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Body Logistics > Lecture19- Skin > Flashcards

Lecture19- Skin Flashcards

1
Q

What are the three layers of the skin ?

A

1) epidermis ( outer layer )
2) dermis ( middle layer )
3) hypodermis ( bottom layer)

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2
Q

What is the hypodermis also referred to ?

A

Sub-cutaneous layer

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3
Q

What is the structure of the hypodermis - what does it contain ?

A
  • main,y contains adipose tissue
  • contains loose connective tissue ( which contains mast cells , fibroblasts , macrophages )

-

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4
Q

Where in men is the hypodermis the thickest ?

A

The abdomen and shoulders

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5
Q

Where in females is the hypodermis the thickest ?

A
  • nips , thighs, buttocks
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6
Q

Where in male and females is the hypodermis relatively thick ?

A

Palm of the hands

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7
Q

What are the functions of the hypodermis layer ?

A
  • provides energy store
  • shock absorber
  • insulator for underlying muscle heat generation
  • connects skin to underlying muscle and bones
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8
Q

What is thinning of the hypodermis layer responsible for ?

A

Wrinkling and hypothermia in old age ( due to the lack of adipose tissue so less insulation of heat )

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9
Q

What are the three layers of the dermis ?

A

1) papillary layer( upper )
2) recticular layer ( Lower)
3) dermal papillae

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10
Q

What are functions of the dermis layer ?

A
  • contains hairs , sweat glands = responsible for thermoregulation of the skin
  • contains sensory structures - special senses
  • gives structure to the skin
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11
Q

Why do people have different body shapes , but the same muscle size ?

A

Because they have a variation of thickness in the dermis layer

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12
Q

Is epidermis vascular ?

A
  • no , it is avascular
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13
Q

What is the epidermis made up of - which type of cells ?

A

Keratinocytes

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14
Q

How many layers of the epidermis are found in thin skin ?

A

4

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15
Q

How many layers of the epidermis are found in thick skin ?

A

5

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16
Q

How is th epidermis held together - laterally ?

A

Adhererens junctions

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17
Q

What are the functions of the dermis ?

A
  • prevents water loss
  • prevents entry to bacteria and parasites
  • synthesis of keratin
  • prevents underlying tissue loss due to abrasion
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18
Q

What is the top most layer of the epidermis called ?

A

Stratum corneum ( horny layer )

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19
Q

What is the stratum corneum made up of ?

A

Dead keratinocytes

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20
Q

On what parts of the body is the stratum corneum thick?

A
  • soles of the feet sand palm of the hands
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21
Q

Can we rub the stratum corneum ?

A

Yes , it continuously sheds - for example In Hammam.

22
Q

What comes below the stratum corneum in the palms and the soles of the feet ?

A
  • stratum lucidum - which is made up of a very thin layer of keratin.
23
Q

Win thin skin , what layer comes below the stratum corneum ?

A

Granular layer

24
Q

What types of epithelial cells does the stratum corneum have ?

A

Stratified squamous epithelium.

25
Q

What is found in the granular layer ?

A
  • tonofibrils which are bundles of keratin filaments and keratohyalin granules made by lamellar bodies.
  • lamellar granules which make proteins that assemble the keratin fibres and push it into the outer layer.
26
Q

What layer then comes after the granular layer ?

A

Stratum spinosum

27
Q

What types of epithelium is found in stratum spinosum ?

A
  • cuboidal epithelium which is held together by desmosomes.
28
Q

What is the function of the stratum spinosum ?

A
  • they are th reproducers of the lamellar bodies.

- first time Golgi apparatus appears

29
Q

What type of

epithelium is found in the basal cell layer ?

A

Tall columnar epithelial cells

30
Q

What is the function of the basal cell layer ?

A
  • constantly renew keratinocytes by cell division
  • as daughter cells differentiate they move away from the epidermis - dermis junction.
  • these make keratin filaments ( tonofilaments )
  • they lose their ability to divide
  • basal cell layer is also home to melanocytes which produce melanin

-

31
Q

Where is keratin found ?

A

In the hair , nail and animal horns

-

32
Q

At what intervals do melanocytes appear ?

A

1:8 intervals of basal layer of epidermis

33
Q

Where are langerhans cells found ?

A
  • basal and superbasal layer
34
Q

What is the function of langerhans cells ?

A
  • they have a highly specialised capacity to present antigens to T lymphocytes
35
Q

Where are merkel cells found ?

A

In the epidermis

36
Q

What is the function of merkel cells ?

A
  • they are a type of mechanoreceptors associated with a sensory nerve ending.
  • they are essential for light - touch sensation in the skin.
  • they account for approx 6-10% of the cells in the epidermis

6% in light skinned coloured people and 10% in dark skinned individuals

37
Q

What are the two types of skin

A

1) thin ( hairy)

2) thick ( non-hairy)

38
Q

What are exceptions to the ‘ thin ( hairy) , thick ( non-hairy) rule ?

A

1) exSome areas of the external genitalia
2) the lips
3) back of the ear

39
Q

What does the external

Part of the lips skin contain ?

A
  • sweat glands
  • thin skin
  • hair follicles
  • sebaceous glands
40
Q

What does the vermillion zone contain ?

A
  • thin skin

- capillary loops close to the skin , hence why it is pink

41
Q

What does theinternal part of the lips contain ?

A
  • stratified squamlus non-keratinised epithelium
42
Q

What are three examples of non-hairy thick skin?

A
  • areas between the fingers and toes
  • palmar surface of the hand
  • plantar surface of the foot
43
Q

What are features of thick ( non hairy ) skin ?

A
  • n1) no sebaceous glands
    2) no hair follicles
    3) no erector pills muscles
    4) stratum lucidium can be seen
    5) regular shaped dermal papillae
    6) pronounced ridges and furrows on the surface
44
Q

What are features of the thin ( hairy) skin?

A

1) presence of the hair follicles
2) presence of sebaceous glands
3) presence of erector pili muscles
4) smaller ridges and furrows
5) irregular dermal papillae
6) stratum lucidium absent

45
Q

What is the structure of the palm of the hands , places in between our fingers and toes and base of our feet ?

A
  • no hair follicles
  • no erector pili muscles
  • no sebaceous glands
  • thicker stratum corneum
  • thinner dermis
  • increased density of mechanoreceptors
46
Q

What are the three types of hairs ?

A

1) lanugo- covers the developing fetus at birth
2) vellus - replaces lanugo , short , thin , light coloured and soft.
3) terminal hairs - thick , long , wide , dark coloured , produced by actions of testosterone. Found in the external genital region , axillae region , nasal passage , scalp , eyebrows

47
Q

What are 3 functions of hairs ?

A

1) thermoregulatiom :hairs lay flat when we are too hot. Hairs stands when erector pili muscles contract when temperature is lower than normal. Also acts a partial barrier to UV rays , eg in the scalp.
2) protection: eg eyebrows reduce amount of light and sweat from reaching the eyes. Eyelashes and nasal hair prevent dust and pathogens from entering the body
3) sensation : hairs have sensory nerve endings in the bulb - any air movement , physical interaction , vibrations are transmitted to the bulbs and transmitted to the CNS.

48
Q

What receptors are responsible for sensation in the skin?

A

Mechanoreceptors

49
Q

Give a few examples of mechanoreceptors

A

Pack Ian corpuscle recognises vibrations

2)

50
Q

Structure of nails

A
  • consists of mainly alpha keratin

- has a nail plate , nail matrix , and the nail bed below it

51
Q

What are functions skin a.

A

1) lubrication : sebaceous glands release oil onto the surface
2) absorption : absorbs small amounts of water and O2
3) sensation : contains mechanoreceptors which detect pain , pressure , touch , arousal
4) vitamin D synthesis
5) storage of white adipose tissue in the hypodermis which provides lipids for energy
6) temperature regulation by sweat glands in the dermis , erector pili muscles
7) protection and repair : Uv protection by melanocytes , physical barrier to prevent pathogen entry , langerhan cells which are highly specialised to presemt antigens to T cells. Hypodermis contains loose connective tissue which contains mast cells , macrophages.

Body Logistics (20 decks)

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