Skin

Question 1

What are the functions of skin?

Answer 1

• protection - light, chemical, thermal, mechanical, water, infection
  
  • sensation - touch, pressure, temperature, pain
  • thermoregulation - hair, sweat, blood flow, shivering, subcutaneous adipose tissue
  • metabolism - vitamin D, adipose tissue (energy storage)
  • immunologic - immune cells help to deal with invasion
  • sexual attractant - appearance - in animals release hormones

Question 2

What type of epithelium is in the epidermis?

Answer 2

keratinising stratified squamous

Question 3

What are the layers of the epidermis?

Answer 3

basal layer, stratum spinosum, stratum granulosum, stratum corneum

Question 4

What are the features of the basal layer of the epidermis?

Answer 4

cuboidal low columnar cells on the basement membrane - this is where replication occurs

Question 5

What are the features of the stratum spinosum?

Answer 5

diamond shaped cells with intercellular bridges

Question 6

What are the features of the stratum granulosum?

Answer 6

purple granules in the cells - involved in the process of keratinisation

Question 7

What are the features of the stratum corneum?

Answer 7

cells have lost their nuclei and are full of keratin

Question 8

What are epidermal rete ridges?

Answer 8

the down pouches of the epithelium

Question 9

What are the dermal papillae?

Answer 9

the parts of the dermis between the epidermal rete ridges

Question 10

What type of cell junctions are in the stratum spinosum?

Answer 10

desmosomes

Question 11

What are tonofibrils?

Answer 11

keratin intermediate filaments - in the stratum spinosum

Question 12

What other types of cells are present in the epidermis?

Answer 12

melanocytes, langerhans cells, merkel cells

Question 13

How many melanocytes are there?

Answer 13

1 per 8-10 epithelial cells

Question 14

What is the role of melanin?

Answer 14

to protect the nucleus of the epithelial cells from UV exposure

Question 15

What is the role of langerhans cells?

Answer 15

antigen recognition and antigen presenting

Question 16

What do sebaceous glands look like?

Answer 16

foamy cytoplasm because of lipid rich secretion

Question 17

What is the embryological origin of adnexal structures?

Answer 17

epidermis

Question 18

What are the two layers of cells in sweat glands?

Answer 18

superficial layer is cuboidal secretory cells and deep layer is myoepithelial cells

Question 19

What are the two vascular plexuses in the skin?

Answer 19

the papillary plexus in the superficial dermis and the cutaneous plexus between the dermis and hypodermis

Question 20

What are the two layers of the dermis?

Answer 20

the papillary dermis superficially and the reticular dermis deep - the reticular dermis has more coarse collagen bundles

Question 21

What is different about the skin on the scalp?

Answer 21

the hair follicles are from deeper down

Question 22

What is different about the skin on the palms and soles?

Answer 22

the keratin layer in the epidermis is thicker and there are no hair follicles

Question 23

Where does the root of a nail attach?

Answer 23

to the periosteum of the distal phalynx

Question 24

What are the stages of healing of the skin?

Answer 24

in the first 24 hours there is vasoconstriction and a blood clot forms and neutrophils infiltrate. Over 3-7 days granulation tissue is formed, bringing in macrophages, fibroblasts and myofibroblasts and there is angiogenesis. Over weeks a mature scar forms and the collagen changes from type 3 to type 1

Question 25

What cytokines released by macrophages contribute to the chemotaxis and proliferation of fibroblasts and keratinocytes?

Answer 25

PDGF, TGFbeta, IL-1, TNF, KGF-7

Question 26

What cytokines released by macrophages contribute to angiogenesis?

Answer 26

VEG-F, FGF-2, PDGF

Question 27

What cytokines released by macrophages contribute to deposition and remodelling of the ECM?

Answer 27

TGF beta, PDGF, TNF, OPN, IL-1, collegenase, MMPs

Question 28

What are the different types of burns?

Answer 28

superficial (epidermis only), partial thickness (epidermis and part of dermis) and full thickness (epidermis, dermis and parts of subcutaneous tissue)

Question 29

What factors affect healing of burns?

Answer 29

burn depth, surface area, location

Question 30

What local factors affect healing in general?

Answer 30

``` – Blood supply – Infection – Foreign material – Excessive blood clot – Movement – Tissue in which the injury has occurred – Size of wound – Previous radiotherapy ```

Question 31

What systemic factors affect healing in general?

Answer 31

– Nutrition: deficiency of vitamin C, certain amino acids, zinc – Old age: deterioration in immune system – Diabetes - increased susceptibility to infection, narrowing of blood vessels – Imunosuppressant drugs e.g. corticosteroid therapy, chemotherapy

Question 32

What are cleavage lines?

Answer 32

the orientation of the collagen in the dermis - if incisions are made parallel to cleavage lines then healing will be quicker