Integument (Ch. 5)

Question 1

Skin

Answer 1

An organ (diff. tissues working together)
Largest organ in the human body system
7% of total body weight

Question 2

What are the 6 functions of the skin?

Answer 2

1. protect against mechanical damage
2. barrier to fluid loss and pathogens
3. vitamin D production
4. sensory reception
5. body temp regulation (sweating)
6. excretion of salt/wastes

Question 3

Epidermis

Answer 3

Keratinized stratified squamous epithelium

Question 4

How many cell types are in the epidermis?

Answer 4

4 cell types

Question 5

Does the epidermis have a blood supply?

Answer 5

No, it’s avascular

Question 6

How often does the epidermis regenerate?

Answer 6

every 35-45 days

Question 7

How many cell layers are in the epidermis?

Answer 7

4-5 layers (thin vs thick skin)

Question 8

Epidermis: cells

Answer 8

1. Keratinocytes: produce keratin, most abundant
2. Melanocytes: produce melanin (helps shield nuclei of keratinocytes from UV radiation)
3. Merkel cells: sensation
   4: Dendritic cells: immune cells

Question 9

Name all the layers of the Epidermis (from superficial to deep)

Answer 9

1. Stratum Corneum
2. Stratum Lucidum
3. Stratum Granulosum
4. Stratum Spinosum
5. Stratum Basale

Question 10

Stratum Corneum

Answer 10

most superficial

dead cells full of keratin, shed regularly

Question 11

Stratum Lucidum

Answer 11

“clear layer”

ONLY IN THICK SKIN

Consists of a few rows of flat, dead keratinocytes

Question 12

Stratum Granulosum

Answer 12

1-5 layers of cells. Granules in this layer help waterproof skin

Question 13

Stratum Spinosum

Answer 13

Multiple cell layers of keratinocytes.

ONLY LAYER WITH DENDRITIC CELLS

Question 14

Stratum Basale

Answer 14

deepest layer, attached to dermis. Mostly keratinocytes w/ rapid division. Melanocytes and merkel cells

Question 15

Dermis

Answer 15

Underlies epidermis
Strong, flexible CT
Highly vascularized
Innervated (sensation)
2 cell layers - papillary (20%) and reticular (80%)

Question 16

Does the Dermis have a blood supply?

Answer 16

Yes, it’s highly vascularized

Question 17

Dermis: Papillary Layer

Answer 17

Papillary Layer ~ superficial 20%

Areolar CT
Provides nutrients to epidermis
Dermal Papillae increase surface area for transport of materials into epidermis

Question 18

Dermis: Reticular Layer

Answer 18

80% of dermis

Mostly dense irregular [CT]
Network of collagen and elastic fibers provide stretch, strength

Question 19

Hypodermis

Answer 19

Supports skin (epidermis and dermis)
Areolar and Adipose loose CT (mostly adipose)
–stores fat, provides insulation, anchors skin to muscles

Allows movement of skin over muscle and bones

Question 20

List the 3 layers of the skin from superficial to deep

Answer 20

1. Epidermis
2. Dermis
3. Hypodermis

Question 21

Fingerprints

Answer 21

Dermal papillae push up and elevate the overlying epidermis (create epidermal ridges). Patterns are unique

Question 22

Hair

Answer 22

flexible strands made of keratin
Pigment comes from melanocytes
Fxns: sensation (light touch), protection, insulation

Question 23

Hair Structure:

Answer 23

Basic:

• -shaft (exposed)
• -root (embedded portion)

Hair Follicle:

• -bulb (innervation)
• -papilla (blood supply)

Arrector Pili Muscle
–contraction raises (erects hair), causes “goosebumps”

Question 24

Sweat Glands

Answer 24

Can be eccrine (a form of merocrine gland) or apocrine

Question 25

Eccrine Sweat glands

Answer 25

Secreted ONTO skin surface. Allows evaporative cooling Development: invaginate from skin surface Product: 99% water, 1% salts/wastes Acidic; antibacterial properties

Question 26

Apocrine Sweat glands

Answer 26

Discharge into hair follicles and NOT body surface Development: outgrowths from hair follicles Product: complex molecules, odorous Found in armpits/genitals

Question 27

Modified Sweat glands

Answer 27

Ceruminous: line external ear canal, produce earwax Mammary: secrete milk

Question 28

Sebaceous Glands

Answer 28

Multicellular exocrine glands Open into hair follicles Secrete sebum (oil): --Holocrine secretion: cells accumulate sebum and burst to release product Moisturize hair and skin Blocked hair follicle --> acne

Question 29

Skin Color - Melanin

Answer 29

Melanin acts as a natural sunblock, determines skin tone Number of melanocytes does NOT vary among individuals; activity of melanocytes does Not much melanin = decrease in folate levels

Question 30

Skin Color and UV Rays

Answer 30

Some exposure to sunlight is essential - -UV rays cause epidermis to produce vitamin D - ->needed for calcium absorption - ->light skin in northern climates (low sun) facilitates this) But excessive exposure is dangerous - -reduces folate levels needed for embryonic development - -promotes skin cancer Skin color affects amount of UV absorbed --darker skin in tropical (high sun) environments reduces UV absorption, protects folic acid levels

Question 31

Skin Cancer

Answer 31

Most common form of cancer Basal cell carcinoma originates in the stratum basale (germinativum). Metastasis is rare Melanoma is potentially life-threatening, because cancerous melanocytes grow rapidly and spread through the lymphatic system

Question 32

ABCDE of Skin Cancer

Answer 32

``` A. Asymmetry: irregular shape B. Border: indistinct C. Color: mottled D. Diameter: > 5mm is dangerous E. Elevation: not flat ```

Question 33

What's the mnemonic for the 5 layers of the epidermis?

Answer 33

``` Come [Stratum Corneum] *Let's [Stratum Lucidum] Get [Stratum Granulosum] Sun [Stratum Spinosum] Burned [Stratum Basale] ``` *Only in thick skin