Skin

Question 1

What are the components of skin?

Answer 1

Keratinised stratified squamous epithelium

Dermis

Hypodermis

Question 2

What are the functions of the skin (7)

Answer 2

Protective physical barrier against friction microorganisms and excessive water loss

Sensory via sensory receptors allow the skin to monitor and respond to the environment

Metabolic cells fo the skin synthesise vitamin D3 from UV radiation (needed for Ca2+ absorption form the Gi tract and bone mineralisation)

Thermoregulatory insulating role and a role in rapidly decreasing temperature through various glands and BV

Sexual signalling pigmentation and hair are visual indicators of health. Pheromones released from apocrine sweat glands

Question 3

What is the lowermost epithelial layer?
What happens here
How does it appear histologically?

Answer 3

Stratum basale

Dark satining simple cuboidal cell

Active mitosis and production of keratinocytes
produces progenitor cells for all epidermal layers

Question 4

How is the epidermis attached to the dermis

Answer 4

Invaginations of the epidermis forming epidermal ridges that interdigitate with underlying dermal papillae forming the dermo-epidermal junction

Question 5

What is the Stratum spinosum?

What are its characteristics?

Answer 5

Thickest epidermal layer

Polyhedral cells with dark nuclei actively synthesising keratin that is assembled into tonofibrs that aggregate at the desmosomes casing cells to bind strongly to one another. Gives the appearance of spines

Question 6

What is the stratum granulosum or granular layer?

What are its characteristics?

Answer 6

3-5 layers of polygonal cells

Cytoplasm full of kerationhyaline granules aggregate via keratinisation to produce long keratin chains
Lamellar granules also present that are exocytosed and help int he formation of a lipophilic barrier

Question 7

What is the stratum lucidum?

Answer 7

Only found in thick skin

thin translucent layer of flattened squamous cells

now dead as diffusion distance too great

no nuclei or organelles just tightly packed cross linked keratin filaments

Question 8

What is the stratum corneum?

Answer 8

Outermost layer of squamous non nucleated heavily keratinised cells

Continuously shed as desmosome and lipid rich layer breaks down allowing the body to withstand friction

Question 9

How many layers are there in thick skin name them all?

Answer 9

5 layers

Stratum corneum
Stratum lucidum
Stratum granulosum
Stratum spinosum
Stratum basale

Question 10

What is the role of mealanocytes in the skin

Answer 10

located on the stratum basale produce melanin that migrates in long processes into the stratum spinosum and is exocytosed and absorbed by surrounding cells giving skin pigmentation and a protective UV barrier

Question 11

What is the role of langerhans cells?

Answer 11

found in the stratum spinosum serve the immunological protection of the skin.
Can phagocytose microorganisms and display antigens triggering an immune response

Question 12

What are Merkel cells?

Answer 12

low threshold mechanoreceptors located in the straum basale
Slow touch receptor slowly adapting
Allow perception of touch and texture of an object

Question 13

What is psoriasis?

Answer 13

Abnormal epidermal growth and differentiation of keratinocytes

common skin disease resulting in raised and scaled looking skin emotional impacts large

Question 14

What is allergic contact dermatitis?

Answer 14

Due to hypersensitive langerhans cells

Occurs due to nickle in lots of cheap earrings or garden chemicals

Question 15

What is a malignant melanoma?

Answer 15

Aggressive malignant tumour of melanocytes
Raised darkly pigmented irregular shaped spots on skin

If spreads to the dermis poor prognosis as can enter blood vessels and spread. retention above the dermis much easier to treat and remove

Question 16

What is vitilligo

Answer 16

Autoimmune condition that attacks melanocytes resulting in loss of pigmentation
Huge impact emotionally

Question 17

What are the two layers of the dermis?

Answer 17

Papillary dermis (most superficial)
Reticular dermis (deepest layer)

Question 18

What is the role of the dermis?

Answer 18

Support the metabolic needs of the epidermis
Support the overlying epidermis structurally dermal papillae interdigitate with epidermal invaginations to provide structural stability

Question 19

What is the structure of the papillary dermis?

Answer 19

Loose areolar connective tissue layer type I and type II collagen
Anchoring Type VII collagen also present that insert into basal lamina anchoring dermis to epidermis

Question 20

What is the structure of the reticular dermis?

Answer 20

Thicker layer

dense irregular connective tissue that has many more fibres including elastic fibres that give the skin its elasticity

Question 21

What is the role and structure of the hypodermis?

Answer 21

Loose connective tissue that binds the skin loosely to subjacent organs and structures
contains adipocytes that form fat store dependant on location

Question 22

What is the vascularature of the dermis?

Answer 22

two plexus in the dermis
at the interface between the papillary ad reticular dermis
And at the interface between the hypodermis and the reticular dermis
Allows for diffusion of nutrients into the epidermal layer
Also allows for thermoregulation blood flow can be directed or redirected away from the skin using shunts

Question 23

What are free nerve endings?

Answer 23

free nerve endings located in papillary dermis and lower epidermal layers allow the perception of pain (nocioceptors) and temperature (thermoreceptors)

Are rapidly adapting phasic (respond maximally and briefly)

Question 24

What are Meissner corpuscles

Answer 24

Oviod in shape stacks of flattened Schwann cells with central nerve ending
located in the dermal papillae
Rapidly adapting allow for two point tactile discrimination

Question 25

What are pacinian corpsules?

Answer 25

Large onion like endings
Found in dermis and subcutaneous tissue
Myelinated fibres that enter onion like capsule with free Nerve endings in the middle
Rapidly adapting sensing pressure by distortion on rings pushing on free nerve endings

Question 26

What are sebaceous glands?
Where are they located?
What is their function?

Answer 26

Located everywhere except the palm of the hand and sole of the foot
In the dermis
Associated with hair follicles
produce oily sebum that is secreted onto the skin and acts as a protective barrier

Question 27

What are eccrine sweat glands?

Answer 27

located in the dermis
produce sweat that is mainly water having a thermoregulatory role
Sweat is secreted directly onto the surface of the skin via a duct

Question 28

What are apocrine sweat glands?

Answer 28

Located mainly in the axillae and genital areas
Secrete protein rich sweat into hair follicles that is then eventually released onto the surface of the skin
Proteins in sweat broken down by microflora to give smell

Question 29

Where are hairs found?

What is there structure and function?

Answer 29

not on thick skin of the palms and hands and not on some thin skin such as shaft of penis, lips and the eyelids
Hairs are keratinised structures produced from the keritinsation of keratinocytes and form from invaginations of the epidermis
hair bulb is connected to inferior dermal paille so gets capillary supply
Also has an erector pilli muscle associated with it that contracts to make hairs erect allowing for trapping of heat

Question 30

What are nails?

How are they formed?

Answer 30

Nails also produced from the rapid keratinisation of keratinocytes to produce a nail plate

Question 31

What is port wine stain?

Answer 31

Caused by presence of blood vessels in superficial dermis causing red skin

Question 32

What is angio-oedema and urticaria

Answer 32

Malformation of mast cells locate in the dermis
Hypersensitive reaction causing release of histamine and increase capillary permeability causing swelling

Urticaria localised less sever and acute (e.g touching plant in garden)

Angio-oedema much more severe prolonged swelling

Question 33

What are first degree burns?
What layer is damged?
Are they painful?
What is the prognosis?

Answer 33

Damage to outermost epidermal layer of skin (stratum corneum and granulsoum in some cases
Tender and red skin
painful
Heal fast

Question 34

What are second degree burns

Answer 34

Two categories
Superficial partial thickness burns
Deep partial thickness burns

Question 35

What are second degree superior partial thickness burns?

Answer 35

Burn stretches into papillary dermis
very painful 
Red with blistering , blanches
Healing time usually two the three weeks
prognosis local cellulitis no scaring

Question 36

What are second degree deep partial thickness burns?

Answer 36

Burn stretches through into reticular dermis
appear yellow and white cherry red drier
less/no blanching
pressure and discomfort
prognosis scaring usually needing skin grafting

Question 37

What is deep full thickness 3rd degree bruns?

Answer 37

Through the whole of the dermis
Painless all the nerve endings have been burnt
white brown appearance with no blanching
healing prolonged and incomplete
prognosis scaring, skin grafting, amputation, contracture requiring escharotomy