Skin Anatomy and Function

Question 1

Skin is divided into two fundamental types

Answer 1

Glabrous (hairless)

Nonglabrous (hair bearing)

Question 2

Primary feature of glabarous is what

Answer 2

The presence of arteriovenous anastomosis

Allows for shunting of blood from the periphery to the core during exposure to cold

Question 3

Skin is home to what type of cells

Answer 3

Langerhan

Question 4

Langerhan cells are considered to be what

Answer 4

antigen presenting cells

they find pathogens that have invaded the dermis and present these to lymphocytes for destruction

Question 5

Largest sensory organ

Answer 5

skin

Question 6

Vit D is needed for what

Answer 6

Bone health
Immune function
Cell growth
neuromuscular health

Question 7

What triggers vit D synthesis

Answer 7

UV

UVB

Question 8

Vit D synthesis

Answer 8

Skin contains 7-dehyfroxycholesterol which converts to Vit D3 when exposed to sunlight
THe inactive compound is then acted on by the liver and then the kidney to transform it into vit D

Question 9

Main layers of the skin

Answer 9

Epidermis
Dermis
Subcutaneous tissue

Question 10

Epidermis

Answer 10

outer layer of skin
composed of 5 layres
thickness varies
continues to thicken into 40s and then starts to thin

Question 11

Epidermis - turnover

Answer 11

14 to 21 days

Question 12

Epidermis - primary cell type

Answer 12

keratinocyte

Question 13

Dermis

Answer 13

made of 2 layers

thickest component of the skin

Question 14

Dermis - primary cell type

Answer 14

fibroblast, also contains mast cells, macrophages, lymphocytes

Question 15

Dermis - Extracellular matrix of the dermis is primarily

Answer 15

collagen (the rest is elastin)

Question 16

Dermis - what percent is collagen and why

Answer 16

90% - improves integrity, anchoring, and general skin strength

Question 17

Subcutaneous tissue -

Answer 17

adipose cells

Question 18

Keratinocytes

Answer 18

Squamous cells

Synthesize keratin

Question 19

Keratin

Answer 19

a protein that is the primary structural component of skin, hair, and nails

Question 20

Keratinocytes - migrate from where to where

Answer 20

from the stratum basale through to the stratum corneum

Takes about 28 days and at this point thery are anucleated and dead - they then act as a moisture barrier

Question 21

Desmosomes

Answer 21

a type of junctional connection between keratinocytes holding them together
They do not exist in cancers - that is why cells are more able to metastasize

Question 22

Melanocytes

Answer 22

account for the pigmentation of skin

Dendritic cells that supply melanin, via melanosomes, to the cells around them

Question 23

Melanocytes are found where

Answer 23

Found in basal layer of epidermis within hair follicles

Question 24

Melanocytes - Account for what percent of cells in epidermis

Answer 24

5%

1 melanocyte to every 35 keratinocytes

Question 25

Melanomas originate from

Answer 25

melanocytes

Question 26

Skin tone and pigmentation are related to

Answer 26

the size and amount of melanosomes | the amount of melanin is greater in darker pigmented skin (the number of melanocytes is the same though)

Question 27

Langerhan cells - what are they

Answer 27

part of immune system They are mobilized by antigens produced by various substances that make contact with the skin Cell takes up the antigen and moves it into the lymph system

Question 28

What is a postulated theory about Langerhan cells

Answer 28

A dysfunction of their migration may be involved in development of psoriasis

Question 29

Merkel cells are part of the

Answer 29

sensory system

Question 30

Merkel cells are located where

Answer 30

in the basal portion of the epidermis | connect to the sensory nerve fiber located in the dermis layers of the skin

Question 31

Merkel cells are considered to be

Answer 31

slow adapting touch receptors | often grouped in clusters - they are the site of a rare aggressive cancer called merkel cell carcinoma

Question 32

Basement membrane does what

Answer 32

Anchors the erpidermis and dermis via hemidesmosomes

Question 33

Basement membrane is primarily composed of

Answer 33

collagen fibers | Blisters generate secondary to frictional forces at this level!

Question 34

Basement membrane - what is located here

Answer 34

Terminal nerve endings - unmyelinated C fibers (slow pain) | Myelinated A delta fibers (sharp acute pain)

Question 35

unmyelinated C fibers respond to

Answer 35

mechanical, thermal and chemical induced pain

Question 36

Myelinated A delta fibers respond to

Answer 36

sharp acute pain | respond to pressure and cold

Question 37

Aging does what to basement membrane

Answer 37

flattens and dec level of contact between the dermis and epidermis - this is what the basement membrane is responsible for controlling - increases the risk of separation (skin tears) Genetic skin disorders sometimes occur in this layer as well

Question 38

What is the thickest part of the skin

Answer 38

Reticular layer of the dermis

Question 39

Upper part of the dermis AKA

Answer 39

papillary layer

Question 40

Lower part of the dermis is AKA

Answer 40

reticular layer

Question 41

Papillary dermis

Answer 41

Collagen and reticular fibers loose CT Thin, very vascular, well hydrated

Question 42

Papillary dermis projects into

Answer 42

the epidermis giving unique patterns to the skin (fingerprints)

Question 43

Papillary dermis - primary function

Answer 43

cushion

Question 44

Reticular layer -

Answer 44

accounts for 80% of the thickness of the dermis Highly structured irregular dense CT Contains dermal appendages

Question 45

Reticular layer - functions

Answer 45

shock absorber

Question 46

Subcutaneous tissue AKA

Answer 46

hypodermis

Question 47

Subcutanous tissue - thickness

Answer 47

``` Varies according to location mostly loose CT (aerolar tissue) Fat cells (adipocytes) - cushion, storage, insulation Collagen - fascia Blood vessels ```

Question 48

Dermal appendages - sensory nerves

Answer 48

Meissner, Pacini, and Rafiini Non of these extend into epidermis Free nerve endings do extend into the lower epidermis - they amplify pain and temp signals

Question 49

Dermal appendages - sebaceous glands

Answer 49

Exocrine glands not found in palms, soles, dorsum of feet Provide - moisture with their oily, waxy secretion of sebum Associated with hair follicles - allows sebum to travel along follicles to reach skin surface

Question 50

Dermis appendages - hair follicle - function

Answer 50

Lined with erpidermal cells that go deep into the dermis Offer source of epithelization in partial thickness injuries Provide route for flow of sebum

Question 51

Dermis appendages - sweat gland - two types

Answer 51

Eccrine | Appocrine

Question 52

Dermis appendages - sweat gland - eccrine

Answer 52

ALL areas of skin deposit water/Na mixture onto skin surface Acts as temp regulator in warmer environments

Question 53

Dermis appendages - sweat gland - apocrine

Answer 53

Found in axilla, perineal and ubic areas, genitalia, nasal flares, eyelids Inactive until puberty Excrete protein rich secretions into hair follicles in that area Odorless until microbial activity and then will smell