Skin

Question 0

what is vitilgo

Answer 0

autoimmune depigmentation (more noticable in darkskin)

Question 1

describe the macroscopic structure of the human skin and how it varies between people

Answer 1

hair,thickness,colour,lety, oiliness

Question 2

what is alopecia areata?

Answer 2

autoimmune hair loss

Question 3

what is the effect of uv?

Answer 3

ages skin, causes basal cell carcinoma and malignant melanoma

Question 4

what are the layers of the epidermis?

Answer 4

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

Question 5

describe the horny layer

Answer 5

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

Question 6

describe the granular layer

Answer 6

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

Question 7

describe the prickle cell layer

Answer 7

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

Question 8

describe the basal layer

Answer 8

pale staining

keratinocyte mitosis occurs here, then moves to prickle layer

Question 9

describe keratinocyte differentiation

Answer 9

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

Question 10

describe epidermal dendritic cells (langerhans)

Answer 10

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

Question 11

describe melanocytes

Answer 11

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

Question 12

what are the cellukar constituents of the dermis

Answer 12

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

Question 13

explain the components of the extracellular matrix

Answer 13

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

Question 14

describe skin appendages

Answer 14

hair follicles, sebacs glands, sweat glands, nails

Question 15

describe the main functions of the skin

Answer 15

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

Question 16

Describe psoriasis

Answer 16

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

Question 17

Describe malignant melonoma

Answer 17

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

Question 18

Describe vitiligo

Answer 18

Autoimmune destruction of melanocytes - depigmentation

Question 19

Describe alopecia areata

Answer 19

Autoimmune attack against hair follicles - loss of hair

Question 20

Describe hairy skin

Answer 20

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

Question 21

Describe palmar skin

Answer 21

Thick stratum corneum

Dermis