Biology of skin L2 Flashcards
1
Q
what does skin do (4) (overview)
A
physical barrier
physiological functions
appendages
site of pathology
2
Q
3 layers of skin
A
epidermis
dermis
subcutis
3
Q
what is the epithelial cells of the epidermis called
A
keratinocytes
4
Q
What is the dermis
A
dense irregular connective tissue supported by fibroblasts
5
Q
what does the dermis contain
A
glands
sensory nerves
some immune cells
6
Q
what is the subcutis
A
loose connective tissue with adipose cells
7
Q
2 types of skin
A
thick and thin skin
8
Q
what classifies what is thin and thick skin
A
extent of the thickening of the layer of the epidermis
9
Q
what is thick skin associated with
A
mechanical stress and pressure
10
Q
where is thick skin found
A
soles of the feet and palms
11
Q
what is the bottom layer of the epidermis like
A
protrudes deep (undulating )
12
Q
which type of skin is more common
A
thin skin
13
Q
which skin has a more defined stratum corneum
A
thick skin
14
Q
does thick skin contain hair or sebaceous glands
A
no
15
Q
what extra layer may thick skin have
A
stratum lucidum
16
Q
where is the stratum lucidum
A
between the stratum granulosum and stratum corneum
17
Q
what type of skin lines most of the body
A
thin skin
18
Q
what is less prominent in thin skin
A
stratum corneum
19
Q
where is the thinnest skin
A
eyelids
20
Q
what layer of the epidermis is not in thin skin
A
stratum lucidum
21
Q
layers of the epidermis (4) top to bottom
A
cornified
granular
spinous
basal
22
Q
how many layers of cells in the basal layer
A
1
23
Q
what can the cells in the basal layer of the epidermis be described as
A
stem cells
24
Q
what are stem cells capable of
A
division by mitosis
25
How many cell layers in the stratum spinosum
multiple cells thick
26
in the stratum spinosum what links adjacent cells
desmosomes
27
what are desmosomes
cell-cell junction link them mechanically to adjacent cells
28
what property do differentiated cells in the stratum spinosum lose
they can no longer divide
29
what is formed within the cells of the spinosum
prominent intracellular keratin filaments
30
what is directly above the spinosum
granular layer
31
what happens to cells in the granular layer
further differentiation through the production of keratohyalin granules and lamellar bodies
32
top layer of the epidermis=
cornified layer
33
what happens in the cornified layer
cells undergo apoptosis, losing their nuclei and organelles to form a tough surface layer
34
most abundant cells of the epidermis
keratinocytes
35
4 cells of the epidermis
keratinocytes
Melanocytes
immune cells
Merkel cells
36
what do keratinocytes produce
keratin
37
how do cells in the basal layer attach to the basale lamina
hemi desmosomes
38
what are melanocytes purpose
skin pigmentation and protection of UV damage
39
shape of melanocytes
dendritic
40
where do melanocytes reside
in lower layers of the epidermis
41
mode of action of melanocytes=
they synthesise melanin pigment which is packaged into organelles which are transferred into keratinocytes
42
what are the organelles melanin is packaged into called
melanosomes
43
what do melanocytes arise from in early development
neural crest cells
44
can melanocytes divide
yes
45
immune cells of the epidermis=
langerhans cells
46
what type of immune cell are langerhans
APC (antigen presenting cells)
47
shape of langerhans cells=
dendritic
48
where do langerhans arise from
bone marrow and migrate via blood
49
other type of immune cell present in the epidermis
lymphocytes
50
what are merkel cells
they are in association with nerve fibres responsible for fine touch
51
where are merkel cells found
basal layer
52
what forms the hydrophobic layer of the epidermis (3)
lipids
insoluble proteins
(and strong filaments linked by cell-cell junctions)
53
scaling=
imbalance between cell renewal and cell loss
54
blisters=
breakage of cell-cell junction
55
2 layers of the dermis
papillary
| reticular
56
most superficial layer of dermis=
papillary
57
which layer of the dermis gives skin flexibility
papillary dermis
58
what is the papillary dermis made out of
loose connective tissue made of collagen and elastin fibres
59
what is also contained within the papillary dermis (3)
extensive capillary network
, lymphatic networks
and nerve endings
60
what are the upward projections in the papillary dermis called
pili
61
what is the purpose of pili (2)
1. provide a surface area-->good blood supply to the avascular epidermis
2. Attachment to epidermis
62
what layer makes up the majority of skin overall
reticular dermis
63
what is the reticular dermis made up of
dense irregular connective tissue
64
what is the dense irregular connective tissue made up of
thick bundles of collagen fibres
65
what cells does the reticular dermis contain
fibroblasts
| immune cells
66
what is the reticular dermis a site of
skin appendages (e.g hair follicles and glands)
67
3 cells of the dermis
adipocytes
immune cells
fibroblasts
68
what is below the dermis
subcutis
69
what is the subcutis made out of
adipose tissue
70
what is the purpose of adipose tissue in the subcutis (3)
insulator
protector
energy store
71
3 skin appendages
sebaceous glands
eccrine sweat glands
apocrine glands
72
what is a nail plate
hard kertanised plate at distal end of each digit
73
what is the nail plate analogous with
the cornified layer
74
what is the nail plate renewed by
cells within the nail root which proliferate to form the nail matrix
75
where is a hair follicle formed
basal layer of epidermis
76
what is at the end of every hair follicle
bulbous expansion containing hair papilla
77
3 layers of hair
cuticle
cortex
medulla
78
what do sebaceous glands secrete
sebum that coats hair to keep it soft, supple and waterproof
79
what is the structure of sebaceous glands
branched acinar structure
80
type of secretion of acinar glands=
holocrine secretion
81
eccrine sweat glands
secrete sweat directly onto skin surface
82
type of eccrine secretion
merocrine secretion
83
what type of gland are eccrine glands
coiled tubular
84
where are eccrine glands found
deep reticular dermis
85
where are eccrine glands on the body
all tissues especially palms, soles, forehead and axillae
86
where are apocrine glands (3)
axillae,
mammary
groin
87
how do secretions occur in apocrine glands
apocrine manner with secretions discharged into upper part of a hair follicle
88
where are apocrine glands found in the skin
deep reticular dermis or subcutis
89
what are hairs and nails formed from
hard keratin
90
which layer of the skin does vasodilation or vasoconstriction effect
papillary dermis
91
what is vitamin D synthesis carried out by
keratinocytes in presence of UV light
92
langerhans and lymphocytes are found in the
epidermis
93
macrophages, mast cells and lymphocytes are found in the
dermis
94
4 stages of wound healing
haemostasis
inflammation
fibroplasia
remodelling
95
whats haemostasis
formation of fibrin clot stopping blood loss and filling wound
96
inflammation=
removal of bacteria and damaged tissue
97
fibroplasia=
fibroblasts laying down new collagen and angiogenesis
98
angiogenesis=
bridges gap
99
remodelling=
initial new tissue replaced through turnover to create stronger structure
100
liquid filled lesions= (4)
blister
vesicle
bulla
pustule
101
solid lesions= (4)
papule
nodule
wheal
plaque
102
lesions of colour= (4)
macule
patch
naevis
erythema
