Skin

Question 1

How can variations in skin affect susceptibility/ manifistation of skin disesase?

Answer 1

vitiligo - an autoimmune depigmentation more of an issue in darker skin as can see it more

alopecia areata - autoimmune hair loss
impact on women as large patches of hair loss

uv -induced abnormalities
sunburn doesnt occur in black skin
skin aging in whites - damake to dermal collagen and elastin
skin cancer in whites (basal cell carcinoma, malignat melanoma,
squamous cell carcinoma
more susceptible to sunburn if fairskinned

Question 2

Give the four layers of skin

Answer 2

stratum corneum
stratum granulosum
stratum spinosum
stratum basale

Question 3

describe what happens in the stratum basale and spinosum?

Answer 3

the stratum basale is the site of keratinocyte mitosis

daughter keratinocytes move up into the stratum spinosum and lose their ability to divide and terminal differentiation begins

keratinocytes also synthesis keratins

Question 4

what creates the prickle effect of prickle cells?

Answer 4

the desmosomes - intercellular junctions

Question 5

what changes occur between the statum spinosum and statum granulosum?n

Answer 5

keratinocytes lose their plasma membrane and begin differentiating into corneocytes

Question 6

what is in the statum granulosum

Answer 6

keratohyalin granules:

keratin, fibrous proteins and enzymes that degrade the phospholipid bilayer and cross link proteins

Question 7

describe the statum corneum

Answer 7

flattened corneocytes

Question 8

describe the process of keratinocyte differentiation

Answer 8

in basale layer keratinocyte mitosis occurs
daughter keratinocytes move up into the stratum spinosum where they lose their ability to divide and produce keratins
in the statum granulosum keratinocytes lose their plasma membranes and begin to differentiate into corneocytes
the statum corneum consists of flattened corneocytes

Question 9

give brief description of melanocytes and langerhans cells

Answer 9

melanocytes are dendritic cells of neural crest origin
they produce melanin and are spaced along the basal layer

langerhans cells are dendritic cells of bone marrow origin
they are professional antigen presenting cells to t lymphocytes and mediate immune responses (nb in allergic contact dermatitis). they are throughout the prickle layer

Question 10

describe psoriasis

Answer 10

abnormal proliferation of keratinocytes in the epidermal basal layer = abnormal epidermal growth and differentiation

produces gross thickening of the prickle layer and excessive production of corneocytes

Question 11

describe contact dermatitis

Answer 11

hypersensitivity reaction

mediated by langerhans cells in the prickle layer presenting antigens to t lymphocytes

Question 12

describe malignant melanomas

Answer 12

malignant growth of melanocytes

Question 13

describe vitiligo

Answer 13

autoimmune destruction of melanocytes causing well demarcated depigmentation

Question 14

what is in the extracellular matrix of the dermis?

Answer 14

collagen and elastin

Question 15

give four dermal components

Answer 15

blood vessels
lymphatic vessels
mast cells (contain histamine)
nerves

Question 16

give four functions of the skin

Answer 16

barrier - poor function = loss of fluid, protein, nutrients and heat

NB psoriasis

sensation - very important as without minor injuries can lead to major infections

NB leprosy and diabetic sensory neuropathy

thermoregulation - vascular (vasoconstriction and dilation) and eccrine (evap of sweat causes cooling

NB in erythrodermic psoriasis inability of vasoconstrict - heat loss

Question 17

How can skin vary?

Answer 17

site
sex 
age 
ethnicity 
exogenous influences