Chapter 5 Part 1

Question 1

Contents of the Integumentary System

Answer 1

-Skin, Hair, Nails, Sweat Glands, Sebaceous (oil) glands.

Question 2

Main Regions of Skin

Answer 2

• Epidermis) Top layer of skin. consists of epithelial tissue and is made of dead keratinized cells.
• Dermis) Underlies Epidermis. made of areolar and dense irregular tissue.
• Hypodermis) (Superficial Fascia) anchors skin to underlying muscles. (not part of skin but shares some function)

Question 3

Types of Epidermis cells

Answer 3

-Keratinocytes, Melanocytes, Dendritic (langerhans) cells, and Tactile (Merkel) cells.

Question 4

Keratinocytes

Answer 4

• Produce Fibrous Keratin. Gives epidermis its protective properties. Most cells of epidermis are keratinocytes
• Connected by desmosomes
• Arise from the stratum basale.
• Thickened areas of the epidermis are called callus’

Question 5

Melanocytes

Answer 5

• Spider shaped cells that synthesize melanin. Found in deeper layers of epidermis.
• Melanin is packaged into granules called melanosomes.
• Melanosomes accumulate toward the apical surface of epidermal cells to protect the DNA from UV damage.

Question 6

Dendritic (Langerhans) cells

Answer 6

-Star-shaped macrophages that patrol deep epidermis. Key in the immune system

Question 7

Tactile (Merkel) cells.

Answer 7

• Sensory receptors that sense touch.

- Each cell is associated with a dislike neuron ending called a merkel disc

Question 8

5 Layers of the Epidermis (bottom to top)

Answer 8

1) Stratum Basale (bottom)
2) Stratum Spinosum
3) Stratum Granulosum
4) Stratum Lucidum (only found in thick skin)
5) Stratum Corneum

Question 9

Stratum Basale

Answer 9

• Deepest epidermal layer (basal layer). Attached to the dermis
• Made of a layer of stem cells that continuously make keratinocytes. When the cell divides one daughter cell becomes keratinocyte and one remains in Stratum Basale.
• Actively involved in the process of Mitosis. Because of this it is also called the stratum Germinativum.

Question 10

Stratum Spinosum

Answer 10

• Prickly layer. Several layers of keratinocytes unified by desmosomes.
• Cells contain pre-keratin which looks like spines coming out of the cell. (giving it the nickname prickly layer)
• Dendritic cells are also present in this layer. More abundant in this layer than any other layer.

Question 11

Stratum Granulosum

Answer 11

• Thin layer, one to 5 cells thick.
• Process of keratinization (cells fill with keratin) begins here. cell appearance flattens and nuclei dissolve.
• Hold two types of granules
  1) Keratohyalin Granules) Help form keratin in the upper layer
  2) Lamellar granules) Water-resistant glycolipid that slows water loss.
• Cells above this layer die because they are too far from the dermal capillaries to diffuse nutrients and because lamellar granules stop nutrients.

Question 12

Stratum Lucidum

Answer 12

-Only found in thick skin. Layer of clear keratinocytes.

Question 13

Stratum Corneum

Answer 13

• 20-30 layers of dead, flat, anucleated keratinocytes. account for 3/4 of the thickness of the epidermis.
• Protect deeper cells, against water loss, and acts as a barrier.

Question 14

Dermis

Answer 14

• Strong, flexible connective tissue found below the epidermis.
• Made of Fibroblasts, Macrophages, and occasionally white blood cells and mast cells (Immune Response). Structures include epidermal hair follicles and oil/sweat glands.
• Contains nerve, lymph, and blood vessels.

Question 15

Two Layers of the Dermis

Answer 15

• Palpilary (areolar connective) layer

- Reticular (Dense irregular connective) layer

Question 16

Papillary Layer.

Answer 16

• Top layer of the dermis. Made of areolar connective tissue, collagen and elastic fibers, and blood vessels.
• Looseness of this connective tissue allows phagocytes to wander freely.

Question 17

Dermal Papillae

Answer 17

• Dermal Ridges that occur in thick skin following the pattern of the underlying papillary layer (dermis).
• Increase friction between objects that you hold and your hands.
• Each is unique to us (fingerprint). Small sweat pores on our fingertips leave fingerprints.

Question 18

Reticular Layer.

Answer 18

• Accounts for 80% of dermal thickness. Made of dense irregular connective tissue.
• Also contain elastic fibers which provide stretch and recoil properties and collagen fibers which provide strength and bind water.
• Cutaneous Plexus) network of blood vessels that runs between reticular layer and the dermis.

Question 19

Cleavage lines

Answer 19

• Lines in Reticular Layer of the dermis caused by many collagen fibers running parallel to the skin. Invisible on the surface.
• Important to surgeons because cuts along these lines heal better.

Question 20

Flexure Lines

Answer 20

• Dermal Folds of the Reticular layer which are near joints.

- Ex: Palm lines.

Question 21

Stretch Marks

Answer 21

-Extreme stretching of the skin cause dermal tears which appear as white scars. tears are called Striae

Question 22

Blisters

Answer 22

-Fluid filled pockets between the epidermal and dermal layers due to trauma.

Question 23

Skin Color

Answer 23

• Three Pigments contribute to skin color

Melanin) (see melanocyte) can be reddish yellow or brownish black. Skin color differences are due to differences in melanin.

• Carotene) Yellow/orange pigment most obvious in palms and soles. Accumulates in stratum corneum and hypodermis. Can be converted to vitamin A
• Hemoglobin) Pinkish hue due to this pigment.