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Body logistics > BL Skin Structure And Function > Flashcards

BL Skin Structure And Function Flashcards

1
Q

What are the layers of the skin?

A

Epidermis
Dermis
Hypodermis

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2
Q

Structure of the epidermis

A
  • made of epithelial cells - keratinocytes
  • keratinised stratified squamous epithelium
  • thick skin - 5 layers
  • thin skin - 4 layers
  • adherens junctions
  • desmosomes
  • avascular
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3
Q

Function of the epidermis

A

Prevents water loss
Protection against bacteria + parasites
Presents pathogens to immune cells
Prevents underlying tissue loss from abrasion
Keratin synthesis
Temperature regulation
Sensation

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4
Q

Layers of the epidermis

A

Come, Let’s Get Sunburnt

Stratum Corneum - corny/horny later
Stratum Lucidum - only in palms + sole of feet
Stratum Granulosum - granular layer
Stratum Spinosum -spinous layer
Stratum Basale - basal cell layer

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5
Q

Outline the structure of the stratum corneum

A

Made of squames: dead keratinocytes
Thick on palms + soles of feet - prone to injury
Continuously shed

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6
Q

Outline the structure of the stratum granulosum

A

Very darkly stained
Stratified squamous epithelium
Many Golgi apparatus for vesicles
Lamellar granules + keratohyalin granules
Tonofibrils

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7
Q

What are lamellar granules?
Where are they found?

A

Filament associated proteins that assemble keratin fibrils + release it
Stratum granulosum

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8
Q

What are tonofibrils?
Where are they found?

A

Bundles of keratin filaments + keratohyalin granules
Stratum granulosum

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9
Q

Outline the structure of the stratum spinosum

A

Cuboidal epithelium arranged in 3 layers - held together by desmosomes
Producer of lamellar bodies - lipid production
- keratohyalin factories
Keratohyalin granules

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10
Q

Outline the structure of stratum basalt

A

Columnar epithelium
Keratinocytes are constantly dividing by mitosis
Melanocytes

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11
Q

What are do melanocytes release and what stimulates this?

A

Melanin
MSH - melanocyte stimulating hormone

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12
Q

Outline the structure of the dermis

A

Loose connective tissue - upper papillary layer
Dense irregular connective tissue - lower reticular layer
Collagen
Elastin
Contains blood vessels

0.6mm-10mm thick

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13
Q

Functions of the dermis

A
  • thermoregulation - contains hairs and sweat glands
  • touch - contain sensory structures
  • structure + body shape
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14
Q

What causes skin wrinkling?

A

Thinning of the dermis
Less collagen and elastin

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15
Q

Structure of the hypodermis

A

Mainly adipose tissue
Loose connective tissue - fibroblasts, macrophages

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16
Q

Functions of the hypodermis

A
  • provides energy store - generate heat
  • insulator for underlying muscle heat generation
  • shock absorber
  • makes hormones
  • connects skin to underlying muscles + bones
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17
Q

What is the varying thickness of the hypodermis based on?

A

Location
Person - men vs women

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18
Q

Hypodermis thickness in men

A

Thick in abdomen - white adipose - energy storage
Thick in back of shoulders - brown adipose

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19
Q

Hypodermis thickness in women

A

Thick in hips, thigh and buttock

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20
Q

What part of the body has a thick hypodermis in both sexes?

A

Palms of the hand

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21
Q

Function of the skin

A
  • protection and repair
  • temperature regulation + excretion of waste products
  • lubrication
  • storage
  • vitamin D synthesis
  • absorption
  • aesthetics
  • sensations
22
Q

How does the skin provide protection?

A

Epidermis of keratinocytes - abrasion
UV protection by melanocytes

23
Q

Outline vitamin synthesis in the skin

A

1- cholecalciferol produced in the skin
2- converted into 25-hydroxyl cholecalciferol by liver
3- converted into 1,25-hydroxyl cholecalciferol VitD3 - active vitamin by kidneys

24
Q

What is desquamation?

A

Shedding of the outer layer of the skin

25
Q

Describe the process of keratinocyte differentiation

A
  • upwards maturation of basal keratinocytes into cornified cells with the progressive flattening of cells, loss of nuclei + other organelles
    .
  • stranum basale - keratinocytes are made via cell division - one cell remains + others move up layers. Tonofibrils are synthesised
  • stranum spinosum - where keratohyalin granules + lamellar bodies begin in form - start of cornifying cells + aggregating keratin filaments
  • stratum granulosum - more keratohyalin granules + lamellar bodies produced. Tonofibrils act as water barrier
  • stranum corneum - progressive flattening + lose of organelles to form the corny layer
26
Q

What hormone does the hypodermis produce?
What does it do?

A

Leptin
Involved in regulating food intake

27
Q

Where is soft and hard keratin found?

A

Soft - skin
Hard - horns, hair + nails

28
Q

Location of langerhan’s cells

A

Stratum spinosum

29
Q

What is a merkel cell?
What does it look like in H+E staining?

A

Mechanorecpetor cells associated with sensory nerve endings - surrounded by Schwann cells

Schwann cell contains lipids > don’t stain in H+E > pale circle around purple dot

30
Q

Who are at the greatest risk of skin cancer?

A

People with albinism
Don’t produced melanin

31
Q

What are the four types of skin?

A

Hairy skin + non hairy skin

Thin skin + thick skin

Hairy skin tends to be thin
Non-hairy skin tends to be thick

32
Q

Location of non-hairy/thick skin

A

Palms of hand
Sole of feet
Area between fingers and toes

33
Q

Function of non-hairy/thick skin

A

Prevents tissue loss due to abrasion
Increased friction between skin + surfaces
Increased sensation

34
Q

Structure of non-hairy/thick skin

A

No hair
No arrector pili muscles
No sebaceous glands
Thicker startum corneum
Thinner dermis
Increased density of mechanoreceptors

35
Q

Thick skin vs thin skin in relation to:
- hair follicles
- sebaceous glands
- arrector pili muscles
- ridges + furrows
- dermal papillae
- stranum lucidum

A

Thick:
- no hair follicles
- no sebaceous glands
- no arrector pili muscles
- pronounced ridges + furrows
- regular shaped dermal papillae
- stratum lucidum present

Thin
- presence of hair follicles
- presence sebaceous glands
- presence of arrector pili muscles
- smaller ridges + furrows
- irregular dermal papillae
- stratum lucidum absent

36
Q

What are skin appendages derived from?
Examples

A

Derived from down growths of epidermal epithelium during 3rd month of fetal development

  • hairs
  • arrector pili
  • sebaceous glands
  • sweat glands
  • nails
37
Q

What are the types of hair?
Describe them + location

A

Lanugo - covers developing fetus
Vellum - replaces lanugo
- short, thin, light coloured + soft
Terminal - scalp, eyebrows, nasal passage,
axillae, external genital region
- long, wide, dark coloured, coarse
- produced by the actions of
testosterone

38
Q

Functions of hair

A
  • Thermoregulation
  • Sexual attraction
  • Sensation
  • Protection
39
Q

Explain the hair’s function in thermoregulation

A

Piloerection - when body temp is low
Pilorelaxation - when body temp is normal or raised
Arrector pili muscles contract when stimulated by sympathetic fibres&raquo_space; piloerection

40
Q

Explain the hair’s function in sexual attraction

A

Apocrine sweat glands secrete pheromones that attract the opposite sex
Hair traps the pheromones

41
Q

Explain the hair’s function in sensation

A
  • Hairs have sensory nerve ending within bulb
  • Movements sensed by the bulls an transmitted to CNS
  • Provide sensory awareness
42
Q

Explain the hair’s function in protection

A
  • barrier to UV rays - scalp
  • eyelashes and nasal hair prevent dust and pathogens
  • eyebrows reduce the amount of light and sweat entering the eyes
  • axilla hair conducts sweat away from body
43
Q

Explain the role of arrector pili muscles and how they work

A
  • Consist of smooth muscle fibres attached to papillary region of dermis and hair bulb
  • Can induce sebum release from sebaceous gland
  • piloerection + pilorelaxation
44
Q

What are holocrine glands?

A

Secretions are produced in the cytoplasm
Released by rupture of plasma membrane&raquo_space; destroys the cell
Substance secreted

45
Q

Functions of sebaceous glands

A

Produce sebum

  • lubricate skin/hair
  • reduce water loss
  • aid skin flexibility
  • protect from UV damage
  • reduce friction damage
  • facilitate cooling of skin
46
Q

Where are sebaceous glands found?

A

Mostly in face and scalp

Eyelids, penis, labia, nipples, lip

47
Q

List mechanoreceptors and what they detect

A
  • end bulbs: thermoreceptor - temp.
  • free nerve endings: nociceptors - pain
  • tactile discs: touch, pressure + texture
  • meissner corpuscle: tapping + flicker movements - light + touch
  • pacinian corpuscle - vibrations/pressure
  • ruffini’s corpuscle - joint movements + stretch
  • root hair plexus - vibrations in hair shaft
48
Q

Frequencies used for pacinian corpuscle
Range
Optimum

A

100 to 1000 Hz
Optimum - 450 Hz

49
Q

Frequencies used for meissner’s corpuscle
Range
Optimum

A

10 to 50 Hz
Optimum 35 Hz

50
Q

Structure of nails

A

Only made of alpha keratin

51
Q

Functions of nails

A
  • protection of distal phalanx
  • enhances precise delicate movements - extra grip
  • enhances sensitivity of the fingertip
  • as a tool
52
Q

What are the epithelium of the layers of epidermis?

A
  • stratum corneum: squames (dead keratinocytes with no organelles)
  • stratum granulosum: stratified squamous epithelium
  • stratum spinosum: cuboidal epithelium
  • startum basale: columnar epithelium

Body logistics (20 decks)

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