Skin Structure and Function 3

Question 1

what is the dermo-epidermal junction?

Answer 1

interface between epidermis and dermis which holds them together

Question 2

what is the role of the dermo-epidermal junction?

Answer 2

support/adhesion of basal cells

semi-permeable membrane so allows blood to diffuse across layers

Question 3

what are the 3 layers of the dermo-epidermal junction?

Answer 3

lamina lucida
lamina densa
sub-lamina densa zone

Question 4

give an example of what can happen if the dermo-epidermal junction fails?

Answer 4

bullous pemphigoid
epidermolysis bullosa (problem with protein)

Question 5

what problems can arise with the dermo-epidermal junction?

Answer 5

can have antibodies against the junction which can be shown by immunofluorescence

Question 6

what is ground substance in the dermis?

Answer 6

collections of proteins that give structure to the dermis

Question 7

what is contained within the dermis?

Answer 7

ground substance
cells - fibroblasts, macrophages, mast cells, lymphocytes, langerhans
fibres - collagen and elastin
muscles, vessels, lymphatics, nerves

Question 8

what changes happen in the dermis to cause aging?

Answer 8

disordered collagen

disordered, broken up elastin

Question 9

describe blood flow in the skin

Answer 9

horizontal plexuses

arteriole > precapillary sphincters > arteriole > venous capillaries > post-capillary venules > collecting venules

Question 10

what are the 2 plexuses in the skin and what do they supply?

Answer 10

deep vascular plexus supplies the hair follicle

superficial vascular plexus just below epidermis

Question 11

what is angioma?

Answer 11

benign overgrowth of blood vessels

disordered, not well formed blood vessels

Question 12

describe lymphatic vessels in the skin?

Answer 12

sub-epidermal mesh networks/plexuses which continuously drain plasma proteins, cells and excess interstitial fluid
smaller non-contractile vessels > larger contractile lymphatic trunks

Question 13

what are the immune functions of lymphatic vessels in the skin?

Answer 13

immune surveillance by circulating lymphocytes and Langerhans cells
channelling of micro-organisms and toxins

Question 14

what is chronic lymphoedema?

Answer 14

increased pressure on lymphatic system (obesity/infection etc) means muscles cant pump the fluid back up and it gathers in lower limb

Question 15

what nervous system controls sebaceous glands and arrector pili muscle?

Answer 15

autonomic

Question 16

what senses deep pressure?

Answer 16

pancinian corpuscles

Question 17

what is neurofibromatosis?

Answer 17

overgrowth of nerve endings causing multiple tumours

Question 18

what is the function of sebaceous oil?

Answer 18

lubricates hair and stops bacteria entering the follicle

Question 19

what causes whiteheads and blackheads?

Answer 19

whitehead = oil covered with skin so doesn’t oxidise
blackhead = oil oxidises and turns black
both result in inflammation and infection of pore

Question 20

what are the 3 types of gland in the skin?

Answer 20

sebaceous
apocrine
eccrine

Question 21

what do sebaceous glands do?

Answer 21

hormone sensitive secretion of sebum opening into pilary canal
most in face and chest

Question 22

what is the function of sebum?

Answer 22

controls moisture loss

protects from infection (mainly fungal)

Question 23

what do apocrine sweat glands do?

Answer 23

androgen dependant glands that produce oily fluid in axillae and perineum

Question 24

where are eccrine sweat glands found?

Answer 24

whole skin surface but palms, soles and axillae in particular

Question 25

what innervates eccrine sweat glands and what is the implication of this?

Answer 25

sympathetic cholinergic innervation

therefore stress, heat and spicy foods can activate them

Question 26

what is the function of eccrine sweat glands?

Answer 26

cool by evaporation
moisten palms and soles to aid grip
ultrafiltration function as they secrete hypotonic fluid by reabsorbing NaCl and HCO3