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Flashcards in Physiology Deck (113):
1

Embryologically the epidermis comes from the ____derm

Ectoderm

2

Embryologically the dermis comes from the ____derm

Mesoderm

3

Embryologically melanocytes comes from ______

Neural crest cells

4

The skin is fully developed at wk __ gestation

Week 26

5

At 4wks gestation the components of the skin are :

Periderm, basal layer, dermis (corium)

6

At 16wks gestation the ____ migrate from ____ and the layers of the skin =

Melanocytes migrate from the neural crest
Keratin, granular, prickle cell, basal and dermis

7

The epidermis is ________ epithelium.

Stratified squamous

8

____ make up 95% of the epidermis

Keratinocytes

9

The prickles in the prickle cell layer are _____

Lots of desmosomes

10

The basal cell layer is ____ for rigidity

Undulating

11

Takes keratinocytes ____ to get from basement membrane until they are shed from the keratin layer

28 days normally

12

Basal cell layer : usually ____ thick
Shape of cells = ________
Contains lots of _______

1 cell thick
Small cuboidal cells
Lots of Intermediate filaments (keratin)

13

Prickle cell layer: shape of cells =
Lots of _____ connecting to _____

Larger polyhedral cells
Lots of desmosomes connecting to intermediate filaments

14

Granular layer: ____ layers of cells = thin/thick layer
Shape of cells =
Contain ___ granules which contain ___ + _____
____ secreted from keratinocytes release _____ => high ____ content
Origin of ____ and _____ are lost here

2-3 layers - thin layer
Flattened cells
Keratinohyalin granules contains structural filaggrin and involucrin proteins
Lamellar/Odland bodies release lipids => high lipid content
Cornified envelope origin, cell nuclei lost

15

Keratin layer- composed of ____ that overlap and have no ____
Other name =
80% ____+____
___ from ____ glues keratin together

Corneocytes with no nuclei
Cornified envelope
80% keratin and filaggrin
Lamellar bodies produce FAs

16

The cells that make up the epidermis =

Keratinocytes (95%) melanocytes ( basal and suprabasal) langerhans (suprabasal) merkel cells (basal)

17

Melanocytes are present in _____ layers

Basal layer and above

18

Melanocytes are ____ cells that produce _____

Dendritic cells
UV protection pigment

19

Melanocytes - organelle that is transferred via dendrites to adjacent keratinocytes, synthesise store and transport _____

Melanosomes
Melanin

20

Melanocytes convert ____ to _____

Tyrosine to melanin

21

Melanin comes in two forms ____ and ____ (give the colour of pigmentation they each give to skin)

Eu (brown/black)
Phaeo ( yellow/red)

22

Melanin forms a cap over the nucleus to protect ___ in the ____ cells and stopping it ___

Protects DNA in basal cells and stops it crosslinking

23

Langerhans originate from ____

Mesenchyme - from bone marrow

24

Langerhans cells are found in the ___ layer, ___ and ____

Prickle cell layer, dermis and lymph nodes

25

Function of Langerhans cells in the skin

APCs - take antigens from skin to lymph nodes- dendritic cells

26

Only cells to contain birbeck granules (racquet shaped)

Langerhans cells

27

Lamellar bodies are ___ shaped

Racquet

28

Merkel cells are found in ____ layer between ___ and _____
Function =

Basal cell layer between keratinocytes and nerve fibres
Mechanoreceptors

29

Pigmentation in pilosebaceous is due to ____ above the ____

Melanocytes above dermal papilla

30

90% of hairs are in this phase of growth
It takes ____

Anagen - growing phase
3-7 years

31

10% of hairs are in this phase of growth
Takes _____

Catagen - involuting
3-4 wks

32

<1% of hairs are in this phase of growth
Occurs in____ hairs per day

Telogen
Resting/ shedding - 50-100 hairs a day

33

Hair and nails are both composed of ____

Specialised keratin

34

Underneath nail plate lies ___ proximally and _____ distally

Nail matrix proximally ( similar to hair bulb)
Nail bed (CT)

35

Functions of DEJ

Epithelial-mesenchymal interactions - support, anchorage, adhesion, growth and differentiation of epidermal cells
Semi permeable membrane

36

Contents of the dermis

Collagen, elastin, ground substance, blood vessels, lymphatics, nerves, cells

37

Cells found in the dermis

Mostly fibroblasts (=>collagen) macrophages, mast cells, lymphocytes, Langerhans

38

Ground substance in dermis is composed of

Mucopolysaccharides and glycosaminoglycans

39

Blood vessels in dermis - supply is > than metabolic needs
Organised in ______ that ____and don't/do enter the epidermis

Supply > metabolic needs
Horizontal plexuses branch up and stop at DEJ along with lymphatics

40

Pressure sensors deep in dermis

Pacinian corpuscles

41

Very sensitive vibration sensors in superficial dermis

Meissners corpuscles

42

3 types of skin glands

Sebaceous
Apocrine sweat
Eccrine sweat

43

Skin glands that are hormone sensitive and cause acne if blocked

Sebaceous

44

Sebaceous glands are _____ distributed. Largest are found on __,___+___

Widely distributed
Face back chest

45

Function of sebaceous glands

Control moisture loss
Bacterial and fungal infection protection

46

Skin glands that produce sebum and mainly open up onto hair follicles

Sebaceous

47

Components of sebum

Squalene, wax esters, triglycerides, FFAs

48

Skin glands that are part of the pilosebaceous unit and found in axils and perineum

Apocrine sweat glands

49

Androgen dependent glands that secrete oily fluid (odorous after bacterial decomposition)

Apocrine sweat gland

50

Locations of eccrine sweat glands

Whole skin surface - especially palms, soles and axillae

51

Eccrine sweat glands have a ___ nerve supply
Stimulated by __,___+___

Sympathetic cholinergic
Mental, thermal and gustatory stimulation

52

sebaceous glands are ___ distributed and are largest on the __+__+__

widely distributed
face, back and chest

53

skin glands that produce sebum
they mainly open onto _____

sebaceous
hair follicle

54

functions of sebaceous glands

control moisture loss
bac and fungal infection protection

55

skin gland that is part of pilosebaceous unit and found in axillae and perineum

apocrine sweat glands

56

sebum components =

squalene, wax esters, triglycerides, FFAs

57

apocrine sweat glands are ____ dependent
they produce ___ that becomes odourous after ___

androgen dependent
oily fluid
bacterial decomposition

58

skin glands that cover the whole skin surface especially palms, soles and axillae

eccrine sweat glands

59

eccrine sweat glands have a ____ nerve supply - stimulated by ___+___+___

sympathetic cholinergic
mental, thermal ad gustatory stimulation

60

functions of eccrine sweat glands = (3)

ultrafiltration (NaCl-HCO3 into hypotonic fluid)
cooling by evaporation
palms and sole grip

61

2 metabolic functions of the skin

converts cholecalciferol to vit D3 (290-320nm UV)
T4 to T3 conversion

62

Immunological functions of keratinocytes in keratin layer (3) =

sense pathogens and mediate response eg. UV/allergens
produce AMPs and directly kill
produce cytokines and chemokines to recruit and reg immune cells

63

epidermis contains mainly ___ T cells
dermis contains ____ T cells
___ also present

epidermis = CD8+
dermis = CD4+ and 8+
NK also present

64

Th1 cells activate ___ and produce __+__

macrophages
IL2 and IFNgamma

65

Th2 cells produce _+_+_ and help ___ make ___

IL4+5+6
B cells make Ig

66

CD4+ cells ass with inflammation ___ (psoriasis) ___ (atopic dermatitis) ___ (both)

Th1
Th2
Th17

67

immunological cells in the epidermis

keratinocytes, langerhans, T cells

68

immunological cells in the dermis

dendritic cells, mast cells, macrophages, neutrophils

69

MHC I is present in ___ cells and present __to ___

most cells
endogenous antigens to CD8+

70

MHC II is present in ___ cells and present ___ to ___

APCs
exogenous antigens to CD4+

71

Scale that gives categories of skin tones and tanning patterns
Type __ to __

Fitzpatrick scale
I to VI

72

part of dermis that is thin and just below epidermis

papillary dermis

73

part of dermis that has thicker bundles of type I collagen with sweat glands and pilosebaceous units

reticular dermis

74

ECM of dermis is composed of

hyaluronic acid and chondroitin sulfate

75

components of the dermis

type 1+2 collagen matrix
elastic fibres
ECM

76

persistance of nuclei in keratin layer =

parakeratosis

77

parakeratosis is present in psoriasis where there is ___

high cell turnover

78

acanthosis =

increased thickness of epidermis

79

papillomatosis =

irregular epidermal thickening

80

spongiosis =

oedema fluid between squames appears to increase prominence of intercellular prickles

81

chemicals in skin that mediate itch

histamine
PGE2
ACh
serotonin
IL2
kallikrein
substance P

82

nerve transmission of itch in skin is by

unmyelinated C fibres

83

mediators in the CNS for itch

opiates (endo+exogenous)

84

orange naevi that if irritated causes a wheal =

mast cell naevi

85

something usually inflam/dryness in skin triggers itch = ___ cause of itch
eg.s (4)

pruritoceptive
asteatotic eczema
insect bites
lichen planus (sometimes ass with hep C)
psoriasis

86

basis of cause of itch in asteatotic eczema

direct exposure of unmyelinated C fibres in bases of microfissures and inflammatory mediators in skin released

87

type of eczema that is very xerototic => crazy paving/chicken wiring

eczema craquele

88

4 types of causes of itch

pruritoceptive
neuropathic
neurogenic
pyschogenic

89

basis of itch in neuropathic itch

damage of any sort to central/peripheral nerves that causes itch

90

basis of itch in neurogenic itch

no evident damage in CNS but caused by something affecting the CNS receptors

91

examples of causes of neurogenic itch

haematological, paraneoplastic, opiates, kidneys (endogenous opiates), hyperthyroid, PBC

92

non specific anti pruritics =

sedative antihistamines
emollients
antidepressants (doxepin)
phototherapy
opiate antagonists
ondansetron
anti-epileptics for some neuropathic ones

93

cells in the skin that metabolise vitamin D

keratinocytes

94

growth development of skin follows

Blaschko's lines

95

maceration =

softening and break down of skin due to prolonged moisture exposure

96

erythropoeitic protoporphyria = lack of __ leading to __ build up
presents at__ (age) with __

ferrochelatase
protoporphyrin IX
early childhood
discomfort, itch/tingling in sun

97

most common sweat gland on the face =

eccrine

98

acute intermittent porphyria is due to the reduced function of ___ leads to ___ in many tissues

porphobilinogen deaminase
acute neurotoxic reaction

99

Odland bodies are found in which epidermal layer

granular

100

it takes ___ days for cells to migrate from basal to keratin layer

28 days

101

Pressure sensation corpuscles

Pacinian

102

Vibration sensation corpuscles

Meissner's

103

tuberous sclerosis mode of inheritance =

auto dom

104

type 1-4 HPV =

warts

105

type 16 + 18 HPV =

cervical cancer

106

type 6 and 11 HPV =

genital warts

107

__ more likely than ointments to cause contact sensitisation

cream

108

___g of ointment for overall coverage

roughly 30g

109

medial/lateral malleolus ulcers are likely to be __ in origin

venous

110

cancer that can develop on skin ulcers

squamous cell ca

111

Breslow thickness =

depth from granular layer to deepest melanoma cell

112

SCALP layers =

Skin
CT
Aponeurosis
Loose CT
Periosteum

113

sebaceous cyst has an obvious ___ on examination

punctum