skin and dermatology

Question 1

general structure of the skin

Answer 1

top= epidermis
middle - Dermis
underneath = hypodermis

Question 2

structure of the hypodermis

Answer 2

mainly adipose tissue and some loose connective tissue containing fibroblast, macrophages and fibres. The thickness of this layer varies e.g in women its thicker in legs, buttocks and thighs and in men its thicker the abdomen and shoulders

Question 3

what happens when hypodermic layer thins

Answer 3

get wrinkling

Question 4

function of hypodermis

Answer 4

Its function is to provide an energy store, be an insulator and act as a shock absorber. It connects skin to underlying tissues and makes hormones e.g leptin (controls eating habits)

Question 5

structure of the dermis

Answer 5

3 layer;
papillary layer - upper
dermal papillae - middle, its the protrusions that hold the 2 layer together ( not really a whole layer )
recticular layer - Lower

Question 6

functions of the dermis

Answer 6

contains hair and sweat glands and is therefore involved in thermoregulation. It also has sensory structures which are used for touch

Question 7

name the 5 layers of the epidermis

Answer 7

stratum corneum - upper 
stratum lucidum 
stratum granulosum 
stratum spinosum 
stratum basale - lower

Question 8

stratum corneum

Answer 8

(horny cell layer) it is made of squares ( dead keratinocytes ). Its continuously shed and is thick on palms and feet

Question 9

stratum lucidum

Answer 9

only present in thick skin on palms and feet. transparent layer

Question 10

stratum granulosum

Answer 10

stratified squamous epithelium with lamellar granules which assemble keratin fibres and secrete them. Tonofibrils also present they are bundles of keratin filaments are are made by lamellar bodies

Question 11

stratum spinosum

Answer 11

cuboidal epithelial cells in 3 layers held together by desmosomes. They produce lamellar bodies and this is the first time where the Golgi is present

Question 12

stratum basale

Answer 12

columnar epithelial cells which constantly renew keratinocytes by cell division. As these daughter cells move away they lose their ability to divide. Melanocytes are also found here

Question 13

function of epidermis

Answer 13

prevent water loss and pathogen ingress. it synthesises keratin and prevents tissue loss due to abrasion. Has special cells that present pathogens to immune cells

Question 14

describe the keratin synthesis pathway

Answer 14

desmosomes break allowing top layer of squames to be lost. This is then replaced by keratinocytes which have migrated up the layer of skin and were specialised on the way by lamellar bodies and tonofibrils.

Question 15

normal transit time of keratinocytes and transit time in psoriasis

Answer 15

normal = 28-40 days 
psoriasis = 2-3 days. makes skin scaly

Question 16

what is hyperkeratosis

Answer 16

too much keratin deposited on surface of skin. Often on feet or palms but sometimes can cause horns

Question 17

what is a melanocyte

Answer 17

produce melanin which gives skin its colour. don’t increase in number though if more tanned

Question 18

langerhan cells

Answer 18

highly specialised to present antigens to T lymphocytes and mediate immune reactions

Question 19

Merkel cells

Answer 19

mechanoreceptors cells with sensory nerve endings. Respond to touch

Question 20

other cells found in the epidermis

Answer 20

melanocytes, langerhan cells and Merkel cells

Question 21

the 2 types of skin

Answer 21

hairy and thin skin
non-hairy and thick skin
there are exceptions to this e.g the lips or ear

Question 22

structure of non hairy thick skin

Answer 22

No hair or arrestor pills muscles. No sebaceous gland. Thicker stratum corneum and thinner dermis. Also has more mechanoreceptors. pronounced ridges on surface. stratum lucidum seen. regular papillae

Question 23

functions of non hairy thick skin

Answer 23

prevent tissue loss to abrasion and increased sensation

Question 24

structure of thin hairy skin

Answer 24

hair cockles, arretcor pilli muscles, iregular dermal papillae, smaller ridges and no stratum lucidum

Question 25

types of hair

Answer 25

languo- covers developing foetus
villus - replaces langue is short, light and tin
terminal- head, axilla and genital area. is long thick and dark. produced by actions of testosterone

Question 26

functions of hair

Answer 26

thermoregulation- trap heat and stand up when cold= insulating layer
sensation - have nerve endings and feel air movement
protection - eyelashes/ eyebrows prevent dust and pathogens entering body and reduce sweat and light getting into eyes.

Question 27

arrector pilli muscles

Answer 27

smooth muscle fibres attached to papillary region of dermis and a hair bulb insertion. causes goosebumps in fight or flight or when cold and may induce sebum release to make more slippery

Question 28

mechnoreceptos

Answer 28

end bulb- temperature
free nerve endings- pain
tactile discs- sense pressure
messier corpuscle- tapping/ flicker movements
pacinians corpuscle- vibration
ruffians corpuscle - joint movements/ tissue stretch
root hair plexus - vibrations in hair shaft
LOOK AT IMAGE

Question 29

structure and function of nails

Answer 29

consist of foley alpha keratin
its function is to protect soft tissue from injury, used aas a tool and increases dedicated movements. also enhances sensitivity of fingertip

Question 30

functions of skin

Answer 30

lubrcation, vitamin D synthesis, sensation, protection from UV and pathogens, temperature regulation, excretion of co2 and water/cl-, storage of adipose, absorption of small amounts of waterman as aesthetics

Question 31

what is psoriasis

Answer 31

scaly patches of skin that are itchy and sore. skin cells are replaced more quickly than usual. transit time is shortened so outer layer is thin and crusty

Question 32

what causes psoriasis

Answer 32

unknown what causes it but its believed to be autoimmune where T cells attack dividing cells. triggers can include smoking, stress, hormonal changes, alcohol and injury to skin

Question 33

what is malignant melanoma

Answer 33

type of skin cancer shown through new mole or change in old mole. 2 types; nodular which is fast developing and red in black in colour. lentigo looks like large freckle and develop over years especially on people who spent lots of time in the sun

Question 34

what is vitiligo

Answer 34

pale white patches develop on skin due to lack of pigment. 2 types; segmental where white patches only affect 1 area of body. non-segmental where white patches appear on both sides of body as symmetrical

Question 35

what causes vitiligo

Answer 35

non sentimental is though to be autoimmune where T cells attack melanocytes but increased risk if family have is or have another autoimmune disease

Question 36

what is alopecia

Answer 36

hair loss from some or all areas of body. alopecia totalis= hair on scalp and alopecia = all body hair. can be permanent

Question 37

what causes alopecia

Answer 37

cause unknown something to do with T lymphocytes causing inflammation and therfore hair loss. possibly genetic as risk increases if family members have it or if you have other genetic disease e.g diabetes or arthritis