Lecture 23A - Topical Infections

Question 1

How do you calculate the area of your skin?

Answer 1

0.007184 x weight (kg)^0.425 x height (cm)0.725

Question 2

What is the outer layer of the skin?

Answer 2

the waterproof cornified out layer of keratin proteins and lipids, made by epidermis

Question 3

What is the outermost section of the skin called?

Answer 3

the epidermis

Question 4

What does the epidermis include?

Answer 4

the waterproof layer and cells from which the surface coat of skin is derived

Question 5

What is the dermis?

Answer 5

a supporting layer with blood and lymphatic vessels, sensory nerve ending, hair roots depending on the type of skin and sweat glands

Question 6

Where can sweat gland secrete into?

Answer 6

a sub-surface enclosed space (apocrine) or directly onto the skin surface (eccrine)

Question 7

What is the hypodermis?

Answer 7

a fatty layer which insulates the body from heat loss and fluid loss and protects muscle and organ tissue beneath

Question 8

What are eccrine sweat glands?

Answer 8

secrete directly onto skin surface

thermoregulation, salt excretion, antibacterials

Question 9

What are apocrine sweat glands?

Answer 9

bud fatty secretions in vesicles off into enclosed areas like hair follicles

Question 10

Where are apocrine sweat glands especially found?

Answer 10

in axilla and pubic areas - pheromones

Question 11

Where are hair follicles housed?

Answer 11

A specialised mini organ called the psilosebaceous unit which lies in the dermis

Question 12

What does the psilosebaceous unit contain?

Answer 12

a muscle which can be used to pull the lower end of the hair shaft towards a verticle position and make your hair stand on end

Question 13

What does the psilosebaceous unit secrete?

Answer 13

sebum

Question 14

What is sebum?

Answer 14

an oily, waxy liquid of low pH

Question 15

What does sebum do?

Answer 15

can be antibacterial, helps lubricate the skin, waterproof it in cold wet conditions and with different lipid composition helps slow the rate of evaporation of sweat in hot conditions which helps flid retention

Question 16

How is sebum antibacterial?

Answer 16

it contains antibacterial proteins but can also be antibacterial because of its pH

Question 17

What can blockage of the psilosebaceous unit cause?

Answer 17

acne amongst a variety of other conditions

Question 18

How often does skin renew itself?

Answer 18

every 4 weeks

Question 19

What are the components of the epidermis?

Answer 19

dead anuclear squammes layer

granual layer with keratin vacuoles

spindle layer with early differentiation

germinal layer

Question 20

What is the cornified envelope?

Answer 20

in the dead layer

physical barrier and immune modulation

Question 21

What are keratin filaments?

Answer 21

provide structural integrity in the granular layer

SRC signaling

Question 22

What are desmosomes and adherens junctions?

Answer 22

provide intercellular adhesion and differentiation in the spinel layer

Question 23

What are integrins?

Answer 23

ECM adhesion

stem cell maintenance in germinal layer

Question 24

What other cells are in the spindle layer?

Answer 24

langerhans antigen presenting cells

which are tissue specific macrophages

Question 25

Where does generation of skin begin?

Answer 25

in the lowest level, the germinal layer

Question 26

What happens in the germinal layer?

Answer 26

keratinocytes divide and begin their transition through the 3 layers above them to the outer surface of the skin

Question 27

What happens as keratinocytes migrate upwards?

Answer 27

they differentiate and mature

Question 28

What helps to drive migration of keratiocytes?

Answer 28

a small potential difference of tens of millivolts across the epidermis

Question 29

What do cells in the spindle secrete?

Answer 29

proteins to aid adherence between cells so that a uniform sheet of cells is created

Question 30

What do cells in the granular layer produce?

Answer 30

keratin filaments, which give mechanical strength to the maturing skin layer

Question 31

What other cells are found in the germinal layer?

Answer 31

melanocytes

Question 32

What happens to the cells in the sqammes layer?

Answer 32

they have lost their nucleus and are dead

Question 33

What creates the tough waterproof barrier?

Answer 33

the tight bonding between cells in the sheet and abudance of keratin fibres and lipid

Question 34

What mediates the sense of touch?

Answer 34

innervation of glabrous (non-hairy) skin by fast conducting, low threshold mechano-receptors (LTMRs)

Question 35

What is glabrous skin?

Answer 35

most sensitive for and to touch hands, feet, genitalia, lips, cheeks very specialised ski areas

Question 36

What is glabrous skin innervated by?

Answer 36

A-beta LTMRs including Abeta SA1-LMTRs terminating in merkel cells

Question 37

What responds to light pressure?

Answer 37

meissner corpuscles

Question 38

What responds to deeper pressure?

Answer 38

pacinian corpuscles

Question 39

What can sustained light pressure be detected by?

Answer 39

merkel cells

Question 40

What is skin on the back like?

Answer 40

less densely innervated and it is more difficult to discriminate between two closely positioned pressure points

Question 41

What can skin sense?

Answer 41

vibration and pressure

Question 42

What does skin respond do?

Answer 42

temperature, touch, pain, itch

Question 43

Where are low threshold mechanoreceptors found?

Answer 43

close to the skin surface, have narrower receptive fields

Question 44

What does innervation of hair shafts on hairy skin in rodents allow?

Answer 44

enables them to be used a sense organs

Question 45

What is innervation of hairy skin?

Answer 45

less dense and therefore less sensitive to touch, conveys affective sensations

Question 46

What is hairy skin in rodents innervated by?

Answer 46

distinct combinations of LTMRs

Question 47

Where are touch domes of merkel cells found in rodents?

Answer 47

above the level of the sebaceous glands of guard hair follicles

Question 48

What are guard hairs innervated by?

Answer 48

A-beta RA-LTMR lanceolate endings

Question 49

What are awl/auchene hairs innervated by?

Answer 49

three tyes of lanceolate ending LTMRs Aβ RA-LTMRs, Aδ-LTMRs, and C-LTM

Question 50

What are zigzag hairs innervated by?

Answer 50

Aδ-LTMRs and C-LTMRs

Question 51

What do circumferential endings encircle?

Answer 51

the longitudinal lanceolate endings of all three types of hair follicles

Question 52

Where is glabrous skin found?

Answer 52

on the palms and soles of the feet

Question 53

What is glabrous skin rich in?

Answer 53

sensory nerve endings

Question 54

Where is hair skin found?

Answer 54

major part of the body surface, but quite varied back, scalp, eyebrows

Question 55

Where is thick/flexible skin found?

Answer 55

knees, elbows, soles of the feet

Question 56

Why is the thickness of skin important?

Answer 56

some drugs are applied as ointments or dermal patches where the drug is absorbed by the skin

Question 57

What is the microenvironment?

Answer 57

different skin regions vary greatly in their appearance and in the amounts of moisture and oiliness they typically carry temperature and pH vary also

Question 58

Functions of the skin?

Answer 58

a physical barrier to noxious agents and entry of pathogens immunological barrier to ingress of pathogenic organisms assist retention of heat and regulation of temp retains moisture and maintains osmotic balance i the body sensory organ excretion, salt balance, secretion of antibacterial peptides and pheromones vit D production protection from UV

Question 59

What can widespread burns remove?

Answer 59

the skins role in osmoregulation

Question 60

What is a life threatening complication of burns?

Answer 60

fluid loss which can be followed by circulatory collapse