Lecture 19: Skin Thermoregulation and wound healing

Question 1

what are the 2 types of skin?

Answer 1

Glaborous skin

hair bearing skin

Question 2

what are glamorous skin?

Answer 2

palm and soles

thick epidermis

Question 3

hear bearing skin _____ depending on site

Answer 3

differs

Question 4

Stratified squamous epithelium is constantly _____

Answer 4

growing

Question 5

Stratified squamous epithelium contains ___…

Answer 5

no blood vessels , fed by vessels in the dermis

Question 6

Stratified squamous epithelium skin turnover is …

Answer 6

52-75 days

Question 7

what cells are in the epidermis ?

Answer 7

keratinocytes
Melanocytes
Langerhans Cells

Question 8

epidermis is a barrier for?

Answer 8

water loss and infection

Question 9

epidermis is colonised by?

Answer 9

microorganisms,

e.g. Staphylococcus epidermidis

Question 10

what does a structure of a dermis contain?

Answer 10

blood vessels
Nerves 
hair follicles
smooth muscle
Glands
lymphatic tissue

Question 11

what loose connective tissue is in the dermis?

Answer 11

collagen
elastin
reticular fibers

Question 12

what do Arrector pili muscles

do in the dermis?

Answer 12

attached between hair papilla and epidermis

contract, hair pulled upright – goose bumps

Question 13

what do sebaceous glands

do in the dermis?

Answer 13

sebum (lipids and waxy substances)

lubrication, water-proofing, softening, bactericidal

Question 14

what glands does the dermis have?

Answer 14

sebaceous glands

sweat glands

Question 15

what is the outermost layer of the dermis?

Answer 15

papillary layer

Question 16

papillary layer ….

Answer 16

extends into the epidermis 
supply epidermis with nutrients
papillary ridges ( finger and foot prints)

Question 17

what’s a dense layer the dermis has?

Answer 17

reticular layer

Question 18

reticular layer facts…

Answer 18

continuous with the hypodermis
contains the bulk of the structures 
e.g. sweat glands
irregularly arranged fibres
resists stretching

Question 19

where is the hypodermis located?

Answer 19

below dermis

Question 20

where is the hypodermis made from?

Answer 20

Loose connective tissue and elastin

Question 21

what does the hypodermis do?

Answer 21

Attaches skin to bone and muscle

Supplies skin with blood vessels and sympathetic nerves

Question 22

what are three cells found in the hypodermis?

Answer 22

Fibroblasts, macrophages and adipocyte

Question 23

How do we get pigment?

Answer 23

melanin form melanocytes

melanosomes transfer to keratinocytes

Question 24

what does melanin protect us from?

Answer 24

UV light

Question 25

what can the skin absorb ?

Answer 25

Oxygen, nitrogen and carbon dioxide Drugs can be administered through the skin important site of transport in many other organisms

Question 26

what can the skin store and synthesise?

Answer 26

storage centre for lipids and water | synthesis of vitamin D by action of UV

Question 27

what can the skin excrete?

Answer 27

urea in sweat Sodium chloride in sweat Lactic acid in sweat

Question 28

what's the average body temperature supposed to be ?

Answer 28

36.5 C to 37.5 C

Question 29

what does body temp have to be maintained between ?

Answer 29

+- 0.6 c

Question 30

what is skin temperature dependent on ?

Answer 30

dependent on outside temp

Question 31

what is body temperature controlled by?

Answer 31

regulating the balance between heat production and heat loss

Question 32

what's Basal Metabolic Rate | ?

Answer 32

Rate of metabolism of all cells

Question 33

what extra metabolic rate?

Answer 33

``` Muscle contractions Activity in deep organs Hormone Adrenaline, noradrenaline and sympathetic stimulation of cells Digesion, absorption and storage of food ```

Question 34

How does heat loss happen?

Answer 34

Transfer of heat from core to skin | via blood flow

Question 35

order of skin formation

Answer 35

epidermis papillary loops dermis papillary plexus

Question 36

How does heat from skin go to surroundings?

Answer 36

radiation conduction convection evaporation

Question 37

what percent of heat is lost through radiation and how?

Answer 37

60% (nude) | lost as infrared heat rays

Question 38

where is heat from conduction lost too and what percent?

Answer 38

3% to solids | 15% to air

Question 39

How Is heat lost through convection?

Answer 39

hot air to rises | increases with wind velocity

Question 40

In what ways does our body evaporate heat and how much?

Answer 40

sweating | 600-700ml skin and lungs a day

Question 41

what's lost in sweat ?

Answer 41

sodium chloride 15-30g

Question 42

sweating involved stimulation of the _____

Answer 42

hypothalamus

Question 43

what does the hypothalamus contain?

Answer 43

heat sensitive neurons - anterior | 1/3 cold sensitive

Question 44

when temp increases how does the firing rate of the hypothalamus increase?

Answer 44

2-10 folds

Question 45

where are thermoreceptors found?

Answer 45

skin and deep tissue

Question 46

what thermoreceptors signal to the posterior hypothalamus?

Answer 46

peripheral tissues

Question 47

if its too hot the hypothalamus will start...

Answer 47

Vasodilation Sweating Pilorelaxation Inhibition of shivering Inhibition of chemical thermogenesis

Question 48

if its too cold the hypothalamus will start...

Answer 48

``` Vasoconstriction Piloerection Shivering chemical thermogenesis Increased thyroxine ```

Question 49

what happens when you have a epidermal wound?

Answer 49

Basal epidermal cells leave basal membrane Enlarge and migrate Contact inhibition Other cells divide to replace those moving Continues until wound is resurfaced Occurs within 24-48 hours of injury

Question 50

what are the four phases of wound healing?

Answer 50

inflammation migration poliferation maturation

Question 51

How does a wound heal ?

Answer 51

1. bv dilate, phagocytes invade 2. scab, epithelial cells and fibroblasts migrate, fb synthesis collagen and glycoproteins 3. growth of epithelial cells an bv, deposition of collagen fibres 4. scab gone, cf organised, bv normal

Question 52

what are some problems that can happen when a wound is healing?

Answer 52

Ischaemia Dry wound environment Infection/foreign body poor nutrition

Question 53

what is a scar formed form?

Answer 53

collagen and matrix materials

Question 54

what's the difference between scard skin and normal skin?

Answer 54

vessels than normal skin Lack of hair, sensory neurones or skin glands

Question 55

whats keloid scaring?

Answer 55

Scar extends past the original wound and into surrounding tissues More common in darker skins

Question 56

whats hypertrophic scarring?

Answer 56

Raised scar Remains within original wound boundary

Question 57

what cells does skin cancer involve?

Answer 57

squamous cell, basal cell, melanocyte

Question 58

what skin disorder is Psoriasis?

Answer 58

very rapid skin cell turnover cells build up on the skin forms thick, flaky patches called plaques

Question 59

what does eczema cause?

Answer 59

intense itching | inflammation occurs