CH 5 Flashcards
Test 2
-Is the largest system of the body
-16% of body weight
-1.5 to 2 m2 in area
-is made up of two parts:
Cutaneous membrane (skin)
Accessory structures
Integument
Two Components of the Cutaneous Membrane
Outer epidermis
Inner dermis
Superficial epithelium (epithelial tissues)
Outer epidermis
Connective tissues
Inner dermis
Cardiovascular system
Blood vessels in the dermis
connections
Sensory receptors for pain, touch, and temperature
Nervous system
- Loose connective tissue
- Below the dermis
- Location of hypodermic injections
Hypodermis
- Protects underlying tissues and organs
- Excretes salts, water, and organic wastes (glands)
- Maintains body temperature (insulation and evaporation)
- Synthesizes vitamin D3
- Stores lipids
- Detects touch, pressure, pain, and temperature
Functions of Skin
- Is avascular stratified squamous epithelium
- Nutrients and oxygen diffuse from capillaries in the dermis
The Epidermis
- Contain large amounts of keratin
- Are the most abundant cells in the epidermis
Keratinocytes
- Covers most of the body
- Has four layers of keratinocytes
Thin Skin
- Covers the palms of the hands and soles of the feet
- Has five layers of keratinocytes
Thick skin
-The five strata of keratinocytes in thick skin
-From basal lamina to free surface
Stratum germinativum
Stratum spinosum
Stratum granulosum
Stratum lucidum
Stratum corneum
Structures of the Epidermis
- Is attached to basement membrane
- Forms a strong bond between epidermis and dermis
- Forms epidermal ridges (e.g., fingerprints)
Stratum Germinativum
- Increase the area of basement membrane
- Strengthen attachment between epidermis and dermis
- Has many basal cells or germinative cells
Dermal papillae
- Found in hairless skin
- Respond to touch (trigger nervous system)
Merkel cells
- Contain the pigment melanin
- Scattered throughout stratum germinitivum
Melanocytes
- Produced by division of stratum germanitivum
- Continue to divide, increasing thickness of epithelium
- Contain dendritic (Langerhans) cells, active in immune response
Stratum Spinosum — the “spiny layer”
Stops dividing, starts producing
Stratum Granulosum — the “grainy layer”
- A tough, fibrous protein
- Makes up hair and nails
Keratin
- Dense granules
- Cross-link keratin fibers
keratohyalin
- Produce protein fibers
- Dehydrate and die
- Create tightly interlocked layer of keratin surrounded by keratohyalin
Cells of Stratum Granulosum
- Found only in thick skin
- Covers stratum granulosum
Stratum Lucidum — the “clear layer”
- Exposed surface of skin
- 15 to 30 layers of keratinized cells
- Water resistant
- Shed and replaced every 2 weeks
Stratum Corneum — the “horn layer”
- The formation of a layer of dead, protective cells filled with keratin
- Occurs on all exposed skin surfaces except eyes
- Skin life cycle
- It takes 15–30 days for a cell to move from stratum basale to stratum corneum
Keratinization
- orange-yellow pigment
- found in orange vegetables
- accumulates in epidermal cells and fatty tissues of the dermis
- can be converted to vitamin A
Carotene (pigment)
- yellow-brown or black pigment
- produced by melanocytes in stratum germinativum
Melanin
Causes DNA mutations and burns that lead to cancer and wrinkles
Ultraviolet (UV) radiation
-Melanin protects skin from sun damage
-Ultraviolet (UV) radiation
Causes DNA mutations and burns that lead to cancer and wrinkles
-Skin color depends on melanin production, not number of melanocytes
Function of Melanocytes
- Bluish skin tint
- Caused by severe reduction in blood flow or oxygenation
Cyanosis
- Buildup of bile produced by liver
- Yellow color
Jaundice
Excess MSH
Pituitary tumor
- A disease of the pituitary gland
- Skin darkening
Addison’s disease
- Loss of melanocytes
- Loss of color
Vitiligo
-Located between epidermis and subcutaneous layer
-Anchors epidermal accessory structures (hair follicles, sweat glands)
Two components:
1. Outer papillary layer
2. Deep reticular layer
The Dermis
- Consists of areolar tissue
- Contains smaller capillaries, lymphatics, and sensory neurons
- Has dermal papillae projecting between epidermal ridges
Papillary Layer
- Consists of dense irregular connective tissue
- Contains larger blood vessels, lymphatic vessels, and nerve fibers
- Contains collagen and elastic fibers
- Contains connective tissue proper
Reticular Layer
- An inflammation of the papillary layer
- Caused by infection, radiation, mechanical irritation, or chemicals (e.g., poison ivy)
- Characterized by itch or pain
Dermatitis
- Very strong, resist stretching but bends easily
- Provide flexibility
Collagen fibers
- Permit stretching and then recoil to original length
- Limit the flexibility of collagen fibers to prevent damage to tissue
Elastic fibers
Properties of flexibility and resilience
Skin turgor
Sagging and wrinkles:
- Dehydration
- Age
- Hormonal changes
- UV exposure
Skin Damage
- Thickened tissue resulting from excessive stretching of skin due to:
- Pregnancy
- Weight gain
Stretch marks
Bruising
An accumulation of blood from damaged vessels
- Lies below the integument
- Stabilizes the skin
- Allows separate movement
- Made of elastic areolar and adipose tissues
- Connected to the reticular layer of integument by connective tissue fibers
- Few capillaries and no vital organs
- The site of subcutaneous injections using hypodermic needles
Hypodermis (Subcutaneous Layer)
- Protects and insulates
- Guards openings against particles and insects
- Is sensitive to very light touch
Functions of Hair
- Located deep in dermis
- Produces nonliving hairs
- Wrapped in a dense connective tissue sheath
- Base is surrounded by sensory nerves (root hair plexus)
Hair Follicle
- Involuntary smooth muscle
- Causes hairs to stand up
- Produces “goose bumps”
Arrector pill
- Lubricate the hair
- Control bacteria
Sebaceous glands
- Lower part of the hair
- Attached to the integument
Hair root
- Upper part of the hair
- Not attached to the integument
Hair shaft
The central core
Medulla
The middle layer
Cortex
The surface layer
Cuticle
- Soft, fine
- Cover body surface
vellus hairs
- Heavy, pigmented
- Head, eyebrows, and eyelashes
- Other parts of body after puberty
Terminal hairs
- Holocrine glands
- Secrete sebum
Sebaceous Glands (oil glands)
- Contains lipids and other ingredients
- Lubricates and protects the epidermis
- Inhibits bacteria
Sebum
- Found in armpits, around nipples, and groin
- Secrete products into hair follicles
- Produce sticky, cloudy secretions
- Break down and cause odors
Apocrine Sweat Glands
- Widely distributed on body surface
- Especially on palms and soles
- Coiled, tubular glands
- Discharge directly onto skin surface
- Sensible perspiration
- Water, salts, and organic compounds
merocrine (Eccrine) Sweat Glands
- Cools skin
- Excretes water and electrolytes
- Flushes microorganisms and harmful chemicals from skin
Functions of merocrine sweat gland activity
Produce milk
Mammary glands (mammals)
- Produce cerumen (earwax)
- Protect the eardrum
Ceruminous glands
