Chapter 5

Question 1

What are the 2 major layers of the skin?

Answer 1

Epidermis- most superficial layer
Dermis- a layer deep to the epidermis. Contains the hypodermis which is composed of areolar and adipose tissue.

Question 2

What are the major types of cells in the epidermis?

Answer 2

Keratinocytes- provide strength to the cell.
Melanocytes- secrete melanin.
Intraepidermal macrophages(Langerhabs cells)- eat cells.
Tactile epithelial cells(Merkel cells)- contact nerve cells, function as touch.
Dendritic cells- Eat cells and call for help.

Question 3

What are the types of skin?

Answer 3

Thin (hairy) skin- covers all body regions except the palms, palmar surfaces of digits and soles.
Thick (hairless) skin- covers the palms, palmar surfaces of digits and soles. (Multiple layers in these regions)

Question 4

What are the layers of the epidermis? Thick and Thin.

Answer 4

Thin consists of four layers;
The Stratum basale, the stratum spinosum, the stratum granulosum, and the stratum corneum.
Thick skin has all of these plus an extra layer that is called the stratum lucidum.

Question 5

Describe the Stratum Basale.

Answer 5

The deepest layer is composed of a single row of cuboidal or columnar keratinocytes. Stem cells undergo cell division.

Question 6

Describe the Stratum Spinosum.

Answer 6

8-10 rows of many-sided keratinocytes.

Question 7

Describe the Stratum Granulosum

Answer 7

3-5 rows of flat keratinocytes. Organelles begin to degenerate. Contains the protein keratohyalin and lamellar granules.

Question 8

Describe the Stratum Lucidum

Answer 8

Present only in the skin of fingertips, palms, and soles. 4-6 rows of clear, flat, dead keratinocytes with large amounts of keratin. Only in thick skin.

Question 9

Describe the Stratum Corneum

Answer 9

Few to 50 or more rows of dead, flat keratinocytes that contain mostly keratin.

Question 10

What is the dermis composed of?

Answer 10

Connective tissue containing collagen and elastic fibers.

Question 11

Describe the Papillary region of the dermis.

Answer 11

The superficial portion of the dermis; consists of areolar connective tissue with thin collagen and fine elastic fibers; and contains dermal ridges.

Question 12

Describe the Reticular region of the dermis.

Answer 12

Deeper portion of the dermis; consists of dense irregular connective tissue with bundles of thick collagen and some coarse elastic fibers. Spaces between fibers contain adipose cells, hair follicles, nerves, sebaceous glands, and sudoriferous glands.

Question 13

What makes blood red?

Answer 13

a red pigment called Hemoglobin.

Question 14

What pigment is stored in the stratum corneum and adipose tissue?

Answer 14

A yellow-orange pigment called Carotene.

Question 15

What is Albinism?

Answer 15

congenital disorder characterized by the complete or partial absence of pigment in the skin, hair, and eyes due to a defect of an enzyme involved in the production of melanin.

Question 16

What is Vitiligo?

Answer 16

A chronic disorder that causes depigmentation patches in the skin.

Question 17

What is Hair?

Answer 17

Composed of dead, keratinized epidermal cells. Genetic and hormonal influences determine the thickness and distribution of our hair.

Question 18

Describe the Anatomy of Hair.

Answer 18

Hair structure consists of:
The shaft (above the skin surface)
The root(below the surface of the skin; penetrates into the dermis)
The follicle (structure surrounding the root of the hair)
Hair bulb

Question 19

Describe the process of the hair growth cycle.

Answer 19

Growth stage- cells of the hair matrix divide.
Regression stage- hair moves away from the blood supply in the papilla of the hair.
Resting stage- old hair falls off or is pushed out of the hair follicle.

Question 20

What are the types of skin glands?

Answer 20

Sebaceous (oil) gland
Eccrine sweat glands
Apocrine sweat glands
Ceruminous glands.

Question 21

Describe Sebaceous (Oil) glands

Answer 21

Absent in palms and soles. The secretory portion is found in the dermis, and the excretory duct is mostly connected to hair follicles. Secretes sebum and prevents hairs from drying out, prevents water loss from the skin, and keeps skin soft. Activated during puberty.

Question 22

Describe Eccrine sweat glands

Answer 22

Throughout the skin of most regions of the body. The secretory portion is found mostly in the deep dermis and the excretory duct is on the surface of the epidermis. Secretes Perspiration and regulates body temperature, waste removal, and stimulation during emotional stress.
Soon after birth.

Question 23

Describe Apocrine sweat glands.

Answer 23

The secretory portion is found mostly in the deep dermis and upper subcutaneous layer. The excretory duct is the hair follicles. Secretes Perspiration and is stimulated during emotional stress and sex excitement.
Puberty.

Question 24

Describe Ceruminous glands

Answer 24

External auditory canal. The secretory portion is found in the hypodermis. The excretory duct is the surface of the external auditory canal. Secretes cerumen and impedes entrance of foreign bodies and insects into the external ear canal, a waterproof canal, that prevents microbes from entering cells.
Soon after birth.

Question 25

What are nails made of?

Answer 25

Keratinized epidermal cells.

Question 26

What is the structure of a nail?

Answer 26

Free edge.
Nail body (nail plate)
Nail bed (below the nail body)
Lunula
Eponychium (cuticle)
Nail root
Nail Matrix

Question 27

What secures the nail to the fingertip?

Answer 27

The Hyponychium

Question 28

What are the functions of the skin?

Answer 28

Thermoregulation
Blood reservoir
Protection
Cutaneous sensations
Excretion and absorption
Synthesis of Vitamin D

Question 29

Describe thermoregulation

Answer 29

Sweat- cools us down
Blood flow to the dermis- controls body temperature by controlling blood flow.

Question 30

Describe the Protection of skin

Answer 30

Keratin- protein
Lipids released by lamellar granules- water resistance.
Sebum- water resistance.
Acidic sweat
Melanin
Macrophages

Question 31

What are Cutaneous sensations?

Answer 31

Tactile sensations- touch, pressure, vibration, and tickle.
Thermal sensations- warm and cool.
Pain

Question 32

Describe the excretion and absorption of skin

Answer 32

Excretion- elimination of substances from the body.
Absorption- passage of material from the external environment into body cells. (nonpolar substance)

Question 33

Describe the synthesis of Vitamin D

Answer 33

Ultraviolet rays activate a precursor vitamin D molecule in the skin to make calcitriol. Enzymes in the liver and kidney produce calcitriol.
Vitamin D is a hormone that aids in the absorption of calcium from foods in the GI tract.

Question 34

Describe the process of epidermal wound healing.

Answer 34

Occurs when superficial wounds affect only the epidermis. No blood comes out. The basal epithelial cells divide and migrate across the wound resulting in the thickening of the epidermis.

Question 35

Describe the process of deep wound healing.

Answer 35

Goes through 4 stages:
Inflammatory phase- Redness, swelling, heat, pain. Forms blood clots.
Migratory phase- migrate, reestablish the epidermis, and fibrosis occurs. Leaving a scar where the previous function is now lost.
proliferative phase- Continous growth of cells beneath the scab.
maturation phase- Scab falls off.