Biology of the Skin

Question 1

What the three layers of the skin?

Answer 1

Epidermis, Dermis, Subcutis

Question 2

Epidermis is primarily composed of what type of cell>

Answer 2

Keratinocytes

Also some melanocytes, Langerhans cells, Merkel cells

Question 3

The Dermis is primarily composed of what types of cells

Answer 3

Fibroblasts, collagen, Elastin

Also contains blood vessels and nerve endings

Question 4

The subcutis is primarily composed of

Answer 4

Fat

Also some blood vessels and fibrous septae

Question 5

Primary function of the epidermis

Answer 5

Primarily for wound healing and barrier function

Question 6

Dermis and subcitis

Answer 6

Structural support and innervation

Question 7

Epidermis sheds itself every 28 days

Answer 7

truth

Question 8

Epidermis consists of how many sublayers?

Answer 8

4
They are:
Stratum Corneum (top layer)
Stratum granulosum
Stratum spinosum
Stratum basale

Question 9

Stratum basale contains

Answer 9

stem cells, Basal cells adhere to the dermis via hemidesmosomes

Question 10

What occurs in the corpus spinosum

Answer 10

Cells stop dividing and commence terminal differentiation.

Develop lipids important in barrier function.

Question 11

What makes the corpus spinosum spiny?

Answer 11

Desmosomes linking Keratin cells.

Question 12

What is fillaggrin

Answer 12

Present in the stratum corneum, helps keep water inside cells.
Keratins combine with filaggrin into macrofibrils that help create a protective barrier

Question 13

Brick and mortar analogy

Answer 13

Stratum corneum is a brick wall. The keratinocytes filled with keratin and filaggrin make the bricks and the mortar is a lipid mixture surrounding the keratinocytes providing a water barrier.

Question 14

The lipids in the brick and mortar analogy come from where?

Answer 14

lamellar granules

Question 15

Keratin contains what that makes it smell bad when burnt?

Answer 15

Sulfur containing cysteine

Question 16

What are melanocytes

Answer 16

pigment producing cells. There is about one melanocyte for every 10 keratinocytes

Question 17

What are Langerhans cells

Answer 17

Dendritic cells in the mid-epidermis. They recognize abnormal antigens in the skin, take them in, process them, present them

Question 18

Primary cell in the dermis

Answer 18

Fibroblast

Question 19

Fibroblasts are responsible for

Answer 19

Synthesis and degradation of connective tissue proteins like collagen, elastin, glycosaminoglycans, other glycoproteins.
Injury to skin triggers mitosis of fibroblasts.
They are responsible for would healing and scar formation

Question 20

Mast cells

Answer 20

specialized cells rich in heparin and histamine

Question 21

Mast cells release heparin and histamine when?

Answer 21

When they are triggered by injury or binding to IgE antibodies during allergic reaction

Question 22

What is a pilosebaceous unit

Answer 22

The “hair/oil” unit. Contains a hair follicle, oil gland, apocrine sweat gland( only if in the axilla and anogenital region) and arrector pili muscle

Question 23

Eccrine sweat glands

Answer 23

True sweat glands, open thoughout the body, not associated with a hair follicle

Question 24

What is the subcutis

Answer 24

a fat layer that separates the dermis from underlying structures like the fascia, muscles, organs.

Question 25

What is the role of apoptosis in the epidermis

Answer 25

Normal response to sundamaged cells. Sundamaged keratinocytes are called sunburn cells. Failure to delete these damaged cells can be skin cancer.

Question 26

Epidermolysis Bullosa Simplex is a disease caused by a genetic mutation in what

Answer 26

Keratin 5/14

Question 27

What is a Nevus?

Answer 27

A mole…it is just a benign collection of melanocytes

Question 28

What is melanoma

Answer 28

A malignant collection of melanocytes