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Flashcards in Skin Deck (22)
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describe the macroscopic structure of the human skin and how it varies between people

hair,thickness,colour,lety, oiliness


what is vitilgo

autoimmune depigmentation (more noticable in darkskin)


what is alopecia areata?

autoimmune hair loss


what is the effect of uv?

ages skin, causes basal cell carcinoma and malignant melanoma


what are the layers of the epidermis?

horny layer (strateum corneum)
graular layer (stratum granulosum)
prickle cell layer (stratum spinosum)
basal layer (stratum basale)


describe the horny layer

top layer, flattened
no nuclei as dead cells (corneocytes)
protects underlying tissue from infection, dehydration, chemicals


describe the granular layer

below horny layer
keratinocytes migrating from stratum spinosum accumulate here
contain ktinolin granules filled with histadine and cystidine richproteins that bind the keratin filaments together
at transition between stratum granulosum and stratumcorneum, cells secrete lamellar bodies into extracellular space forming hydrophobic envolope responsible for skins barrier properties
when cells loose their nuclei nd organelles causing granular cells to become non-viable corneocytes in strateum corneum


describe the prickle cell layer

dark pink
spiny shape due to shrinking microfilaments
large, pale staining nuclei actively synthesising proteins
loose availability to divide


describe the basal layer

pale staining
keratinocyte mitosis occurs here, then moves to prickle layer


describe keratinocyte differentiation

occurs in the basal layer
migrate upwards towards prickle cell layer
keratinocytes synthesise keratin that strengthens the epidermis


describe epidermal dendritic cells (langerhans)

dendritic cells of bone marrow origin
scattered throughout prickle cell layer
highly specialised to present antigens to t lymphocytes
mediate immune reactions e.g. contact dermititis


describe melanocytes

dendritic cells of neural crest origin
occur at intervals along basal layer of epidermis
produce melanin (pigmentation)
produce more melanin in darker skin


what are the cellukar constituents of the dermis

fibroblasts - synthesise extracellular matrix
blood vessels
lymphatic vessels - bathe tissues with lymph
mast cells - part of immune system contains granules rich in histamine and heparin - allergy and anaphalais and protection
nerves - pain receptor


explain the components of the extracellular matrix

collagen - provide strength
elastin - elasticity
ground substance - granular extracellular material that binds components, binds water and hydrates skin


describe skin appendages

hair follicles, sebacs glands, sweat glands, nails


describe the main functions of the skin

barrier - outer stratum corneum forms major barrier preventing percutanous absorbtion of exogenous substances
sensation - nerves detect heat, pressure, contact - reflex minimises injury
thermoregulation - sweat glands and blood vessels allow regulation, subcutanous fat acts as insulation


Describe psoriasis

disrupted skin barrier leads to loss of fluid, nutrirnts and heat and excessive absorbtion of exogenous agents


Describe malignant melonoma

Malignant growth of melanocytes
Superficial above basement membrane
Penetrating modular = poor progress


Describe vitiligo

Autoimmune destruction of melanocytes - depigmentation


Describe alopecia areata

Autoimmune attack against hair follicles - loss of hair


Describe hairy skin

Stratified keratinised epithelium
Dermis with collagen bundles hair follicles sebacous glands and sweat glands
Vellus hairs - soft fine short pale everywhere
Terminal hairs - hard, coarse, large, long, dark


Describe palmar skin

Thick stratum corneum