Skin

Question 1

What type of epithelia is the epidermis mostly made up of?

Answer 1

stratified squamous epithelium

Question 2

what are the 4 layers of the epidermis called (outermost to innermost)

Answer 2

stratum corneum
stratum granulosum
stratum spinosum
stratum basale

Question 3

function and location of desmosomes

Answer 3

anchor neighbouring cells, all through the epidermis

Question 4

function and location of the hemidesmosomes

Answer 4

anchors the stratum basale to the dermis. Only found in the stratum basale.

Question 5

what is the extra layer of skin called for thick skin and where does it sit between?

Answer 5

the stratum lucidum in the epidermis

Question 6

what are the two layers of the dermis called and what do they have in common?

Answer 6

papillary and reticular layer
both contain blood vessels, lymphatics, sensory nerve fibres and accessory structures

Question 7

features of the papillary layer

Answer 7

highly vascularised tissues (for nourishment)

Question 8

features of the reticular layer

Answer 8

mesh like structure of collagen and elastin ( for strength)

Question 9

features of the cutaneous plexus

Answer 9

blood vessels at the junction of the dermis and hypodermis
Supplies the hypodermis, deeper dermis including capillaries for hair follicles and sweat glands

Question 10

features of the subpapillary plexus

Answer 10

branches from the cultaneous plexus
lies deep to the papillary layer of the dermis
network of blood vessels providing oxygen and nutrients to upper dermis and epidermis.

Question 11

what layers of the skin make up the cultaneous layer?

Answer 11

the epidermis and the dermis

Question 12

what layers of the skin make up the subcultaneous layer?

Answer 12

the hypodermis

Question 13

features of the hypodermis

Answer 13

mostly adipocytes producing subcutaneous fat
this fat stores energy and provides insulation

Question 14

effects of first degree burns
layers, effects, heal time

Answer 14

superficial layer only the outer layer of epidermis
skin remains water and bacterial barrier
3-10 days healing

Question 15

normal second degree burn

Answer 15

epidermis and varying amounts of dermis effected. blistered and painrul
1-2 weeks healing

Question 16

deeper 2nd degree burn

Answer 16

whitish waxy areas
hair follicles and sweat glands remain intact
possible loss of sensation or scarring
usually heel in 1 month

Question 16

3rd degree burn

Answer 16

full thickness burn
extends into subcultaneous tissue and may involve bone and muscle
no pain due to destroyed nerve endings

Question 17

arrector pili muscle

Answer 17

contraction produced goose bumps- improving insulation

Question 18

root hair plexus

Answer 18

at the base of each hair follicle, allow for heightened sensation.

Question 19

sebaceous glands

Answer 19

produce sebum, nourishing the hair shaft and naturally moistursing the skin.
water repellent

Question 20

what happnens when hair follicles become blocked

Answer 20

too much sebum being produced= infection which increases the sebum production resulting in acne

Question 21

what is lanolin

Answer 21

sheep sebum

Question 22

eccrine sweat glands

Answer 22

most areas of the skin
watery secretions directly onto skin surface
important for excretion and thermoregulation
some antibacterial action

Question 23

apocrine sweat glands

Answer 23

specific areas- underarm, groin and nipples.
secrete sticky, oily smelly secretions into base of the hair follicle
influence by hormones eg lactation

Question 24

function of nails

Answer 24

protect fingertips and toes enhance sensation sensory receptors require deformation

Question 25

what occurs as the skin ages?

Answer 25

epidermis thins as basal cells arent replaced as fast dermis thins, reduced collagen slower skin repair less sebum= drier epidermis less sweat= impaired cooling less pigmentation

Question 26

function of melanin

Answer 26

to absorb UV light- protecting cells from UV damage

Question 27

function and location of melanocytes

Answer 27

to produce melanin, only found in stratum basale

Question 28

function and location of melanosomes

Answer 28

vesicles to transfer melanin found throughout epidermis ( able to be shed )

Question 29

what causes a mole

Answer 29

cluster of melanocytes- cant be shed

Question 30

what causes a freckle

Answer 30

melanocytes overproducing melanosomes. can be shed

Question 31

vitamin d function, what occurs in its deficiency, and what is required for its synthesis

Answer 31

essential for calcium metabolism and strong bones without it can cause rickets and affect mood UV exposure is required for vitamin D synthesis

Question 32

basal cell carcinoma

Answer 32

common but mostly benign originates in stratum basale spread is rare

Question 33

malignant melanoma

Answer 33

rare but deadly without treatment originates in melanocytes highly spreadable mortality rate dependent on tumour.

Question 34

tattoo

Answer 34

artificial pigmentation deposited into the dermal layer so it isnt shed.

Question 35

free nerve endings where are they, what is their function, what do they respond to?

Answer 35

small swellings at the ends of axons= sensory terminals temp pain movement and pressure itch- response to histamine

Question 36

tactile disks where are they, what is their function, what do they respond to?

Answer 36

free nerve endings in deepest layer of epidermis large disk shaped epidermal cells communicate through seratonin in fingertips, small receptive fields, good two point discrimination sensitive to touch and light pressure texture, shape and edges low frequency vibration (5-15 hz)

Question 37

tactile corpuscles where are they, function, and what they respond to

Answer 37

papillary layer of dermis- particularly hairless skin encapsulated- surrounded by schwann cells and a thin over fiberous connective tissue capsule capsule being deformed= Na entry into nerve terminal= AP senstive to... light pressure delicate touch low frequence vibration (10-50HZ)

Question 38

lamellar corpuscles where are they, function and what they respond to?

Answer 38

deep in dermis and hypodermis single sensory axon terminal within layers of collagen fibres and fibroblasts, layers seperated by intersistual fluid. isolated from stimulu apart from deep pressure also stimulated by vibration as theyre rapidly adapting (250HZ)

Question 39

Bulbous Corpuscles where are they, function and response

Answer 39

dermis and subcutaneous tissue nerve endings intertwined with collagen fibres sustained deep pressure and stretching of skin important for signalling, also found in joint capsules for proprioception

Question 40

what are the 4 heat transfer mechanisms

Answer 40

radiation, convection, conduction, evaporation

Question 41

what causes reduced skin bloodflow?

Answer 41

noradrenaline acting on increased number of a1 recptors on skin smooth muscle gpcr coupled to intracellular 2nd messengers, increasing intracellular Ca= vasoconstriction

Question 42

what causes increased skin bloodflow

Answer 42

reducing sympathetic nervous system activation of a1 receptors= dilation of arteries= increased skin blood flow

Question 43

where does the normal core body temperature sit between?

Answer 43

36.5-37.5

Question 44

when body temp is above set point how does the heat loss centre decrease the temp?

Answer 44

sympathetic nervous system activation of a1 receptors for skin blood vessels= vasodilation increases SNS cholinergic activation of mAchrs on sweat glands= sweating increased respiratory rate

Question 45

when body temp is below set point how does the heat gain centre warm it up

Answer 45

shivering- oscillatory contractions of the agonist and antagonist muscles ATP--> ADP+Pi+movement+heat non shivering thermogenesis increased sympathetic nerve activity= vasoconstriction increase in adrenaline from adrenal medulla increased cellular metabolism (glycogenolysis in liver and muscle) uncoupling of oxidative phosphorylation, fuel goes straight to heat rather then ATP

Question 46

what occurs if an individual is in a cold envrionment for days/weeks

Answer 46

Increase in thyroxine in response to RRH and TSH. increases the basal metabolic rate.

Question 47

in heat terms what is a physiological feedforward example

Answer 47

hairy animals heat conservation by trapping a layer of warm air around skin making you look bigger. this occurs before the body temperature drops