Structure and function Flashcards
What is the epidermis made up of?
Stratified cellular epithelium
What is the dermis made up of
connective tissue
Where does Epidermis arrive from in embryology
Ectoderm- single layer
IS the dermis formed from mesoderm or endoderm?
Mesoderm
Where do melanocytes come from and what are they?
Pigment producing cells from the neural crest and they are pigment producing dendritic cells
What are the 5 layers that make up the skin starting from outside
Keratin, granular, prickle cell, basal cell, dermis
Where do melanocytes chill
on the dermo-epidermal junction
What are blaschkos lines?
Growth patterns of skin not following nerves, vessels, lymphatics
What type of cells mostly make up the epidermis
Keratinocytes
Name other cells present in the epidermis
melanocytes, langerhans cells, merkel cells
What controls the epidermal turnover of cells? And name 2 diseases due to the loss of control
Growth factors, cell death, hormones.
Skin cancer and Psoriasis
What type of cell makes up the basal layer
Small cuboidal, one cell thick. Lots of keratin and highly metabolically active
Prickle cell layer is mad of which type of cells
Larger polyhedral cells, desmosomes ad keratin filaments
What type of cells is the Granular layer mad up of?
Flatter cells, filaggrin, cell nuclei is lost
What is the keratin layer made up of
Cornerocytes, keratin, filaggrin, lamellar granules release lipids
What is the keratin layers role?
Tight waterproof barrier
What do melanocytes do
Convert tyrosine to melanin pigment and form a protective cap over the nucleus
What is vitiligo
An autoimmune disease with a loss of melanocytes leading to depigmentation
What happens in Nelsons syndrome?
Melanin producing hormone is produced in excess by pituitary
What do langerhans cells do and where are they?
Langherhans are found in the Prickle cell layer in epidermis, dermis, lymph nodes and involved in skin immune system. Antigen presenting cells.
Birbeck granules are shaped like what?
A racket
Where are merkel cells found?
Basal layer between keratinocytes and nerve fibres and mechanoreceptors
What are the three phases of hair follicle growth?
Anagen (3-7years), Catagena (3-4 weeks) nd Telogen (every day)
What is virilisation
Formation of male characteristics on a female due to excess androgen from a tumour
What makes up nails?
Specialised keratin
What does the demo epidermal junction do?
supports, anchors, growth and differentiation of epidermal cells
Name an inherited disease of the DEJ
Epidermolysis Bullosa Simplex or Dystrophica
Name an acquired disease if DEJ
auto-antibodies are produced in pemphigoid, pemphigus and dermatitis herpetiformis
Name the components of the dermis
fibroblasts, macrophages, mast cells, lymphocytes, langerhans cells, collagen and elastin, blood vessels
Do blood vessels flow horizontally or vertically?
Horizontally
What is angioma?
Overgrowth of blood vessels
What results in lymphatic disruption?
Chronic lymphoedema
What do Pacinian recdptors do?
Control pressure
What of Meissners control
Vibration
What are the three types of skin glands
Eccrine, apocrine, sebacious
What does the sebaceous gland do?
Produces sebum, open onto hair follicles and control moisture loss and protect from infections
What does the apocrine gland do?
Its a sweat gland present in axilla and perineum. Depends on androgen and produces an oily fluid
What does Eccrine gland do?
Moistens palms and soles of feet for grip. Controls ultrafiltration.
Name some things that the skin acting as a barrier prevents
UV exposure, allergens, toxins, irritnts, friction, trauma, bacteria, viruses and funghi
Melanin absorbs UV rays to oprotect DNA in cells nuclei- true or false?
True
How is the skin metabolically active?
Vit D metabolism, Thyroid metabolism, defence against UV, chemicals, drugs, pollutants
