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Molecular Bioscience > Skin structure and function > Flashcards

Skin structure and function Flashcards

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1
Q

What are the layers of skin?

A

-Epidermis
-Dermis
-Hypodermis

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2
Q

What is the epidermis?

A

-Stratified squamous epithelial layer

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3
Q

What is the epidermis made of?

A

-Keratinocytes: Changes shape

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4
Q

What is the dermis?

A

Supportive connective tissue matrix

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5
Q

What is the dermis made of?

A

Fibroblasts: Forms connective tissue
Immune cells: WBCs

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6
Q

What is the hypodermis?

A

Fat layer

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7
Q

What is the hypodermis made of?

A

-Adipocytes: stores energy as fat

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8
Q

In what layers are your nerve endings and blood vessels?

A

Dermis and hypodermis

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9
Q

What are rete ridges in the skin layers?

A

-Increase surface area
-Increases cell contact with the basement membrane
-Hold epidermis in place to prevent blisters

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10
Q

When does the epidermis form?

A

By 1 month of gestation

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11
Q

When does the dermis form?

A

In week 11 of gestation

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12
Q

What are the functions of skin?

A

-Prevents mechanical abrasion
-Prevents dessication or water absorption
-Prevents injury by chemicals
-Barrier to pathogens
-Mechanism of sensation
-Metabolic functions
-Thermoregulation

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13
Q

What are the components of the skin structure?

A

-Hair
-Hair follicles
-Sebaceous gland
-Arrector pill muscle
-Pore
-Blood vessel
-Sensory nerve endings
-Sweat glands

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14
Q

What is the role of the hypodermis?

A

-Acts as a cushion
-Stabilises structures above
-Insulation
-Absorbs blows
-Energy reserve

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15
Q

Where are rete ridges in the epidermis highly developed?

A

Areas exposed to stress, i.e hands and feet

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16
Q

What is present in the epidermis to produce pigment?

A

melanocytes

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17
Q

Why is the epidermis stratified?

A

-Stem cell population protected deep inside
-Upper cells provide protection
-Monolayer is more difficult to replace if abraded

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18
Q

Where are stem cells in the epidermis?

A

At the rips of rete ridges

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19
Q

What makes up the rest of the basal layer of the epidermis?

A

Transit amplifying cells

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20
Q

What does the basal layer consist of?

A

Columnar cells anchored to the basement membrane

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21
Q

What are the properties of the cells in the basal layer?

A

-Proliferative: Grow and increase in no. rapidly
-Undifferentiated: No specialised functions

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22
Q

What is the spinous layer of the epidermis?

A

-Cells are larger and flattened
-Differentiation of cells start

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23
Q

What is the name of the cells in the basal layer?

A

Hemidesmosomes

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24
Q

What is the name of the cells in the spinous layer?

A

Desmosomes

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25
What is the granular layer of the epidermis?
Contains: -Keratohyalin granules with profilaggrin -Lipid-filled lamellar granules
26
What is the transition zone in the epidermis?
-Layer between granular (live) and cornified (dead) layers -Cells are recycled -Cornified envelope forms
27
What happens to organelles in the transition zone?
Destroyed by proteases, DNase, RNase
28
What is the cornified layer of the epidermis?
-Terminally differentiated -Forms corneocytes
29
What are corneocytes?
-Flattened cells -Forms a protective surface
30
What does the cornified layer consist of?
-80% keratin encased in cornified envelope -Remnants of organelles, melanin pigment -Interstitial fluid
31
How is damage from radiation prevented?
Melanocytes synthesise melanin
31
What is the role of melanin?
-Absorbs UV radiation -Scavenges free radicals
32
What are the 2 types of melanin?
-Eumelanin (Brown/black) -Phaemelanin (Yellow/red)
33
How is infection prevented?
-Langerhan's cells migrate from bone marrow to spinous layer
34
What do langerhan's cells do?
-Take up and process microbial antigens -Become antigen-presenting cells -Present antigens to T-cells (lymphocytes)
35
What does the dermis contain?
-Mast cells (immune cells) -Dermal appendages (hair follicles,sweat glands, blood vessels) -Fibroblasts
36
What is the function of fibroblasts?
-Produce chemicals to control proliferation -Produce collagen for strength -Produce elastin for stretch and recoil -Make extracellular matrix
37
What is the superficial papillary layer of the dermis?
Contains sensory nerves and loose connective tissue
38
What is the mechanism of sensation?
Nerves
39
What are the sensors in the epidermis and dermis?
Merkel cells in the basal layer
40
What are the touch sensors?
Meissner's corpuscles
41
What are the pressure/vibration sensors?
paccinian corpuscles
42
What are the pain/temperature sensors?
Myelinated and non-myelinated sensory nerve endings
43
What are the metabolic functions of the dermis?
-Synthesis of vitamin D3 -Lipid metabolism storage -Lipid soluble vitamins storage
44
Where does hair emerge from?
Hair follicles from deep in the dermis
45
What are the 3 layers of hair?
-Inner medulla containing keratin -Outer cortex with hard keratin -Cuticle coated in keratin
46
What are the 2 layers of the epithelial wall?
-internal root sheath surrounding roots -External root sheath covers length of follicle
47
What is the dermal papilla?
-Formed from connective tissue -Hold capillaries and nerves
48
How is hair colour produced?
Melanocytes at the base of hair produce melanin pigment
49
What are lanugo hairs?
-Form week 20 of gestation -Shed before birth -Fine and long
50
What are vellus hairs?
-Common hair type over body surface -Short, fine, light colour
51
What are terminal hairs?
-Thick and long -On scalp, eyebrows, eyelashes, beard, pubic area
52
Where does hair growth stem from?
Hair root firmly attached to the matrix
53
When does hair growth stop?
When the follicle becomes inactive, shrinks and attachment breaks down
54
What drugs can alter hair growth?
-Cytotoxins, heparin, warfarin, vitamin A, poisons
55
What are your nails?
Dense plates of cells packed with hardened keratin
56
What is the role of the nail?
Protects fingernails and help grasping
57
Where does the blood supply in the skin come from?
-Deep vessels in subcutaneous layer -Superficial vessels in reticular dermis
58
What is body temperature maintained at?
37 degrees
58
What is the role of blood vessels in the skin?
Controls dilation and contraction to regulate flow and control heat loss
59
What is the relation between body temperature and forensics?
-Body temp rises and releases sweat -Leaves latent fingerprints
60
Where are there no sebaceous glands?
Hair less skin like soles or palms
60
What are exocrine glands?
Secrete products into ducts leading to the environment, e.g. sweat
60
What are sebaceous glands?
-Derived from epithelial cells -Associated with hair follicles -Found on scalp, face, chest, back
61
What pH is the skin kept at and why?
6-7, discourages microbial growth
62
What is the role of sebaceous glands?
-Produces an oily sebum protects hair and skin from drying -Toxic to bacteria to stop infection
63
What are sweat glands?
-Within the dermis -Coiled tubes that secrete watery substance
64
What are the 2 types of sweat glands?
-Eccrine -Apocrine
64
What are eccrine sweat glands?
-On palms, soles, forehead, armpits -Not in mucous membrane -Under thermal control
65
What is the composition of sweat?
-Mostly water -Minerals: Calcium, Potassium, Calcium, Magnesium -Fatty acids -Urea
66
How is sweat analysis conducted?
-Take sweat swab -Remove water by sublimation (freeze dry) -Leaves amino acids and proteins -Analyse by chromatography
67
What are the problems with sweat analysis?
-No biomarkers -Difficult to locate -Heterogeneity of composition between samples
68
What are the uses of sweat analysis?
-Detect incidental impurities, e.g. drugs -New biomarkers found identified with antibodies
69
What are apocrine sweat glands?
-Large sweat glands -Empty into hair follicles -Active at puberty -Produces sticky odourless protein rich secretion

Molecular Bioscience (16 decks)

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