Integumentary System Flashcards
Functions of the Integumentary system
Protection (proteins, lipids, glandular secretions, melanin pigment), blood reservoir (specifically dermis), thermoregulation (sweat, vasoconstriction/vasodilation, adipose in hypodermis), Cutaneous sensation, Excretion/secretion and absorption (sweat, oil, vitamin D synthesis)
Composition of Integumentary system
3 layers (epidermis, dermis, and subcutaneous layer). Layers include sweat and oil glands, hair follicles, hair root, and adipose
Layers of Epidermis (from superficial to deep)
Corneum, Lucidum (only present in thick skin), Ganulosum, Spinosum, Basale. (Come, Let’s Get Sun-Burned)
Stratum Basale
single layer of round/alive cells, multiple types of cells. creates new cells that move superficially
Stratum Spinosum
Numerous layers of keratinocytes, some retain ability to divide
Stratum granulosum
transition layer –> some cells are alive, some are undergoing apoptosis
Stratum Lucidum
thick skin only, ~3-5 cell layers thick, composed of dead keratinocytes
Stratum Corneum
Variably thick layer of dead, flattened keratinocytes
Psoriasis
a chronic skin disorder where keratinocytes divide and are produced more quickly and move up superficially faster than in a typical individual. This forms plaque which will appear white and scaly and there can be redness and inflammation.
What type of tissue makes up the epidermis?
keratinized stratified squamous epithelial tissue
Types of cells in epidermis
Mostly keratinocytes (produce keratin and lamellar granules), also include melanocytes, Langerhans cells, and Merkel cells
Melanocytes
produce melanin, and have extensions that go between keratinocytes allowing melanin to move into those cells.
Langerhans cells
very large cells that engulf/ingest microbes from within the epidermis. (part of immune response)
Merkel cells
a touch receptor important from fine touch (texture/shape)
Dermis
Middle layer of skin, includes mostly fibroblasts (create collagen) but also macrophages (engulf microbes) and adipocytes (fat cells).
2 divisions of dermis
Papillary region: (~20%) projects into epidermis (creates fingerprints)
Reticular region: (~80%) lower region and contains most components of dermis ( such as muscle, glands, corpuscle, etc) and collagen and elastic fibers are organized into lines of cleavage (tension lines)
Lines of Cleavage (Tension Lines)
the collagen and elastic fibers of the dermis are organized into lines. These lines play a big role in how wounds heal. (parallel injuries have a better chance of healing with only a fine scar)
Hypodermis (subcutaneous layer)
Deepest layer of skin(although not a part of skin proper), contains mostly adipose, is well vascularized, and is important for thermoregulation and energy storage
Melanin Production
produced by melanocytes in stratum basale, where it moves through extensions to protect the nuclei and DNA or keratinocytes. Synthesized from tyrosine.
Melanin function
absorbs UV radiation, prevents damage to DNA in keratinocytes, neutralizes free radicals (cancer-causing agents). Affects skin, hair, and iris color
Melanin clinical considerations
Sunburn (when amount of UV surpasses amount of melanin produced), freckles (accumulation of melanin), moles (accumulations of molanasides), skin cancer (basal cell carcinoma - ~78% starts in stratum basale and less serious, squamous cell carcinoma - ~20% originates in stratum spinosum and intermediate seriousness, malignant melanoma - ~20% originate in melanocytes will spread and highest mortality.
Gland
Epithelial tissue that secretes something, can be endocrine (releases secretion within body) or exocrine (released onto a surface (skin or oral cavity))
Sebaceous gland
releases oil(sebum), typically associated with hair follicle. during puberty they become larger and secrete more, infections lead to acne
Sudoriferous glands
releases sweat. most common: eccrine (important for thermoregulation). Also can be apocrine which is sweat in armpit, beard, and external genitalia, has an odor, and secretes during sexual excitement and nervousness.
