Lecture 1- Anatomy of the skin part 1

Question 1

What’s special about the skin as an organ?

Answer 1

• Largest organ

- Its visible

Question 2

What’s the difference between our skin and that of other animals?

Answer 2

• bare (no hair)

- Sweaty as contains sweat glands

Question 3

What are the functions of the skin and accessory structures? (the are 8)

Answer 3

• Protects underlying tissues and organs against impact, abrasion, fluid loss and chemical attack
• Excrete salts, water, and organic wastes by integumentary glands
• Maintain normal body temperature through either insulation or evaporative cooling, as needed
• Produce melanin, which protects underlying tissues from ultraviolet radiation
• Produce keratin, which protects against abrasion and serves as a water repellent
• Synthesis vitamin D3, a steroid that is subsequently covered to calcitriol, a hormone important to normal calcium metabolism
• Store lipids in adipocytes in the dermis and in adipose tissue in the subcutaneous layer
• Detect touch, pressure, pain and temperature stimuli, and relay that information to the nervous system

Question 4

Cells +extracellular fluid=

Answer 4

Tissues

Question 5

What are the four basic tissue types?

Answer 5

• Epithelial
• Connective
• Muscle
• Nervous

Question 6

What tissue type is the skin made of?

Answer 6

All four

Question 7

What are the three primary layers of the skin?

Answer 7

• epidermis
• dermis
• hypodermis

Question 8

Describe the epidermis layer of skin…

Answer 8

• Stratified barrier
• mostly Keratinocytes (skin cells that have heaps of keratin to help protect skin)
• No circulation (avascular) :means won’t bleed when cut

Question 9

Describe the dermis layer of the skin…

Answer 9

• Protein fibers present for strength - elastin and collagen
• Vascular (nourishes the epidermis) :means if cut will bleed
• Not shed: if a cell dies in the dermis, it gets broken down through the vasculature just like any other cell in the internal part of our body

Question 10

Describe the hypodermis layer of the skin…

Answer 10

Contains adipose tissue (insulation and also important for storing energy)

Question 11

What primary layers of the skin are in the cutaneous membrane?

Answer 11

• Epidermis

- Dermis

Question 12

What primary layer of the skin is in the subcutaneous layer?

Answer 12

Hypodermis

Question 13

What are the two sub parts of the dermis called?

Answer 13

• Papillary layer

- Reticular layer

Question 14

What is in the papillary layer?

Answer 14

Capillaries reach up into papules (curves of boundary between dermis and epidermis)

Question 15

What is the structure/ function of the reticular layer?

Answer 15

Mesh like structure primarily made of collagen which gives skin strength +rigidity

Question 16

What is the the shape of the epidermis/dermis border and why?

Answer 16

• Wavy for increased surface area
• This means higher nutrient diffusion from dermis to epidermis
• Also means stronger so don’t lose layers due to abrasion so easily

Question 17

What are the layers of the epidermis in correct order from outermost to inner? (there are 5)

Answer 17

• Stratum Corneum
• Stratum Lucidum (only found in thick skin)
• Stratum Granulosum
• Stratum Spinosum
• Stratum Basale

Question 18

Describe the Stratum Corneum layer of the epidermis…

Answer 18

• dead, dried out hard cells, without nuclei (are shed)
• lots of keratin
• known as the horny layer

Question 19

Describe the Stratum Granulosum layer of the epidermis…

Answer 19

-contains granules the promote dehydration of the cell
-crosslinking of keratin fibers makes a barrier that
stops anything from outside getting in
-waxy material is secreted into the intercellular spaces
-is the granular layer

Question 20

Describe the Stratum Spinosum layer of the epidermis…

Answer 20

• intercellular bridges called desmosomes link the cells together
• the cells become increasingly flattened as move upwards
• spinous, spiny or prickly layer

Question 21

Describe the Stratum Basale layer of the epidermis…

Answer 21

• columnar (tall) regenerative cells
• as a basal cell divides a daughter cell migrates upwards to replenish the layer above
• is the basal layer

Question 22

What is skin taping?

Answer 22

You can remove the Stratum Corneum (horny layer) of the epidermis

Question 23

What does this phrase mean?
:the epidermis is a keratinocyte conveyor….

And what happens to cells?

Answer 23

Basal cells in the epidermis divide and move outwards to replace cells in horny layer which fall off, therefore every few days skin cells are completely replaced.

As this happen the shape of the cells change from columnar to squamous, they also lose their nucleus and more cross linking and adhesion creates a waterproof layer.

Question 24

What tissue type dominates in the epidermis?

Answer 24

Epithelial tissue

Question 25

What are the three epithelial cell types for both simple and stratified epithelia?

Answer 25

• Squamous (flat)
• Cuboidal (cube)
• Columnar (tall)

Note: all stratified means is that it exists in many layers,
Pseudostratified means it appears to be stratified but instead consists of a single layer of cells. Usually pseudostratified only occurs with columnar cells

Question 26

What epithelial cell type is the epidermis made from?

Answer 26

Stratified squamous epithelium

Question 27

Where do you find thick skin, what does this mean?

Answer 27

• only in two places : palms of hands and soles of feet as this is where extra protection due to wearing away is required
• no hair
• extra epidermal layer (Stratum Lucidum)

Question 28

What happens when skin ages?

Answer 28

• Thin epidermis
• Thin dermis (sagging/wrinkling) due to decreased collagen and so less structural integrity
• Slower skin repair due to decreased blood supply
• Drier epidermis due to less sebum
• Impaired cooling due to less sweat
• Less pigmentation (pale skin, grey hair) due to fewer melanocytes
• Fewer active follicles means altered hair and fat distribution

Question 29

Why does smoking increase skin aging?

Answer 29

• Reactive oxygen damages collagen and elastin

- Vasoconstriction (as a result of nicotine) decreases the circulation in outer skin and thus mimics aging