Skin structure and function Flashcards
what is the outermost layer of the skin called?
epidermis
what is the layer beneath the epidermis called?
dermis
what is the epidermis made up of?
stratified cellular epithelium (squamous?)
what is the dermis made up of?
connective tissue
which germ layers form the dermis?
mesoderm
what are melanocytes?
pigment producing cells
where are melanocytes derived from in the embryo?
neural crest
where did the epidermis derive from in the embryo?
derives from ectoderm cells from a single layer periderm, there is then a gradual increase in cells until the periderm cells cast off and only epidermis is left
what is present in the first 4 weeks of fetal development?
Pretty basic derm (PBD)
Periderm
Basal layer
Dermis (corium)
what is present at 16 weeks of fetal development?
Keratin Layer
Granular Layer
Prickle cell Layer
Basal Layer
Dermis
what is present at 26 weeks of fetal development?
Epidermis
Melanocyte
Sebaceous gland
Arector pili muscle
Hair follice
What is Blaschko’s lines?
the developmental growth pattern of skin
what does skin consist of ?
Epidermis
Appendages (nail, hair, glands, mucosae)
Dermo-epidermal junction
Dermis
Sub- cutis
what is sub cutis predominantly made of?
fat
what are the epidermal cell layers from the outermost layer to the innermost layer?
keratin layer
granular layer
prickle cell layer
basal layer
what are some examples of a loss of control in regulation of epidermal turnover?
psoriasis
skin cancer
what are some things that can regulate epidermal turnover?
growth factors
cell death
hormones
what happens to keratinocytes as the epidermis is regenerated?
keratinocytes migrate and differentiate into flattened, dead squames from the basement membrane to the surface
what cells is the basal layer made up of?
small cuboidal
how thick is the basal layer?
one cell thick
what are the types of epidermal cells?
keratinocytes
melanocytes
langerhans cells
merkel cells
what cell produces pigment?
melanocytes
what organelles fo melanocytes contain?
melanosomes
what is an example of an autoimmune disease where there is a loss of melanocytes?
vitiligo
what is a tumour of the melanocyte cell line?
malignant melanoma
why do Blashko’s lines exist?
they exist due to the germ layer cells migrating during gastrulation
what are appendages?
structures in the skin that are not the different layers (keratin layer, granular layer, prickle layer, basal layer and dermis)
what is located between the prickle cells?
desmosomes
role of desmosomes?
let the cells hang on and come apart, allow cell to cell contact
what are the granule cells full of?
filaggrin
what happens if you lack filaggrin?
the skin dries out, can cause eczema
what stops water from entering your body?
the tight, thin, waterproof keratin layer
what disease affects the keratinocytes?
Human papilloma virus affects keratinocytes causing warts
why is healthy mucosal membrane in the mouth red?
because the layers are so thin you can see the vascular plexus
what colour is unhealthy mucosal membrane in mouth and why?
white because the layers have thickened so you can no longer see the vascular plexus
where are merkel cells found?
between keratinocytes and nerve fibres in the epidermis
3 parts of hair cycle?
anagen, catagen and telogen
what is the anagen phase?
growing
what is the catagen phase?
involuting
what is the telogen phase?
resting phase of hair
what is structure behind the blue box called?
subaceous gland
what is the structure behind the blue box?
hair shaft
what is the structure behind the blue box?
external root sheath
whats the structure behind the blue box?
internal root sheath
whats the structure behind the blue box?
matrix
what’s the strucutre behind the blue box?
arrector pili muscle
whats the structure behind the blue box?
medulla
whats the structure behind the blue box?
cortex
what structure is behind the blue box?
papilla of hair follicle
what is the dermo-epidermal junction?
an interface between the epidermis and dermis
what is the role of the dermo epidermal junction?
It has a key role in epithelial- mesenchymal interactions
- support, anchorage, adhesion, growth and differentiation of basal cells
- is. semi permeable membrane so actd as barrier and filter
what is the layer of the skin highlighted in red called?
epidermis
what is the layer highlighted in red called?
dermo- epidermal junction
what is the layer of skin highlighted in red called?
dermis
what is the layer of skin highlighted in red called?
subcutaneous fat
what is the dermo epidermal junction made up of?
lamina lucida, lamina densa and sub lamina densa zone
whats are examples of diseases that can occur f there’s a problem with the dermo epidermal junction?
- bullous pemphigoid
- epidermolysis bullosa
what cells does the dermis contain?
- fibroblasts
- macrophages
- mast cells
- lymphocytes
- langerhans cells
how is the dermis different depending on ethnic background?
thickness is propotional to degree of pigmentation so it is thicker in asian, hispanic/ latino and african/ american skintypes compared to caucasion.
African/ American skin has larger and more fibroblasts and macrophages
where is the basal layer found?
at the bottom of the epidermis
what occurs to skin when there’s sun damage?
dermis thickens and skin loses its elasticity
what is the order of blood flow to the skin?
arteries-> arteriole -> precapillary sphincters -> venous capillaries -> post capillary venues -> collecting venues -> back to heart
what occurs if theres a benign dilatation of the blood vessels in the dermal tissue?
angioma
what is the role of lymphatic vessels in the skin?
- immune surveillance by circulating lymphocytes and Langerhans cells
- continual drainage of plasma proteins, extravasated cells and excess interstitial fluid
- the channelling of microorganisms/ toxins
what can occur if theres recurring bacteria getting into the epidermis?
chronic lymphoedema
what nerves detect pressure?
Pacinian
what nerves ditect vibrations?
Meissner’s corpuscles
what is the pilosebaceous unit made out of?
hair follicle, hair shaft, arrector pili muscle and sebaceous gland
what are the 3 segments that the hair follicle is made up of?
the infundibulum, the isthmus and the hair bulb
how many hairs is it normal to lose a day?
up to 100
what are the 3 types of glands that can be found in the dermis?
sebaceous
apocrine
eccrine
what does the sebaceous gland secrete?
sebum
what does the eccrine gland secrete?
watery sweat
where abouts are sebaceous glands found?
all over body however are extra big on face, chest and back
in what way can skin act as a barrier?
- physically (friction/trauma + UV radiation)
- Chemically (irritants, allergens + toxins)
- Pathogens (bacteria, viruses, fungi)
what does skin metabolise?
vitamin D and thyroid hormone
what is the role of sebaceous glands?
- control moisture loss
- protection from fungal infection
what gland is responsible for odour?
apocrine
