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Histo > The Integument (skin) > Flashcards

The Integument (skin) Flashcards

1
Q

Skin Fxn: Barrier system

A

Protection from microorganisms/UV light

Relatively impermeable to water (prevents evaporation of body fluids)

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2
Q

Skin Fxn: Sensation

A

Highly innervated with lots of receptors

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3
Q

Skin Fxn: Thermoregulation

A

Sweat glands, vasodilation

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4
Q

Skin Fxn: Plasticity-elasticity

A

Allows for changes in size and shape

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5
Q

3 Layers of skin

A
  • Epidermis: epithelial cells
  • Dermis: CT
  • Hypodermis: Subcutaneous tissue; superficial fascia CT
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6
Q

Thick Skin (Glabrous)

A

400-600 um (thinkness)–more force put on
Hairless
Soles feet
Palms

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7
Q

Thin Skin

A

75-100 um
Hairy
Everywhere else

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8
Q

Cell Layers of Epidermis

A 
Stratum basale (inner most)
Stratum spinosum
Stratum granulosum
Stratum lucidum
Stratum corneum (most superficial)
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9
Q

Stratum Basale (Germinativum)

A

Single layer of cuboidal cells sitting on the basement membrane
Fxn: constant renewal (every 15-30 days) of epidermal cells via constant mitotic division

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10
Q

Stratum Spinosum

A

-“Spiny” cells; cuboidal cells like the stratum basale
-filled with keratin filaments that are anchored into desmosomes
-desmosomes firmly bind cells of this layer together
Fxn: resist abrasion

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11
Q

Stratum Granulosum

A

-3-5 layers of squamous cells; cytoplasm filled with vesicles
-vesicles fuse w/the cell membrane and discharge contents into the intercellular spaces
-secreted material contains high conc of lipid molecules
Fxn: provides intercellular cement
creates a barrier to foreign materials (seals the skin)

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12
Q

Stratum Lucidum

A
  • Most apparent in thick skin; minimal layer in thin skin
  • Translucent lauer of squamous cells with no apparent organelles
  • Densely packed keratin filaments anchored to desmosomes (provide strength to this layer)
  • Fxn: resist abrasion
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13
Q

Stratum Corneum

A
  • Outermost surface of skin
  • 15-20 layers of flattened non-nucleated cells; cytoplasm filled with keratin
  • Cells consist of only keratin fibers, proteins, and thick cell membranes (no organelles; lifeless cells)
  • Cells of this layer are continuously shed: desquamation
  • resist abrasion, create water-tight barrier
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14
Q

Keratinocytes

A

Generic term for epithelial cell in any and all layers

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15
Q

Melanocytes

A

produce melanin-dark brown pigment
found in basal layer-b/w stratum basale and spinosum
Protect DNA from UV rays * most important fxn
transferred to keratinocytes at deep layers and is deposited “on top” of cell nuceli
Highest concentration=deeper layers of skin
Lowest most superficially because granules fuse with lysosomes for digestion

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16
Q

Langerhans’ cells

A

Skin macrophages
Inner layers of epidermis-stratum basale and spinosum 2-8% of epidermal cells
provide the immune function for taking out the foreign bodies
bone marrow derived; carried to the epidermis via the blood
can bind and present antigen to lymphocytes for immune fxn against micro-organisms

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17
Q

Dermis

A

-made up of loose CT (papillary layer) and dense irregular CT (reticular layer)
-neuronal innervation (skin sensory receptors)
-Pain, temp, pressure, vibration
Blood vessels are abundant

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18
Q

Skin appendages to Dermis

A

Hair follicles, nails

sebaceous glands, sweat glands

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19
Q

Subcutaneous Layer

A

Loose CT that binds skin to underlying structures
—hypodermis and superficial fascia
Often contains numerous fat cells
Also contains neurovascular network

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20
Q

Epithelial Glands

A

Holocrine (sebaceous glands)
Merocrine (eccrine)
Apocrine (sweat gland)

21
Q

Holocrine: epithelial

A

secretory product is released along w/the entire contents of the cell
Holocrine glands put their material onto the hair follicle and from there it is released===oily skin
–burst open and material goes to hair follicle to be released onto skin

22
Q

Merocrine: epithelial

A

sweat gland

secretory product is released through exocytosis

23
Q

Apocrine: epithelial

A

secretory product is released with portion of cellular cytoplasm
filled with fluid material buds off and then released into the duct

24
Q

Sebaceous glands

A

Consists of epithelial cells that take up large quantities of lipids
Cells die and release lipid (sebum) into the hair follicle–active during puberty
Sebum has anti-bacterial and anti-fungal properties
highly concentrated in face and scalp

25
Q

Holocrine gland: sebaceous

A

lipids are secreted with the remnants of a dead cell

stem cells in the base of the gland proliferate to replace lost cells–rapid rate of renewal

26
Q

Merocrine sebaceous glands

A

coiled tubular glands opening onto skin surface
ducts release sweat onto skin surface when body temp increases
sweat evaporates cooling the skin surface
sweat composition: H20, NaCl, urea, uric acid, ammonia

27
Q

Apocrine sebaceous glands

A

release a viscous, odorless fluid
bacterial decomposition of fluid creates a distinctive scent
found in axillary and ano-genital regions

28
Q

Sweat gland activity controlled by what?

A

autonomic nervous system (apocrine and merocrine)-sympathetic nervous system

Apocrine (adrenergic)
Merocrine (cholinergic)

29
Q

Sensory receptors

A

responsible for touch-pressure, tactile reception, hot-cold, pain and itching

most found in dermal layer

30
Q

Types of sensory receptors

A

Free nerve endings-pain/temp
Ruffini’s endings-touch/temp
Pacinian corpuscles-pressure/vibration
Meissner’s corpuscles-touch

31
Q

Nails

A

plates are keratinized epithelial cells
nail root is source of dividing cells for growth
cuticle is formed fromt he stratum corneum
nail bed=basale and spinosum

32
Q

Nail growth matrix

A

proximal portion of the nail bed contains dividing cells

divide more distally and are cornified at proximal part of nail plate

33
Q

Hair-Follicle

A

Derived from invaginations of epidermal cells
Dermal papilla contains dividing cells for hair growth and blood supply
Arrector pili muscle=contraction=goose bumps
Melanocytes provide pigment for hair color

34
Q

Hair Growth

A

6 inches/yr, variable growth cycles

35
Q

Anagen

A

active growth phase (30-45 days up to 2-6 years)

36
Q

Catagen (3% of all hairs)

A

2-3 week phase no growth occurring

37
Q

Telogen (10-15%)

A

Lasts 100+ days

Full resting phase; no growth occurs, hair loss

38
Q

Effects of aging on skin

A

Atrophy of strata of skin-layers become thinner
-skin becomes more fragile
reduced elasticity
areas of skin exposed to sun are affected more rapidly
Reduced sweating capability

39
Q

Effects of Acute Activity on Skin

A

Blood flow to skin increases with normal activity

—at activity levels >50% blood flow to skin decreases and is diverted to working muscles at high levels of activity

40
Q

Effects of chronic training on skin

A

Hyperplasia of skin: callous formation
Increased ability to sweat: improved thermoregulatory ability
Blisters

41
Q

Blisters

A

fluid deposition at the jxn of epidermis and dermis
epidermis raises away from the dermis
caused by shearing forces
continual training ability to regulate becomes for efficient

42
Q

Effects of immobilization on skin

A

Increased risk of skin breakdown=pressure ulcer

decuberutus ulcer

43
Q

Pressure ulcers occur in these areas most frequently

A 
heels
sacrum
greater trochanter
scapula
elbows
back of the head
44
Q

Back, abdomen, thighs, arms: epidermal specializations

A

Thin epidermis, loosely packed keratin

few follicles produce fine hairs, variable eccrine glands

45
Q

Sole of foot: epidermal specializations

A

Thick epidermis, densely packed keratin
developed epidermal ridge system
No hair follicles, abundant eccrine gland

46
Q

Scalp: epidermal specializations

A

tightly packed follicles

47
Q

Fingertips: epidermal specializations

A

thick epidermis, developed ridges, abundant sensory receptors

48
Q

Axilla/groin: epidermal specializations

A

thin epidermis, numerous oblique hair follicles

numerous eccrine and apocrine glands

Histo (12 decks)

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