Integumentary System (Exam 1) Flashcards
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Epidermis
Outermost
Stratified squamous epithelium
Most cells produce keratin
The skin
Largest organ of the body
Composed of epidermis and dermis
Stratum corneum
Top layer of epidermis
Hard layer
20-30 layers of dead cells filled with keratin
Water proofing glycolipids
Stratum lucidum
Clear layer
2nd layer
2-3 layers of dead cells filled with keratin
Only found in hard skin (soles, palms)
Stratum granulosum
Granular layer
3rd layer
3-5 layers of cells that are alive but dying
Keratinacyte
Produce granules of keratohyaline
Which secrete keratin
Lamellar bodies
Produce lamellated granules
Which secrete the glycolipids
Stratum spinosum
Spiny layer 4th layer 5-7 layers of living cells Has melanin granules Has langerhan's cells
Langerhan’s cells
Cells of the immune system that have migrated from the bone marrow
Stratum basalt
Basal layer 5th layer One layer of rapidly dividing cells Has melanacytes Has merkel discs
Melanacyte
Produces melanin granules
Merkel discs
Touch receptors
Dermis
Dense irregular connective tissue Has: Blood vessels Nerve endings Hair follicles Glands Smooth muscle
Papillary layer
1st layer of dermis
Immediately below that stratum basale
Areolar connective tissue with collagen and elastin
Dermal papillae on palms form fingerprints
Reticular layer
2nd layer of dermis
80% of the dermis
Dense irregular connective tissue with large bundles of collagen and elastin
Hypodermis
Below the dermis
Functions:
Stores fat for insulation and shock absorption
Anchors the skin to underlying bone and muscle
Pathway for blood vessels and nerves to reach upper layers
Merocrine/eccrine
Sweat glands
Most common
Secretory portion is coiled deep in the dermis
Releasing duct extends to the surface of the epidermis
Secretes sweat made of H2O and salt
Apocrine
Larger sweat glands Releasing duct opens into hair follicles Found in the Axillary and pubic region Not active till puberty Organic substances in secretions: Odorless when first released Odiferous when bacteria begin breaking down organic constituents
Sebaceous gland
Present everywhere except palms and soles
Secretes sebrum
Softens and lubricates hair and skin