SKIN PHYSIOLOGY

Question 1

what are the 5 types of skin receptor?

Answer 1

• free nerve endings
• tactile discs
• tactile corpuscles
• lamellar corpuscles
• bulbous corpuscles

Question 2

what is the most common receptor in skin?

Answer 2

free nerve endings

Question 3

the fibre characteristics of free nerve endings?

Answer 3

unmyelinated small diameter but also some myelinated

Question 4

small swellings at distal ends also referred as

Answer 4

sensory terminals at free nerve endings

Question 5

TRPV1 receptors is

Answer 5

cation channels at free nerve endings

Question 6

H1 receptors is chemical stimuli for

Answer 6

free nerve endings

Question 7

pathway of stimuli at free nerve endings?

Answer 7

activation –> APs in afferent sensory axons –> CNS –> somatosensory cortex

Question 8

what does free nerve endings mainly respond to?

Answer 8

• temperature/thermal
• painful stimuli (nociceptive)
• movement and pressure

Question 9

itchy respond to histamine is trait of which type of skin receptor?

Answer 9

free nerve endings

Question 10

where is free nerve endings located?

Answer 10

deepest layer of epidermis

Question 11

what is the associated structure with free nerve endings?

Answer 11

tactile (merkel) discs

Question 12

what is the purpose of serotonin 5HT over skin physiology?

Answer 12

communication between tactile epithelial and ner ending

Question 13

where can you find most tactile discs?

Answer 13

fingertips

Question 14

which type of skin receptor is good for 2 point discrimination?

Answer 14

tactile disc because small receptive fields

Question 15

what does tactile disc mainly detect?

Answer 15

• fine touch and light pressure
• texture, shape and edge

Question 16

where is the tactile corpuscle located?

Answer 16

papillary layer of dermis
(especially hairless skin)

Question 17

which type of skin receptor could be found around the finger pads, lips, eyelids, external genitalia, soles of feer, nipples?

Answer 17

tactile corpuscle

Question 18

structure of the tactile corpuscle?

Answer 18

• encapsulated
• spiralling/branching unmyelinated sensory terminals surrounded by modified Schwann cells and thin oval FCT capsule

Question 19

how does stimuli triggers the tactile corpuscle?

Answer 19

deformation of capsule –> triggers entry of Na+ ions –> nerve terminal –> action potential

Question 20

what can tactile corpuscle detect?

Answer 20

• delicate ‘fine’ / discriminative touch
• light pressure
• low frequency vibration

Question 21

if you are reading Braille text, which skin receptor you would most likely be using?

Answer 21

tactile corpuscles and likely tactile discs

Question 22

which type of skin receptor is scattered deep in dermis and hypodermis

Answer 22

lamellar (pacinian) corpuscles

Question 23

lamellar corpuscles’ characteristics?

Answer 23

• single dendrite within concentric layers of collagen fibres
• specialised fibroblasts

Question 24

what are the layers of collagen fibres in lamellar corpuscles being seperated by

Answer 24

gelatinous interstitial fluid

Question 25

how does lamellar corpuscles transmit signals

Answer 25

deformation of capsule --> opens pressure sensitive Na+ channels in sensory axon --> inner layers covering axon terminal 'relax' quickly --> APs discontinued (rapidly adapting)

Question 26

what type of contact does lamellar corpuscle detect?

Answer 26

- deep pressure - vibration

Question 27

where is bulbous corpuscles located?

Answer 27

- dermis and subcutaneous tissue - joints capsules

Question 28

why can you find bulbous corpuscles at joint capsules?

Answer 28

- help signal degree of joint rotation - proprioception - e.g. monitoring slippage of object accross surface skin --> modulate grip in fingers

Question 29

describe the structure of bulbous corpuscle?

Answer 29

- network of nerve endings - core collagen fibres - continuous with surrounding dermis - capsule through entire structure

Question 30

function of bulbous corpuscle?

Answer 30

- sustained deep pressure - stretching/distortion of skin

Question 31

_____(1)______ muscle in walls of _____(2)______ and _______(3)______ innervated by the ______(4)_______ nervous system

Answer 31

(1): smooth (2): arteries (3): pre-capillary (4): sympathetic

Question 32

which acts on alpha1 adrenergic receptors?

Answer 32

noradrenaline

Question 33

pathway of reducing skin bloodflow?

Answer 33

GPCRs coupled to intracellular 2nd messengers --> increased intracellular Ca2+ --> constriction --> reduce skin bloodflow

Question 34

____(1)_____ SNS activation of _____(2)_____ causes relaxation of arteries to skin to increase skin bloodflow

Answer 34

(1): reducing (2): alpha1 receptor

Question 35

reducing activation of alpha1 receptors on vascular smooth muscle cause _____(1)______, therefore increase skin bloodflow activation of alpha1 receptors cause ____(2)_____, therefore reduce skin bloodflow

Answer 35

(1): vasodilation (2): vasoconstriction

Question 36

what are the 4 primary mechanisms of heat transfer?

Answer 36

- radiation - evaporation - convection - conduction

Question 37

eccrine sweat glands are innervated by?

Answer 37

SNS - adrenaline beta receptors

Question 38

what is sympathetic cholinergic?

Answer 38

release of ACh onto mACHRs

Question 39

which area of hypothalamus contains heat and cold sensitive for central thermoreceptors?

Answer 39

preoptic

Question 40

what happens to the body if body temperature increases above set point?

Answer 40

- reduce SNS activation of alpha1 on skin blood vessel for vasodilation - increase SNS cholinergic activation of mAChRs on swaet glands --> sweating - increase respiratory rate - behavioural changes

Question 41

what happens to the body if body temperature decreases below set point

Answer 41

- Heat Gain centre activated - increased generation of body heat through nonshivering or shivering thermogenesis - conservation of body heat by decrease blood flow --> reduce heat loss by radiation and convection - countercurrent exchange

Question 42

how does shivering generate heat?

Answer 42

- oscillatory contractions of agonist and antagonist muscle - ATP --> ADP + Pi + movement + heat

Question 43

increase in ________(1)_______ nerve activity and increase in circulating: ______(2)/(3)_______ from adrenal medulla is one of the activities during non-shivering thermogenesis

Answer 43

(1): sympathetic (2): adrenaline (3): noradrenaline

Question 44

increased glycogenolysis in liver and muscle is an example for ____________________ in heat generating mechanism

Answer 44

increase cellular metabolism of non-shivering thermogenesis

Question 45

how does body produce heat instead of ATP in non-shivering thermogenesis?

Answer 45

'uncoupling' of oxidative phosphorylation

Question 46

what does an increase of thyroxine respond to?

Answer 46

TRH and TSH

Question 47

what does increase of thyroxine do to the body>

Answer 47

increase basal metabolic rate

Question 48

which muscle attach hair follicle to upper dermis?

Answer 48

arrector pili (smooth muscle)

Question 49

which innervate arrector pili muscle?

Answer 49

SNS - alpha1 receptor

Question 50

how do we have goosebumps?

Answer 50

contraction of arrector pili muscle as a physiological feed forward to pull hair upright, compress sebaceous gland which lubricate skin and dimples skin

Question 51

which potential complication of severe burn help remind us of normal skin function?

Answer 51

dehydration, hypovolemic shock, infection/sepsis, hypothermia

Question 52

which system dysfuction can also be caused by severe burn?

Answer 52

- electrolyte imbalance - hypermetabolism - GI ulceration - renal failure - respiratory dysfunction

Question 53

what is an example of electrolyte imbalance?

Answer 53

hyperkalaemia - increase of K+