Year 1; Phase 1; Pbl 1

Front 1

Give differences between thin and thick skin

Back 1

Front 2

What are the three layers of skin (superficial to deep)

Back 2

- epidermis

- dermis

- subcutaneous/hypodermis

Front 3

What cell type is the epidermis composed of?

What are the main cell types in the epidermis?

Back 3

- keratinisedsquamuos epithelium

- keratinocytes. melanocytes, langerhans cells, and merkel cells

Front 4

Give a brief descriptio of the following;

keratinocytes

melanocytes

langerehans cells

merkel cells

Back 4

keratinocytes: the dominant cell type inskin accounting for ~90 of cells. Keratinocytes produce keratinswhich provide skin with its durable quality

melanocytes: Melanocyte projectionsextend between keratinocytes producing melanin. Inside keratinocytes,melanin shields the cell nucleus offering protection from UV rays

langerehans cells: i nvolved in signallingother cells of the immune system to launch an immune response againstinvading microbes.

merkel cell: Inconjunction with neurons, Merkel cells mediate different aspects oftouch responses

Front 5

Back 5

Front 6

Describe the main features of the stratum basale

Back 6

- deepestlayer of the epidermis

- composedof a row of cuboidal or columbar keratinocytes

- keratinintermediate filaments bind the cells of this layer together, and to stratum spinosum above

- hemidesmosomes bind to keratinocytes in the basement membrane between theepidermis and dermis

- contains melanocytes and merkel cells

Front 7

Describe the main features of the stratum spinosum

Back 7

- consistsof 3-5 layers of apoptosing keratinocytes

Front 8

Describe the main features of the stratum lucideum

Back 8

- 4-6rows of dead, flattened keratinocytes

- onlyfound in thick skin, such as the soles of the feet and palms of thehand

Front 9

Describe the main features of the stratum corneum

Back 9

- ~25-30rows of dead, flattened keratinocytes; however, in thin skin, thislayer may be only a few cells thick, while in thick skin, there maybe more than 50 rows.

- Thetop layer is increasingly shed, and replaced by new cell below.

Front 10

Back 10

Front 11

What are the two layers of the dermis

What cell types might you find in the dermis?

Back 11

thin, superficialpapillary region, and thick, deeper reticular region

fibroblasts, though alsomacrophages and adipocytes

Front 12

What are dermal pappilae?

Back 12

- nipple-likeshaped projections which increase surface area

- contain capillaryloops and Meissner corpuscles – the latter are nerve endingssensitive to touch (mechanoreceptors), and thus involved tactilesensation.

- Other dermal pappilae contain free nerve endings whichrelay signals involved in sensations of warmth, coolness, pain,tickling and itching.

Front 13

What are dermal ridges?

Back 13

- groovesfound on thick skin

- projectdownwards from the epidermis between the dermal papillae of thedermis – creating a strong bond between the dermis and epidermis

- increasesurface area, meaning more increased grip, and a higher number ofMeissner corpuscles for touch sensation. The increased surface areaalso means a higher number of blood vessels, providing nutrition forthe epidermis

Front 14

What are the functions of the skin?

Back 14

- Thermoregulation:homeostatic regulation of body temperature. This occurs by twoprincipal methods: (1) adjusting blood flow in the dermis and (2)releasing sweat onto the skin surface

- Storesblood: The dermis is blood reservoir which holds 8-10% of total blood

- protection: keratins (durable barrier); lipids (retard water); sebum (moisturises and protects skin and hair and is bacteriostatic); pH (retards bacterial growth); melanin (photoprotective chromophore preventing DNA damage); immune function (langerhand and macrophages)

- sensation: mechanoreceptors for touch and stretch, thermoreceptos, nociceptors and neurons

- excretion and absorption

- vitamin D synthesis

Front 15

Give 3 functions of vitamin D

Back 15

geneactivation, immune responses, and the reduction of inflammation.

Front 16

Describe first intention healing (laceration)

Back 16

1. Nuetrophils appear at themargin of the wound within 24 hours. Within 48 hours, epithelialcells move from the wound edges to the cut margins of the dermis,while depositing basement membrane components. They then fuse in themidline beneath the scab, producing a thin layer of epithelium whichcloses off the wound.

2. Within three days theneutrophils are largely replaced by macrophages, and granulationtissue progressively invades the incision space. Collagen fibres arefound at the margins of the incision, though do not bridge it at thisstage. The epidermal layer is thickened by proliferating epithelialcells.

3. Granulation tissuefills the incision by day 5, with evidence of high amount ofneovascularisation. Collagen fibrils are also more abundant and beginto bridge the incision. The epidermins returns to normal thickncess,and keratin begins to be deposited on the surface cells(keratinisation).

4. In the second week,fibroblast proliferation continues, and collagen is increasinglydeposited into the incision. The leukocytic inflitrate and oedemahave largely disappeared by this stage, as has the increase invasculature. The process of blanching begins as collagen continues otaccumulate, and the vascular channels begin to recede.

5. Within the firstmonth, the fluid exudate disappears leaving cellular connectivetissue.

Front 17

Give 9 factors which affect wound healing

Back 17

Wound site – differenttissue type heal to varying degrees e.g. skin verses neurons.

Mechanical factors – ifthe wound has opposed edges, such as surgical suture, healing isimproved.

Restriction of movementetc

Wound size – obvs

Infection – due topersistent tissue injury and inflammation.

Nutrition – proteindeficiency impedes healing An example is the absence of vitamin C,which inhibits collagen synthesis and retards healing.

Metabolic status –diabetes, in particular, is associated with reduced healing. Onereason is due to microangiopathy (lesions), which disrupts thedelivery of nutrients and the adherence, chemotaxis, and phagocytosisof polymorphonuclear leuckocytes.

Circulatory status – aninadequate blood supply, such as caused by arteriosclerosis, impedeshealing due to reduced oxygen, nutrients and collection of wastes.

Foreign body –maintains chronic inflammation

Front 18

What is the difference between implied and informed consent?

Back 18

Impliedconsent: permissionfor the provision of healthcare without a formal agreement betweenthe healthcare worker and the patient e.g. when a patient makes anappointment to see a doctor it is implied the patient is givingpermission for the doctor to offer diagnosis and treatment options.

Informedconsent: thepatient makes a decision on consent based on the information providedby the physician, including; a justification and explanation of theintended decision/procedure, its potential risks/benefits, anyalternative treatment options, and the implications of withholdingtreatment. Finally, the physician should receive and confirm thedecision made by the patient.

Front 19

What is capacity?

Back 19

Having the ability toprovide informed consent i.e. the patient understands (1) thephysicians justification and explanation for the intended treatment,(2) the potential risks/benefits, (3) knows the implications ofwithholding treatment and (4) is able to respond to the physicianstreatment/decision to give or deny consent.