Skin structure

Question 1

intergumentary system

Answer 1

skin and its accessory structures

hair,nails, glands and sensory receptors

Question 2

2 main parts of skin

Answer 2

epidermis and dermis

Question 3

dermis thickness

Answer 3

1mm

Question 4

epidermis thickness

Answer 4

0.1 mm

Question 5

composition of dermis vs epidermis

Answer 5

epidermis mostly cells, dermis mostly components eg glands

Question 6

thick skin

Answer 6

hairless
eg palms
fingertips, toes, soles
0.6-4.5 mm

Question 7

thin skin

Answer 7

hairy
all other parts of the body
four layers
density of hair follicles depends on where in the body
hair follicles extend through the layers
0.1-0.15 mm

Question 8

5 layers of what makes up epidermis

Answer 8

keratinocytes

Question 9

stratum basale

Answer 9

single layer of columnar keratinocytes resting on basement membrane: site of production of new keratinocytes- stem cells

Question 10

stratum spinosum

Answer 10

multiple rows of close packed, many sided keratinocytes linked by desmosomes
lots of keratin

Question 11

stratum granulosum

Answer 11

rows of flattened keratinocytes containing darkly staining keratohyalin granules and lipid rich lamellar bodies- on release these form a hydrophobic, impermeable barrier

Question 12

stratum lucidium

Answer 12

rows of clear, flat, keratin rich keratinocytes

present only in thick skin

Question 13

stratum corneum

Answer 13

rows of dead, flat enucleate keratinocytes that have mostly cross-linked keratin fibres
have lipid in between

Question 14

controlled apoptosis

Answer 14

as cells differentiate and reproduce, they are forced towards the skin’s surface, and are further from the blood supply and food supply, so die

Question 15

how do keratinocytes differ in each layer

Answer 15

types of keratin change
evolve in shape
cell contents breakdown, rearrange and denucleate

Question 16

keratins

Answer 16

cytoskeletal filament forming proteins
form branching, rope like bundles in cytoplasm
associate with desmosomes and hemidesmosomes at cell periphery
maintain structural integrity of epidermis, allow it to resist and dissipate mech forces

Question 17

desmosomes

Answer 17

anchor epithelial cells to each other

Question 18

lipid matrix

Answer 18

acts as skin’s main water proofing agent

Question 19

hemidesmosomes

Answer 19

tie epidermal cells to fibres of the basal lamina

Question 20

basal lamina/basement membrane

Answer 20

acellular layer between epidermis and dermis

Question 21

where are melanocytes found

Answer 21

bottom of the epidermis

Question 22

process of transfer of melanosomes

Answer 22

produced by golgi of melanocyte
melanosomes move into melanocyte cell processes, and epithelial cells phagocytize the tips of the melanocyte cell processes
The melanosomes have been transferred to the epithelial cells (keratinocytes in epidermis)

Question 23

what happens next

Answer 23

melanosomes migrate to the peri-nucelar region and form a protective ‘cap’

Question 24

what is skin colour determined by

Answer 24

amount of eumelanin and pheomelanin synthesised
not number of melanocytes
size of melanosomes

Question 25

two regions of the dermis

Answer 25

papillary and reticular | papillary above, reticular below

Question 26

how are desmosomes broken down

Answer 26

enzymes in stratum corneum

Question 27

Langerhans cell

Answer 27

move within epidermis, APC Present foreign antigens to T cells macrophages of the skin in the stratum spinosum layer

Question 28

Merkel cell

Answer 28

sensory receptor cells Make synapse-like contacts with somatosensory nerve endings v sensitive touch receptors in the stratum basale?

Question 29

function of basal lamina

Answer 29

bridging structure, regulator of proliferation in stratum basale and movement of cells and molecules between epidermis and dermis

Question 30

papillary matrix

Answer 30

loose connective tissue composed of fine elastic fibres with interspersed capillary loops and nerve fibres lots of capillaries Has Meissners corpuscles (touch receptors)

Question 31

reticular matrix

Answer 31

dense connective tissue randomly orientated collagen fibre, elastin, proteoglycans and glycosaminoglycans has fibroblasts, macrophages and fat cells

Question 32

cell types in the dermis

Answer 32

matrix synthesising fibroblasts, immune cells, vascular smooth muscle cells, and sweat gland myoepithelial cells

Question 33

hair

Answer 33

grow from hair follicles in the dermis composed of columns of dead, keratinised epithelial cells originate from stratum basale in the hair bulb

Question 34

function of smooth muscle

Answer 34

enables hair to stand on end, contraction elevates hair, forming goosebumps

Question 35

function of sebaceous gland

Answer 35

produces sebum-oily lipids | lubricates hair shaft

Question 36

function of blood vessels at the base of the hair follicle

Answer 36

give hair nourishment it needs to grow

Question 37

types of glands general

Answer 37

endocrine and exocrine

Question 38

how can exocrine glands be further categorised

Answer 38

based on structure and mode of secretion

Question 39

3 modes of secretion

Answer 39

merocrine, apocrine (pinched off portion of the cell in secretion) and holocrine (dying cell releases secretory products)

Question 40

2 main types of glands in the skin

Answer 40

sebaceous and sudoriferous

Question 41

types of sudoriferous glands

Answer 41

apocrine and eccrine

Question 42

apocrine

Answer 42

``` limited distribution merocrine secretion more viscous due to presence of lipids and proteins activity linked to emotional state active from puberty ```

Question 43

eccrine

Answer 43

``` wide distribution duct opens at epidermal surface merocrine secretion hypotonic and slightly acidic Active from soon after birth ```

Question 44

Types of skin sensory receptors

Answer 44

mechanoreceptors, thermoreceptors and nociceptors

Question 45

epidermis

Answer 45

keratinised squamous epithelium

Question 46

dermis

Answer 46

connective tissue layer | has nerves, blood supply and fibroblasts, sweat glands and hair

Question 47

how are damaged cells replaced in the epidermis

Answer 47

continually shed, and constant proliferation of cells in stratum basale which move up to the top, to replace lost cells

Question 48

Meissners corpsucles

Answer 48

v sensitive mechanoreceptors | found on palms

Question 49

what type of secretion for sebaceous glands

Answer 49

holocrine