A&P of Skin, Hair and Nails

Question 1

What are the 9 functions of the skin?

Answer 1

1. ) Protect against microbial and foreign substance invasion and minor physical trauma
2. ) Retard body fluid loss by providing a mechanical barrier
3. ) Regulate body temperature through radiation, conduction, convection, and evaporation
4. ) Provide sensory perception via free nerve endings and specialized receptors
5. ) Produce vitamin D from precursors in the skin
6. ) Contribute to blood pressure regulation through constriction of skin blood vessels
7. ) Repair surface wounds by exaggerating the normal process of cell replacement
8. ) Excrete sweat, urea, and lactic acid
9. ) Express emotions

Question 2

Describe the Epidermis.

Answer 2

Outermost part of skin

Avascular and depends on the underlying dermis for its nutrition

Question 3

What are the two major layers of the skin?

Answer 3

Stratum corneum
- Protects the body against harmful environmental substances and restricts water loss

Cellular stratum
- Keratin cells are synthesized

Question 4

What Lies beneath the cellular stratum and connects the epidermis to the dermis?

Answer 4

The basement membrane

Question 5

Describe the dermis.

Answer 5

Richly vascular connective tissue layer

Separates epidermis from cutaneous adipose tissue

Question 6

What are the components of the dermis and their functions?

Answer 6

Elastin, collagen, and reticulin fibers
- Provide resilience, strength, and stability

Sensory nerve fibers
- Provide sensations of pain, touch, and temperature

Autonomic motor nerve
- Innervate blood vessels, glands, and the arrectores pilorum muscles

Question 7

What is the hypodermis and it’s functions?

Answer 7

Connects dermis to underlying organs
Subcutaneous layer filled with fatty cells

Functions

• Generates heat
• Provides insulation
• Provides shock absorption
• Provides calorie reserve

Question 8

What are eccrine sweat glands and where are they located?

Answer 8

Open directly onto the surface of the skin and regulate body temperature through water secretion

Distributed throughout the body except at the lip margins, eardrums, nail beds, inner surface of the prepuce, and the glans penis

Question 9

What are apocrine sweat glands and where are they located?

Answer 9

Larger and located more deeply than the eccrine glands
In response to emotional stimuli, secrete a white fluid containing protein, carbohydrate, and other substances

Secretions from these glands are odorless.

Body odor is produced by bacterial decomposition of apocrine sweat.

Found only in the axillae, nipples, areolae, anogenital area, eyelids, and external ears

Question 10

What are sebaceous glands and when are they released?

Answer 10

Secrete sebum, a lipid-rich substance that keeps the skin and hair from drying out

Secretory activity, which is stimulated by sex hormones (primarily testosterone), varies according to hormonal levels throughout the life span.

Question 11

How is hair formed and how does it get its color?

Answer 11

Formed by epidermal cells that invaginate into the dermal layers
Melanocytes in the shaft provide its color

Question 12

What are the two kinds of hair?

Answer 12

vellus―short, fine, soft, and nonpigmented

terminal―coarser, longer, thicker, and usually pigmented

Question 13

What are nails and how do they get their color?

Answer 13

Epidermal cells converted to hard plates of keratin

Highly vascular nail bed lies beneath the plate, giving the nail its pink color

Question 14

Define cuticle, or eponychium.

Answer 14

Stratum corneum layer of skin covering the nail root

Question 15

Define paronychium.

Answer 15

Soft tissue surrounding the nail border

Question 16

What are the 5 different appendages of the skin?

Answer 16

Nails, hair, sebaceous glands, apocrine sweat glands, and eccrine sweat glands