Background On Dermatology Flashcards
1
Q
What are functions of normal skin?
A
- Protective barrier against environmental insults
- Temperature regulation
- Sensation
- Vitamin D synthesis
- Immunosurveillance
- Appearance/cosmesis
2
Q
What are major cell types and functions of the skin?
A
- Keratinocytes: Produce keratin as a protective barrier
- Langerhans’ cells: Present antigens and activate T-lymphocytes for immune protection
- Melanocytes: Produce melanin, which gives pigment to the skin and protects the cell nuclei from ultraviolet (UV) radiation-induced DNA damage
- Merkel cells: Contain specialised nerve endings for sensation
3
Q
What are the epidermal layers? (from bottom to top)
A
- Stratum basale (Basal cell layer): Actively dividing cells, deepest layer
- Stratum spinosum (Prickle cell layer): contains differentiating cells
- Stratum granulosum (Granular cell layer): So-called because cells lose their nuclei and contain granules of keratohyaline.They secrete lipid into the intercellular spaces.
- Stratum corneum (Horny layer): Layer of keratin, most superficial layer
4
Q
What is the Stratum Lucidum?
A
- Present in areas of thick skin such as the sole beneath the stratum corneum. This consists of paler, compact keratin.
5
Q
What are patholgies involving the epidermis?
A
- Changes in epidermal turnover time - e.g. psoriasis (reduced epidermal turnover time)
- Changes in the surface of the skin or loss of epidermis - e.g. scales, crusting, exudate, ulcer
- Changes in pigmentation of the skin - e.g. hypo- or hyper-pigmented skin
6
Q
What is the dermis made of?
A
- The dermis is made up of collagen (mainly), elastin and glycosaminoglycans, which are synthesised by fibroblasts. Collectively, they provide the dermis with strength and elasticity.
- The dermis also contains immune cells, nerves, skin appendages as well as lymphatic and blood vessels.
7
Q
What are the pathologies of the dermis?
A
- Changes in the contour of the skin or loss of dermis e.g. formation of papules, nodules, skin atrophy and ulcers
- Disorders of skin appendages e.g. disorders of hair, acne (disorder of sebaceous glands)
- Changes related to lymphatic and blood vessels e.g. erythema (vasodilatation), urticaria (increased permeability of capillaries and small venules), purpura (capillary leakage)
8
Q
What are the main types of hair?
A
There are 3 main types of hair:
- Lanugo hair (fine long hair in fetus)
- Vellus hair (fine short hair on all body surfaces)
- Terminal hair (coarse long hair on the scalp, eyebrows, eyelashes and pubic areas)
9
Q
What are the main phases of hair growth?
A
- Anagen (long growing phase)
- Catagen (short regressing phase)
- Telogen (resting/shedding phase)
10
Q
What are pathologies of the hair?
A
- Reduced or absent melanin pigment production e.g. grey or white hair
- Changes in duration of the growth cycle e.g. hair loss (premature entry of hair follicles into the telogen phase)
- Shaft abnormalities
11
Q
What is the structure of Nails?
A
- The nail is made up of a nail plate (hard keratin) which arises from the nail matrix at the posterior nail fold, and rests on the nail bed.
- The nail bed contains blood capillaries which gives the pink colour of the nails.
12
Q
What are pathologies of the Nails?
A
- Abnormalities of the nail matrix e.g. pits and ridges
- Abnormalities of the nail bed e.g. splinter haemorrhage
- Abnormalities of the nail plate e.g. discoloured nails, thickening of nails
13
Q
What are sebaceous glands?
A
- Sebaceous glands produce sebum via hair follicles (collectively called a pilosebaceous unit). They secrete sebum onto the skin surface which lubricates and waterproofs the skin.
14
Q
What are pathologies of the Sebaceous Glands?
A
- Increased sebum production and bacterial colonisation e.g. acne
- Sebaceous gland hyperplasia
15
Q
What are the purpose of sweat glands?
A
Sweat glands regulate body temperature and are innervated by the sympathetic nervous system.
