skin structure Flashcards
epidermis
outer layer
stratified squamous epithelium
layers of skin at 16 weeks
keratin layer granular layer prickle cell layer basal layer dermis
what is the developmental growth pattern of skin
blaschko’s lines
what does skin consist of (layers)
epidermis
dermis
dermis is thicker
whats different about skin in the armpit
additional glands
differentiation
keratinocytes migrate from basement membrane
continuous regeneration
prickle cell layer
larger polyhedral cells
desmosomes
cell contact
allow cells to move about
if you dont have the filaggrin protein what happens
skin gets very dry
-excema
what cells in keratin layer
corneocytes
lamellar granules release lipid
what are the mucosal membranes
oral mucosa
ocular mucosa
name some epidermal cells
melanocytes
langerhans cells
merkel cells
what are melanocytes
pigment producing dendritic cells
whats loss of pigment called
vitiligo
merkel cells
basal
between keratinocytes and nerve fibres
mechanoreceptors
whats merkel cell cancer caused by
viral infection
phases of hair follicle growth
anagen - growing
catagen - involuting
telogen - resting
dermo-epidermal junction
interface between epidermis and dermis
key role in epithelial-mesenchymal interactions
role of dermo-epidermal junction
support, anchorage, adhesion, growth and differentiation of basal cells
semi-permeable membrane acting as barrier and filter
what can happen when this junction goes wrong
bullous pemphigoid
what is dermis derived form
mesoderm
what cells are in the dermis
mainly fibroblasts, macrophages, mast cells, lymphocytes, langerhans cells
what fibres are in dermis
collagen and elastin
what is the function of blood vessels in the dermis
supply greater then metabolic needs
vessel walls well supported
flow of the blood vessels in dermis
arteriole - precapillary sphincters - arterial - venous capillaries - post-capillary venules - collecting venules
immune functions of lymphatic vessels in dermis
immune surveillance by circulating lymphocytes and langerhans cells
channelling of micro-organisms/toxins
what nerves are in the dermis
somatic sensory -free nerve endings -special receptors (pacinian and meissners) automatic nerve supply -blood vessels, nerves and glands
pacinian
pressure nerve receptors
meissners
vibration nerve receptors
what is the pilosebaceous unit composed of
hair follicle
hair shaft
arrector pili muscle
sebaceous glands
three segments of hair follicle
infundibulum
isthmus
hair bulb
what are the three types of skin gland
sebaceous
apocrine
eccrine
sebaceous glands
holocrine secretion opening into pilary canal
face chest back
when you hit puberty
produce sebum
control moisture loss and protection from fungal infection
apocrine sweat glands
develop as part of pilosbaceous unit
axillae, groin, eyelids, ears, mammary and perineal regions
eccrine sweat glands
whole skin surface
sympathetic cholinergic nerve supply
what absorbs UV rays to protect DNA?
melanin
what are the main functions of the skin
barrier metabolism and detoxification thermoregulation immune defence communication sensory functions
where do splits cause blistering
dermo-epidermal junction
what different tissue groups are found in the skin?
epithelium nervous tissue connective tissue glands muscle hair adipose tissue
Found over the whole body except the lips & genitals.
Coiled tubular structures which regulate heat and salt loss. What are these glands?
eccrine glands
Limited to axillae/nipple/genitals.
Develop at puberty and open into hair follicles. What are these glands?
apocrine glands
structure of a nail
nail plate
matrix
cuticle
hyponychium
stage 1 of wound healing
inflammation Platelets form the initial clot and release inflammatory mediators.
Leucocytes debride the wound bed by phagocytosing bacteria and scavenging cellular debris.
Inflammation gradually decreases as keratinocyte proliferation and new tissue formation becomes predominant.
stage 2 of wound healing
cells divide to re-epithelialise the wound surface. granulation tissue formation is stimulated
fibroblasts lay down matrix, and contract the wound
endothelial cells develop into new blood vessels
stage 3 of wound healing
tissue remodelling
-new tissue is converted into mature scar tissue over a period of months.
fibroblasts lay down collagen to improve the tensile strength of the scar and restore the normal dermal matrix
what is a surface slough
a mixture of dead cells, polymorphs and bacteria
what is stage 1 of pressure sore development
Skin is unbroken but shows a pink or reddened area .May look like a mild sunburn. Skin may be tender, itchy or painful
what is stage 2 of pressure sore development
Skin is red, swollen and painful. Blisters that may be broken or intact may be present. Upper layers of skin begin to die
stage 3 of pressure sore development
Sore has broken through the skin and wound extends down to deeper layers of skin tissue.
Crater-like ulcers are present.
Wound is prone to infection
stage 4 of pressure sore development
Sore extends past the skin and into fat, muscle and bone tissue .
Blackened dead tissue called eschar may be seen in deep opened wounds
