chapter 5 part 1

Question 1

Function of integumentary system

Answer 1

• Protection – protects against U V light, microorganisms, water loss.
• Sensation – sensory receptors for heat, cold, touch, pressure, pain.
• Temperature regulation – modulation of blood flow through the skin and
  activity of sweat glands.
• Vitamin D production from a molecule made in the skin when exposed to
  U V light.
• Excretion – small amounts of waste products eliminated.

Question 2

epidermis

Answer 2

Superficial layer of stratified squamous epithelial issue
reduces water loss
* Avascular; nourished by diffusion from capillaries of the
papillary layer of the dermis.
* Composed of epithelial cells arranged into layers or strata.
* Separated from dermis by basement membrane.

Question 3

Keratinocytes

Answer 3

epidermal cell type
Kera-nocytes: most cells. Produce keraCn for strength.

Question 4

Melanocytes:

Answer 4

epidermal cell type
Melanocytes: contribute to skin color. Melanin produced by these cells then transferred to keratinocytes. Same number of melanocytes in all people.

Question 5

Langerhans cells:

Answer 5

epidermal cell type
part of the immune system

Question 6

Merkel cells:

Answer 6

epidermal cell type
detect light touch and superficial pressure.

Question 7

Keratinization:

Answer 7

epidermal cell type
as cells move outward through the layers they fill with keratin, die, and serve as a layer that resists abrasion and forms permeability layer.

Question 8

name epidermal cell types

Answer 8

Keratinocytes, Melanocytes, Langerhans cells, Merkel cells, Keratinization

Question 9

Stratum basale (germinativum).

Answer 9

part of Epidermal Strata
* Deepest portion of epidermis and single layer of cuboidal or columnar cells.
* High mitotic activity; keratinocyte stem cells undergo mitosis about every 19 days; one daughter cell remains in the stratum basale to divide again, while the other daughter cell is pushed to the surface and becomes
keratinized.
* Desmosomes hold the keratinocytes together and provide structural strength.
* It takes 40 to 56 days to move from the stratum basale to the surface and
be sloughed off.

Question 10

Stratum spinosum.

Answer 10

part of Epidermal Strata
* Eight to ten layers of many-sided cells that flatten as they are pushed upward.
* Contain new desmosomes, lipid-filled lamellar bodies, and additional keratin fibers.

Question 11

Stratum granulosum

Answer 11

part of Epidermal strata
* Two to five layers of flattened, diamond-shaped cells.
* Contains protein granules of keratohyalin that accumulate in the cytoplasm.
* Lamellar bodies move to the plasma membrane and release their lipid contents
into the extracellular space.
*the keratin fibers and keratohyalin granules do not degenerate.

Question 12

Stratum lucidum.

Answer 12

part of Epidermal strata
* Thin, clear zone of dead keratinocytes with indistinct boundaries.
* Found only in palms and soles.

Question 13

Stratum corneum.

Answer 13

• Most superficial and consists of 25 or more layers of dead, overlapping squamous cells joined by desmosomes called cornified cells.
• Cell remnants have a soft protein envelop of keratin, a mixture of keratin fibers and keratohyalin.