Integumentary System Flashcards
What is the integumentary system?
Organ system consisting of the skin, hair, nails, and exocrine glands
What does the integumentary system do?
-Protects the body from chemicals, disease, UV light, physical damage
-Produces sweat, oil, wax
-Waterproofing
-Supplying triglycerides
-Synthesis of vitamin D
What is the epidermis?
-Outer layer of the skin
-Consists of keratinized stratified squamous epithelium
-Avascular, must be nourished by tissue fluids from the dermis
What is the dermis?
-Second layer of the skin
-Thick layer of fibro-elastic connective tissue
-Highly vascular
-Contains receptor organs
What is subcutaneous tissue?
Layers of loose connective tissue containing various amounts of adipose tissue
What is the epidermal strata?
-Five distinct layers of cells attached to basement membrane
-Best defined in thick skin
-Consists of keratinocytes
What is a keratinocyte?
Cell that manufactures and stores keratin
What is keratin?
An intracellular fibrous protein that gives hair, nails, and skin their hardness and water resistance
What is a melanocyte?
Cell that produces melanin
What is melanin?
Gives hair and skin its colour, and helps protect the living cells of the epidermis from UV damage
What are the two layers of the dermis?
Papillary dermis
Reticular dermis
Describe the anatomy of the papillary dermis:
-Loose areolar connective tissue comprised of collagen + elastin fibres to form a loose mesh
-Projects into the stratum basale of the epidermis
-Contains: fibroblasts, adipocytes, phagocytes, lymphatic capillaries, nerve fibres, touch receptors (meissner corpuscles)
Describe the anatomy of the reticular dermis:
-Thicker than papillary
-Dense irregular connective tissue
-Well vascularized
-Elastin enables movement
-Collagen binds water to keep skin hydrated
What is the hypodermis?
-Directly below the dermis
-Well vascularized
-Loose connective & adipose tissue
What does adipose tissue in the hypodermis do?
-Energy reserve
-Insulation
-Cushion
What is hair?
-Keratinous filament grows in the epidermis in a hair follicle
-In the follicle is a hair papilla lined with stratum germinativum which produces the hair
-Hair bulb surrounds the papilla containing capillaries and nerve endings from the dermis
What are the functions of hair?
-Protection
-Sensory input
-Thermoregulation
-Communication
-Specialized hairs defend the body by trapping dust particles
What are sebaceous glands?
-Exocrine gland attached to hair follicle
-Produces sebum
What is sebum?
-Fatty/oily substance that coats the hair and skin
-Natural lubrication
-Prevents moisture loss and brittleness
-Inactive during childhood
-Secretion is stimulated by hormones
What are sweat glands?
-Exocrine sudoriferous glands produce sweat to cool the body
-Secretions are excreted by exocytosis
What are eccrine sweat glands?
-Produce hypotonic sweat for thermoregulation
-Found all over skin (esp. palms, soles, forehead)
-Sweat is mostly water, some salt, antibodies, metabolic waste, dermicidin, an antimicrobial peptide
What are apocrine sweat glands?
-Hair follicles in densely hairy areas (e.g., armpits)
-Larger than eccrine
-Sweat includes organic compounds that make the sweat thicker and more odorous
What are nails?
-Formed on the nail bed
-Composed of densely packed dead keratinocytes
-Forms at the nail root, a matrix of proliferating cells from the stratum basale that allows the nail to grow continuously
Vitamin D synthesis:
-Epidermal skin layer synthesizes vit D when exposed to UV
-D3 (cholecalciferol) is synthesized from a derivative of cholesterol
-Liver converts D3 to calcidiol, then converted to calcitriol in the kidneys
