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PH112 > The Skin ✅ > Flashcards

The Skin ✅ Flashcards

1
Q

keratinocytes

A

85% of epidermis cells arranged in 4-5 layers
produce keratin (tough/fibrous protein)

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2
Q

melanocytes

A

8% epidermal cells

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3
Q

dendritic cells

A

5% of the epidermis, immune response against infections.

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4
Q

tactile epithelial cells or Merkel cells

A

2% of epidermal cells.

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5
Q

cell layers of the epidermis

A

stratum basale
stratum spinosum
stratum granulosom
Stratum lucidum
Stratum corneum

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6
Q

stratum basale

A

-a single layer of columnar cells.
-only cells in this deep layer of a stratum of the epithelial will undergo mitosis.

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7
Q

stratum spinosum

A

8-10 layers of irregularly shaped cells have very prominent intercellular bridges or demosomes.

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8
Q

stratum granulosum

A

process of surface keratin formation begins.
cells arranged in a sheet two or four layers deep, are filled with keratohyalin.

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9
Q

keratohyalin

A

required for surface keratin formation

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10
Q

stratum lucidum (‘clear layer’)

A

keratinocytes in this layer are very flat and closely packed, and clear.

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11
Q

stratum corneum (‘horny layer’)

A

tough stratum layer
most superficial layer in the epidermis.
composed of very thin squamous cells

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12
Q

what are squamous cells

A

flat cells
at the skin surface are dead and continually being shed off.

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13
Q

what is keratinization?

A

a process where cells in this layer are formed by cells from the deeper layer of the epidermis. it is then filled with keratin and moved to the surface.

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14
Q

cell layers of the epidermis

A
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15
Q

how do cell signaling proteins influence skin regeneration?

A

epidermal growth factor (EGF)
growth hormone (GH)

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16
Q

what does the epidermal growth factor do?

A

regulates the regeneration and repair of the epidermis.

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17
Q

what does the growth hormone do?

A

growth-promoting effect on the epidermal cells.

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18
Q

how are the epidermis and the dermis joined together?

A

by the dermoepidermal junction (DEJ)

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19
Q

dermo-epidermal junction (DEJ)

A
  • basement membrane
  • has a unique polysaccharide gel that strongly cements the superficial epidermis to the dermis.
  • junction glues the two layers together which provides mechanical support for the epidermis. - this is attached to the upper surface
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20
Q

what are the functions of the epidermis?

A

skin repair
prevents fluid loss
UV protection
produces vitamin D3
prevents damage abrasion
innate immune barrier

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21
Q

in the dermis, what are the two layers which give the skin its strength?

A

papillary layer
reticular layer

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22
Q

what is the papillary layer?

A

loose fibrous connective tissue elements
a network of thin collagenous and elastic fibers.

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23
Q

what does the dermal papillae do? (papilary layer)

A

increases the surface area of the gluelike DEJ.
leads to dermal ridges e.g. fingerprints
provides sensory information to the skin e.g. touch

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24
Q

what is the reticular layer?

A

a dense layer of tough and interlacing white collagenous fibers where elastic fibers are also present.
these fibres make the skin stretchable and elastic.

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25
Q

hair and the dermis

A

-dermal layer anchors the hair
-hair follicles have small bundle of involuntary muscles attached to them (arrector pili muscles)
-hair stands ‘on end’ due to contraction of these muscles which is caused by extreme fright or cold. this is responsible for goosebumps.

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26
Q

sensors in the dermis

A

somatic sensory receptors are located in the dermis
allow for senses, e.g. pain, pressure, touch, temperature.

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27
Q

what is the hypodermis / subcutaneous layer

A

the innermost layer of the dermis which contains fat and nutrients. forms a connection between the skin and the underlying structures of the body.
- connects skin to underlying tissue, which is known as adipose tissue.

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28
Q

skin colour and melanin

A

melanocytes found in the stratum basale of the epidermis.
amount and type of melanin pigment produced determines skin color.
only melanocytes have the ability to tyrosine into melanin pigments. pigment granules are produced then released by melanosomes.

29
Q

what type of melanin pigments makes brown - dark brown skin?

A

eumelanin

30
Q

what type of melanin pigments makes red-orange skin?

A

pheomelanin.

31
Q

how does melanin protect the skin from uv light?

A

migrates into the cell

UV light can cause dna to mutate
UV links to cancer
melanin protects dns from becoming damaged.

32
Q

melanin and albinism

A

rare genetic mutation for melanocytes cant produces melanin.
People with albinism tend to need more protection from UV radiation
they are more prone to sunburn and skin cancer.

33
Q

what is the key for vitamin D synthesis?

A

UV RAYS
UV rays activate precursor molecules in the skin in sunlight.

34
Q

why is vitamin D important?

A

helps regulate the amount of calcium and phosphate in the body
keeps bones, teeth and muscles healthy.

35
Q

what can high consumption of beta carotene do?

A

high consumption of carrots/sweet potatoes
can lead to orange colouration

36
Q

what is bilirubin?

A

the breakdown product of red blood cells.
liver normally processes this, if it is damaged then skin accumulates it. this is called jaundice

37
Q

hemoglobin

A

when the volume of blood flowing through the skin capillaries changes.
blood pressure, heat, cardiac problems, stress etc.]
hemoglobin is a reddish color.

38
Q

main functions of the inetgument

A
39
Q

what type of epithelial cells covers the epidermis to make the skin a barrier?

A

keratinized stratified squamous epithelial

40
Q

how do the keratinized stratified squamous epithelial cells make the skin a barier?

A

-protects underlying tissue against invasion by microorganisms to minimize injury
- supply of immune cells and chemicals to resist microbes and pathogens
-protects from dehydration, loss if internal body fluids, and unwanted entry of fluids.
- melanin pigment to protect us from UV rays.

41
Q

surface film of the skin

A
  • spread of emulsified material over the surface
  • a mixture of sweat, sebaceous glands, and microbial cells.
    -desquamation happens whilst this takes place.
  • form a skin microbiome.
42
Q

what is desquamation?

A

where the epithelial cells shed off from the skin surface.

43
Q

skin functions - sensation

A
44
Q

Skin functions - excretion and body temperature.

A

-stratum corneum evaporates about 400mL of water daily (sweat), besides removing water and heta from the body this can also help with the excretion of salts, carbon dioxide, ammonia and urea.
-certain drugs can be absorbed by the skin.

45
Q

skin functions - temperature regulation

A

-80% or more of heat transfer happens through the skin
- blood flow allows the temperature to be regulated, so heat loss can be regulated by altering the blood flow.

46
Q

what term describes the narrowing of blood vessels in the skin?

A

vasoconstriction

47
Q

what term describes the widening of the blood vessels?

A

vasodilation

48
Q

4 basic processes of temperature regulation through the skin

A
49
Q

how does sweat form?

A

sweat glands gather water from the blood stream
transfers in the duct to the actual surface to then be evaporated.

50
Q

in hot environments how does the skin regulate temperatures?

A
51
Q

in cold environments how does the skin regulate temperatures?

A
52
Q

what is the function of the hair on the head?

A

guards scalp from injury and suns rays
decreases heat loss form scalp

53
Q

what is the function of the hair?

A

eyebrows and eyelashes protect from foreign stuff
hair in the nose protects from inhaling particles

54
Q

how are hair root plexuses activated?

A

touch receptors (hair root plexuses) associated with hair follicles are activated where there is a light move to a hair, therefore hairs also function when they sense light touch.

55
Q

why does grey hair appear?

A

grey - low melanin
white - no melanin
due to the diffusion of light through the translucent hair shaft.

56
Q

what are the three stages of hair growth?

A

anagen:
hair matric divides. new cells from the hair matrix are added to the hair root, existing cells of the hair root are pushed upward and the hair grows longer.
catagen:
movement of hair away from the blood supply in the papilla of the hair. cells of the hair matrix stop dividing, the hair follicle shrinks.
telogen:
hair root falls out or is pushed, new growth stage begins.

57
Q

sudiferous glands / eccrine glands (sweat)

A

distributed over body surface except from lip, ear, canal and nail beds.
-coiled, tubular type of gland.
-produces sweat which is rich in salts, ammonia, uric acid, urea and other wastes.
- for temperature regulation

58
Q

sudiferous glands / apocrine glands (sweat)

A

deep in the subcutaneous layer
-armpit, eyelids.
-areola, genitalia
- perineum, ears.
larger and connected to hair follicles.
more secretions than eccrine glands
odors may be associated with this due to the decomposition of the secretion by skin bacteria.

59
Q

sebaceous glands

A
  • secretes for the hair and skin.
    -found in the dermis, except in the skin of the palms and soles.
  • where there is hair growth on the skin, this gland is present.
  • sebaceous glands secrete sebum, which keeps the hair supple and pilant. this is natures own way f preventing excessive water loss from epidermis, like a cream.
60
Q

sebum (skin oil)

A
  • from the sebaceous gland
    -antifungal
  • increases skins surface film and helps protect against numerous fungal infections.
  • increases during adolescence (acne)
61
Q

how are blackheads formed?

A

sebum gathers and enlarges some of the ducts of the sebaceous glands which forms a white pimple. when oxidized, the sebum darkens and turns into a blackhead.

62
Q

what oils are sebum made of?

A

triglycerides, fatty acid breakdown products.
wax esters, squalene and cholesterol.

63
Q

roles of sebum in the skin

A
64
Q

ceruminous glands

A
  • specialist apocrine sweat glands
  • coiled tubular glands with excretory ducts that open into the external ear canal, or with sebaceous glands into the necks of hair follicles in this area. the mixture of these secretions makes earwax.
65
Q

why is cerumen (earwax) important?

A

protects from dehydration
lubricates/cleans the ear canal
kills bacteria
the barrier to prevent foreign particles from entering the ear.

66
Q

mammary gland

A
  • production and expression of milk
  • development requires the coordinated action of many hormones.
  • glands have specialized epithelium and stroma. this can lead to benign and malignant lesions (stage 4)
    -contains around 10-20 lobes.
67
Q

tissue architecture | lobules and ducts

A

lobules are the secretary units of the breast

each lobule has acini glands which connect to the intralobular duct.

the intralobular duct connects with the extralobular duct

the epithelial cells synthesise milk.

68
Q

hormone impact: pregnancy and lactation

A

during pregnancy, lobules undergo controlled proliferation and enlargement to prepare for lactation.
the acini in each lobule increase
epithelial cells become differentiated and synthesize/secrete milk.

69
Q

how is lactation affected after birth?

A

after birth hormonal fall, prolactin initiates lactation.

when breastfeeding ceases, there is a change to the lobular structure where the breast returns back to the pre pregnancy structure.

PH112 (17 decks)

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