3: Skin structure & function 2 Flashcards
Where do melanocytes originate from?
Neural crest
Which organelle, found in melanocytes, is responsible for producing converting an amino acid to melanin?
What is this amino acid called?
Melanosomes
Tyrosine
Melanin absorbs ___ ___.
UV radiation
Melanocytes have long projections which allow them to transfer melanosomes between themselves - what are these projections called?
Dendrites
___ caps protect the nuclei of ___ layer cells.
Melanin , basal
Name an autoimmune disease which targets melanocytes.
Vitiligo
Where are melanocytes found?
Basal layer AND above the basal layer
Where are Langerhans cells found?
Suprabasal (i.e in the prickle cell layer)
Where are Merkel cells found?
Basal layer
What is vitiligo?
Autoimmune disease causing destruction of melanocytes
Patient presents with loads of hypopigmented patches
What is albinism?
Complete / partial lack of pigment in skin, hair and eyes
Classic white appearance
What is Nelson’s syndrome?
What causes it?
Excess melanin production leading to hyperpigmented skin
Overproduction of MSH by anterior pituitary
What is a tumour of melanocytes called?
Malignant melanoma
Where do Langerhans cells originate from?
Bone marrow (immune function)
Langerhans cells pick up ___ and transfer them to lymph nodes via lymph vessels.
antigens
What are the tennis-racquet-shaped organelles found exclusively in Langerhans cells?
Birbeck granules
What is the function of Merkel cells?
Mechanoreceptors
Cancer of which epidermal cell is caused by viral infection and has a high mortality rate?
Merkel cell cancer
Which layer(s) of skin are hair follicles found in?
Epidermis
and
Dermis
What substance is a hair follicle made of?
Keratin
Which type of gland is found adjacent to hair follicles?
Sebaceous gland
What is the deepest component of a hair follicle called?
Dermal papilla
Hair follicles are pigmented by melanocytes - where are these found?
Nail matrix (above the dermal papilla)
What is another name for a hair follicle?
Pilosebaceous unit
What are the muscles responsible for moving hair follicles?
Arrector pili muscles
What are the three phases of hair growth?
Anagen
Catagen
Telogen
What happens in the anagen phase of hair growth?
Hair growth
What happens in the catagen phase?
Involution - hair follicles get ready to shed
What happens in the telogen phase?
Hair sheds
Name a hormone which influences hair growth.
Thyroxine
Androgens - e.g testosterone
For roughly how long is hair in the anagen phase of growth?
3 - 7 years
Roughly how many hairs are shed every day by the average person?
30 - 150 hairs
Not all human hair enters the telogen phase at the same time - this prevents total loss of hair. What is this characteristic called?
Asynchronicity
What is telogen effluvium?
Marked increase in hair loss triggered by a stressful event (e.g childbirth, bereavement)
What is alopecia areata?
Hair loss caused by an autoimmune disorder (attacking the hair follicles)
What is androgenic alopecia?
Pattern hair loss
i.e male pattern baldness
caused by decrease in androgens
What is the bed of keratinocytes below the proximal nail plate called?
Nail matrix
What is the name of the layer of epithelium found deep to the distal nail plate?
Hyponychium
What is the white half moon part of a nail called?
Lunula
What is the part of the nail proximal to the lunula?
Cuticle
