Ch 5 - Integument

Question 1

6 Primary Functions of the Skin

Answer 1

1) Protection - Chemical, Physical, and Biological
2) Temperature Regulation - (in)sensible perspiration
3) Sensation - Exteroceptors: cutaneous sensory receptors
4) Metabolic functions - vitamin D production
5) Blood Reservoir
6) Excretion/waste elimination - sweat out some nitrogenous wastes

Chemical Protection - secretions kill bacteria, melanin prevents damage caused by UV light
Physical Protection - skin prevents enterance of bacteria/viruses
Biological Protection - Dendritic cells and Macrophages prevent infection
Exteroceptors - can be nociceptors, thermoreceptors, mechanoreceptors, etc.
Blood Reservoir - ~5% of total blood volume - can be “moved”
Nitrogenous wastes - urea, ammonia, uric acid

Question 2

Layers of the skin:

Answer 2

1) Epidermis - unvascularized outermost portion
2) Dermis - vascularized, most of ingtegument

Hypodermis - At the base of the dermis, not a true structure

Question 3

Cell types found in Epidermis

Answer 3

1) Keratinocytes - produce keratin protein; linked by desmosomes + tight junctions
2) Melanocytes - produce contain melanosomes (produce melanin)
3) Dendritic cells (Langerhans cells) - “presenting cells” - from bone marrow
4) Tactile cells (Merkel cells) - present in epidermal-dermal junction; sensory receptor function

Keratin protein - gives epidermis its tough and dry protective qualities
Melanocytes - produce melanin which is then transferred to shallow side of keratinocyte for protection

Question 4

Layers of the Epidermis

Answer 4

1) Stratum basale (base layer)
2) Stratum spinosum (spiny layer)
3) Stratum granulosum (granular layer)
4) Stratum lucidum (clear layer)
5) Stratum corneum (horny layer) - outermost

Question 5

3 basic characteristics of the stratum basale

Answer 5

1) Innermost layer
2) Simple layer of stem cells - rapid division
3) 10-25% melanocytes; most keratinocytes

Question 6

3 basic characteristics of the stratum spinosum

Answer 6

1) stratified
2) contains pre-keratin protein (filaments that resist tension)
3) Dendritic cells most abundant

Question 7

4 characteristics of the stratum granulosum

Answer 7

1) Keratinization begins
2) Keratohyaline granule: elps with formation of keratin in upper layers of epidermis
3) Lammelar granules: contains water-resistant glycolipid (makes skin waterproof)
4) Cells are especially tough and water resistant ^^^

Question 8

3 Characteristics of Stratum Lucidum

Answer 8

1) “clear”
2) not living cells
3) not found in thin skin

Question 9

5 characteristics of stratum corneum

Answer 9

1) outermost layer
2) not living
3) makes up most of epidermal thickness
4) Glycolipids between cells help waterproof
5) Keratin inside cells protects from friction/abraision

Question 10

Layers of the dermis

Answer 10

1) Papillary dermis
2) Reticular dermis

Filled mostly with fibroblasts and macrophages, lots of fibers

Question 11

What kind of tissue makes up the papillary dermis

Answer 11

Thin areolar connective tissue

The fibers are thin so that defensive cells can wander freely

Question 12

What are the projections (bumps) found in the papillary dermis and what is their function?

Answer 12

Dermal papillae - can have pain receptors or tactile corpuscles
These projections form “Friction Ridges” - AKA: fingerprints

Question 13

What kind of tissue makes up the reticular dermis

Answer 13

Dense irregular connective tissue

Question 14

Definition

Lines in skin formed by alternating dense & less dense regions of fibers

Not Visible Externally

Answer 14

Cleavage lines in reticular dermis

Question 15

Definition

Area where dermis is tightly anchored, not as flexible, and is forced to fold

Answer 15

Flexure lines (at/near joints) in reticular dermis

Question 16

Three pigments that determine skin color

Answer 16

1) Melanin: polymer that comes in two forms (reddish yellow/brownish black)
2) Carotene: yellow-orange pigment (accumulates in stratum corneum and adipose tissue)
3) Hemoglobin: pink/red pigment (oxygenated)

Question 17

What protein synthesizes melanin

Answer 17

Tyrosinase

Exposure to sun - DNA in cells damaged by sun - repair is first signal to produce melanin — keratinocytes release chemical to “activate” melanocytes

Question 18

Where is carotene stored and why?

Answer 18

In stratum corneum & adipose tissue; can be used by the body to proudce vitamin A

Vitamin A is useful for vision and epideral health

Question 19

4 homeostatic imbalances of skin color

Answer 19

1. Jaundice (liver failure)
2. Cyanosis (low oxygenated blood/hemoglobin)
3. Argyria (silver buildup)
4. Albinism/melanism (genetic mutations cause no melanin or too much melanin)

Question 20

Regions of a Hair (pili)

Answer 20

1. Root: part of hair imbedded in skin (from follicle)
2. Shaft: part of hair projecting out of skin

** all cells are dead and keratinized

Question 21

Functions of Hair

Answer 21

1) Sensory structures: nerves associated with hair follicles
2) Protection: scalp, eyes, nose

Question 22

Layers of each hair

Answer 22

1) Medulla: central core composed of large cells and air space - absent in fine hairs
2) Cortex: several layers of flattened cells
3) Cuticle: outermost layer (most heavily keratinized) - shingled

** all cells are dead and keratinized

Question 23

Structures associated with hair:

Answer 23

1) Hair follicle - growing part of hair (results from fold of epidermis entering dermis)
2) Root hair plexus - hair bulb (contains nerve endings)
3) Dermal papilla - provides capillaries to follicle
4) Arrector pili - muscle attached to hair follicle

Question 24

Layers of a hair follicle

Answer 24

1) Peripheral sheath: outermost layer composed of dermis
2) Glassy membrane: “basement membrane” joining the peripheral sheath to root sheath
3) Root sheath: innermost layer derived from epidermis

hair matrix at bulb

Question 25

Hair shape = follicle shape

Round follicle = 1)
Oval follicle = 2)
Flattened follicle = 3)

Answer 25

1) Round
2) Wavy/slightly curly
3) Very curly/coiled

Question 26

How does hair grow

Answer 26

• Rapidly dividing cells from hair bulb of follicle
• Pushes cells up and out
• Growth is cyclical

Cyclic hair growth: anagen (growth), catagen (transition), and telogen (rest)

Question 27

Types of hair

Answer 27

1) Vellus hair: thin/fine hairs
2) Terminal hair: thick/coarse hairs (darker)

Question 28

What makes up a nail

Answer 28

Hard keratin
1) root
2) nail plate
3) free edge

Nail matrix responsible for nail growth

Question 29

Function of a nail

Answer 29

protective covering for distal portions of fingers, contributes to dexterity

Question 30

Glands of the skin

Answer 30

1) Sweat glands - myoepithelial (eccrine or apocrine)
2) Sebaceous glands (oil glands)

Question 31

Types of sweat glands

Answer 31

1) Eccrine sweat glands: simple tubular glands that open directly to skin surface at pore (mostly water)
2) Apocrine sweat glands: release sweat into hair folicles, has added fatty substances & proteins (react to sex hormones)

Sweat glands are myoepithelial - contract when stimulated
Modified Versions of Apocrine glands: ceruminous glands and mammary glands

Question 32

Functions of Sebaceous Glands

Answer 32

• Secretes sebum (oily substance, largely lipid based, some cells)
• Lubricant for skin/hair
• Slows water loss from epidermal surface
• Kills bacteria

Question 33

Forms of skin cancer:

In US - 9500 people diagnosed each day

Answer 33

1) Basal cell carcinoma - most common, least malignant
2) Squamous cell carcinoma - second most common - fast
3) Melanoma - lowest amount of overall skin cancer cases, causes most death

Question 34

Cancer caused from statum basale with colorless “rolled” edges

Answer 34

Basal cell carcinoma

Slow-growing, mostly on face

Question 35

Cancer started from statum spinosum with scaly, red lesions on skin

Answer 35

Squamous cell carcinoma (keratinocytes)

Question 36

Cancer that starts in melanocytes, black/brown blotches

Answer 36

Melanoma

Use ABCDE