Skin Week 6 Flashcards by Ethan Wong

Describe the skin

Cutaneous membrane forming the external body surface

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What is the largest organ in the body

The skin

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What % of an adult body weight does the skin make up

15%

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What are the 2 main layers that forms the skin

Epidermis & Dermis

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What is the epidermis

ectodermally derived epithelial tissue

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What is the dermis

mesodermally derived connective tissue

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What is the basement membrane

Epidermo-dermal junction

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What is the hypodermis

subcutaneous layer of fascia and fat

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Where are the glands, nail and hair found

Epidermis

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Where are blood vessels, smooth muscle, lymphatics and sensory organs found

dermis and hypodermis

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what are the 2 types of skin

hairy (thin) skin and glabrous (thick) skin

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What are the differences between hairy and glabrous skin

Hair and certain type of glands: hairy skin has but glabrous skin dont

Presence of encapsulated sense organs in dermis: hairy skin dont but glabrous skin has

thickness of epidermis: hairy skin is thinner but glabrous skin is thicker

location: hairy skin is most regions except palms and soles but glabrous skin is confined to palms and soles

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What is a unique characteristic of glabrous skin

Furrows and ridges (dermatoglyphics)

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What can be found at the epidermis

dermal papillae

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what can be found at dermis

rete ridges, sebaceous glands, arrector pili

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what can be found at subcutis

hair follicle, hair bulb, eccrine sweat gland

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What is the epithelium like in epidermis

Stratified squamous epithelium

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What is the sequence of cells in epidermis

From bottom to top
- stratum basale
- stratum spinosum
- stratum granulosum
- stratum lucidum
- stratum corneum

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What type of cells in stratum granulosum

lamellar granules

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what is stratum basale

single layer of cuboidal/columnar epithelium and attached to basement membrane

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what cells can be found in stratum basale

keratinocytes, stem cells, melanocytes, merkel cells

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what cells can be found in stratum spinosum

several layers of spiny keratinocytes

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what is each layer in stratum spinosum attached by

desmosomes

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what is stratum granulosum

few layers of keratinocytes containing granulosomes

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what cells can be found in stratum granulosum

keratins, keratohyalins, lamellar bodies

what unique thing could be seen in stratum granulosum

many dying pyknotic cells

what is stratum corneum

thick layer of dead keratinocytes and cross linked keratins dominate this layer

Where can stratum lucidum be found

between stratum granulosum and stratum corneum

What protein gives the clear appearance in stratum lucidum

eleidin and allows few layers of keratinocytes to appear clear

What is hair

dead epidermal cells that have been converted to keratin

how does hair grow

hair growth occurs when cells in hair matrix at base of the bulk divide and push upwards. when it reaches skin surface, they have been converted completely to keratin

what is nails

nails are hard plates of dead epidermal cells that have been converted into keratin

how does the nail grow

beneath root is the nail matrix where epidermal cells divide to produce new nail cells and allow nail to grow

what is the function of sweat glands

thermoregulation, excretion of wastes and toxins

what does sweat consists of

water, salt, urea

where can eccrine sweat glands be found

throughout body in the dermis

what is eccrine sweat glands innervated by

cholinergic innervation

where can apocrine sweat glands be found

axilla, areola and genital areas

what innervates apocrine sweat glands

adrenergic innervation

what is the difference between apocrine and eccrine sweat glands

Innervation: (A) adrenergic, (E) cholinergic Location: (A) axilla, areola & genitals, (E) throughout body in dermis Duct openings: (A) into hair follicle, (E) into skin surface

Sources of skin colour

Beta carotene, hemoglobin in capillaries of dermis, jaundice, melanin

what is the function of melanocytes

produce melanin pigment

what are the 3 types of melanin

pheomalenin, eumalenin, neuromalenin

what form is melanin produced and donated to keratinocytes

melanosomes

what is the function of melanin

UV radiation protection

where can melanocytes be found

basal layer @ 1:4 - 1:15 vis-a-vis keratinocytes

what is the function of langerhans cells

immunity and antigen presenation

where can langerhans cells be found

epidermal layer

when does langerhans cells migrate to lymph nodes

upon antigen stimulus

when do langerhans cells number increase

upon skin inflammation

where can merkel cells be found

basal layer and hair follicle

what is the function of merkel cells

sensory to touch

what is the function of merkel cells

neuroendocrine function

How do merkel cells transmist signals and sensory nerves

basal surface contacts an axonal terminal

what are the 2 layers of the dermis

papillary and reticular layers

what is the difference in tissue between papillary and reticular layers

papillary - loose connective tissue (aerolar tissue) reticular - dense connective tissue (collagen)

Which layer forms peg like projections into epidermis

papillary layer

what is the function of papillary layer

transfer nutrients to epidermis

what are the differences in receptors for papillary and reticular layers

papillary - sensory receptors for fine touch reticular - sensory receptors for deep pressure and vibration

which layer in the dermis can sweat glands, hair follicles, sebaceous glands and blood vessels be found

reticular layer

where is the hypodermis located

under the dermis

what is the function of hypodermis

act as padding to allow skin to slide on deeper structures fat helps with thermal insulation rich in blood vessels for absorptive function (drugs)

what are the main components of hypodermis

loose connective tissue and fat

what are the 2 main sensory structures in the skin

Meissner's corpuscle Pacinian Corpuscle

What are the similarities between Meissner's corpuscle and Pacinian Corpuscle

they have Fast adapting receptors

Where is the Meissner's Corpuscle found

Papillary dermis (finger tips)

Where is the Pacinian corpuscle found

Recticular dermis

What is the difference between Meissner's Corpuscle and Pacinian Corpuscle

Meissner's - sense fine discriminatory touch Pacinian - sense deep transient pressure and vibration

How does skin function as a thermosensor

When cold, blood circulation occurs further from the skin to keep heat When hot, blood circulation is closer to skin surface to lose heat

Why do people not feel anything after 3rd degree burns

Nerves have been damaged

How is dermal papillae innervated

sympathetically innervated

what causes goosebumps in the skin

arrector pili muscles

What glands are not found in palms and soles

sebaceous glands

What makes thick skin thick?

stratum lucidum

What is the function of lamellar bodies in stratum granulosum

Prevent loss of water to skin

What changes occurs in dying pyknotic cells

begins to lose its nucleus

What stimulates sebaceous glands

androgens

Does eccrine sweat gland create an odour

What does sebaceous glands secrete

sebum

Does the excretions from apocrine and sebaceous glands create an odour

Yes

What causes the thick sweat and sebum to have an odour?

Contains lipids and proteins which bacteria metabolize, creating the odour

What does UVB do to the skin

Increase melanin content of skin

What are the effects of UVA and UVB

UVA reaches the dermis and UVB reaches epidermis

what do 1st degree burns injure

epidermis

what do 2nd degree burns injure

dermis

what do 3rd degree burns injure

hypodermis

The distribution of burns is known as

Wallace Rule

What is the risk of having 3rd degree burns

More prone to water loss and have little ROM and function

What are the effects of aging on skin

Loss of collagen and elastin Loss of fat in hypodermis which makes elderly more prone to cold temperatures

What is the clinical significance of Borge's relaxed skin tension lines

Used to decide direction of cut to minimize scarring

What is the process of wound healing

Bleeding > inflammatory > proliferative > remodeling

What is the distribution of burns according to Wallace Rule

Head and neck - 9% upper limbs - 9% each trunk - 36% genitalia - 1% lower limbs - 18% each

What is the clinical significance of dermatones

Allows one to identify possible spinal problems as each part of skin is innervated by certain spinal region (Ex: C4, T6)

What are some examples of dermatomes

shingles, cutaneous hemangiomas, angina pectoris

How are dermatomes applied in angina pectoris

Pain due to lack of blood supply to myocardium is felt at - anterior chest - neck and jaw - left upper limb all the way to little finger Spinal segments conveying visceral pain from injured myocardium also receive sensations from skin of left upper limb, anterior chest wall, neck & jaw