Unit 1 Topic 3 Flashcards

1
Q

Epidermis Description

A

top layer of skin composed of simple squamous epithelium

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2
Q

Epidermis features

A

-5 layers: Stratum Basale, Stratum Spinosum, Stratum Granulosum, Stratum Lucidieum, Stratum Corneum
-contains keratinocytes, melanocytes, langerhans cells and merkel cells

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3
Q

Dermis Description and Features

A

-2 layers: Papillary and Reticular
-Papillary: loose CT; contain dermal papillae with BVs that support the epidermis; includes type I and II collagen and some elastic fivers
-Reticular: DICT with net like fibers; contains elastic for flexibility and more type I collagen for strength

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4
Q

Hypodermis Description and Features

A

deep to dermis; contains adipose tissue

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5
Q

Stratum Basale Features

A

-single layer that rests on the basal lamina
-only mitotically active epidermal layer
-contains stem cells that give rise to keratinocytes
-anchored to the basal lamina by hemidesmosomes and to the other cells by desmosomes

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6
Q

Stratum Spinosum Description

A

-several layers thick
-cytoplasmic processes (spines) composed of desmosomes
-As cells move to the surface they increase in size and flatten

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7
Q

Stratum Granulosum Features

A

-most superficial nonkeratinized layer
-contains basophillic keratohyalin granules in lamellar bodies that are exocytosed to create a barrier to water

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8
Q

Stratum Lucidum Features

A

-Normally only seen in thick skin
-advanced keratinization of cells leads to difficulty staining
-considered a subdivision of corneum by some

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9
Q

Stratum Conreum Features

A

-Stratum granulosum cells flatten (desquamate), desiccate (dry out), and undergo apoptosis as they reach the stratum corneum
-Loss of nucleus and cytoplasmic organelles and almost entirely composed of keratin filaments
-contain most mature keratinocytes

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10
Q

Keratinocytes Functions

A

-primary cell type of epidermis
-creation of extracellular water barrier between the stratum granulosum and corneum

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11
Q

Keratinocytes Features

A

-desmosomal attachments to neighboring keratinocytes throughout the epidermis
-continuously being lost and replaced by stem cells within the stratum basale

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12
Q

Melanocytes Functions

A

-present in the stratum basale and hair follicles
-produce melanin pigment from tyrosine that offers protection to the basal cells from UV radiation

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13
Q

Melanocytes Features

A

-melanin is internalized by keratinocytes
-attached to basal lamina, but not neighboring keratinocytes
-determines skin color

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14
Q

Langerhans Cells Functions

A

-phagocytic immune cells that serve as antigen presenting cells

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15
Q

Langerhans Cells Features

A

-found in the stratum spinosum
-continuously being replaced by monocytes
-cannot be distinguished by H and E

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16
Q

Merkel Cells Functions

A

-modified epidermal cells
-associated with free nerve endings-sensory mechanoreceptors and may secrete local neuroendocrine secretions

17
Q

Merkel Cells Features

A

-found in basal layer, but prevalent in thick skin
-modified epidermal cells

18
Q

Sweat Glands Description

A

-2 Types: Eccrine and Apocrine
-Eccrine: distributed across the entire body, except lips and external genitalia
-Apocrine: distribution limited to the axilla, areola/nipple of mammary glands, the skin surrounding the anogenital region, and eyelashes

19
Q

Sebaceous Glands Description

A

-holocrine secretion of sebum into the canal associated with the hair follicle
-Appear clear due to the high lipid content

20
Q

Sebaceous Glands Functions

A

-dead cells are replaced by the proliferation of basal cells
-secretions are bacteriostatic and may act as an emollient, lubricant, barrier, and pheromone

21
Q

Nails Description

A

-keratinized cells containing hard keratin
-Eponychium (cuticle): skin covering over the root
-Hyponychium (quick): secured free edge of nail at the fingertips

22
Q

Hair Description

A

present all over body except for sides and palmar surface of hand, sides and plantar surfaces of foot, lips and region around urogenital orifces, but distribution depends on hormones/genetics; color is determined by melanin content

23
Q

Hair Follicles Description

A

invaginations of epithelium into dermis; responsible for production/growth of hair; living cells that contribute to hair from the proximal attachment

24
Q

Layers of the Hair Follicles

A

internal root sheath (innermost), external root sheath, glassy membrane, outermost CT root sheath
-hair bulb: proximal expansion

25
Q

Dermal Papilla

A

invagination of bulbs by vascularized loose CT

26
Q

Free Nerve Endings

A

epidermis and dermis; pain and temperature

27
Q

Messiner’s Corpuscles

A

dermis only; tactile

28
Q

Pacinian Corpuscles

A

dermis and hair suit; pressure

29
Q

Ruffini’s Corpuscles

A

dermis only; mechanical displacement and stretching

30
Q

Merkel Cell

A

epidermis only; tactile

31
Q

What is the method of apocrine swat gland secretion?

A

simple coiled glands composed of secretory and myoepithelial cells → Merocrine secretions into ducts → secretions function as pheromones

32
Q

What are the steps of skin regeneration?

A

-Coagulation/Inflammation: scab forms
-Granulation Stage: collagen and ECM are deposited to stabilize wound; reestablisment of blood vessels
-Remodeling Stage: type III collagen is replaced with stronger type I collagen to form a scar
Fibroblasts and inflammatory cells are degraded
Myofibroblasts allow contraction of wound
Epidermis is replenished

33
Q

What is the difference between light and dark skin structure?

A

the only difference in light and dark skin is the type/amount of melanin that is produced by melanocytes