skin physiology and wound healing

Question 1

8 functions of skin

Answer 1

protection mechanical support retaining moisture sensory temperature regulation immunity vitamin d production excretion of waste

Question 2

what are the three layers of the skin

Answer 2

epidermis dermis hypodermis

Question 3

what are the 5 layers that make up the epidermis

Answer 3

stratum - basale - spinosum - granulosum - lucidum - corneum

Question 4

what is the epidermis

Answer 4

outer layer of skin no blood supply replaced every 2-3 days

Question 5

what are the major cell types present in the epidermis

Answer 5

keratinocytes merkel cellsmelanocytes langerhans cells T cells

Question 6

what are keratinocytes

Answer 6

stem cells that start in granulosum and move up, flattening and losing nuclei - can secrete IL1 b

Question 7

what are merkel cells

Answer 7

pressure receptors attached to nerves in stratum basale

Question 8

what are melanocytes

Answer 8

cells producing melanin found in the spinosum

Question 9

how is melanin produced

Answer 9

tyrosine –> tyrosinase –> dopaquinone with cysteine –> pheomelanin (red)no cysteine –> leucodopachrome –> eumelanin (black/brown)

Question 10

what are langerhans cells

Answer 10

dendritic cells, distinguish between self and non-self cells

Question 11

which T cells are found in the epidermis

Answer 11

CD8

Question 12

what is the dermis layer

Answer 12

middle layer comprised of fibrous/elastic tissue

Question 13

two layers of the dermis

Answer 13

papillary - 20%, vascular rich, pilireticular - dense, irregular connective tissue

Question 14

which immune cells are present in the dermis

Answer 14

dermal/plasmacytoid dendritic cells melanocytes CD4 T helpers NK Mast macrophages fibroblasts

Question 15

which structures are present in the dermal layer

Answer 15

nervesblood/lymph vessels piloerector muscles hair follicles sweat glandssebaceous glands

Question 16

what is the hypodermis layer

Answer 16

mechanical protector and thermal insulator

Question 17

which appendages can be found in the skin

Answer 17

sweat glands oil glands hair/follicles Meissner’s corpuscle Pacinian corpuscle

Question 18

what is the role of sweat glands

Answer 18

apocrine - protein rich sweat (bacterial growth) armpits eccrine - watery sweat - hands/face regulates body temperature

Question 19

what is the role of oil glands

Answer 19

found in dermis to keep hair and skin moist

Question 20

what is the role of hair and follicles

Answer 20

root hair plexus in dermis, detects fine touch

Question 21

what is the role of Meissner’s corpuscle

Answer 21

found in epidermal layer, receptor for light touch

Question 22

what is the role of pacinian corpuscle

Answer 22

found in dermis, detects vibration in skin

Question 23

what is the mechanism for inflammation in the skin

Answer 23

signal mediated response to cellular insult protective response - remove necrotic cells/tissues

Question 24

what are the advantages to the skin microbiome

Answer 24

protect - occupy space and nutrients interacts with immune system - cytokine production, priming APCsdecreases inflammation strengthens epidermal barrier

Question 25

what are the disadvantages to the skin microbiome

Answer 25

exacerbate lesions promote diseasedelay healing

Question 26

define wound

Answer 26

break in the epithelial integrity of the skin, may affect deeper layers

Question 27

what are the stages of wound healing

Answer 27

1. bleeding 2. inflammation 3. proliferation 4. remodelling

Question 28

what happens in stage 1 of wound healing

Answer 28

blood clot forms to stop bleeding injured vessels contract coagulation cascade platelets release PGDF, IGF

Question 29

what happens in stage 2 of wound healing

Answer 29

early phase late phase stops infection

Question 30

what happens in early stage of phase 2 of wound healing

Answer 30

compliment activation + neutrophil infiltration phagocytosis removal of dead cells

Question 31

what happens in late stage of phase 2 of wound healing

Answer 31

monocytes --> macrophages fibroblast and endothelial recruitment lymphocytes enter after 72hr

Question 32

what happens in phase 3 of wound healing

Answer 32

fibroblast migration - construct new extracellular matrix angiogenesis and collagen synthesis granulation tissue formation

Question 33

what happens in phase 4 of wound healing

Answer 33

matrix matures and remodels Collagen becomes more organised and shrink to bring wound margins closer together Fibroblasts and macrophages apoptose Capillary outgrowth halted and blood flow reduced Acellular, avascular scar results

Question 34

what is a chronic would

Answer 34

When normal process of healing is disrupted at one of the stages, usually inflammatory or proliferative

Question 35

clinical features of chronic wounds

Answer 35

necrotic tissue exudate/sloughlack of blood supply pain wound breakdown (sub)clinical infection

Question 36

what causes chronic wounds

Answer 36

neuropathy ischaemia pressuresystemic diseases malignancy

Question 37

local factors that affect wound healing

Answer 37

pressure mechanical injury necrosis ischaemia

Question 38

systemic factors affecting wound healing

Answer 38

age obesity disease immunosuppression malnutrition stressradiation