WEEK 1 - SKIN Flashcards

1
Q

what are the 8 functions of skin?

A
  1. protect - underlying tissue fr impact/ebrasion/loss
  2. excrete - salt water waste
  3. maintain body temp - insultation or evapourative
  4. produce melanin - UV protection
  5. produce keratin - abrasion protection/ water repel
  6. synthesise vitamin D
  7. stores lipids
  8. detects pain/pressure/touch/temp
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2
Q

how many tissue types can be found in skin?

A

all - connective, epthielial, muscle, and nervous, BUT mostly epithelial

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3
Q

what are the three layers of the skin in order?

A

epidermis, dermis, hypodermis

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4
Q

what are the feautres of the epidermis?

A
  • stratified barrier
  • mostly keratinocytes
  • no circulation (avascular)
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5
Q

what are the features of the dermis?

A
  • protein fibres for strength
  • vascular (nourished epidermis)
  • doesnt shed
  • has two layers
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6
Q

what are the features of the hypodermis?

A
  • adipose tissue (insulation)

- ‘subcutaneous’ (under the skin)

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7
Q

what are the two layers of the dermis?

A

papillary and reticular (proteins/elastin)

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8
Q

what are the 4/5 layers of the epidermis?

A
stratum cornea (horny layer) 
[stratum lucidum - only in thick skin]
stratum granulosum 
stratum spinosum
stratum basale
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9
Q

what are the features of the stratum cornea?

A

it can be renewed

it is made of dead/dried cells with no nuclei

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10
Q

what are the features of the stratum granulosum?

A

promotes dehydration, waxy material

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11
Q

what are the features of the stratum spinosum?

A

spiny bridge-like desmosomes - intercellular bridges.

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12
Q

what are the features of the stratum basale?

A

tall column structures, regenrative cells.

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13
Q

what does ‘keratinocyte conveyor’ mean?

A

infections and other unwanted material will be moved out pf the skin as cells are constantly being made and moved to the epidermis to be removed.

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14
Q

what are the 6 types of epithelial cell?

A

simple OR stratified

squamous/cuboidal/columnar

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15
Q

what tupe of epithelial cell is the epidermis?

A

stratified squamous epithelium

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16
Q

what are the characteristics of thick skin?

A

it has a large stratum corneum
no hair
special layer - stratum lucidum

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17
Q

what are the charactistics of aging skin?

A
  • thin epidermis
  • thin dermis (reduced collagen, wrinkling/sagging)
  • slow repair
  • dry epidermis (less sebum)
  • less sweat, impaired cooling
  • less pigmentation
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18
Q

why is smoking thought to age skin quicker?

A

vasoconstriction - less blood to skin for repair/growth.

reactive oxygen damages collagen and elastin.

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19
Q

what are the skins acessory structures?

A
hair
acne
sweat glands
receptors
nails
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20
Q

what are the characterisitcs of hair?

what are the 4 things that hair consists of?

A
  • loated all over body

- consists of hair shaft, hair follicle, erector pili muscle, sebaceous gland (produces sebum)

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21
Q

what is acne?

A

blockage of hair follicles and infection.

- increased sebum increases acne risk

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22
Q

what are the two types of sweat gland?

A
  • accrine (salty): everywhere, thermoregulation

- apocrine (oily): specialised, deep in skin next to follicle.

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23
Q

what are the three types of receptors?

A

tactile, lamellar, bulbous

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24
Q

what ius the function of the nails?

A

protect fingertips, enhance sensation

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25
Q

why is skin pigmented and what are the things involved?

A

melanin pigment absorbs UV light and so protected the skin.

Melanin is produced in melanocytes and tranfered to epidermal cells by melansomes (vesicles containing melanin)

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26
Q

what is a melansome?

A

a vesicle containing melanin that tranfers it from melanocytes to epidermal cells.

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27
Q

where is melanin produced?

A

melanocytes

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28
Q

what is a mole?

A

a cluster of melanocytes. overproliferation from sun exposure.

29
Q

what is a freckle?

A

melanocytes overproducing melanosomes. overproduction triggered by sun exposure

30
Q

where are melanocytes found?

A

In the stratum basale (epidermis) so they are not shed.

31
Q

what varies between races to cause difference in pigmentation?

A

production of melansomes, not the density.

32
Q

what does vitamin D do?

A

calcium metabolism and mood

33
Q

what causes the syntehsis of vitamin d and who is more susceptable to deficiencies?

A

sun exposure is needed. highly pigmented people are more susceptable to vit d deficiencies if they arent in the sun enough.

34
Q

what is caused by vit d deficiency?

A

ricketts - weak bones due to lack of calc metabolism.

35
Q

what happens when pale people live in high sun exposure areas?

A

skin cancer

36
Q

what happens when dark people live in areas with little sun exposure?

A

ricketts

37
Q

what are the 2 types of skin cancer?

A

basal cell carcinoma and malignant melanoma.

38
Q

explain basal cell carcinoma:

A
  • common but relatively benign
  • originates in stratum basale
  • very rarely metastic
39
Q

explain malignant melanoma:

A
  • rare but deadly if not treated
  • orgiignates in melanocytes
  • highly metastic (spreads fast and far)
  • the bigger the tumour, the higher the chance of dying
  • the deeper it is the more dangerous
40
Q

why are malignant melanoma so dangerous?

A

the deeper they get, they may reach the dermis which has circulation allowing it to spread into the blood and arround the body.

41
Q

explain what tattoos are:

A

ink that is captured around the immune cells and scar tissue in the dermis. Pigment sometimes is deposited in the lymph nodes.

42
Q

what type of junction connects the epidermis and the dermis?

A

hermidesmosomes

43
Q

what are the type of junction that connects adjacent cells?

A

desmosomes

44
Q

what are the features of free nerve endings?

A
  • most common receptor
  • unmyelinated
  • has sensory terminals at distal ends that act as cation channels
  • wrap around hair follicles to feel movement
45
Q

what are the five types of receptors in the skin?

A
  • free nerve endings
  • tactile discs
  • tactile corpuscles
  • lamellae corpuscles
  • bulbous corpuscles
46
Q

what do free nerve endings feel?

A

temp, pain, movement, pressure, itch,

47
Q

what are the features of tactile discs?

A
  • a type of free nerve ending located in the deepest layer of the epidermis
  • communicates with tactile epithelial cells and nerve endings possibly through seratonin
  • lots in finger tips
  • have a small receptor feild so good at feeling texture, edges, fine touch, light pressure
48
Q

what are the features of the tactile corpuscles?

A
  • in the papillary layer of the dermis
  • mostly hairless skin
  • encapsuled in connective tissue capsule
  • deformation of capsule triggers entry of Na+ ions intro terminal triggering APs
49
Q

what do tactile corpuscles sense?

A

fine touch, light pressure, low frequency vibrations

50
Q

what are the features of the lamellae corpuscles?

A
  • deep in the hypodermis and dermis
  • single dendrite within collagen fibre layers
  • layers seperated by gelatanous fluid
  • pressure senisitve Na+ channels in axon
51
Q

what do lammelae corpuscles sense?

A

deep pressure and vibration

52
Q

what are the features of bulbous corpuscles?

A
  • dermis in subcutaneous tissue

- network of nerve endings entertwined with fibres.

53
Q

what do bulbous corpuscles feel?

A

sustained deep pressure, stretching or distortion of skin, in joints to tell degree of rotation, grip in fingers.

54
Q

what is the optimal body temp range?

A

36.5 - 37.5

55
Q

what are the four primary mechanisms of heat?

A

radiation, evapouration, convection, conduction

56
Q

what do the eccrine sweat glands do?

A
  • loose heat through evapouration
  • glands are deep in the dermis
  • controlled by sympathetic nerve system releasing acetylcoline
  • can also be stimulated by adrenaline
57
Q

when the body temp increases what can happen?

A
  • vasodilation: loosing heat through convection/conduction/evapourationn surface of skin
  • sweat
  • respiratory rate increases (evapouration through mouth)
  • behavioural changes
58
Q

when in hot temperatures, which heat mechanisms stop working?

A

radiation, convection, conduction. because the external environement is hotter than the body.

59
Q

what happens when the body temp falls?

A

heat gain centre is activated:

  • shivering thermogenesis
  • nonshivering thermogenesis
  • vasomotor centre decrease heat to the dermis cing radiation/convection loss.
  • increased basal metabolic rate due to high levels of thyroxine.
60
Q

what is shivering?

A

contractions of agonist and antagonist muscles by muscle spindles (stretch receptors)

61
Q

what is non-shivering thermogenesis?

A

increased nerve activity and more adrenaline, more metabolism. this works to generate heat. heat is also produced instead of ATP.

62
Q

what things can be a result of burns?

A

dehydration, infection, shock, hypothermia

63
Q

what are 1st degree burns?

A

outer layer of epidermis, 3-10 day recovery

64
Q

what are 2nd degree burns?

A

epidermis and dermis, 1-2 weeks recovery, scarring

65
Q

what are 3rd degree burns?

A

subcutaneous tissue, muscle, and bone.
nerve endings are killed so no pain
weeks and months to recover, extensive scarring, skin grafts may be needed.

66
Q

what a person is burned they loose a lot of:

so you need to:

A

fluid. calculate the surface % that the burn is taking up and then find the amount of fluid they need daily to rehydrate.

67
Q

what is the sensor and control centre of core body temp?

A

hypothalamus

68
Q

what does exocrine mean?

A

secretes into epithelium rather than directly into blood