Human Anatomy & Physiology: Epidermis Flashcards


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Flash cards about epidermis
updated 10 years ago by iaranda
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1

What is Epidermis

Keratinized stratified squamous epithelium

2

What are the 5 layers of the epidermis starting with the superficial layer?

Corneum, Lucidium, Granulosum, Spinosum, and Basal

3

What are the 4 cell types of the Epidermis?

Keratinocytes, Melanocytes, Dendritic cells, and Tactile cells

4

What is the function of Keratinocytes?

To produce Keratin

5

What is Keratin?

The fibrous protein that helps give the epidermis it's protective properties

6

What connects Keratinocytes together?

Desmosomes

7

Where do Keratinocytes arise from?

In the deepest part of the epidermis, the stratum basal

8

How often do we get a new epidermis?

Every 25-45 days

9

How do Keratinocytes reproduce and how fast?

By mitosis and continuously

10

What kind of cells are the majority found in the epidermis?

Keratinocytes

11

What are Melanocytes?

Spider shaped epithelial cells that synthesize the pigment melanin

12

Where are Melanocytes found?

The deepest layer of the epidermis called the stratum basal

13

What is another name for dendritic cells?

Langerhans cells

14

Where do dendritic cells arise from and where do they migrate to?

Bone marrow and migrate to the epidermis

15

What is the function of Langerhans cells?

Ingest foreign substances and activate our immune system.

16

What is another name for tactile cells?

Merkel Cells

17

Where might you find Merkel cells?

At the epidermal-dermal junction

18

What is the function of a Merkel cell?

A sensory receptor for touch

19

What is a Merkel cell shaped like?

Spiky hemisphere with disc like sensory nerve ending

20

What stratum is missing when skin is thin?

Stratum Lucidum

21

How many stratum does thick skin have?

5

22

What kind of cells are located in the Stratum Basal?

A single row of actively mitotic stem cells; keratinocytes
occasional melanocytes and dendritic cells

23

Stratum Basal is also know as

Stratum germinative

24

How do the cells in the Basal

Each time a basal cell divides, one daughter cell is pushed into the cell layer just above to begin it's specialization into a mature keratinocyte . Other basal cells remain to continue to divide mitotically

25

What % of Stratum Basal cells are Melanocytes?

10-25%

26

Describe the Stratum Spinosum

Several layers of keratinocytes unified by desmosomes. Cells contain thick bundles of intermediate filaments made of pre-keratin

27

What cells are found in the Stratum Spinosum?

Keratinocytes, melanin granules, and dendritic cells, which are most abundant

28

Describe the stratum granulosm

Typically 5 layers of flattened cells, organelles deteriorating; cytoplasm full of lamellar granules and keratohyaline granules

29

What do the Keratohyline granules do in the Stratum Granulosm?

They help to form keratin in the upper layers

30

What are Lamellar granules?

They contain a water resistant glycolipid that is spewed into the extracellular space and is a major factor in slowing water loss across the epidermis

31

Where are Lamellar granules found?

Stratum Granulosum

32

Which stratum to the keratinocytes "toughen up"?

Stratum Granulosm

33

Above which Stratum are nutrients cut off and the cells die?

Above the Stratum Granulosm

34

What are tonofilaments?

Large cable like parallel arrays of intermediate filaments

35

What is the thickest Stratum of the epidermis?

The stratum corneum

36

Describe the Stratum Corneum

The most superficial layer
20-30 layers of dead cells
Are essentially flat membranous sacs filled with keratin
Glycolipids in extracellular space

37

What is the function of the Stratum Corneum?

Protection from hostile external environment and from water loss

38

What are cornified or horny cells?

shinle like cell remnants of the stratum corneum that slough off skin surface. AKA dandruff or dander

39

How many dead cells does the average person shed each minute?

50,000