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BIOL 1190 > Chapter 5: Skin > Flashcards

Chapter 5: Skin Flashcards

1
Q

2 Major layers of the skin

A

Epidermis and dermis

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2
Q

Hypodermis/Subq layer: location + composition

A

located deep to dermis and composed of areolar and adipose tissue

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3
Q

4 major types of cells in the epidermis

A
  • keratinocytes
  • melanocytes
  • dendritic/langerhans cell
  • Tactile epithelial cells (merkel cells)
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4
Q

Keratinocytes

A
  • contains intermediate filament called keratin
  • provide strength and protection
  • are water repellent
  • 85% of epidermal cells are keratinocytes
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5
Q

Melanocytes

A
  • produce pigment
  • their long slender projections extend between keratinocytes and transfer melanin granules
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6
Q

Dendritic cells

A
  • their role in the immune response is to help other cells of the immune system recognize an invading microbe and destroy it
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7
Q

Tactile epithelial cells (merkel cells)

A
  • detect touch sensations through non-encapsulated sensory corpuscle or merkel disc
  • located in the deepest layer of the epidermis
    (attached to sensory neuron)
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8
Q

Thin (hairy) skin covers…

A

all body regions except the palms, palmar surfaces of digits and soles

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9
Q

Thick (hairless) skin covers…

A

palms, palmar surfaces of digits, and soles. contains more layers of cells

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10
Q

The 4/5 layers of thick/thin skin

A
  • stratum basale - deepest
  • stratum spinosum
  • stratum granulosum
  • stratum lucidum (only present in thick skin)
  • stratum corneum (most superficial layer)
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11
Q

Stratum basale

A
  • deepest layer of the epidermis (closest to blood vessels)
  • consist of single row of cuboidal or columnar cells
  • stem cells undergo cell division to produce new keratinocytes (active mitosis)
  • melanocytes and tactile epithelial cells associated with tactile discs are scattered among keratinocytes
    connects to basement membrane (hemidesmosomes)
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12
Q

Stratum spinosum

A
  • 8-10 rows of many-sided kertinocytes
  • keratinocytes contain coarser bundles of keratin intermediate filaments
  • ^ provides strength and flexibility to the skin
  • desmosomes connect to cells and to intermediate filaments
  • dendritic cells and melanocytes also present
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13
Q

Stratum granulosum

A
  • middle of epidermis
  • consists of 3-5 layers of flattened keratinocytes
  • undergoing apoptosis (genetically programmed cell death)
  • keratohyalin assembles keratin intermediate filaments into keratin
  • lamellar granules release lipid rich, water repellant secretion
    -transition between active and dead cells
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14
Q

Stratum lucidum

A
  • present only in thick skin
  • consists of 4-6 layers of clear, dead keratinocytes
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15
Q

Stratum corneum

A
  • consists of 25-50 layers of flattened dead keratinocytes
  • cells are continuously shed and replaced in this layer
  • protects deeper layers from injury and microbial invasion
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16
Q

The dermis is composed of…

A

dense irregular connective tissue containing collagen and elastic fibers

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17
Q

The dermis can be divided into

A

thin superficial papillary dermis and thick deeper reticular dermis

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18
Q

Papillary dermis

A
  • makes up 1/5th of thickness
  • consists of areolar connective tissue with thin collagen and fine elastic fibers
  • contains dermal papillae (nipple shaped structures) that contain capillary loops (blood vessels)
    contain tactile corpuscles (meissner corpuscles) and nerve endings that are sensitive to touch
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19
Q

Reticular dermis

A
  • deeper portion of the dermis (4/5ths)
  • consists of dense irregular connective tissue with bundles of collagen and coarse elastic fibers
  • space between fibers contain some adpose cells, hair follicles, nerves, sebaceous glands and sudoriferous glands
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20
Q

Where is melanin produced

A

in the stratum basale by melanocytes

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21
Q

Pheomelanin

A

yellow to red pigment

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22
Q

Eumelanin

A

brown to black pigment

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23
Q

Hair is composed of

A

dead keratinized epidermal cells

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24
Q

Parts of a hair

A
  1. the shaft
  2. the root
  3. the follicle
  4. hair bulb
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25
Q

The shaft of hair and it’s 3 parts

A
  • superficial portion of hair
    1. medulla- middle
    2. cortex; surround medulla
    3. cuticle of hair; hard protective layer
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26
Q

The root of hair and it’s 3 parts

A
  • below the surface of the skin, penetrates dermis
    1. medulla
    2. cortex
    3. cuticle of the hair
27
Q

The follicle of hair and it’s components

A
  • structure surrounding the root of the hair
    1. internal root sheath; surround cuticle
    2. external root sheath; surround internal root sheath
28
Q

Hair bulb composes of

A
  • papilla of the hair; nipple shaped production that provides blood supply
  • hair matrix: dividing cells that form hair and
29
Q

Stages of hair growth

A
  1. growth stage
  2. regression stage
  3. resting stage
30
Q

Hair growth;Growth stage:

A
  • cells of the hair matrix divide
  • as new cells are added , existing cells of the hair root are pushed up, they become keratinized and die
31
Q

Hair growth;Regression stage:

A
  • movement of the hair away from the blood supply
  • cells of the hair matrix stop dividing
32
Q

Hair growth;Resting stage:

A
  • old hair root falls out and regrowth begins
33
Q

Lanugo

A

hair that covers the fetus

34
Q

Terminal hair

A

long, course, heavily pigmented hairs (regular)

35
Q

Vellus

A

short, fine, pale hairs. ex: on the arm

36
Q

4 types of skin glands

A
  1. sebaceous (oil) glands
  2. Eccrine sweat glands
  3. Apocrine sweat glands
  4. Ceruminous glands
37
Q

Sebaceous glands

A
  • attached to hair follicles
  • absent in palms
  • secretes sebum
  • prevents hairs and skin from drying out, prevents water loss from skin, inhibits growth of some bacteria
  • located in lips, glans penis, labia minora, and tarsal glands; small in trunk and limbs
  • activated during puberty
38
Q

Eccrine sweat glands

A
  • located throughout most skin regions; forehead, palms, and soles. Not present in lips, nail beds, glans penis and glans clitoris
  • mostly in deep dermis excreted from epidermis
  • secretes sweat (perspiration) - water, ions, urea, glucose, lactic acid
  • regulates body temperature, waste removal, stimulated during emotional stress
  • activated soon after birth
39
Q

Apocrine sweat glands

A
  • distributed at axilla, groin, bearded regions, labia minora
  • mostly in deep dermis and upper subcutaneous layer
  • excreted through hair follicles
  • secretes perspiration which consists of same things as eccrine sweat glands plus lipids and proteins
  • stimulated during emotional stress and sexual excitement
  • activated at puberty
40
Q

Ceruminous glands

A
  • comes from external acoustic meatus
  • located in subq layer and excretes at surface of auditory canal or into ducts of sebaceous glands
  • secretes cerumen
  • present soon after birth
  • impedes entrance of foreign bodies and insects into external ear canal
41
Q

What type of cells are nails made out of

A

keratinized epidermal cells

42
Q

Components of nails

A
  • free edge
  • hyponychium
  • nail plate/ body
  • nail bed
  • lunula
  • eponychium (cuticle)
  • nail root
  • nail matrix
43
Q

The skin attaches to the nail at the…

A

cuticle

44
Q

Compare and contrast thick/thin skin

A
  • thin lacks while thick has epidermal ridges
  • thin has while thick lacks hair follicles
  • thin has while thick lacks sebaceous glands
  • thick has more numerous sudoriferous glands while thin lacks
  • sensory receptors sparser on thin and denser in thick
45
Q

Functions of the skin

A
  • thermoregulation
  • blood reservoir
  • protection against microbes and abrasion
  • cutaneous sensations
  • excretion and absorption
  • synthesis of vitamin D
46
Q

The skin can hold what % of bloodflow while resting

A

8-10%

47
Q

What components are responsible for protection of the skin

A
  • keratin; protects from microbes, abraision, heat and chemicals
  • lipids released prevent loss of water
  • sebum: reduces bacteria
  • melanin: protects against UV
  • macrophages: eat bacteria by phagocytosis
48
Q

Cutaneous sensations

A
  • tactile sensations: touch, pressure, vibration, tickle
  • thermal sensations: warm, cool
  • pain
49
Q

How is vitamin D synthesized in the skin

A

UV rays activate vitamin d to the active form (calcitriol)

50
Q

What further modified vitamin d

A

enzymes in the liver and kidneys

51
Q

Why is vitamin D important for our body

A

aids in the absorption of calcium and phosphorus from foods in the GI tract

52
Q

Epidermal wound healing only occurs when…

A

superficial wounds affect only the epidermis. (no significant bleeding)

53
Q

4 phases of deep wound healing

A
  1. inflammatory phase
  2. migratory phase
  3. proliferative phase
  4. maturation phase
54
Q

Inflammatory phase

A
  • clot forms
  • inflammation: redness, swelling, heat, pain, immobility
  • vasodilation occurs to allow wbcs to reach surface of wound
55
Q

Migratory phase

A
  • clot becomes a scab
  • fibroblasts migrate and synthesize scar tissue
  • damaged blood vessels begin to regrow
56
Q

Proliferative phase

A
  • growth of epithelial cells beneath scab
57
Q

Maturation phase

A

scab sloughs off once epidermis restored

58
Q

Age associated changes in skin

A
  • wrinkles
  • dry brittle nails
  • decreased number of melanocytes, therefore white hair
  • subq fat loss, skin thickness decreases
  • sweat production decreases
  • dehydrated and cracking skin
59
Q

Warning signs of malignant melanoma

A

A: assymetry
B: border irregular
C: color uneven
D: diameter is greater than 6mm
E: evolving shape and size

60
Q

What is a burn and it’s 3 severities

A

tissue damage caused by heat, electricity, radioactivity, or corrosive chemicals
1. first degree burn
2. second degree burn
3. third degree burn

61
Q

First degree burn

A
  • involves epidermis only
  • mild pain and redness
  • example: sunburn
62
Q

Second degree burn

A
  • destroys epidermis and part of dermis
  • some skin functions are lost
  • redness, blister, edema and pain
63
Q

Third degree burn

A
  • destroys epidermis, dermis and subq layers
  • most skin functions are lost
  • marked edema, numbness due to lost of sensory nerve endings

BIOL 1190 (16 decks)

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