Chapter 1- Horny Layer- Stratum Corneum

Question 1

The outer layer of terminaly differentiated keratinocytes that is constantly being shed describes what layer?

Answer 1

horny layer/stratum corneum

Question 2

The stratum corneum is a multilayered zone of _________ (cell type) suspended in an extracellular lipid matrix

Answer 2

corneocytes

Question 3

The stratum corneum is often likened to a series of brocks (________= cell type) bonded by mortar (_____- cell type)

Answer 3

corneocytes; lipids

Question 4

The stratum corneum consists of what kind of cells? Describe tehm (shape, nucleated or anucleated, color)

Answer 4

flattened anuclear eosinophilic cells

Question 5

Define glabrous skin

Answer 5

tough, thick, hairless skin

Question 6

The stratum corneum is thicker in what kind of skin?

Answer 6

glabrous (hairless) or lightly haired skin

Question 7

The gradual desquamation of the horny layer is normally balanced by proliferation of what kind of cells?

Answer 7

basal cells

Question 8

How is a constant epidermal thickness maintained?

Answer 8

By the gradual desquamation of the horny layer and the balanced proliferation of the basal cells

Question 9

What cell type contains a variety of humectants and natural sunscreens?

Answer 9

corneocytes

Question 10

The terminally differentiated corneocyte has a highly specialized structure that forms under its plasma membrane called the_____ _______

Answer 10

cornified envelope (CE)

Question 11

The cornified envelope develops beneath the plasma membrane of what four structures?

Answer 11

1. stratified epidermal cells 2. cells of the inner root sheath 3. cells of the medulla of the hair follicle 4. the cuticle of the claw

Question 12

Does the corneocyte have a true cell membrane? Why or why not?

Answer 12

No. Bc it contains no phospholipids

Question 13

Cornified envelope formation is associated with increased activity of what enzymes?

Answer 13

increased activity of calcium-dependent epidermal or hair follicle TRANSGLUTAMINASES

Question 14

The transglutaminases that help cornified envelope formation catalyze what reactions?

Answer 14

catalyze cross-linking of soluble and particulate protein precursors into large insoluble polymers

Question 15

Name the protein components of the cornified envelope

Answer 15

loricrin, involucrin, filaggrin, elafin, cystatin A, cornifelin, small proline-rich proteins, “late-envelope proteins”

Question 16

Is the cornified envelope permeable or impermeable?

Answer 16

Impermeable

Question 17

What is the function of the cornified envelope?

Answer 17

provides structural support to the cell and resists invasion by microorganisms and deleterious environmental agents

Question 18

Name the protective functions of the stratum corneum

Answer 18

1. permeability barrier 2. mechanical integrity 3. desquamation 4. hydration 5. waterproofing 6. UV protection 6. antimicrobial defense 7. cytokine signaling