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Inflammation & Infection > Skin > Flashcards

Skin Flashcards

1
Q

What type of epithelia is found in the epidermis?

A

Stratified squamous keratinized epithelium

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2
Q

How does thick skin differ from thin skin?

A
  • Thicker epidermal layer
  • Found only on the soles of feet and palms of hands
  • Hairless
  • Has merocrine sweat glands
  • Has a 5th layer called the stratum lucidum, a thin, translucent layer
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3
Q

What are keratinocytes?

A
  • Predominant cell type in the epidermis
  • Arise from the s. basale and migrate towards the surface
  • Undergo keratinization
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4
Q

How is cellular turnover affected in psoriasis?

A

Can be as rapid as 1 week due to accelerated keratinocyte cell cycling, leading to thockening of the epidermis and accelrated keratinization and desquamation.

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5
Q

What are warts?

A

Benign epithelial growths caused by papilloma viral infection of keratinocytes

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6
Q

What type of cancer affects the s. basale layer?

A

Basal cell carcinomas - most common skin cancer

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7
Q

What type of cancer arises from the s. spinosum layer?

A

Squamous cell carcinomas - 2nd most common

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8
Q

In the s. spinosum, keratinocytes begin to produce ____ ____ on their free ribosomes, which consist of ____ ____ ____. Membrane-bound ____ ____ containing pro-barrier lipids begin to form on the RER.

A

Keratohyalin granules; intermediate filament-associated proteins; lamellar granules

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9
Q

Cells in the ____ layer first begin to undergo keratinization.

A

S. Granulosum

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10
Q

The epidermal water barrier is formed when ____ ____ release their lipid contents via exocytosis into the intercellular space.

A

Lamellar granules

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11
Q

Keratinized cells are shed or “desquamated” from the s.corneum when ____ degrade.

A

Desmosomes

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12
Q

What are Merkel cells?

A
  • Mechanosensitive touch receptors in the s. basale
  • Basal surface of cell associates with afferent nerve ending from the dermis
  • Release neuroactive chemicals that stimulate afferent nerve endings
  • Most abundant in fingertips
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13
Q

What are Langherhan’s cells?

A
  • Also called dendritic cells
  • Found in s. spinosum
  • Are the immune cells/APCs of the skin; derived from monocyte-macrophage lineage
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14
Q

What are melanocytes?

A
  • Found in s. basale
  • Produce melanin in membrane-bound melanosomes
  • Donate melanosomes to keratinocytes for protection against UV radiation
  • More melanocytes in areas exposed to the sun
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15
Q

How does melanin provide protection?

A

Takes a supranuclear position in the cell so that pigment shields the nuclei of keratinocytes from UV radiation

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16
Q

What is malignant melanoma?

A
  • Rare but most dangerous form of skin cancer
  • Invades the underlying dermis, and metastasizes by lymph and blood
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17
Q

True or False:

The ratio of melanocytes : keratinocytes varies between races.

A

False - the activity varies between races

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18
Q

What are three examples of adaptive changes to melanocyte activity?

A
  1. Genetically determined forms of melanin (pheomelanin vs eumelanin)
  2. Rate of melanin production - higher in darker-skinned people
  3. Rate of lysosomal degradation of melanin - slower in darker-skinned people
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19
Q

____ ____ decreases with age, resulting in paler skin and hair.

A

Melanocyte population

20
Q

____ results from autoimmune destruction of melanocytes in symmettrical patches.

A

Vitiligo

21
Q

What features increase the surface area between the epidermis and the dermis?

A

Epidermal ridges and dermal papillae

A: epidermal ridges B: dermal papillae
22
Q

What creates fingerprints?

A
  • Dermal ridges
  • Only present in thick skin
23
Q

The greater the surface area of the dermal-epidermal interface, the greater the…

Three things

A
  1. # of hemidesmosomes (ie. adhesion b/w epidermis and BM to resist friction)
  2. Gas, nutrient, and metabolite exchange b/w avascular epidermis and dermis
  3. Population of dividing cells in the germinal layer, and thus the # of keratinocytes being produced

All of these are important in thick skin

23
Q

What are the two layers of the dermis?

A
  1. Papillary layer - consists of loose areolar CT, more cellular, richly vascularized, rich in collagen type I and III
  2. Reticular layer - consists of dense irregular CT; thicker, less cellular, rich in collagen type I
A: papillary layer B: reticular layer
24
Q

Label the following diagram, A through D.

A

A: Subcutaneous plexus - in hypodermis
B: Cutaneous plexus - at dermal-subcutaneous junction
C: Subpapillary plexus - at the papillary-reticular junction
D: Capillary loops - in the dermal papillae, which serve the dermal-epidermal interface

25
Q

Anastomoses in the ____ plexus control blood flow into the ____ plexus and change to regulate temperature.

A

Cutaneous; subpapillary

26
Q

What are the different components of a hair follicle?

A
  1. Sebaceous glands - produce sebum to lubricate hair and skin
  2. Arrector pili - smooth muscle that contracts for a) thermoregulation and b) to compress the sebaceous glands and promote secretion
  3. Follicular bulge - epidermal stem cells that sustain growth of hair and sebaceous glands
  4. Hair bulb - germinative cells that give rise to the hair matrix (ie. the hair and its inner covering)
  5. Melanocytes - within the matrix, supply keratinocytes with melanin
  6. Dermal papilla - highly vascularized “peg” of loose CT that nourishes the matrix
27
Q

What are the two types of hair?

A
  1. Vellus hairs - fine, pale hair over most of body
  2. Terminal hairs - coarse, dark hair
28
Q

Terminal follicles can be converted to vellus follicles, and vice versa, by…

A

Androgens

29
Q

What happens to follicles in androgenetic alopecia (male-pattern baldness)?

A

Terminal hair follicles on the head are converted to vellus follicles in a well-characterized pattern.

30
Q

What are the three phases of the hair cycle?

A
  1. Anagen - active growth takes place
  2. Catagen - involution of the hair and follicle towards skin surface
  3. Telogen - resting phase where hair is shed
31
Q

A hair follicle with its sebaceous gland and arrector pili muscle is called a…

A

Pilosebaceous unit

32
Q

What occurs in acne vulgaris?

A
  • Chronic inflammation of pilosebaceous unit
  • Hypersecretion of sebum and accelerate keratinization results in a blocked follicle
  • Anaerobic bacteria flourish, creating a localized inflammatory response
33
Q

What are apocrine glands?

A
  • Found in the axillae, areolae, and groin
  • Become active at puberty
  • Open into hair follicles superficial to sebaceous glands
  • They are stimulated by emotions
  • No clear function in humans
33
Q

What are eccrine glands?

A
  • Also called merocrine glands
  • Widely distributed, including hands and feet
  • Not associated with follicles; ducts open onto skin surface
  • Function in thermoregulation and limited excretion
  • Reabsorb sodium as fluid moves along duct; thus sweat is salty
34
Q

What are mammary glands?

A
  • Modified apocrine sweat glands
  • Develop along milk lines in the embryo
  • The parenchyma is derived from the epithelia and is supported by surrounding CT stroma
35
Q

Each mammary glands consists of how many lobes?

A

15-25

36
Q

Each lobe in a mammary gland consists of…

A

Numerous lobules, connected to a lactiferous duct system by an extralobular terminal duct

37
Q

Lactiferous ducts form ____ before opening independently at the nipple.

A

Lactiferous sinuses

38
Q

What changes happen to the breasts during puberty?

A
  • Nipples and areolae enlarge
  • Sebaceous follicles in the areola enlarge to form Montgomery’s tubercles
  • Lactiferous ducts expand
  • Adipose tissue accumulates
  • Dense CT septa, called suspensory/Cooper’s ligaments, develop to support the weight of the breast
39
Q

A lobule and its extralobular terminal duct is called a…

A

Terminal duct lobular unit (TDLU)

40
Q

During pregnancy, terminal ductules develop into…

A

Secretory acini

41
Q

Breast enlargement in the premenstrual period is caused by…

A

Edema in the loose CT lobular stroma

42
Q

Breast milk expulsion is caused by…

A

Myoepithelial cells and SM fibres contracting around the lactiferous ducts and sinuses

43
Q

Lobar carcinomas arise from…

A

The terminal ductules

Inflammation & Infection (6 decks)

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