Integumentary System (Ch 5)

Question 1

Skin

Answer 1

• largest organ in body (different tissues working together)

- 7% of body weight

Question 2

Functions of skin

Answer 2

• protection against mechanical damage
• barrier to fluid loss/pathogens
• Vit D production
• sensory reception
• body temp regulation
• excretion of salts/wastes

Question 3

Epidermis

Answer 3

• ->keratinized stratified squamous epithelium
• four cell types
• avascular
• regenerates often
• 4/5 cell layers (thin vs. thick)

Question 4

What are the four cell types of the epidermis?

Answer 4

1. keratinocytes: product 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 5

What is the structure of the epidermis?

Answer 5

1. Stratum Corneum (sup)
2. Stratum Lucidum
3. Stratum Granulosum
4. Stratum Spinosum
5. Stratum Basale (inf)
   - -> “Come Let’s Get Sun Burnt”

Question 6

Stratum Corneum

Answer 6

*layer of epidermis (most superior)

dead cells full of keratin, shed regularly

Question 7

Stratum Lucidum

Answer 7

*layer of epidermis (2nd layer)

“clear” layer, only in THICK skin, consists of a few rows of flat/dead keratinocytes

Question 8

Stratum Granulosum

Answer 8

*layer of epidermis (3rd layer)

1-5 layers of cells, granules in this layer help waterproof skin

Question 9

Stratum Spinosum

Answer 9

*layer of epidermis (4th layer)

multiple cells layers of keratinocytes, only layer with DENDRITIC cells

Question 10

Stratum Basale

Answer 10

*layer of epidermis (most inferior)

attached to dermis, mostly keratinocytes with rapid division, melanocytes/merkel cells

Question 11

Dermis

Answer 11

• underlies epidermis
• strong/flexible CT
• highly vascularized
• innervated (= sensation)
• 2 cell layers: papillary and reticular

Question 12

Papillary Layer

Answer 12

• layer of dermis
• 20% of dermis
• areolar CT
• provides nutrients to epidermis
• dermal papillae increase SA for transport of materials into epidermis

Question 13

Reticular Layer

Answer 13

• layer of dermis
• mostly dense irregular
• network of collagen + elastic fibers provide stretch/strength

Question 14

Hypodermis

Answer 14

• supports skin (dermis/epidermis)

- areolar + adipose loose CT (mostly adipose)

Question 15

What are the functions of the hypodermis?

Answer 15

• stores fat
• provides insulation
• anchors skin to muscles
• allows movement of skin over muscle and bones

Question 16

Fingerprints

Answer 16

• increase friction for grasping
• have dermal papillae which push up/elevate the overlying epidermis
• patterns are unique

Question 17

Hair

Answer 17

• flexible strands made of KERATIN

- pigment comes from MELANOCYTES

Question 18

What are the functions of hair?

Answer 18

• sensation (light touch)
• protection (ex. eyelashes)
• insulation

Question 19

Structure of Hair

Answer 19

1. Basic
   - shaft (exposed)
   - root (embedded into dermis/epidermis)
2. Hair Follicle
   - bulb (innervated)
   - papilla (blood supply)
3. Arrestor Pili muscle
   - -> contraction raises hair/causes goosebumps

Question 20

Eccrine Sweat Glands

Answer 20

• -> secreted onto skin surface
• allows for evaporative cooling
• development: invaginate from skin surface
• product: 99% water, 1% salts/wastes
• acidic/antibacterial properties

Question 21

Apocrine Sweat Glands

Answer 21

• -> discharge into hair follicles
• development: outgrowths from hair follicles
• product: complex molecules, odorous
• found in armpits/genitals

Question 22

Ceremonious Glands

Answer 22

line external ear canal, produce earwax

Question 23

Mammary Glands

Answer 23

secrete milk

Question 24

Sebaceous Glands

Answer 24

multicellular exocrine glands (secrete onto hair follicles)

• secrete sebum (oil) –> holocrine secretion (cells accumulate sebum then burst to release)
• moisturizes hair/skin
• blocked hair follicle = acne

Question 25

Melanin

Answer 25

- acts as natural sunblock against UV radiation - determines skin tone - # of melanocytes among individuals does not vary, but activity level does (ex. pale = less active)

Question 26

Why is some exposure to sunlight necessary?

Answer 26

production of Vit D --> calcium absorption

Question 27

What are the dangers of too much exposure to sunlight?

Answer 27

reduction in folate levels needed for embryonic development | -promotes skin cancer

Question 28

Basal Cell Carcinoma

Answer 28

- most common form of skin cancer - originates from stratum basale (a.k.a. stratum germinativum) - metastasis is rare

Question 29

Melanoma

Answer 29

- potentially life threatening | - cancerous melanocytes grow rapidly and spread throughout lymphatic system

Question 30

How to detect skin cancer

Answer 30

``` A: asymmetry- irregular shape B: border- indistinct C: color- mottled D: diameter- >5mm is dangerous E: elevation- not flat ```