Integumentary System Flashcards
(41 cards)
What are the functions of skin?
Protection
Physical
Immune
UV radiation
Desiccation
Thermal regulation
-blood cells
-hair
-eccrine glands
Sensation
- receptors
-hair
Secretion
-sweat gland(s)
-sebaceous glands
Vitamin D synthesis
-stimulated by UV light
Immunity
-langerhans cells
Excretion
- water, salts, other chemicals
What are the two layers of the skin?
Epidermis
-ET outer, thinner layer
Dermis
-CT inner, thicker layer
Under dermis is subcutaneous layer (superficial fascia, hypodermis) : areolar and adipose tissue.
Define the integumentary system
A group of organs that function together to perform certain functions
Unusual in that there is only one organ on the skin, cutaneous membrane.
This system also includes accessory structures: nail, hair, exit ring, glands: sweat, subcutaneous, mammary
Thick vs thin skin
Thin skin has hair, found everywhere but palms and soles
Thick skin is found in palms and soles, no hair more. Pronounced dermal papillae.
Define epidermis
Composed of stratified squamous epithelium, keratinized: four kinds of cells, five layers.
What are the 5 cell layers and 4 cell types of the epidermis?
Layers:
Stratum basale
Stratum spinosum (spin-o-sum)
Stratum granulosum (gran-oo-law-sum)
Stratum lucidum (luc-e-dum)
Stratum corneum (corn-e-um)
Cells:
Keratinocytes
Melanocytes
Langerhans
Merkel cell
What is the stratum basale
The deepest layer of the epidermis
Mitotic, stem cells, give rise to keratinocytes which migrate upwards, other cells from this layer migrate downwards to form glands and hair follicles
What is the stratum spinosum?
Second deepest layer in epidermis
Cells have many spine like desmosomes, melanocytes scattered here
What is the stratum granulosum
Middle layer of epidermis
Produce keratin precursor, nuclei break down this layer, cells start to die
What is the stratum lucidum?
Second layer from the top of the epidermis
Found in thick hairless skin, three to five layers of dead cells, contains keratin intermediate
What is the stratum corneum
Top layer of epidermis
25 to 30 layers of flat, dead cells: completely filled with keratin
These cells are continuously shared and replaced, from the protective barrier- waterproof, smells together
What are keratinocytes?
Produce keratin, waterproof and protect skin from heat, chemicals, microbes
What are melanocytes?
Produce melanin, transfer to keratinocytes: melanin protects from UV
What are langerhans?
Dentritic cells
Interact with helper t cells, phagocytes, perform immune function
What are Merkel cells?
Tactile cell
Makes contact with sensory nerve endings, function in touch sensation
What is keratinization?
Process of forming stratum cornum: cells originate in basil layer. Move up and out, acquire keratin, lose organelles, die, are shed. Takes 2 to 4 weeks
What are friction ridges?
Fingerprints
Overlie dermal ridges, found in thick skin, increase friction: gripping
Note about epithelial layers
Epithelial layers are highly mitotic therefore subject to copy errors, can lead to cancer
Basal cell carcinoma, squamous cell carcinoma, melanoma
Define dermis
Dermis means skin
Epidermis is above, hypodermis is below
Composed of connective tissue, two layers, varies and thickness contains blood vessels, nerves, glands, hair follicles
What are the cells found in the dermis?
Fibroblast
Adipocytes
Areolar
Defense cells
What are the layers of the dermis?
Papillary region
Reticular region
Subcutaneous layer
Note skin has all four tissues but ET and CT, predominate
What is the papillary region of the dermis?
Areolar connective tissue
Has dermal papilla- projections that extend into epidermis, anchor the two layers together.
Dermal papillae contain capillaries, meissner’ s corpuscles (tactile receptors), free nerve endings (pain)
What is the reticular region?
Dense irregular connective tissue (white fiber is connective tissue) lots of collagen fibers (strength) Plus some elastic fibers (allow skin to stretch).
Space between fibers have sweat glands and ducks, hair follicles subcutaneous glands, nerves, adipose cells
Sensory structures: pacinian corpuscles (deep pressure receptor) Ruffini corpuscles (pressure receptor)
This region provides skin with strength, elasticity
Fibers are like gauze: part of animal you make leather out of
What is the subcutaneous layer?
Superficial fascia, hypodermis
Attaches reticular layer to underlying bone, muscle, contains blood vessels, fat layer and expands and weight gain: site of injection via hypodermic needles
