chapter 7 study guide Essay

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Chapter 7 Review:
The integument: largest system in the body (16% of body weight)
Made up of 2 parts:
1. Cutaneous Membrane (skin)
a. Consists of 2 components:
a.1. Outer epidermis
Superficial epithelium (epithelial tissues)
a.2. Inner dermis
Connective tissues
2. Accessory structures: Originate in the dermis
a. Extend through the epidermis to skin surface. They include:
a.1. Hair
a.2. Nails
a.3. Multicellular exocrine glands

Integumentary system is connected to the:
1. Cardiovascular system
Blood vessels in the dermis
2. Nervous system
Sensory receptors for pain, touch, and temperature

Hypodermis: Superficial Fascia or Subcutaneous Layer
Located below the dermis
Made of loose connective tissue
Location of hypodermic injections
*Not actually a layer of skin

The skin has 5 major functions:
1. Protection of underlying tissues and organs
2. Excretion of salts, water, and organic wastes (glands)
3. Maintenance of body temp (insulation and evaporation)
4. Production of Melanin, keratin, Vitamin D3, and storage of lipids
5. Detection of touch, pressure, pain, and temperature

Epidermis: Composed of stratified squamous epithelium
Avascular, nutrients and oxygen diffuse from capillaries in the dermis
Dominated by keratinocytes( most abundant type of epithelial cells)

Thin skin:
Covers most of the body
Has four layers of keratinocytes
Thick skin:
Covers the palms of the hands and the soles of the feet
Has five layers of keratinocytes

Five strata of keratinocytes in thick skin
1. Stratum basale: (lowest layer) attached to basement membrane by hemidesmosomes
Forms a strong covalent bond between epidermis and dermis
Forms epidermal ridges
Dermal papillae( tiny mounds)
Increases the area of the basement membrane
Strengthen attachment between epidermis and dermis
Has many basal cells (germinative cells)
Specialized cells of stratum basale:
Merkel cells
Found in hairless skin
Respond to touch (trigger nervous system)
Contain the pigment melanin
Scattered throughout the stratum basale
2. Stratum spinosum: the “spiny layer”
Produced by division of stratum basale
8-10 layers of keratinocytes bound by desmosomes
Cells shrink until cytoskeletons stick out (spiny)
Continue to divide, increasing thickness of epithelium
Contain dendritic (Langerhans) cells, active in immune response
3. Stratum granulosum: the “grainy layer”
Stops dividing, starts producing
A tough, fibrous protein
Makes up hair and nails
Dense granules
Cross-link keratin fibers
Cells here:
Produce protein fibers
Dehydrate and die
Create tightly interlocked layer of keratin surrounded by keratohyalin
4. Stratum lucidum: the “clear layer”
Found only in think skin
Covers stratum granulosum
5. Stratum corneum: the “horn layer”
Exposed to surface of skin (15-30 layers of keratinized cells)
All exposed skin surface (except anterior of eyes) undergo cornification (keratinization)- formations of protective, superficial layers of cells filled with keratin
Cells are dead and linked together by desdemosomes
Water resistant
Shed and replaced every 2 weeks
It takes 15-30 days for a cell to move from stratum basale to stratum corneum

Stratum corneum is water resistant: Perspiration can occur by:
1. Insensible Perspiration
Interstitial fluid lost by evaporation through the stratum corneum (lose about 500 mL, or 1 pint of H2O per day)
2. Sensible perspiration
Water excreted by sweat glands
Dehydration can result:
From damage to stratum corneum (e
Ex. Burns and blisters (insensible persipiration
From immersion in hypertonic solution
Ex. Seawater (osmosis)- dangerous for shipwreck survivors
Hydration can also occur through osmosis
Results from immersion in hypotonic solution
Ex. Freshwater (osmosis)
Causes swelling of epithelial cells, evident on the palms and soles

Skin color: influenced by 2 pigments
1. Carotene
Orange-yellow pigments
Found in