Physiology

Question 1

what is the largest organ in the body?

Answer 1

the skin

Question 2

what are the core layers of the skin?

Answer 2

epidermis 
appendages 
derma-epidermal junction
dermis 
sub-cutis layer

Question 3

what are the layers of the epidermis

Answer 3

keratin layer
granular layer
prickle cell layer
basal layer

Question 4

what epithelium is the epidermis composed of?

Answer 4

stratified squamous epithelium

Question 5

another name for the keratin layer

Answer 5

stratum corneum

Question 6

what is the keratin layer made up of?

Answer 6

corneocytes (overlapping, non-nucleated remnants) and lamellar granules containing lipids and keratinocytes

Question 7

function of the keratin layer

Answer 7

waterproof barrier

Question 8

what does the granular layer consist of?

Answer 8

2-3 layers of flatten cells with keratohyalin granules that contain filaggrin and involucres protein

Question 9

role of the granular layer

Answer 9

envelope that protects corneocytes

Question 10

what does the prickle layer consist of?

Answer 10

larger polyhedral cells with lots of desmosomes connected to intermediate filaments

Question 11

what does the basal layer consist of?

Answer 11

cuboidal cells with intermediate filaments
high metabolic rate
melanocytes are found here and transfer melanin via dendritic processes

Question 12

describe epidermal turnover

Answer 12

keratinocytes migrate from the basement membrane to the stratum corneum over 28 days

Question 13

what is epidermal turnover regulated by?

Answer 13

growth factors
cell death
hormones

Question 14

when is epidermal control lost?

Answer 14

cancer

psoriasis (immature epidermis)

Question 15

other cells present in the epidermis

Answer 15

melanocytes
Langerhans cells
Merkel cells

Question 16

describe melanocytes

Answer 16

pigment-producing dendritic cells that contain melanosomes that transfer to keratinocytes via dendrites

Question 17

role of melanocytes

Answer 17

convert tyrosine to melanin (eumelanin- brown and phaeomelanin- yellow/red)

Question 18

what does melanin in melanocytes do?

Answer 18

absorbs sunlight forming a protective cap over the nucleus

Question 19

which layer are langerhans cells found in?

Answer 19

prickle cell layer, dermis and lymph nodes

Question 20

what are Langerhans cells associated with?

Answer 20

birbeck granules

Question 21

where are Meckel cells located?

Answer 21

between keratinocytes and nerve fibres

Question 22

role of Meckel cells

Answer 22

mechnoreceptors

Question 23

risk in Meckel cells

Answer 23

viral cancer

Question 24

what are the three appendages present in the skin?

Answer 24

nails
hair
glands

Question 25

describe nails

Answer 25

specialised keratins

Question 26

what is hair made of

Answer 26

keratin

Question 27

what is hair attached to?

Answer 27

sebaceous gland

Question 28

how is hair colour formed

Answer 28

melanocytes above the dermal papilla

Question 29

phases of hair growth

Answer 29

anlagen catagen telogen

Question 30

hormonal influences on hair

Answer 30

thyroxine | androgens

Question 31

three types of glands

Answer 31

sebaceous apocrine eccrine

Question 32

describe sebaceous glands

Answer 32

attached to hairs hormone sensitive and produce sebum control moisture loss and protect from fungal infection

Question 33

describe apocrine glands

Answer 33

present in axilla and perineum | androgen dependent producing oil

Question 34

describe eccrine glands

Answer 34

whole skin surface under sympathetic cholinergic nerves | functions with ultrafiltration and thermoregulation

Question 35

describe the derma-epidermal junction

Answer 35

epithelial-mesenchymal interaction | basement membrane is laminin and collagen

Question 36

what does the dermis consist of?

Answer 36

connective tissue, fibroblasts, macrophages, mast cells, fibres and ground substances

Question 37

what fibres are in the dermis

Answer 37

collagen and elastin

Question 38

what ground substances in the dermis

Answer 38

hyaluronic acid | chondroitin sulphate

Question 39

what appendages are present in the dermis?

Answer 39

blood vessels muscles lymphatics nerves

Question 40

how are the blood vessels arranged in the dermis?

Answer 40

horizontal plexuses

Question 41

what muscles are present in the dermis?

Answer 41

arrestor pili attached to hair follicles

Question 42

what lymphatics are present in the dermis

Answer 42

lymphocytes and langerhans for immune surveillance and removal of toxins

Question 43

what two types of nerves are present in the dermis

Answer 43

``` somatic sensory (dermatomes) autonomic ```

Question 44

role of somatic sensory

Answer 44

free nerve endings with pacinian (deep pressure and vibrations) and Meissner's (light pressure) corpuscles

Question 45

role of autonomic NS

Answer 45

supplying blood vessels, nerves and glands

Question 46

what is the sub-cutis layer made up of

Answer 46

fat

Question 47

role of the skin

Answer 47

``` barrier thermoregulation immune defence metabolism (vitamin D and thyroxine) communications (visual, odour, stigma) sensation ```