The Integumentary System Flashcards
1
Q
What is the integument?
A
- The body’s largest organ (skin)
- Functions include:
1. Protection:
– Provides physical barrier protecting against trauma
– Protection from solar radiation
– Some chemical absorption (selective permeability)
2. Prevention of water loss and gain:
– Skin is water resistant
– Skin is not waterproof: transepidermal water loss
3. Temp regulation:
– Dilation of vessels, increased sweating in warmth
– Constriction of vessels in cold
4. Metabolic regulation:
– Vitamin D is produced by some skin cells
5. Immune defense:
– Epidermal dendritic cells help initiate immune responses
6. Sensory reception:
– Many skin receptors help detect changes in temperature and touch
7. Secretion:
– Sweating, lubrication of hair and skin with sebum
2
Q
What is the epidermis?
A
- Epithelium of the skin
- Avascular
- Keratinized stratified squamous epithelium
- Composed of several layers (strata)
- Epidermal strata: from deep to superficial…
– Stratum basale
– Stratum spinosum
– Stratum granulosum
– Stratum lucidum (found only in thick skin)
– Stratum corneum
3
Q
Thick vs. thin skin
A
- Thick skin contains five layers in epidermis (includes stratum lucidum):
– Found in palms of hands and soles of feet
– Epidermis is 0.4-0.6 mm thick
– No hair follicles or sebaceous glands - Thin skin lacks stratum lucidum – has four layers in epidermis:
– Covers most of body
– Epidermis is 0.075-0.150 mm thick
4
Q
How is skin colour determined?
A
- Determined by 3 pigments:
1. Hemoglobin: blood pigment; red in color
2. Melanin: Pigment produced by melanocytes - Increases with exposure to ultraviolet radiation
- Relative amounts of 2 types of melanin give people different complexions (all people have about same number of melanocytes)
3. Carotene: Yellow-orange pigment from foods such as carrots; it builds up in the skin
5
Q
What are the types of skin markings?
A
- Nevus: Also called a mole; localized overgrowth of melanocytes
- Freckles: Yellow or brown spots of high melanocyte activity
- Hemangioma: Proliferation of blood vessels that form a benign tumor
- Friction ridges: Folds of epidermis and dermis on fingers, palms, soles, and toes; increase friction for grasping
6
Q
What is the dermis?
A
- Lies deep to epidermis
- Composed of areolar and dense irregular connective tissues
- Has 2 layers:
1. Papillary layer: Superficial; adjacent to epidermis
2. Reticular layer: Deeper and thicker layer
7
Q
What are stretch marks, wrinkles and lines of cleavage?
A
- Majority of collagen and elastic fibers are oriented in
parallel bundles at specific body locations - Lines of cleavage identify the orientation of these
fiber bundles (Incisions across these lines heal slower than those along these lines) - When skin is overstretched, collagen fibers may tear
to form striae (stretch marks) - Ultraviolet light exposure and aging reduce flexibility
and thickness of the dermis, resulting in wrinkles
8
Q
Innervation and blood supply in dermis do what?
A
- Nerve fibers function to:
– Tactile (touch) receptors
– Control blood flow
– Control glandular secretion - Blood vessels function to:
– Supply nutrients to avascular epidermis
– Important in controlling body temperature:
- Vasoconstriction: Narrowing blood vessel diameter;
used to shunt blood away from periphery
- Vasodilation: Widening blood vessel diameter; used
to move blood toward periphery for releasing heat
9
Q
What is the subcutaneous layer?
A
• Deep to the integument – Not actually part of the integument – Composed of areolar and adipose connective tissues • Functions: – Protects underlying structures – Stores energy – Thermal insulation
10
Q
What are some epidermal derivatives?
A
- Nails
- Hair
- Exocrine glands of the skin
11
Q
What are nails?
A
- Scalelike modifications of the stratum corneum
- The nail plate has a whitish free edge, a pinkish nail body, and a nail root that is covered by the skin
- The nail body covers a layer of epidermis called the nail bed
- Nail matrix: Thickened growing part of the nail bed
- Lunula: White semilunar proximal area of nail body caused by thickened underlying stratum basale obscuring capillaries in dermis
12
Q
What is hair?
A
- Functions of hair:
1. Protection
2. Heat retention
3. Sensory reception
4. Visual identification
5. Chemical signal dispersal - Pilus consists of keratinocytes growing from follicles deep in dermis (often projecting to subcutaneous layer)
- Three hair types include lanugo, vellus, and terminal hair
- Zones that make up a hair:
1. Hair bulb: Deep swelling of epithelial cells where hair originates
2. Hair root: Portion that is deep to skin surface
3. Hair shaft: Portion that extends beyond skin surface - Hair production occurs at hair matrix
- Hair has 3 layers:
1. Medulla: core of loose cells, air spaces
2. Cortex: several layers of hardened, flattened cells
3. Cuticle: outer coating - A hair follicle surrounds each hair
- Arrector pili muscles attach to hair shaft: Respond to emotions and cold temperatures by contracting,
standing the hair up, therefore producing “goose bumps”
13
Q
What is hair growth?
A
- 3 stages of the hair growth cycle:
1. Anagen phase: active growth at hair bulb
2. Catagen phase: brief regression period (cell division ceases, follicle shrinks)
3. Telogen phase: resting phase; usual phase when hair is shed - Alopecia is hair thinning
- Male pattern baldness caused by genetic and hormonal
factors - Hirsutism (airiness) is commonly caused by excess androgens
14
Q
What are the exocrine glands of the skin?
A
- Main types:
1. Sweat glands: merocrine and apocrine types (produce watery solutions)
2. Sebaceous glands: produce oily secretions
15
Q
What are merocrine sweat glands?
A
- Simple coiled tubular glands that release secretions
into a duct with a pore on skin’s surface - Secretion is 99% water, clear, and controlled by nervous
system - Numerous on palms of hands, soles of feet, and forehead
- Functions:
– Thermoregulation
– Secretion
– Protection
