocytes, which accumulate them to protect nuclear DNA from UV damage.

29
Q

What are Antigen-presenting cells (APCs) also known as …………and what do they form?

A

Langerhans cells
- they form a network through the epidermis, intercepting and sampling microbial invaders before moving to lymph nodes in an adaptive
immune response.

30
Q

What are the two major layers of dermis:

A

1: a superficial papillary layer or loose connective tissue with a microvascular plexus,
2) a thicker dense irregular reticular layer containing larger blood vessels.

31
Q

Where are Cutaneous Sensory Receptors found?

A

Found in the epidermis

32
Q

What are Cutaneous Sensory Receptors responsible for?

A

Sensory receptors in the epidermis include free nerve endings ,
which detect pain and temperature extremes

33
Q

What are basal Merkel cells associated with ?

A

-light-touch (tactile) receptors associated with sensory fibers.

34
Q

What are basal Merkel cells?

A

Merkel cells, their function as receptors ( mechanoreceptors )are located in the basal epidermal layer of the skin. Merkel cells, also known as Merkel-Ranvier cells or tactile epithelial cells, are oval-shaped mechanoreceptors essential for light touch sensation and found in the skin of vertebrates.

35
Q

What is found Deeper in the dermis and subcutaneous layer ?

A

lamellated or pacinian corpuscles, which are ovoid and much larger than Meissner corpuscles, for detection of pressure or firm touch.

36
Q

How are Epidermal Appendages formed and what are some examples?

A

-Hairs form in hair follicles,

37
Q

What is comprised in the matrix of the deep hair bulb?

A

matrix of the deep hair bulb proliferate rapidly and undergo keratinization
to form the medulla, cortex, and cuticle of a hair root .

38
Q

where is large dermal hair papilla found?

A
  • the lare dermal hair pailla penetrates the base of the hair bulb
    and its vasculature supplies nutrients and O 2 for proliferating and differentiating cell
39
Q

What are the 4 structures a growing hair root surrounded by?

A
  • Internal and external root sheaths continuous with the epidermis,
  • a glassy membrane formed in part by the basal lamina,
  • a connective tissue sheath .
40
Q

Describe how Nails are formed in a manner similar to hairs:

A

-keratinocytes proliferatein the matrix of the nail root and differentiate with the formation of hard keratin as a growing nail plate with edges covered by skin folds.

41
Q

What do Sebaceous glands produce and how?

A
  • sebum
  • by terminal differentiation of sebocytes, the classic example of holocrine secretion, secreting this oily substance onto hair in the follicles or pilosebaceous units .
42
Q

What do Eccrine sweat glands in the dermis produce ?

A

sweat that is mostly water onto the skin surface, where its evaporation provides an important mechanism for cooling the body.

43
Q

A pocrine sweat glands are restricted to what?

A

-skin of the axillae and perineum, have much wider lumens than eccrine glands, develop after puberty, and secrete protein-rich sweat onto the hair of hair follicles.

44
Q

What are sex pheromones produced by?

A

The apocrine sweat glands and other

skin glands

45
Q

Describe the basal layer (stratum basale)

A

is a single layer of
basophilic cuboidal or columnar cells on the basement
membrane at the dermal-epidermal junction

46
Q

Where are Basal stem cells for keratinocytes found?

A

Stratum Basale

Intense mitotic activity occcurs in this layer

47
Q

Describe Stratum Spinosum & what does it consist of?

A

-Is normally the tickest layer, especially in the epidermal ridges
- consists of generally polyhedral cells
having central nuclei with nucleoli and cytoplasm
actively synthesizing keratins

48
Q

Where is Stratum Spinosum found

A

Under Stratum Granulosum

-Consists of Living Keratinocites and some melanocites may also be found

49
Q

The interface between dermis and epidermis in thin skin is held together firmly by what?

A

-Interlocking epidermal ridges or pegs

EP) and dermal papillae (DP

50
Q

The dermis (D) of thin skin is ………………. and well ………….. than that of thick skin, with elastin and ………………….

A
  • more cellular
  • vascularized
  • less coarse bundles of collagen
51
Q

The epidermis usually shows only four layers in thin skin:

Name the 4 Layers of Skin

A
  1. one-cell thick stratum basale (B) containing most mitotic
    cells
  2. stratum spinosum (S) where synthesis of much
    keratin and other proteins takes place
  3. the stratum granulosum (G)
  4. stratum corneum (C), consisting of dead
    squames composed mostly of keratin
52
Q

Where is stratum lucidum found and what does it consist of ?

A

-found only in thick skin
-consists of a thin, translucent layer of flattened eosinophilic keratino cytes held together by desmosomes
-Nuclei and organelles have been lost, and the
cytoplasm consists almost exclusively of packed keratin
filaments embedded in an electron-dense matrix.

53
Q

What does stratum corneum consist of?

A
  • 15 to 20 layers of squamous, keratinized cells

- filled with birefringent filamentous keratins.

54
Q

What are fully keratinized or cornified

cells called?

A
  • squames cells

- are continuously shed at the epidermal surface as the desmosomes and lipid-rich cell envelopes break down.

55
Q

What is Psoriasis caused by?

A
  • overactive T lymphocytes that trigger an autoimmune reaction in the skin, which can also lead to inflammation with redness, irritation, itching, and scaling, with a defective skin barrier.
56
Q

What is psoriasis?

A

-keratocytes
are typically produced and differentiate at accelerated
rates, causing at least slight thickening of the epidermal
layers and increased keratinization and desquamation.

57
Q

What is responsible for the color of the skin & what is the most important factor?

A
  • Melanocites
  • the most important of which are the keratinocytes’ content of melanin and carotene and the number of blood vessels in the dermis.
58
Q

What are Eumelanins?

A
  • brown or black pigments produced by
    the melanocyte, a specialized cell of
    the epidermis found among the cells of the basal layer and in hair follicles.
59
Q

What is the pigment found in red hair called?

A

-pheomelanin (Gr. phaios, dusky + melas, black). Melanocytes are neural crest derivatives that migrate into the embryonic epidermis’ stratum basale, where eventually one melanocyte accumulates for every five or six basal keratinocytes

60
Q

Epidermis:

Describe each layer

A
  1. Stratum corneum: superficial layer; 20-30 layers of dead, flattened, anucleate, keratin-filled keratinocytes;
    protects against friction and water loss
  2. Stratum lucidum: 2-3 layers of anucleate, dead cells; seen only in thick skin
  3. Stratum granulosum: 3-5 layers of keratinocytes with distinct keratohyaline granules
  4. Stratum spinosum: several layers of keratinocytes all joined by desmosomes; Langerhans cells present
  5. Stratum basale: Deepest single layer of cuboidal to low columnar cells in contact with basement membrane; mitosis occurs here; melanocytes and Merkel
61
Q

Dermis Layers:

A
  1. Papillary layer: More superficial layer of dermis; composed of areolar connective tissue; forms dermal papillae; contains subpapillary vascular plexus
  2. Reticular layer: Deeper layer of dermis; dense irregular connective tissue surrounding hair follicles,
    sebaceous glands and sweat glands, nerves,
    and deep plexus of blood vessels extending into
    subcutaneous layer

sum: histology 1 (5 decks)

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