Chapter Six Flashcards
Organ (describe)
Two or more types of tissues grouped
together and performing specialized
functions
Integumentary System (describe)
The skin and its accessory structures (hair, nails, glands, sensory receptors)
Skin (describe)
Contains 2 layers: epithelial tissue and overlying connective tissue
Outer layer is the epidermis; inner layer is the dermis
Skin
Epidermis (describe)
Outer layer
Stratified squamous epithelium
Basement membrane between epidermis and dermis
Protects against water loss, chemicals, mechanical injury, pathogens
Skin
Dermis (describe)
Inner layer
Thicker of the 2 layers of the skin
Connective tissue
Contains collagenous & elastic fibers
Skin
Subcutaneous layer (hypodermis) (describe)
Beneath dermis; insulating layer
Areolar and adipose connective tissue
Not considered part of the skin
Contains blood vessels that supply skin
Keratinization (describe)
Process of hardening, dehydration, and keratin accumulation that occurs in epidermal cells as they migrate outward
Keratin (describe):
Tough, fibrous, waterproof protein made and stored in the cells
As cells reach outer surface, become tightly packed, develop desmosomes, form outer layer, stratum corneum
Stratum corneum cells are eventually shed from skin surface
Stratum Basale
Deepest layer of the epidermis, nourished by blood vessels in dermis
Melanocytes (describe)
Located in the stratum basale produce the dark pigment melanin
Absorbs UV light from sunlight and provides skin color
Factors Affecting Skin Color
Hereditary Factors
Environmental Factors
Physiological Factors
Dermis (describe)
Inner layer of skin; average of 1-2 mm thick
Contains dermal papillae to bind epidermis to underlying tissues
Connective tissue layer; contains muscle fibers
Nerve cell processes
Layers of Dermis
Papillary layer
Reticular layer
Layers of Dermis
Papillary Layer (describe)
Superficial layer; thinner of the 2 layers
Areolar connective tissue
Location of dermal papillae
Layers of Dermis
Reticular Layer (describe)
Deeper layer; thicker of 2 layers
Dense irregular connective tissue
Accessory Structures of the Skin (list)
Hair follicles
Nails
Skin glands (sweat and sebaceous)
Nails (describe)
Protective coverings on ends of fingers and toes
Parts of Nail (list)
Nail plate
Nail bed
Lunula
Nail Plate (describe)
Overlies nail bed
Nail Bed (describe)
Surface of skin, under nail plate
Lunula (describe)
Most active growing region; pale, half-moon-shaped region at base of nail plate
Hair Follicle (describe)
Tube-like depression of epidermal cells from which hair develops
Parts of Hair (list)
Hair bulb (dividing cells) Hair root Hair shaft (dead, epidermal cells)
Skin Glands
Sebaceous Glands
Produce sebum, which consists of fatty material and cellular debris
Sebum keeps hair and skin soft and waterproof
Excess sebum can result in acne
Absent on palms and soles
Skin Glands
Sweat Glands
Also called sudoriferous glands
Widespread in skin
Originate in deeper dermis or hypodermis as ball-shaped coils
Types of Skin Glands (list)
Eccrine (merocrine) glands
Apocrine sweat glands
Ceruminous glands
Mammary glands
Eccrine (Merocrine) Glands (describe)
Numerous, hands, feet, forehead
Respond to elevated body temperature
Apocrine Sweat Glands (describe)
Axillary and groin areas
Secrete by exocytosis
Respond to emotions, pain
Ceruminous Glands (describe)
Produce ear wax
Mammary Glands (describe)
Produce milk
Skin (functions)
Protective covering, barrier against harmful substances and microorganisms Prevents some water loss Contains sensory receptors Excretes some wastes Helps produce Vitamin D Helps regulate body temperature
Regulation of Body Temperature
Important to regulate body temperature; slight shift can disrupt rates of metabolic reactions
Set point is monitored by Hypothalamus
Skin plays key role in homeostatic mechanisms that regulate body temperature
Heat Production and Loss (describe)
Heat is a product of cellular metabolism
The most active body cells are major heat producers: Skeletal muscle, cardiac muscle, cells of the liver
When body is too warm, body responds with vasodilation of dermal blood vessels and vasoconstriction of deep blood vessels. Heat can escape through skin.
Methods of Heat Loss
Radiation
Conduction
Convection
Evaporation
Radiation (describe)
Primary method of heat loss, infrared heat rays escape
Conduction (describe)
Heat moves from skin to cooler objects
Convection (describe)
Heat loss into circulating air currents
Evaporation (describe)
Sweat changes into a gas, carries heat away
Body Temperature Regulation
When Body Temperature Rises
Thermoreceptors signal hypothalamus
Vasodilation of dermal blood vessels
Sweat glands are activated
Body Temperature Regulation
When Body Temperature Falls
Thermoreceptors signal hypothalamus
Vasoconstriction of dermal blood vessels
Sweat glands are inactive
Muscles contract involuntarily (shivering)
Problems in Body Temperature Regulation
Hyperthermia
Abnormally high body temperature
Can occur on hot, humid day, when sweat cannot evaporate
When air temperature is high, radiation is less effective
Body may gain heat from hotter air
Skin becomes dry, person gets weak, dizzy, nauseous, with headache, rapid pulse
Problems in Body Temperature Regulation
Hyporthermia
Abnormally low body temperature
Can result from prolonged exposure to cold, or illness
Shivering is involuntary skeletal muscle contraction, caused by hypothalamus
Progresses to confusion, lethargy, loss of reflexes and consciousness
Without treatment, organs shut down
Inflammation (describe)
Inflammation is a normal response to injury or stress
Inflammation is body’s attempt to restrict spread of infection
Blood vessels in affected tissues dilate and become more permeable, allowing fluids to leak into the damaged tissues
Shallow Cut (describe)
Affects only the epidermis, results in epidermal cells along its margin dividing more rapidly than usual, to fill gap
Deep Cut (describe)
Reaching dermis or subcutaneous layer, results in blood vessels breaking; released blood forms a clot
Burns
Superficial, partial-thickness (first degree) burn (describe):
Injures only epidermis, as in sunburn; redness, heat, inflammation
Healing takes days-weeks, no scarring
Burns
Deep, partial-thickness (second degree) burn (describe):
Destroys epidermis and some dermis, as in burn from hot liquid
May blister, healing varies with severity of burn & stem cell survival
Stem cells in hair follicles and glands can help regenerate skin
Usually recovers completely, no scarring
Burns
Full-thickness (third degree) burn (describe):
Destroys epidermis, dermis, accessory structures
Results from prolonged exposure to heat, flames, hot liquids
Some healing from margins
Often requires skin graft, skin substitutes
