Integumentary System Flashcards
2 parts of the integumentary system.
Cutaneous membrane(skin) and accessory structures.
2 parts of cutaneous membrane
Outer epidermis (epithelial tissues) and inner dermis (connective tissues)
Relationship between the subcutaneous layer and cutaneous membrane.
Subcutaneous layer(superficial fascia or hypodermics) loose connective tissue, below the dermis, location of hypodermic injections.
Functions of the skin
Protects underlying tissues and organs; excretes salt, water, and organic wastes(glands); thermoregulation(maintains body temp w/ insulation and evaporation); synthesizes vitamin d; stores lipids; detects touch,pressure,pain,and temp; non verbal communication.
Characteristics of the epidermis
Avascular stratified squamous epithelium
Nutrients and oxygen diffuse from capillaries in the dermis
Multilayered flexible self repairing barrier
Prevents fluid loss
Protects from UV radiation
Produces vitamin D
Resists abrasion, chemicals, and pathogens
Keratinocytes
Most abundant epidermal cells
Produce keratin
Tightly connected by desmosomes
Thick skin
Covers palms of hands and soles of feets
5 layers of keratinocytes
Layers of epidermis
From outside to inside Stratum Corneum Stratum Lucidum(only in thick skin) Stratum Granulosum(cells start to die here) Stratum Spinosum Stratum Basale
Thin skin
Covers most of body
Has only 4 layers
No stratum lucidium
Stratum Basale
Germinative layer
Single layer of cells
Has many stem(germinative) cells and young keratinocytes resting on basement membrane
Has melanocytes (10-25%)
Attached to basal lamina by hemidesmosomes
Forms strong bond between epidermis and dermis
Stratum Corneum
Horny layer
Exposed surface of skin
Up to 30 years of dead scaly keratinized cells
Keratinization
Formation of a layer of dead protective cells filled with keratin
Occurs on all exposed skin surfaces except eyes
Dehydration
Water loss through skin
Results from:
From damage to stratum Corneum (burns and blisters; insensible perspiration)
From immersion in hypertonic solution (seawater;osmosis)
Hydration
Results from immersion in hypotonic solution (bath water) or osmosis
Keratin of stratum Corneum absorbs water and swells
Causes stretching and wrinkling of skin
Skin color
Depends on melanin
Also carotene and hemoglobin (red blood cells)
Based on quantity of melanin and color of melanin.
Not number of melanocytes
Melanin
Yellow brown or black pigment
Produced by melanocytes in stratum Basale
Surrounding keratinocytes pick up melanin as it is produced
Dark skin
More melanin production, melanin granules more spread out and melanin breaks down more slowly
Light skin
Melanin clumps near nucleus (less color
Imparted on cells)
Breaks down more rapidly
Not seen beyond stratum Basale
Cyanosis
Bluish tint skin
Caused by severe reduction in blood flow or oxygenation
Hypodermis
Subcutaneous layer Lies below the integument Stabilizes the skin Allows separate movement Site for subcutaneous injections Fat storage Conserve body heat and retards penetration of external heat
Importance of hypodermis
Has few capillaries and no vital organs.
The site of subcutaneous injections using hypodermic needles.
Functions of hair
Protects and insulates head.
Alerts us to the presence of particles and insects.
Eyelashes shield the eyes.
Nose hairs filter large particles.
Medulla
Loosely arranged cells and air spaces.
Prominent in think hairs absent in very fine hairs. Contains soft keratin.
Cortex
The middle layer surrounding medulla.
Bulk of the hair, several layers of keratonized cells. Contains hard keratin.
Cuticle
Surface layer. Scaly overlapping single layer of cells. Hair conditioner smooths out the rough surface of the cuticle and makes it look shiny. Contains hard keratin.
Arrector pili
Each hairs has this involuntary smooth muscle. When contracted hairs stand up. Produces goose bumps. Not very useful in humans.
Sebaceous
Lubricate the hair. Control bacteria.
Hair follicle
Diagonal tube located deep in dermis or hypodermis. Anchors each hair into the skin. Wall is composed of 2 layers. Outer dense connective tissue root shaft. And inner epithelial root sheath.
Anagen
Active growth phase. 90% of the time. Stem cells multiply and follicle grows upward. Old hair may persist temporarily alongside newly growing hair.
Catagen
Mitosis ceases and hair follicles shrinks. Happens over a few weeks. Degenerative phase. Hair bulb keratinozes and forms hair. Lower follicles degenerates.
Telogen
Resting phase 1-3 months. Hair stops growth and detaches. New hair begins to grow pushing out the old hair. Dermal papilla has ascended.
Vellus hair
Soft fine hair. Cover body surface.
Terminal hair
Longer coarser. More heavily pigmented Head and eyebrows. Other body parts of body after puberty.
Hair color
Pigment from melanocytes. Melanins of different colors (structure) combine to produce hair color. Brown and black hair are rich in eumelanin. Red hair has a slight amount of eumelanin but a high concentration of pheomelanin. Blonde hair has an intermediate amount of pheomelanin but very little eumelanin. Gray and white hair result from a scarcity or absence of melanins in the cortex and air replaces melanin in the shaft.
Nail body
Visible portion of the nail covers the nail bed
Nail matrix
Responsible for growth. Contains nerves, lymph, and blood vessels.
Eponychium
Cuticle. Where nail emerges.
Hyponychium
Skin beneath free edge of nail. Anchors the free nail.
Lunula
Pale crescent and base of nail. Just last cuticle or eponychium.
Granulation tissue
Germinative cells migrate around the wound. Macrophages clean the area. Fibroblasts and endothelial cells move in to form granulation tissue. (New connective tissue with blood vessels form on surface of wound during healing.
Nasal cell carcinoma
Skin cancer. Most common type. Stem cells of stratum Basale. Usually non invasive.
Squamous cell carcinoma
Not as common. Begins in upper cells of epidermis. Becomes malignant more easily.
Vitamin D importance
Epidermal cells produce cholecalciferol with presence of UV radiation. Liver and kidneys convert to vitamin d to aid absorption of calcium and phosphorus. Insufficient vitamin d can cause rickets. Variations in ancestral exposure to UV are main reasons for geographic and ethnic variation in skin color.
Dermis
Located between epidermis and subcutaneous layer. Anchors epidermal accessory structures(hair follicles and sweat glands. Much thicker than epidermis. 2 components ( outer papillary layer and deep reticular layer.
Papillary Layer
Consists of areolar tissue. Thinner layer of dermis. Contains smaller capillaries that nourish the epidermis. Contains lymphatics, sensory neurons and immune cells. Has dermal papillae indenting the overlying dermis. In thick skin causes the overlying epidermis to form epidermal ridges.
Reticular layer
Consists of dense irregular connective tissue. Contains larger blood vessels, lymph vessels, and nerve fibers. Contains collagen and some elastic fibers.
Stretch marks
Thickened tissue resulting from excessive stretching (weight gain, pregnancy). Tearing of collagen and causes striae.
