Integumentary system Flashcards
Integument
-Is the largest system of the body->16% of body weight
-Protects and interacts with all organ systems
-Changes in skin appearance are used to diagnose disorders in other system
Made up of 2 parts
-Cutaneous membrane (skin)-> epidermis and dermis
-Accessory structures within the dermis
Hypodermis (superficial fascia or subcutaneous layer
-Loose Connective tissue
-Below the dermis
-Location of hypodermic injection
Cutaneous membrane function
-Physical protection from environmental hazards
Storage of lipids
-Coordination of immune response to pathogens and cancers in sking
Accessory structures functin
-Sensory information
-Synthesis of vitamin d2
-Excretion
-Thermoregulation
Epidermis
-Protects the dermis, prevents water loss and the entry of pathogens, and synthesizes vitamin d, sensory receptors detect touch, pressure, pain, and temperature
Dermis
Papillary layer- Nourishes and supports epidermis
Reticular layer- Has sensory receptors that detect touch, pressure, pain, vibration, and temperature. Blood vessels assist in thermoregulation
Hair follicles
-Hair protect skull and provide delicate touch sensation on general body surface
Exocrine glands
-Assist in temperature regulation and waste excretion
Nails
-Protect and support tips of fingers and toes
Function of integumentary system
-Protection of underlying tissues and organs
-Excretion of salts, water, and organic wastes (glands)
-Maintenance of body temperature (insulation and evaportation)
-Production of melanin
Functions of integumentary system
-Production of keratin
-Synthesis of vitamin D3
-Storage of lipids
-Detection of touch, pressure, pain, and temperature
Epidermis
-Consists of Keratinized stratified squamous epithelium
-Avascular (as all epithelia lack blood vessels)
-Depend on the diffusion of nutrients and oxygen diffuse from capillaries of underlaying connective tissue (dermis)
Epidermis
-Separated from the dermis by a basement membrane
-The deepest layer of the epidermis and the underlying dermis interlock, strengthening the bond between the two
Keratinocytes
-Main epidermal cells
-Contain large amounts of keratin -> tough fibrous protein
Stem cells
-Undifferentiated cells that give rise to keratinocytes
-Found in the deepest layer of the dermis (stratum basale)
Melanocytes
-Synthesize pigment melanin that shields DNA from ultraviolet radiation
-Occur only in stratum basale but have branched processes that spread among keratinocytes and distribute melanin
Tactile Cells
-Touch receptor cells associated with the dermal nerve fibers
-In basal layer of epidermis
Dendritic cells
-Macrophages originating in bone marrow that guard against pathogens
-Found in stratum spinosum and granulosum
layers of epidermis
-Two types of skin referring to the thickness of epidermis
Thin skin
-Covers most of the body
-Has four layers
Thick skin
-Covers the palms of the hands and soles of the feet
-Has five layers->from the basement membrane to free surface: Statum basale, stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum
Stratum Basale
-Single layer of basal cells or germinative cells (stem cells) -> cells divide and give rise to keratinocytes that migrate towards skin surface to replace lost cells
-Is attached to basement membrane by hemidesmosomes
Stratum Basale
-Forms epidermal ridges that fit a complementary pattern of corrugation of the underlying dermis (dermal papillae)
-Forms a strong bond between epidermis and dermis
-Increase the area of basement membrane
-Strengthen attachment between wpidermis and dermis
Stratum Basale
-Specialized structures of stratum basale
Tactile discs
-Tactile (Merkel) cells with sensory nerve endings
- Found in hairless skin
- Respond to touch
-Melanocytes contain the pigment melanin
Stratum Spinosum “Spiny layer”
-Eight to ten layers of keratinocytes bound by desmosomes
-Named for appearance of cells (spiny); Cells shrink until cytoskeletons stick out
-Continue to divide, increasing thickness of epithelium
-Contain dendritic (Langerhans) cell, activate in immune response
Stratum granulosum (grainy layer)
-Three to five layers of keratinocytes that derive from stratum spinosum
-Stop dividing, starts producing protein fibers
-Keratin: tough, fibrous protein that makes up hair and nails
-Keratohyalin that form dense granules that promote dehydration of the cell and cross linking keratin fibers
-Dehydrate and die
Stratum lucidum (clear layer)
-Pale layer found only in thick skin
-Coverts stratum granulosum
-Keratinocytes packed with clear protein eleidin
Stratum Corneum “horn layer”
-Exposed surface of skin
-Resists abrasion, penetration, water loss
-Several layers (up to 30) of dead, scaly, keratinized cells
-Keratinization of corneation -> The formation of layer of dead, protective cells filled with keratin
Life cycle of a Keratinocyte
-Keratinocytes are produced by mitosis of stem cells in stratum basale
-Mitoses requires abundant oxygen and nutrients, so once cells migrate away from blood vessels of the dermis, mitosis cannot occur
-New keratinocytes push older ones toward the surface
-Over time, keratinocytes flatten, produce more keratin
-It takes up 7 to 10 days for cell to move from stratum basal to stratum corneum and it takes additional 2 weeks before they shed and wash away
Stratum corneum is water resisting but not waterproof
-Water is lost from skin in two ways
Insensible perspiration
-Water diffuses across stratum corneum and evaporates from skin
-500 mL per day
-Rate increases if stratum corneum is damaged
Sensible perspiration
-Water excreted by sweat glands
Epidermal growth factor (EGF)
-A peptide growth factor
-Produced by salivary glands and duodenum
-Used in laboratories to grwo skin grafts
Function of Epidermal growth factor (EGF)
-Promotes division of basal cells
-Accelerates keratin production
-Stimulates epidermal repair
-Stimulates glandular secretion
The dermis
-Located between epidermis and subcuraneous layer
-Anchors epidermal accessory structures (hair follicles, swear glands)
-Two components
-Outer papillary layer
-Deep reticular layer