wk 9- the skin

Question 1

what is the largest organ of the body?

Answer 1

skin

Question 2

what layers make up the skin? 2

Answer 2

the most superificial layer is the epidermis and
the thicker, deeper layer, the dermis

Question 3

what is the epidermis comprised of?

Answer 3

containing keratinized and stratified squares epithelium. It has four to five layers of epithelial cells (keratinocytes, melanocytes, dendritic cells, tactile cells) depending on if it is thick or thin skin. the epidermis is avascular.

(new cells migrate form basal layer to the apical surface and slough off over time)

Question 4

what is the dermal layer comprised of?

Answer 4

contains extensive capillary beds, lymphatic vessels, nerve cells as well as accessory structures like hair follicles, sebaceous glands, sudoriferous glands.

Question 5

within the skin there are 2 types of structures

Answer 5

the cutaneous membrane
accessory structures

Question 6

desquamation is?

Answer 6

shedding or sloughing off of keratinized dead skin

Question 7

what is below the dermis layer?

Answer 7

superficial fascia (hypodermis/subcutaneous layer)
connects the skin to underlying fascia of bones and muscles. not a true layer of skin however
consists of well-vasuclarised, loose, areolar connective tissue and adipose tissue which functions as a mode of fat storage and provides insulation and cushioning for the skin.

Question 8

dermis has how many layers / strata? and what are they?

Answer 8

2 layers of connective tissue
papillary layer- thin, superficial layer comprised of areolar connective tissue which forms dermal papillae to connect to the superficial epidermal layer
reticular layer- comprises of 80% of dermis and is comprised of dense fibrous connective tissue

Question 9

what % of total body mass does the skin have?

Answer 9

16

Question 10

what surface area does the skin have

Answer 10

approx 2 square metres

Question 11

what are keratinocytes in epidermis layer?

Answer 11

the most abundant cell type in the skin. these cells produce the protein keratin and continuously slough off as they become superficial from basal to apical layer.

Question 12

what are melanocytes in the epidermis?

Answer 12

the pigment producing cells of the skin. located in the stratum basale and protect against UV damage

Question 13

what are dendritic cells in the epidermis?

Answer 13

are phagocytic immune cells located throughout the layers of the skin and are responsible for engulfing debris and infectious agents

Question 14

what are tactile Markel cells?

Answer 14

the sensory cells of the skin, that detect pressure, temperature and vibration

Question 15

what is the difference between thick and thin skin?

Answer 15

thick skin is located on anatomical areas subjected to abrasion and herring forces (palms of hands, soles of feet and is comprised of 5 strata (lacks hair and sebaceous glands)

think skin lacks a stratum lucidum and is only 4 strata.

Question 16

skin color and the types of pigments

Answer 16

melanin - brown pigment (melanocytes)
carotene- orange pigment
hemoglobin- red pigment

Question 17

what is the relationship between pigmentation and location?

Answer 17

concentration of melanin is increased in populations living close to the equator for protective purposes against UV-DNA damage (reasons for reduced skin cancer rates in darker skin)

Question 18

what are dermal modifications and what do they form? what are examples

Answer 18

include friction ridges, cleavage lines, flexure lines which provide individual identity and enhanced flexibility to the skin

1. fingerprinting- friction ridges
2. surgical incsions- cleavage lines
3. movement - flexure lines

Question 19

locations of needle injection 4

Answer 19

intradermal- penetrate epidermis and deposit contents into dermal layers
intravenous- penetrate epidermis and dermis and deposit contents into a blood vessel (vein) in dermal layer
subcutaneous- penetrate epidermis and dermis and deposit content into the superficial fascia layer
intramuscular- penetrate the epidermis and dermis and superficial fascia and deposit contentions in the muscle layer below.

Question 20

hair- what is it comprised of, what are its functions over the body in specific areas and where is it absent?

Answer 20

hair is comprised of filamentous strands and dead keratinized cells (hard keratin and is pigmented by melanocytes)

scalp- reduces heat loss, sun damage and trauma

eyelashes- shield eyes against matter and objects

nose hairs- filter air to remove matter

body hair- sensory information, temp control

absent from thick skin.

Question 21

nails what are they made of and their function?

Answer 21

hard keratin
function is to protect the digits and add to dexterity

Question 22

sweat glands function

Answer 22

produce 2 main secretions
1. perspiration (eccrine glands)- offloading excess sodium chloride and thermoregulate via evaporation
2. pheromones (apocrine glands)

Question 23

sebaceous glands function

Answer 23

produce sebum - secreted into hair follicle to act as lubricant and provide antimicrobial activity (disrupt the skin barrier)

absent in think skin

Question 24

functions of integumentary system 6

Answer 24

-physical barrier for protection against external agents
- temperature regulation by the rich vasculature of dermis where vasodilation or constriction can position blood vessels superficially or deep to retain or lose heat and perspiration/evaporation.
-blood reservoir for shunting to critical organs
-excretion of excess sodium chloride
-cutaneous sensation gives feedback from thermoreceptors (hot cold) and mechanoreceptors (pressure)and nociceptors (pain)
-metabolic functions such as vitamin D absorption

Question 25

what are protective functions of endogenous microbiota of the skin? 3

Answer 25

1. competitive inhibition of opportunistic pathogens
2. fatty acid metabolism
3. immune priming

Question 26

examples of endogenous microbiota

Answer 26

staphyloccus
corynebacterium
propionibacterium

Question 27

examples of exogenous microbiota

Answer 27

other peoples endogenous microbiota
infection

environment:
soil spores
clostridium

Question 28

can the epidermis be a source of infectious agents in endogenous infection?

Answer 28

yes

Question 28

can the epidermis be a source of infectious agents in endogenous infection?

Answer 28

yes

Question 29

what are common bacterial infectious agents associated with skin infections?

Answer 29

• gram positive staphylococci (staphlocccus aureus and epidermidis)
  -steptococci (streptococcus pyogenes)
  -gram=positive, endospore forming bacilli from the clostridium genus

Question 30

what environment do fungi like to grow?

Answer 30

cool, moist locations. typically the extremities because its away from the core body temp

Question 31

what are the three main fungi skin infections in humans?

Answer 31

-epidermophyton
-microsporum
-trichophyton

and also yeast from genus candida

Question 32

what can viral infectious agents do to the skin?

Answer 32

-infect and result in dermal lesions (like HPV and Herpres)
-systemic viral infectious that present skin signs like rashes, lesions, etc

Question 33

what parasites can attach the skin?

Answer 33

-mites (sarcoptes scabiei)
-lice (pediculus)

Question 34

how are skin infections diagnosed?

Answer 34

clinical signs and symptoms including localised inflammation, rashes, lesions and the production of wound exudate. Once diagnosed, wounds are assessed to determine the appropriate course of symptomatic and if appropriate, antimicrobial therapy.

Question 35

management of wounds include what? 4

Answer 35

drainage- used to reduce organic matter that can support the growth/persistance of infectious agents
irrigation- removes debris, increase visualization and maintains hydration for healing
debridement- reduces the bioburden and associated toxins of infectious agents in the wound (also removes necrotic tissue)
dressing- ensures that opportunistic infectious agents cannot access the wound bed.

Question 36

antimicrobial therapy for wounds include

Answer 36

locally (topical application) or systematically (oral/IV)

which depends on host susceptibility, the agent and the site of infection
(host, microbe, environment)

Question 37

what impairs the optimal local dosing of antimicrobial agents?

Answer 37

purulent exudate

Question 38

stages of wound healing 3

Answer 38

1. Haemostasis and inflammation (Inflammatory phase) where the bleeding is regulated and inflammatory mediators recruited.
2. Proliferation and migration (Repair or granulation phase) where the wound is closed through production of new cells and tissue.
3. Maturation and remodeling (Regeneration phase) where there is an attempt to restore the original tissue architecture.