Physiology - Dermatology Flashcards
what is the largest organ in the body?
skin
what is the outermost layer of skin called?
epidermis
which type of epithelium makes up the epidermis?
stratified squamous epithelium
which layer of skin is deep to the epidermis?
dermis
which tissue type makes up the dermis?
connective tissue
which germ layer forms the epidermis?
the ectoderm
forms the periderm that becomes the skin
which germ layer forms the dermis?
the mesoderm
in foetal skin development, which layers are formed after 16 weeks?
keratin layer granular layer prickle cell layer basal layer dermis
which cell makes up most of the epidermis?
keratinocytes
true or false: the basal layer of the skin is metabolically active
true
contains lots of intermediate filaments
name three epidermal cells
melanocytes
langerhans cells
merkel cells
where are melanocytes derived from?
the neural crest
what are melanocytes?
pigment producing dendritic cells
what layer of skin are melanocytes found in?
the basal layer
what do melanocytes do?
convert tyrosine to melanin pigment and load colour onto adjacent keratinocytes
what colour is eumelanin?
brown
what colour is pheomelanin?
red
which disease is caused by loss of melanocytes?
vitiligo
where are langerhans cells derived from?
bone marrow
what are langerhans cells?
antigen presenting cells
where are langerhans cells found?
the prickle cell layer of the skin
what are merkel cells?
mechanoreceptors that aid sensation
where are merkel cells found?
between keratinocytes and nerve fibres
what are the three phases of growth of a hair folicle?
anagen
catagen
telogen
what is the dermo-epidermal junction?
the interface between the dermis and the epidermis
give an example of an inherited skin fragility caused by a mutation in a protein in the DEJ
epidermolysis bullosa complex in young children
give two examples of acquired skin fragility
dermatitis herpetiformis
bullous pemphigoid
what do fibroblasts in the dermis produce?
procollagen
elastin
what does procollagen become?
collagen
true or false: the blood vessel supply to skin is greater than its metabolic need
true
which nerve receptors sense pressure in the skin?
pacinian corpuscles
which nerve receptors sense vibration in skin?
meissner’s corpuscles
what do free nerve endings provide sense for in the skin?
temperature
pain
which inherited condition arises due to overgrowth of nerve endings?
neurofibromatosis
list the three main secretory glands in the skin
eccrine
apocrine
sebaceous
what do eccrine glands secrete?
sweat
what do apocrine glands secrete?
odorous fluid
what do sebaceous glands secrete?
moisturiser
which areas of the body have a high concentration of sebaceous glands?
head
neck
chest
what is the significance of the melanin cap on basal cells?
absorbs UV rays to protect DNA in the cells nuclei
which vitamin does skin metabolise?
vitamin D
true or false: 20% of thyroxine conversion to triiodothyronine is done in peripheral tissues such as skin
false
80%
which cells help protect the skin from UV rays?
melanocytes
what is the ratio of melanocytes to basal cells?
1 to 10
where is the papillary dermis found?
the uppermost layer of the dermis
