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Structure and Function 1- Exam 2 > SKIN > Flashcards

SKIN Flashcards

1
Q

What are the functions of skin?

A
  • Protective: mechanical forces, pathogens, UV light, dehydration
  • Sensory
  • Thermoregulator
  • Metabolic: Electrolytes, Vit. D
  • Sexual signaling: pheromones and indicator of health
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2
Q

How do thick skin and thin skin differ?

A
  • Thick skin
    • Found on the palms of hand and soles of feet
    • Lacks hairs, sebaceous gland, and accrine glands
    • Contains sweat glands
    • Melanin less abundant
    • Ridges that hold epidermis to dermis are higher to resist shear.
    • Has an extra layer- Stratum Lucidum
  • Thin skin
    • Layers are not clearly defined
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3
Q

List the layers of the epidermis from most deep to most superficial. What’s a defining characteristic of each?

A
  1. S. Basale – stem cells
  2. S. Spinosum – spiny-keratinization begins
  3. S. Granulosum – hydrophobic lipid envelope
    1. More pronounced in thick skin
  4. S. Lucidum – translucent appearance
    1. Only in thick skin
  5. S. Corneum – dead cells
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4
Q

What are the three layers of the skin? What is each layer made up of?

A
  • Epidermis: stratified squamous epithelium
  • Dermis: connective tissue
  • Hypodermis: fatty, loose connective tissue
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5
Q

What kind of epitelium is found in the epidermis?

A

Keratinized Stratified squamous

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6
Q

The epidermis is composed mostly of _________cells that are generated in the __________ layer, and differentiate as they are pushed to the surface

A

keratinocyte; stratum basale

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7
Q

What cells are found in the S. Basale?

A

Stem cells

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8
Q

What cells are found in the S. spinosum?

A

Spiny-keratinization begins

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9
Q

What cells are found in the S. granulosum?

A

Hydrophobic lipid enveloped

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10
Q

What cells are found in the S. corneum?

A

Dead cells

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11
Q

How does a histo slide of thick skin differ from a histo slide of thin skin?

A

Layers of the epidermis are not clearly seen in thin skin.

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12
Q

Which epidermis layer is being described below?

  • Highly mitotic
  • Stem cells for all keratinocytes.
  • Single layer of basophilic cuboidal cells attached to basement membrane.
  • Contain intermediate filaments composed of keratin, bundled into tonofilaments.
  • Site of synthesis of Vit D, in response to light.
A

S. Basale

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13
Q

Which epidermis layer is the site of Vit D synthesis?

A

S. Basale

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14
Q

S. Basale is also known as __________

A

S. Germinativum

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15
Q

The stratum basale is composed of a single layer of ___________ cuboidal cells attached to the basement membrane.

A

Basophilic

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16
Q

The keratin found in the stratum basale is bundled into ___________.

A

Tonofilaments

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17
Q

Keratinocytes are held together by ___________ and attached to the basement membrane by _____________.

A

Desmosomes; hemidesmosomes

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18
Q

Hemidesmosomes and desmosomes are attached to bundles of __________ fibers.

A

Collagen

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19
Q

What are the components of hemidesmosomes?

A

Tonofilaments

Plaque

Basal lamina

Anchoring filaments

Collagen Type I

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20
Q

Which molecules are involved in cell adhesion in skin?

A

Desmosomes

Keratin filaments

Hemidesmosomes

Anchoring filaments

Basal lamina

Type IV collagen

Anchoring fibrils (Type VII collagen)

Type I and III collagen

Anchoring plaques (Type IV collagen)

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21
Q

Which epidermis layer is being described below?

  • Polyhedral cells attached by desmosomes.
  • Shrinkage during fixation causes retraction in between desmosomes, to look like spines.
A

S. Spinosum

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22
Q

During the processing of polyhedral cells in s. spinosum layer, the cells contract and form spines, why is this?

A

They contract because they are held together by desmosomes

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23
Q

Which epidermis layer is being described below?

  • Flatter keratinocytes fill with basophilic keratohyaline granules.
    • The granules contain filaggrin, which links tonofibrils together to form dense bundles of keratin that fill the cell.
A

S. Granulosum

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24
Q

What type of granules are found in the stratum granulosom? What do these granules contain?

A

The keratinocytes in this layer are filled with basophilic kerahyalin granules that contain filaggrin.

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25
Q

Filaggrin links ____________ together to form dense bundles of __________ that fill the cell.

A

Tonofibrils; keratin

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26
Q

What do the keratohyaline granules promote?

A

Dehydration of the cell as well as aggregation and cross-linking of the keratin fibers.

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27
Q

How is profilagrrin converted to filaggrin?

A

The phosphate groups are cleaved

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28
Q

____________ crosslinks keratin.

A

Filaggrin

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29
Q

Which layer plays an important role in “waterproofing” the skin? How?

A

S. Granulosum cells also contain lamellar bodies: contain a lipid-rich secretion that is expelled into extracellular space and waterproofs the skin. Barrier is semi-permeable.

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30
Q

Why are the lamellar bodies found in the s.granulosum important in pharmocology?

A

Important in studying which kinds of drugs can penetrate the waterproof barrier of the skin

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31
Q

Which epidermis layer is being described below?

  • Surface cells are flat, anucleate, filled with cross-linked keratins.
  • The plasma membranes are thickened and “cornified”. Continuously shed, and replaced from beneath.
A

S. Corneum

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32
Q

What is the normal skin turnover time?

A

20-75 days

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33
Q

Describe the cells in the S. Corneum and plasma membranes within those cells.

A

Cells: Flat, anucleate, filled with crosslinked keratins

Plasma membrane: Thickened and “cornified”

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34
Q

Which epidermis layer is being describe below?

The keratinocytes do not feature distinct boundaries and are filled with eleidin, an intermediate form of keratin

A

S. Lucidum

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35
Q

An intermediate form of keratin

A

Eleidin

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36
Q

____________ helps stabilize the cell membrane of the dead keratinocyte.

A

Involucrin

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37
Q

involucrin is found in the ___________ layer but synthesized in the __________ layer.

A

S. Corneum; S. Lucidum

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38
Q

List specific abnormalties that can be found in epidermal keratinocytes. Describe each.

A
  1. Psoriasis: abnormal keratinocyte generation and differentiation
  2. Blistering Diseases: autoimmune diseases or keratin mutations
  3. Vitamin D Deficiencies : lack of sun, high latitudes, winter, poor diet
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39
Q

What is the mechanism by which psorasis occurs?

A

It occurs when you have abnormally fast keratinocyte generation, and it doesn’t take the time to differentiate before it comes to the surface.

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40
Q

Blistering diseases occur when?

A

In cases of autoimmune diseases or in cases of keratin mutation

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41
Q

What are some distinguishing characteristics of epidermis/ dermis in cases of psorasis?

A
  • Thickening of the stratum corneum
  • Microabcesses in the epidermis
  • Elongation of the papillae
  • Inflammatory cells in the dermis
  • Cells in the S. corneum display nuclei
    • ​Cells are usually flattened
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42
Q

Keratinocytes normally reach the surface in _________ days, but in cases of psorasis they reach the surface in __________ days.

A

30; 3-5

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43
Q

Bullous pemphigold

A

Autoimmune damage to the dermal-epidermal junction (eg hemidesmosomes) manifest

*Epidermis is lifting off the dermis

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44
Q

Mutations of keratins manifest as ______________ diseases.

A

epidermolysis

  • Skin doesn’t hold well together and you have raw dermis
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45
Q

Pemphigus vulgaris

A

Autoimmune damage to intercellular adhesion molecules (eg desmosomes). Blisters between keratinocytes in skin and mucous membranes.

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46
Q

Bullous pemphigold results from damage to __________ (desmosome/hemidesmosome), while pemphigus vulgaris results from damage to ____________ (desmosome/hemidesmosome).

A

Hemidesmosome; desmosome

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47
Q

Lack of bone mineralization in adulthood is known as ___________. Lack of bone mineralization in childhood is known as _____________.

A

Osteomalacia; Rickets

*Results from Vitamin D deficiencies

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48
Q

Which trilaminar layer gives you epidermis?

A

Ectoderm

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49
Q

Which non-keratinocyte cells migrate into the epidermis?

A

Melanocytes

Langerhans cells

Merkel Cells

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50
Q

Melanocytes are dervied from the ___________.

A

Neural crest

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51
Q

Langerhans cells migrate from ___________

A

Bone marrow

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52
Q

Merkel cells migrate from ___________.

A

Neural crest

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53
Q

Melanocytes can make which two types of pigment?

A

Eumelanin- brown/black

Pheomelanin- red

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54
Q

Melanin is synthesized from __________ and packaged in ____________.

A

tyrosine; melanosomes

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55
Q

Melanosomes are transported along ___________ and phagocytized by ___________.

A

dendrites; keratinocytes

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56
Q

Melanosomes are stored over the nucleus to protect DNA and folic acid from UV light. How?

A

Melanosomes are able to protect DNA becuase the melanin absorbs the UV light and prevents it from getting to DNA

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57
Q

One melanocyte supplies approximately _______ keratinocytes.

A

30

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58
Q

Melanosomes are degraded within ___________
in upper layers of skin

A

lysosomes

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59
Q

Where are melanosomes degraded?

A

In upper layers of skin

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60
Q

UV light induces local __________

A

Melanocyte-stimulating hormone (MSH)

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61
Q

Melanocytes are always seen in what layer of the epidermis?

A

S. Basale

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62
Q

Are melanocytes connected to other cells?

A

Melanocytes are attached to the basment membrane by hemidesmosomes but aren’t attached to other cells becuase they’re not apart of structural support and they need to get their dendrites into as many cells as possible and deliver melanin everywhere.

63
Q

The cell body of melanocytes are in the stratum basale but the dendrites make their way to the ______________ layer to export their melanin.

A

S. Granulosum

64
Q

Albinism

A

Defects in melanin synthesis

  • May have melanocytes but can’t synthesize melanin
  • Varying degrees
  • Could come from a sporadic mutation or other types of mutation
65
Q

Waardenburg syndrome

A
  • Patches of white skin or hair, wideset eyes of blue or different colors
  • Deafness
  • Defect of neural crest mutation

*Remember melanocytes migrate from neural crest cells

66
Q

Addision disease

A
  • Deficient adrenal gland causes bronzing of skin
  • ACTH activates melanocytes
67
Q

Vitiligo

A
  • Depigmentation caused by autoimmune attack
68
Q

Skin conditions

Defect in melanin synthesis: ___________

Defect in neural crest migration:__________

Defect in adrenal gland: ___________

Depigmentation: ______________

A

Albunism

Waardenburg Syndrome

Addison disease

Vitiligo

69
Q

Outside of skin, where can you get melanomas?

A

Iris

Hair

Substantia nigra of brain

70
Q

What are some characteristics of a melanoma?

A

Asymmetrical

Borders are uneven

Multiple colors

Larger the 1/4 inch

Changing in Size, shape, and color

71
Q

In what layer of the epidermis are langerhans cells found?

A

S. Spinosum

72
Q

What do langerhans cells and melanocytes have in common?

A

They both have light cytoplasms

73
Q

Langerhans cells are antigen-presenting immune cells that bind antigens an present to _____________

A

T- Lymphocytes

74
Q

Langerhans cells contain large granules called____________

A

Birbeck granules

75
Q

What are birbeck granules?

A

Endosomes specialized for phagocytosis

  • Shaped like tennis-rackets
  • Facilitate uptake of microbial fragments

*It’s not enough to just phagocytize the antigen but you must also take it back to the lymph node, this is the importances of the endosome portion

76
Q

The presence of Langerhans Cells is diagnostic of what?

A

Langerhans Cell Histocytosis

  • A type of cancer involving clonal proliferation of Langerhans cells.
  • Clinically, manifests from isolated bone lesions to multisystem disease
77
Q

What function do langerhans cells play in immune function?

A

Langerhans cells breach the basement membrane, enter lymph vessels, and are transported to lymph nodes to activate T-cells. T lymphocytes then migrate back to skin to neutralize antigen.

78
Q

Hansen’s disease (leprosy)

A

In Hansen’s disease (leprosy), it is Langerhans cells that pick up the bacterium. Activated T-cells then mistakenly target Schwann cells that surround peripheral nerves.

*Innervation is destroyed and area will become necrotic

79
Q

In ________, Langerhans cells of vaginal mucosa and foreskin take up the virus.

A

HIV

80
Q

langerhans cells actively migrate between __________ to exit the epidermis and reach lymph nodes

A

keratinocytes

81
Q

What do merkel cells and melanocytes have in common?

A
  • Found in stratum basale
  • Migrate from neural crest cells
82
Q

How do merkel cells and melanocytes differ?

A
  • Merkel cells attached to keratinocytes by desmosomes. Melanocytes do not.
  • Merkel cells do not contain hemidesmosomes but melanocytes do.
83
Q

Merkel’s cells are especially frequent in what area of the body?

A

Palms and soles

84
Q

Merkel cells are activated by _____________ and they release their granules of _________ onto the axon, which will transport the action potentail back to the dorsal root ganglion, whcih will go to the dorsal root.

A

Mechanical pressure; neurotransmitters

85
Q

Actinic (solar) keratosis

A
  • Precancerous
  • Crusty scaly growth
  • May progress to squamous cell carcinoma
86
Q

2nd most common skin cancer

A

Squamous cell carinoma

87
Q

Why is melanoma such a dangerous type of cancer?

A

Melanocytes can migrate and once they do they can colonize other areas easily

88
Q

Most common type of skin cancer

A

Basal cell carcinoma

89
Q

What two things attach the epidermis to the dermis?

A

Hemidesmosomes

Interdigitating ridges

90
Q

Papillae are especially pronounced in _____________ skin, where shear forces are greatest.

A

Thick

91
Q

What are the two layers of the dermis? What type of connective tissue is found in each layer?

A

Papillary dermis: loose connective tissue

Reticular dermis: dense irregular connective tissue.

92
Q

What is the importance of the loose connective tissue found in the papillary dermis?

A

Loose connective tissue is important because you need a lot of room for capillaries to come in right next to the basement membrane to nourish the epidermis, which is avascular

93
Q

Outside of dense irreguar connective tissue, what else is found in the reticular dermis?

A

Collagen type I

Elastic fibers

  • Collagen accounts for our tough skin
  • Elastic fibers account for the amount of movement that our skin does
94
Q

Vasospasm

A

Sudden contriction of blood vessels, reducing its diameter and flow rate

95
Q

Which layer of the dermis plays a role in thermoregulation? How?

A

Papillary dermis contains a rich supply of vessels to supply the epidermis (which is avascular).

96
Q

What role do AV shunts play in thermoregulation?

A

Under cold conditions, blood is sent through arteriovenous shunts (AV shunt) ,so less blood reaches the surface and heat is retained. Especially common in extremities.

* If AV shunt goes into overdrive, you get Raynaud’s disease

97
Q

Raynaud’s disease

A

Localized vasopasm in response to cold

98
Q

What does anhidrotic mean?

A

It means you don’t sweat

99
Q

How does the body release heat?

A

Body releases heat through evaporation of eccrine sweat and dilation of cutaneous blood vessels.

100
Q

Anhidrotic ectodermal dysplasia

A
  • No active sweat glands
  • Vulnerable to overheating
  • Symptoms:
    • Delirum
    • Death
101
Q

What happens to skin as we age?

A

Naturally aged skin loses dermal papillae, collagen and elastin, and is thinner; more easily detached.

102
Q

Photaged skin is also known as _____________

A

Solar elastosis

103
Q

What is solar elastosis?

A

A disorder in which the skin appears yellow and thickened as a result of sun damage

  • Skin thicker (epidermal layer is thicker but dermal papillae and epidermal ridges are flattened out)
  • Defective collagen and elastin
  • Wrinkes and fragility
  • Loss of suppleness
104
Q

Cutis laxa (elastolysis)

A
  • Skin is inelastic and hangs in loose folds
  • Excessive mobility of joints
105
Q

Ehlers-Danlos

A
  • Excessive stretching of skin and joints
  • Defective collagen
106
Q

Scleroderma

A
  • Autoimmune
  • Enlarged collagen fibers
    • Hardening of skin and loss of circulation
107
Q

In cases of scleroderma, what will happen to all of the capillaries and arterioles in the dermis?

A

They will get squished by the enlarged collagen, so you lose circulation and you can get nercrosis of the extremities

108
Q

The hypodermis is also known as _____________.

A

Subcutaneous layer or superficial fascia

109
Q

The hypodermis is composed of:

A

Loose connective tissue with copious fat

110
Q

What makes the hypodermis a good injection site?

A

Rich supply of blood vessels

111
Q

The fat in the hypodermis is important in_______

A

Thermoregulation

Energy storage

Ease of movement

112
Q

What are the epidermal appendages?

A

A.Eccrine sweat glands

B.Apocrine glands

C.Hair follicles

  1. Sebaceous glands
  2. Arrector pili muscles

D. Nails

113
Q

Eccrine sweat glands are found primarily in what layer of the skin?

A

Dermis

114
Q

Eccrine sweat glands are activated by _____________that secrete ____________.

A

sympathetic nerves; acetylcholine

115
Q

What kind of gland are eccrine sweat glands?

A

Simple coiled tubular

116
Q

Everywhere else beside eccrine sweat glands, the neurotransmiter for sympathetic nerves is norepinephrine. But in eccrine sweat glands the neurotransmitter is ___________.

A

Acetylcholine

117
Q

On histo slides, which is lighter, the eccrine ducts or glands?

A

The secretory portion of the gland is much lighter than the actual duct

118
Q

What are components of the secretory portion of the eccrine sweat gland? What are the functions of each?

A

Dark cells

  • Secrete antibacterial glycoproteins

Clear cells

  • Secrete fluid sweat by transporting NaCl water

Myoepithelial cells

  • Contract to discharge fluid
119
Q

_______________ sweat glands are the only type of sweat gland found in soles and palms (thick skin).

A

Eccrine

120
Q

What type of epithelium makes up the secretory portion of eccrine sweat glands?

A

Stratified cubodial epithelium

121
Q

Which glycoproteins are secreted by dark cells of eccrine gland?

A

Dermicidin

Defensin

122
Q

______________ between the light cells aid in the rapid extrusion of NaCl and water.

A

Intercellular canaliculi

*Help the light cells “communicate” with the lumen

123
Q

What type of epithelium is found in eccrine ducts?

A

Stratified cuboidal epithelium

124
Q

What is the normal tonic state of sweat? How is this state maintained?

A

Hypotonic

Eccrine ducts are active in resorbing NaCl

125
Q

Sweat is carried from eccrine glands into epidermis by ducts, where it is trasnported in a _____________ cavity between keratinocytes that terminate upon the surface.

A

Spiraling

126
Q

Apocrine glands are primarily found in places with hair. What is the exception?

A

Apocrine glands secrete usually into hair follicle, except for modified apocrine glands (ceruminous glands that produce earwax and tarsal glands of Moll in eyelids).

127
Q

In what layers of the skin are apocrine glands found?

A

Dermis

Hypodermis

128
Q

What type of gland are apocrine glands?

A

Simple coiled branching gland

129
Q

Apocrine glands are activated by ____________ that secrete_______________.

A

Sympathetic nerves; norepinephrine

130
Q

Apocrine glands develop at puberty under the influence of _____________.

A

Sex hormones

131
Q

What tyoe of epithelium is found in apocrine glands?

A

Simple cuboidal epithelium

132
Q

The odor that is produced from fluid secreted by apocrine glands is due to _____________

A

Bacterial decomposition

133
Q

What do apocrine glands secrete?

A
  • Lipid/protein ricj, viscous fluid
  • Pheromones
134
Q

What type of secretion do apocrine glands display?

A

Merocrine

*They secrete by exocytosis of secretory granules

135
Q

What three things make up the pilosebaceous unit?

A

Hair follicles

Sebaceous glands

Arrector pili muscles

136
Q

Hairs are produced only in _________ skin.

A

Thin

137
Q

What intermediate filament makes up hair?

A

Keratin

138
Q

Hair is develop from the _________

A

Epidermis but involutes into dermis, carrying stem cell keratinocytes with them

139
Q

What roles do the dermal papillae and melanocytes play in hair?

A

A dermal papilla inserts into the base of the hair bulb, bringing capillaries (nourish hair) up to the keratinocytes of the hair root. Melanocytes contribute pigment to differentiating keratinocytes, which form the various layers of the hair.

140
Q

Why does chemotherapy result in hair loss?

A

Because keratinocytes are rapidly deivign cells and chemotherapy destroys rapidly dividing cells

141
Q

Male patterned baldness

A
  • Heredity
  • shrinking of the follicle
  • response to testosterone
142
Q

Alopecia areata

A
  • autoimmune
  • round bald patches
143
Q

What are possible causes of hair loss?

A
  • male pattern baldness: heredity; shrinking of the follicle; response to testosterone
  • post-menopausal: thinning; hormonal changes
  • alopecia areata: autoimmune; round bald patches
  • sudden loss: physical or emotional shock; chemotherapy
  • hormonal changes: pregnancy, thyroid problems
144
Q

What type of gland are sebaceous glands?

A

Branched, acinar glands

145
Q

What type of secretion do sebaceous glands display?

A

Holocrine secretion

*The whole cell becomes secretory product. The glands are filled to the brim with lipid droplets and they end up bursting and the whole cell becomes the secretory product

146
Q

Sebaceous glands are stimulated by __________, that begins being dramatically expressed at puberty.

A

Testosterone

147
Q

Sebaceous glands are more numerous where?

A

Scalp

Face

148
Q

Vernix Caseosa

A

Sebaceous glands are highly active in the fetus, under the influence of maternal androgenic hormones, forming the vernix caseosa, a cheesy, waterproof covering that protects the skin from amniotic fluid. After birth, the glands subside until pubertal hormones activate them.

*This why babies aren’t so wrinkly even though they’ve been sitting in fluid for 9 months.

149
Q

Arrector Pili Muscles

A
  • Bundle of smooth muscle fibers
  • Associated with hair follicle and sebaceous glands.
  • Helps expel sebum
  • Makes hair stand on end (piloerection) under sympathetic activation (fear, goose bumps).
150
Q

Arrector pili muscles are made up of ___________ fibers.

A

Smooth muscle

151
Q

Hair, nails, sweat glands, mammary glands, salivary glands, lacrimal glands and teeth all derive from _______________ interactions, using common developmental pathways.

A

epithelial-mesenchymal

152
Q

Hypohidrotic ectodermal dysplasia

A
  • Result from a defect in the cell signaling molecules involved (ectodysplasin) will include thin hair, hypoplastic nails and glands, dry skin, absent teeth.
  • Life threatening because of inability to sweat.
153
Q

When you don’t have epidermal appendages it’s becuase there is a signaling molecule called ____________ that is faulty and you’re not having a complete conversation between your epidermis and the underyling dermis.

A

Ectodysplasin

154
Q

What are the stages to epithelial-mesenchymal interactions?

A
  1. Epidermis secretes signals that cause condensations in underlying dermal mesenchyme.
  2. The condensed dermal mesenchyme responds by secreting factors that cause epidermis to form regionally specific cutaneous structures.

*Epithelium can only make structures coded for in its own species DNA.

Structure and Function 1- Exam 2 (18 decks)

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