Week 1 - Structure and function of the skin

Question 1

What are the 3 main functions of the skin

Answer 1

Protection (both physically and immunologically)
Physiological regulation (body temperature, fluid balance, vitamin D production)
Sensation

Question 2

What are the 3 main layers of the skin

Answer 2

Epidermis
Dermis
Hypodermis

Question 3

What is the name of the muscle which attaches to the hair follicle

Answer 3

Arrector pilli

Question 4

Describe the mechanism by which the arrestor pili warms the body in response to being cold

Answer 4

The muscle contracts to cause the hair to stand on end which traps air and warms the body

Question 5

Describe the structure of the epidermal epithelial cells

Answer 5

Keratinised stratified squamous epithelium

Question 6

What are the epithelial cells that make up the epidermis

Answer 6

Keratinocytes

Question 7

How is the stratum basale layer connected to the basement membrane

Answer 7

By hemidesmosomes (intermediate filament –>extracellular matrix)

Question 8

How are the epithelial cells joined together in the epidermis

Answer 8

Joined together by desmosome cell–>cell junctions

Question 9

Name all the layers of epidermis from top to bottom

Answer 9

Stratum Corneum
Stratum Lucidum (areas of thick skin)
Stratum Granulosum
Stratum Spinosum
Stratum basale

Question 10

What type of cells make up the epidermis

Answer 10

Keratinocytes

Question 11

What do keratinocytes sit on

Answer 11

The basement membrane

Question 12

What type of cells do you find in the stratum basale

Answer 12

Stem cells

Question 13

What is the cell junction between the stem cells and the basement membrane

Answer 13

Hemi-desmasomes

Question 14

What joins together the epithelial cells

Answer 14

Desmosome cell junctions

Question 15

Describe the cells in the stratum corneum

Answer 15

Flat, anucleate cells, filled with keratin and lipids, producing a hydrophobic barrier for the skin

Question 16

What is the extra layer of skin cells found in the epidermis and what is it’s function

Answer 16

The stratum lucidum and it’s role is to reduce abrasion between the stratum corneum and stratum granulosum

Question 17

Describe the way in which the daughter cells move up the layers of skin

Answer 17

The daughter cells move up from the basale layer and differentiate on their way upwards. 2 weeks to get to the stratum granulosin and 2 weeks to make it up to the top of the stratum corneum?

Question 18

What type of epithelial tissue is epidermis tissue

Answer 18

Keratinised stratified squamous epithelium

Question 19

What is the function of the keratinocyte and where found

Answer 19

Provides protection, a barrier and is the site of vitamin D production. Found in the epidermis

Question 20

What is the function of the stem cells in epidermis and where found

Answer 20

Self renewal and repopulation of epidermal layers
Found in the stratum basale

Question 21

Function and location of Merkel cell

Answer 21

Found in epidermis and involved in sensation

Question 22

Function and location of Langerhans cell

Answer 22

Dendritic cell
Antigen presentation phagocytosis. Mainly found in the stratum spinosum

Question 23

Function and location of the melanocyte

Answer 23

Protection from radiation
Found in the basal layer

Question 24

Where is melanin made

Answer 24

In melanocyte cells in the melanosomes

Question 25

How does melanin protect cell from UV

Answer 25

They form a protective layer over the nucleus, thus protecting DNA from damage

Question 26

Function and location of keratins

Answer 26

Major structural protein and a type of intermediate filament. Found in all epidermal layers

Question 27

Function and location of profilaggrin granules

Answer 27

Converted to filaggrin which aggregrates keratin filaments into tight bundles. Found in keratohyalin granules

Question 28

Function and location of involucrin

Answer 28

formation of cell envelope around cells in stratum corneum. Found in keratohyalin granules

Question 29

Function and location of Loricrin

Answer 29

Cross links to involucrin Found in keratohylin granules

Question 30

Function and location of polysaccharides, glycoproteins and lipids

Answer 30

Extrude into intercellular space, form the 'cement' that holds together the stratum corneum cells

Question 31

What type of tissue is the dermis

Answer 31

Connective tissue

Question 32

What are the main 4 components found in the dermis

Answer 32

Fibroblasts Collagen type 1 Elastin Ground substance tissue

Question 33

What allows the strength in the dermis

Answer 33

Collagen

Question 34

What allows the stretch in the dermis

Answer 34

Elastin

Question 35

As you go further down the epidermis, what happens to the strength of collagen and elastin

Answer 35

Collagen gets stronger Elastin gets less stretchy

Question 36

Which portion of the dermis has most blood vessels

Answer 36

Outer layer

Question 37

What do you call the region between the epidermis and the dermis

Answer 37

The dermo-epidermal junction

Question 38

Function of fibroblast cells

Answer 38

Involved in the synthesis of collagen, elastin and other extracellular matrix components

Question 39

Function of lymphocytes

Answer 39

immunosurveillance

Question 40

Function of dermal dendritic cells (langerhan's cells)

Answer 40

Phagocytosis Antigen presentation

Question 41

Functions of mast cells and give examples of substances produced

Answer 41

Produce inflammatory mediators (e.g histamine and heparin) Produce chemotactic factors for eosinophils and neutrophils

Question 42

What is the hypodermis composed of

Answer 42

Adipose tissue

Question 43

What are the 3 main functions of the hypodermis

Answer 43

Energy source Shock absorption Insulation

Question 44

Where do most nerve endings finish

Answer 44

The dermis

Question 45

When nerve endings finish in the epidermis, into what cells do they extend into

Answer 45

Merkel cells

Question 46

What are Meissner's corpuscles

Answer 46

Dermal mechanoreceptors responsible for touch

Question 47

What are pacinian corpuscles

Answer 47

Hypo-dermal receptor that detects deep pressure and vibration

Question 48

What are nails composed of

Answer 48

Plates of heavily compacted, heavily keratinised epithelial cells

Question 49

Name 3 glands found in the skin and describe where they are mainly found

Answer 49

Eccrine glands - found almost everywhere and they excrete sweat Apocrine gland - armpit sweat? Sebaceous gland - secrete sebum and are formed from a hair follicle

Question 50

What are the 3 stages of wound healing

Answer 50

Inflammation Proliferation Remodelling

Question 51

Describe the inflammation stage and for how long this happens

Answer 51

Platelets initiate the blood clot and healing cascade Neutrophils and basophils are recruited towards the site of injury - red swelling Neurtophils and macrophages phagocytose the dead tissues and organsims For 24-48 hours

Question 52

Describe the proliferative stage

Answer 52

Re-epithelialisation occurs Within 1/2 days, cell to cell adhesions are loosened and epithelial cells cover the granulation tissue. Granulation tissue forms, mainly made up from type 3 collagen. Neovascularisation occurs where endothelial cells proliferate

Question 53

Describe the remodelling phase

Answer 53

* The new granulation tissue becomes mature scar tissue through collagen organising itself into extensively cross-linked bundles * Collagen type 3 turns into collagen type I * Final skin strength 70-80% at 1 year