skin physiology

Question 1

what are the skin layers from superficial to deep

Answer 1

epidermis, appendages (nails, hair, glands, mucosae), DEJ, dermis (connective tissue), sub cutis (fat)

Question 2

where is thick skin found

Answer 2

palms and soles

Question 3

what are blaschko’s lines

Answer 3

growth pattern of skin in embryology

Question 4

when does the epidermis form in embryology

Answer 4

16 weeks

Question 5

what is vit D and thyroxine metabolised by

Answer 5

keratinocytes

Question 6

in thyroid metabolism, what % of T4 is converted to T3 and what is the real names

Answer 6

80%. (thyroxine) –> (triiodothyronine)

Question 7

what receptors in the skin detect temperature

Answer 7

thermoreceptors

Question 8

what sense cells are associated with pressure and vibration,

Answer 8

pacinian and meisseners

Question 9

what are the 6 functions of the skin

Answer 9

barrier, metabolism, thermoregulation, immune defence, communication, sensory function

Question 10

what type of epithelium is the epidermis

Answer 10

stratified squamous

Question 11

what are the 4 cells in the epidermis

Answer 11

melanocytes, keratinocytes (95%), langerhans and merkel cells

Question 12

what are the 4 layers of the epidermis

Answer 12

keratin (horny/ stratum), granular, prickle cell, basal

Question 13

what do keratinocytes differentiate into, what is their main function

Answer 13

corneocytes - no nuclei, tight water proof barrier

Question 14

where do keratinocytes migrate from

Answer 14

basement membrane

Question 15

what do keratinocytes produce

Answer 15

keratin

Question 16

what cells are in the granular layer and what is there a high content of

Answer 16

Odland cells, no nuclei, high lipid content

Question 17

what cells are in the prickle cell layer and what are there lots of

Answer 17

Polyhedral, desmosomes and langerhans

Question 18

what cells are in the basal layer, where do they cells proliferate from

Answer 18

cuboidal, proliferate from basal layer to keratin layer

Question 19

what epidermal layer is metabolically active

Answer 19

basal layer

Question 20

what are melanocytes and where do they migrate from

Answer 20

pigment producing dendritic cells, migrate from neural crest

Question 21

how to melanocytes produce pigment

Answer 21

convert tyrosine –> melanin pigment

Question 22

what colour are eumelanin and phaemomelanin

Answer 22

brown/ black and red/ yellow

Question 23

what is the function of melanin, melanin caps and melanosomes

Answer 23

melanin absorbs light, melanin caps protect nucleus, melanosomes (pigment) are transferred to keratinocytes

Question 24

where do langerhan cells come from and where are they found

Answer 24

bone marrow, mainly prickle cell layer in epidermis

Question 25

what are langerhan cells and what granule do they have

Answer 25

main immunological cells - birbeck granules

Question 26

where are merkel cells, what are they

Answer 26

basal level, mechanoreceptors for sense

Question 27

what is the worst type of skin cancer

Answer 27

merkel

Question 28

what is the pathophysiology of vitiligo

Answer 28

autoimmune loss of melanocytes

Question 29

what is the pathophysiology of albinism

Answer 29

genetic partial loss of pigment (melanin)

Question 30

what is the pathophysiology of nelsons disease

Answer 30

pit gland produces excess melanin stimulating hormone

Question 31

what are hair follicles

Answer 31

specialised keratins and dermal papilla (pigment from melanocytes) next to sebaceous glands

Question 32

what are the phases of hair growth

Answer 32

anagen = growing, catagen = involuting, telogen = resting

Question 33

what are nails made of

Answer 33

specialised keratins

Question 34

what are the 3 types of skin glands and where are they found

Answer 34

sebacous - around hair follicles, apocrine - dermis, eccrine - dermis

Question 35

what is the function of sebaceous glands and what activates them

Answer 35

produce sebum (oil) in holocrine secretion to pilary canal and protect from fungus. hormone sensitive

Question 36

what is the function of apocrine glands and what activates them

Answer 36

produces oily fluid that smells bad (sweat), androgen dependent

Question 37

what is the function of eccrine glands and what activates them

Answer 37

sympathetic cholingeric nerve supply, cools by evaporation and grips hands and feet

Question 38

how permeable is the DEJ

Answer 38

semi-permeable

Question 39

what cells are in the dermis

Answer 39

fibroblasts, macrophages, mast cells, lymphocytes,

Question 40

what fibres are in the dermis

Answer 40

collagen (type 1 and 111), elastin

Question 41

what is unique about the blood supply to the skin

Answer 41

blood supply greater than the need for evaporation

Question 42

what role to lymphocytes have in skin immunology

Answer 42

immune surveillance