Topic 9 Integumentary System: Structure of the Skin

Question 1

• Superficial, avascular epithelial tissue that relies on the dermis for oxygen and nutrients. Exposure of the epidermis to pressure/ friction will result in thickening to form a callus. This epidermis is also divided into 5 layers, which are listed here:

Answer 1

1. Epidermis

Question 2

a. Stratum Corneum
b. Stratum Lucidum
c. Stratum Granulosum
d. Stratum Spinous
e. Stratum Basale (germinativum)

Answer 2

Parts of Epidermis

Question 3

• 25-30 dead layers of variable thickness; filled with keratin and surrounded by lipids. This layer contains lamellar granules to make it water repellant

Answer 3

Stratum Corneum

Question 4

• Only in palms, soles of feet, and finger tips; consists of 3-5 layers, and appears clear/dead

Answer 4

Stratum Lucidum

Question 5

• 3-5 layers of dying cells; lamellar bodies release hydrophobic lipids

Answer 5

Stratum Granulosum

Question 6

• Contribute to strength and flexibility; 8-10 layers held together by desmosomes which are keratin involving adhesion proteins

Answer 6

Stratum Spinous

Question 7

• Deepest layer of skin, contains Merkel cells and stem cells that divide to produce keratinocytes; is attached by the basement membrane and melanocytes are found here
• The keratinocytes are pushed to the top layer and as they rise, they accumulate keratin and die by losing cytoplasm / nucleus/ other organelles. As they move to the outermost layer of the body, they slough off

Answer 7

Stratum Basale (germinative)

Question 8

• Remember the layers of the epidermis by using “Come Let’s Get SunBurnt”

Answer 8

Note

Question 9

• 4 main cells to know

Answer 9

2. Cells of Epidermis

Question 10

a. Keratinocytes
b. Melanocytes
c. Langerhans Cells
d. Merkel Cells

Answer 10

Cells of Epidermis

Question 11

• Produce the protein keratin that helps waterproof the skin. As these are pushed to the top layer of skin, they accumulate keratin and die, losing their organelles along the way. Keratin is also the most abundant protein in the epidermis

Answer 11

a. Keratinocytes

Question 12

• transfer skin pigment melanin to keratinocytes

Answer 12

b. Melanocytes

Question 13

• interact with helper T cells of the immune system

Answer 13

c. Langerhans Cells

Question 14

• Attach to sensory neurons and function in touch sensation

Answer 14

d. Merkel Cells

Question 15

• The second layer of skin that consists of connective tissue, collagen and elastic fibers, and contains hair follicles, glands, nerves, and blood vessels. The dermis is also highly vascularized and is tightly connected to the epidermis above via the basement membrane

Answer 15

3. Dermis

Question 16

a. Papillary Region (top 20%)
b. Reticular Region
c. Tattoos are injected here in the dermis

Answer 16

Parts of dermis

Question 17

• Thin vascular network within upward projection papillae that helps supply nutrients to epidermis and regulates temperature. Papillae also contain Meisner’s corpuscles (sensory touch receptors) and their upward projection is what created fingerprint ridges (not to be confused with tongue papillae that have taste buds on their surface)

Answer 17

a. Papillary Region (top 20%)

Question 18

• Region with dense connective tissue, collagen, and elastic fibers; packed with glands, sweat gland ducts, fat, and hair follicles; provides strength and elasticity (stretch marks are dermal tears)

Answer 18

b. Reticular Region

Question 19

• macrophages eat the ink up and as the wound heals, the dermal fibroblasts lock the ink containing macrophages into a collagen network just beneath the dermis/epidermis junction

Answer 19

c. Tattoos are injected here in the dermis

Question 20

• Technically not a part of skin, but it is a part of the integumentary system; consists of areolar and adipose tissue, and function in fat storage, act as a heat insulator, and serves as a shock absorber. Also contains pressure sensing nerve endings and passages for blood vessels

Answer 20

4. Hypodermis (subcutaneous)

Question 21

a. Sebaceous (oil) glands
b. Sudoriferous (sweat) glands
c. Ceruminous (wax) glands
d. Mammary (milk) glands

Answer 21

Glands of the Skin

Question 22

• glands that are connected to hair follicles and are absent in palms and soles. These glands secrete oil (sebum) that keeps skin relatively acidic to discourage microbial growth, and acne is caused by these glands getting clogged

Answer 22

a. Sebaceous (oil) glands

Question 23

• found in ear canal and produce a wax-like material that acts as a barrier to entrance

Answer 23

c. Ceruminous (wax) glands

Question 24

• Secrete milk for breastfeeding

Answer 24

d. Mammary (milk) glands

Question 25

• regulate temperature through perspiration and eliminate urea; open directly to skin

Answer 25

1. Eccrine (most of body)

Question 26

• found in arm pits, pubic region, and nipples; secretions are more viscous and open to hair follicles

Answer 26

2. Apocrine

Question 27

• a column of keratinized cells held tightly together, and stand up via contraction of smooth muscles (arrector/ erector pili)

Answer 27

6. Hair

Question 28

• a first degree burn affects the epithelial layer, a second degree affects the epithelial and part of the dermal layers, and a third degree burn affects both skin layers and extended into the subcutaneous layer

Answer 28

7. Burn Degrees

Question 29

• Differentiate between the two types of sweat glands by remembering that eccrine glands produce your watery sweat while apocrine glands produce sweat that becomes stinky

Answer 29

Note