Final review

Question 0

Name the thick skin layers from the internal junction of dermis to the external surface layers (5):

a.) Which of these layers is not found on thin skin?

Answer 0

1. ) Stratum basale or stratum germinativum
2. ) Stratum spinosum
3. ) Stratum granulosum
4. ) Stratum lucidum
5. ) Stratum corneum
   * Mnemonic: BullShit, Grades are LUC (Lu Co)*

a. ) Stratum Lucidum (L = lost)
p. 11-2, larger on 11-3

Question 1

1. ) How to distinguish between epidermis and dermis, in general?
2. ) On thick skin specifically?
3. ) What characterizes thick skin (2)?

Answer 1

1. ) Epidermis stains more dark than dermis because it is highly cellular.
2. ) The junction is irregular and wavy
3. ) Heightened epidermal region, no hair.

Question 2

How to easily distinguish two layers from the rest? Why do they have this feature?

Answer 2

The stratum LUCIDUM and CORNEUM LACK NUCLEI – because only the deepest layers are metabolically active, while the surface layers have ceased functioning and form a protective layer of KERATIN.

• LACK = LUC (LUci Co)*
  p. 11-2 –> Readily seen on p.11-5

Question 3

1. ) What is the name of the outermost keratinized layer of skin?
2. ) How to identify the next most superficial layer?

Answer 3

1. ) Stratum corneum

2. ) Stratum lucidum –> a CLEAR line of cells

Question 4

1. ) What type of epithelium and cells comprises the MAJORITY of the epidermis?
2. ) Which layer are they in?

Answer 4

1. ) Mainly stratified squamous keratinized epithelium composed of cells called KERATINOCYTES.
2. ) Stratum granulosum

Question 5

1. ) What layer of epidermis lies between the basal layer and the stratum granulosum?
2. ) What is their unique feature? Describe

Answer 5

1. ) Stratum spinosum
2. ) Desmosomes that form ADHERENT JUNCTIONS between the keratinocytes.
   p. 11-3

Question 6

1. ) Which cells of the epidermis divide and mature into the upper layer cells?
2. ) What supplies nutrients to the epidermis?

Answer 6

1. ) Keratinocytes of the stratum basale/germinativum ) hence, GERMinativum.
2. ) Capillaries located in invaginations of the DERMIS called DERMAL PAPILLAE
   p. 11-3

Question 7

On low magnification, the dermis appears as a ________ region. What lies below?

Answer 7

Broad fibrillar region. Hypodermis lies below.

p.11-4

Question 8

In what skin layers are sweat glands visible?

Answer 8

Both dermis and epidermis

p.11-4

Question 9

The cell of the stratum basale are more _____ or ______ than those of the upper layer.

Answer 9

More cuboidal, or more elongated

Question 10

Melanocytes of the skin are visible immediately adjacent to the ______ in which layer?

Answer 10

Adjacent to the DERMIS in the stratum basale/germinativum

Question 11

Cells of the stratum germinativum rest on a ______.

Answer 11

thin basement membrane that separates them from the underlying dermis.
p.11-6

Question 12

The ____ in the _____ undergo mitosis and are the germinal population for the cells in the upper layer.

Answer 12

The KERATINOCYTES (not to be mistaken with MELANOCYTES) in the STRATUM BASALE/GERMINATIVUM
p.11-6

Question 13

The keratinocytes are held together by ______, and contact the basement membrane via ________ ( ________ )

Answer 13

• Held together DESMOSOMES
• Contact via HEMIDESMOSOMES (Half-desmosomes)

-p.11-6

Question 14

1. ) In addition to keratinocytes and melanocytes, what other two types of cells are present in the epidermis?
2. ) How to distinguish them?

Answer 14

1. ) Langerhans cell: stellate cell with characteristic cytoplasmic granules. Thought to be antigen-presenting immune response cells.
2. ) Merkel Cells: Associated with free nerve endings and may be sensory receptor cells.
   * They are not distinguishable with light microscope by routine staining*
   - p.11-6

Question 15

The large clear cells in the stratum basale/germinativum are _______. What do they produce?

Answer 15

Melanocytes: Synthesize melanin and package it in membrane-bound vesicles called MELANOSOMES
p.11-6

Question 16

What is melanin used for?

Answer 16

Produced by melanocytes are TRANSFERRED TO KERATINOCYTES to protect their nuclear DNA from UV radiation.
p.11-8

Question 17

What do melanocytes look like in routinely stained sections? Where are they typically located?

Answer 17

Large, rounded, clear cells (usually less pigment than keratinocytes) with elongated cytoplasmic processes/dendrites that extend THROUGH THE LOWER TWO EPIDERMAL LAYERS. Located in the STRATUM BASALE/GERMIATIVUM. Sometimes situated between epithelial cells in the basement membrane.
p.11-8

Question 18

What is skin color a function of?

Answer 18

Several factors, including the number and stability of melanosomes in the keratinocytes.
p.11-8

Question 19

Melanocyte cell bodies are confined to the ____, but their _____ reach into the ______.

Answer 19

Confined to the STRATUM BASALE/GERMINATIVUM, but their CYTOPLASMIC EXTENSIONS reach into the STRATUM SPINOSUM.
p.11-8

Question 20

1. ) Describe the appearance of keratinocytes as the appear in the stratum spinosum
2. ) Then how they appear as they pass through the stratum spinosum to the next layer….which is?

Answer 20

1. ) Large and appear to have extensions of the cytoplasm from one to another. The extensions are spot desmosomes: Tightly adherent contact regions between two keratinocytes.
2. ) As the pass through the stratum spinosum they become more flattened as they approach the next layer, the STRATUM GRANULOSUM.

Question 21

What is the origin of the name “stratum spinosum” This will help me identify it

Answer 21

The alternation of white and eosin-stained material imparts a spiny, or ladder-like appearance to this area of epidermis, hence the name stratum SPINosum.
p.11-10

Question 22

The first step in melanin production is catalyzed by ______, a transmembrane enzyme in ______ -derived vesicles. What are the intermediate structure?

Answer 22

Catalyzed by TYROSINASE, a transmembrane enzyme in GOLIGI-DERIVED vesicles.
Intermediates: DOPA (tyrosine-derived) –> Melanosome II –> Melanosome III
p.368 Junq

Question 23

1. ) Langerhans cells are ______ -derived ______ cells that reside in the ______.
2. ) _______ and antigen-presenting, they express a ______ surface antigen.
3. ) Describe their nuclei
4. ) They have unique cytoplasmic inclusions known as ______. What do they look like?

Answer 23

1. ) Monocyte-derived dendritic cells that reside in the EPIDERMIS.
2. ) Phagocytotic, they express a CD1a cell surface antigen.
3. ) A single, INDENTED nuclei
4. ) Birbeck granules: Look like tennis rackets on electron microscopy.
   p. 473 Netter

Question 24

1. ) What are the constituents of the epidermis basal lamina? 2. ) Deep reticular lamina?

Answer 24

1. ) Type IV collagen, laminin, fibronectin, and proteglycans. 2. ) Type 1 collagen fibers p. 471 netter

Question 25

1. ) Where are Merkel cells most abundant? Why? | 2. ) What common other skin cell do they share an originating stem cell with?

Answer 25

1. ) Highly sensitive skin, e.g. fingertips and at base of some hair follicles. 2. ) Keratinocytes. p. 370 Junq

Question 26

1. ) In which epidermis layer does keratinization begin? What structures are associated with this process and how do they stain? 2. ) What other structures are present that undergo a process to protect against water loss? Describe

Answer 26

1. ) Stratum granulosum: Contain INTENSELY BASOPHILIC KERATOHYALINE GRANULES with filaggrin. 2. ) Golgi-derived LAMELLAR GRANULES undergoe exocytosis, producing a lipid-rich, impermeable layer around the cells. p. 367 Junq

Question 27

What determines the thickness of skin?

Answer 27

Depth of the dermis

Question 28

What feature of thin skin dermis can differentiate it from thick skin?

Answer 28

Hair follicles | p.11-14

Question 29

Briefly list and describe what is found in the layers under the epidermis, from superficial to deep.

Answer 29

1. ) Dermis: Blood vessels, nerve fibers, skin accessory structures (e.g. hair follicles, sebaceous glands, sweat glands). Collagen fibers and elastic fibrils. 2. ) Papillary layer: Found just beneath the epidermis. Loose connective tissue, contains DERMAL PAPILLAE (with capillaries). 3. ) Reticular layer: Dense, irregular connective tissue. Broader and contains fewer cells than the papillary layer. p. 11-17