Unit 2

Question 1

Largest organ

Answer 1

Skin

Question 2

In hot weather skin can release…

Answer 2

More than 3 gallons of sweat

Question 3

How many cells does skin shed every minute?

Answer 3

50,000 cells

Question 4

How many tons of dead skin accounts for what in the atmosphere?

Answer 4

Dead skin accounts for about a billion tons of dust

Question 5

Skin

Answer 5

Cutaneous Membrane

Question 6

Skin (info)

Answer 6

Dry membrane, outermost protective boundary.

Question 7

Integumentary System

Answer 7

1. Skin (cutaneous membrane)
2. Skin derivatives: sweat glands, oil glands, hair, and nails.

Question 8

Skin Function (protects from…)

Answer 8

Protects deeper tissue from: mechanical damage (bumps), chemical damage (acids & bases), bacterial damage, ultraviolet radiation (sunlight), thermal damage (heat & cold), and desiccation (drying out)

Question 9

Keratin

Answer 9

Orange/yellow pigment from some vegetables, protects the skin from water loss (makes epidermis tough).

Question 10

Skin Function (aids in…)

Answer 10

Aids in loss or retention of body heat (controlled by nervous system), excretion of urea and uric acid, synthesizes vitamin D (uses sun), and detects touch, temperature, pressure, and pain via cutaneous sensory receptors.

Question 11

Outer layer of skin…

Answer 11

Epidermis (cornified or keratinized to prevent water loss).

Question 12

Dense connective tissue…

Answer 12

Dermis

Question 13

Subcutaneous tissue…

Answer 13

Hypodermis (not technically part of the skin, anchors skin to underlying organs, composed mostly of adipose tissue, serves as a shock absorber and insulates deeper tissues).

Question 14

Epidermis

Answer 14

Composed of 5 layers (primarily 4), is avascular (no blood vessels), and most cells are keratinocytes.

Question 15

Layers of the epidermis

Answer 15

1. Stratum Basale (deepest layer - lies next to dermis, wavy borderline with the dermis anchors them together, cells undergoing mitosis, daughter cells are pushed upward to become more superficial layers)
2. Stratum Spinosum (more superifical)
3. Stratum granulosum (further away)
4. Stratum Corneum (top layer of dead cells, continually flakes off dandruff & dust 20-30 flakes thick, average person sheds 40 lbs in a lifetime, new skin every 25-45 days, and shingle-like dead cells are filled with keratin)
   (5.) Stratum Lucidum (formed from dead cells, only in thick hairless skin: palms of hands & soles of feet)

Question 16

Dermis

Answer 16

Dermis structure is collagen & elastic fibers located throughout the dermis.

Question 17

Dermis Layers

Answer 17

1. Papillary Layer (upper dermal region, projections are called dermal papillae, binds skin layers together, fingerprints are identified films of sweat)
2. Reticular Layer (deepest skin layer, blood vessels, sweat & oil glands)

Question 18

Collagen Fibers

Answer 18

Give skin its toughness

Question 19

Elastic Fibers

Answer 19

Give skin elasticity (decreases with age and results in wrinkles)

Question 20

Skin Color (the three pigments are…)

Answer 20

1. Melanin (yellow, reddish brown, black pigments)
2. Keratin (orange/yellow pigment from vegetables)
3. Hemoglobin (red coloring from blood cells in dermal capillaries, oxygen content determines the extent of red coloring)

Question 21

Melanin

Answer 21

Pigment (melanin) is produced by melanocytes, color is yellow to brown to black, melanocytes are mostly in the stratum basale, and amount of melanin produced depends upon genetics and exposure to sunlight).

Question 22

Redness (Erythema)

Answer 22

Due to embarrassment, inflammation, hypertension, fear, or allergies.

Question 23

Pallor (Blanching)

Answer 23

Due to emotional stress (such as fear), anemia, low blood pressure, and impaired blood flow to the area.

Question 24

Jaundice (Yellowing)

Answer 24

Liver disorder (genetic or usually alcoholic).

Question 25

Bruises (Black and blue marks)

Answer 25

Hematomas.