The Integument (skin)

Question 1

Skin Fxn: Barrier system

Answer 1

Protection from microorganisms/UV light

Relatively impermeable to water (prevents evaporation of body fluids)

Question 2

Skin Fxn: Sensation

Answer 2

Highly innervated with lots of receptors

Question 3

Skin Fxn: Thermoregulation

Answer 3

Sweat glands, vasodilation

Question 4

Skin Fxn: Plasticity-elasticity

Answer 4

Allows for changes in size and shape

Question 5

3 Layers of skin

Answer 5

• Epidermis: epithelial cells
• Dermis: CT
• Hypodermis: Subcutaneous tissue; superficial fascia CT

Question 6

Thick Skin (Glabrous)

Answer 6

400-600 um (thinkness)–more force put on
Hairless
Soles feet
Palms

Question 7

Thin Skin

Answer 7

75-100 um
Hairy
Everywhere else

Question 8

Cell Layers of Epidermis

Answer 8

Stratum basale (inner most)
Stratum spinosum
Stratum granulosum
Stratum lucidum
Stratum corneum (most superficial)

Question 9

Stratum Basale (Germinativum)

Answer 9

Single layer of cuboidal cells sitting on the basement membrane
Fxn: constant renewal (every 15-30 days) of epidermal cells via constant mitotic division

Question 10

Stratum Spinosum

Answer 10

-“Spiny” cells; cuboidal cells like the stratum basale
-filled with keratin filaments that are anchored into desmosomes
-desmosomes firmly bind cells of this layer together
Fxn: resist abrasion

Question 11

Stratum Granulosum

Answer 11

-3-5 layers of squamous cells; cytoplasm filled with vesicles
-vesicles fuse w/the cell membrane and discharge contents into the intercellular spaces
-secreted material contains high conc of lipid molecules
Fxn: provides intercellular cement
creates a barrier to foreign materials (seals the skin)

Question 12

Stratum Lucidum

Answer 12

• Most apparent in thick skin; minimal layer in thin skin
• Translucent lauer of squamous cells with no apparent organelles
• Densely packed keratin filaments anchored to desmosomes (provide strength to this layer)
• Fxn: resist abrasion

Question 13

Stratum Corneum

Answer 13

• Outermost surface of skin
• 15-20 layers of flattened non-nucleated cells; cytoplasm filled with keratin
• Cells consist of only keratin fibers, proteins, and thick cell membranes (no organelles; lifeless cells)
• Cells of this layer are continuously shed: desquamation
• resist abrasion, create water-tight barrier

Question 14

Keratinocytes

Answer 14

Generic term for epithelial cell in any and all layers

Question 15

Melanocytes

Answer 15

produce melanin-dark brown pigment
found in basal layer-b/w stratum basale and spinosum
Protect DNA from UV rays * most important fxn
transferred to keratinocytes at deep layers and is deposited “on top” of cell nuceli
Highest concentration=deeper layers of skin
Lowest most superficially because granules fuse with lysosomes for digestion

Question 16

Langerhans’ cells

Answer 16

Skin macrophages
Inner layers of epidermis-stratum basale and spinosum 2-8% of epidermal cells
provide the immune function for taking out the foreign bodies
bone marrow derived; carried to the epidermis via the blood
can bind and present antigen to lymphocytes for immune fxn against micro-organisms

Question 17

Dermis

Answer 17

-made up of loose CT (papillary layer) and dense irregular CT (reticular layer)
-neuronal innervation (skin sensory receptors)
-Pain, temp, pressure, vibration
Blood vessels are abundant

Question 18

Skin appendages to Dermis

Answer 18

Hair follicles, nails

sebaceous glands, sweat glands

Question 19

Subcutaneous Layer

Answer 19

Loose CT that binds skin to underlying structures
—hypodermis and superficial fascia
Often contains numerous fat cells
Also contains neurovascular network

Question 20

Epithelial Glands

Answer 20

Holocrine (sebaceous glands)
Merocrine (eccrine)
Apocrine (sweat gland)

Question 21

Holocrine: epithelial

Answer 21

secretory product is released along w/the entire contents of the cell
Holocrine glands put their material onto the hair follicle and from there it is released===oily skin
–burst open and material goes to hair follicle to be released onto skin

Question 22

Merocrine: epithelial

Answer 22

sweat gland

secretory product is released through exocytosis

Question 23

Apocrine: epithelial

Answer 23

secretory product is released with portion of cellular cytoplasm
filled with fluid material buds off and then released into the duct

Question 24

Sebaceous glands

Answer 24

Consists of epithelial cells that take up large quantities of lipids
Cells die and release lipid (sebum) into the hair follicle–active during puberty
Sebum has anti-bacterial and anti-fungal properties
highly concentrated in face and scalp

Question 25

Holocrine gland: sebaceous

Answer 25

lipids are secreted with the remnants of a dead cell | stem cells in the base of the gland proliferate to replace lost cells--rapid rate of renewal

Question 26

Merocrine sebaceous glands

Answer 26

coiled tubular glands opening onto skin surface ducts release sweat onto skin surface when body temp increases sweat evaporates cooling the skin surface sweat composition: H20, NaCl, urea, uric acid, ammonia

Question 27

Apocrine sebaceous glands

Answer 27

release a viscous, odorless fluid bacterial decomposition of fluid creates a distinctive scent found in axillary and ano-genital regions

Question 28

Sweat gland activity controlled by what?

Answer 28

autonomic nervous system (apocrine and merocrine)-sympathetic nervous system Apocrine (adrenergic) Merocrine (cholinergic)

Question 29

Sensory receptors

Answer 29

responsible for touch-pressure, tactile reception, hot-cold, pain and itching most found in dermal layer

Question 30

Types of sensory receptors

Answer 30

Free nerve endings-pain/temp Ruffini's endings-touch/temp Pacinian corpuscles-pressure/vibration Meissner's corpuscles-touch

Question 31

Nails

Answer 31

plates are keratinized epithelial cells nail root is source of dividing cells for growth cuticle is formed fromt he stratum corneum nail bed=basale and spinosum

Question 32

Nail growth matrix

Answer 32

proximal portion of the nail bed contains dividing cells | divide more distally and are cornified at proximal part of nail plate

Question 33

Hair-Follicle

Answer 33

Derived from invaginations of epidermal cells Dermal papilla contains dividing cells for hair growth and blood supply Arrector pili muscle=contraction=goose bumps Melanocytes provide pigment for hair color

Question 34

Hair Growth

Answer 34

6 inches/yr, variable growth cycles

Question 35

Anagen

Answer 35

active growth phase (30-45 days up to 2-6 years)

Question 36

Catagen (3% of all hairs)

Answer 36

2-3 week phase no growth occurring

Question 37

Telogen (10-15%)

Answer 37

Lasts 100+ days | Full resting phase; no growth occurs, hair loss

Question 38

Effects of aging on skin

Answer 38

Atrophy of strata of skin-layers become thinner -skin becomes more fragile reduced elasticity areas of skin exposed to sun are affected more rapidly Reduced sweating capability

Question 39

Effects of Acute Activity on Skin

Answer 39

Blood flow to skin increases with normal activity | ---at activity levels >50% blood flow to skin decreases and is diverted to working muscles at high levels of activity

Question 40

Effects of chronic training on skin

Answer 40

Hyperplasia of skin: callous formation Increased ability to sweat: improved thermoregulatory ability Blisters

Question 41

Blisters

Answer 41

fluid deposition at the jxn of epidermis and dermis epidermis raises away from the dermis caused by shearing forces continual training ability to regulate becomes for efficient

Question 42

Effects of immobilization on skin

Answer 42

Increased risk of skin breakdown=pressure ulcer | decuberutus ulcer

Question 43

Pressure ulcers occur in these areas most frequently

Answer 43

``` heels sacrum greater trochanter scapula elbows back of the head ```

Question 44

Back, abdomen, thighs, arms: epidermal specializations

Answer 44

Thin epidermis, loosely packed keratin | few follicles produce fine hairs, variable eccrine glands

Question 45

Sole of foot: epidermal specializations

Answer 45

Thick epidermis, densely packed keratin developed epidermal ridge system No hair follicles, abundant eccrine gland

Question 46

Scalp: epidermal specializations

Answer 46

tightly packed follicles

Question 47

Fingertips: epidermal specializations

Answer 47

thick epidermis, developed ridges, abundant sensory receptors

Question 48

Axilla/groin: epidermal specializations

Answer 48

thin epidermis, numerous oblique hair follicles | numerous eccrine and apocrine glands