Chapter 5: The Integumentary System Flashcards
Epidermis
Superficial, thinner portion of skin, composed of epithelial tissue.
Dermis
Deeper thickness connective tissue. Contains collagen and elastic fibers.
Subcutaneous Layer
Or hypodermis
Deep to the dermis not part of the skin. Composed of areolar and adipose tissue.
Lamellated Corpuscles
Contains nerve endings that are sensitive to pressure.
Keratin
Protein produced by keratinocytes
Lamellar Granules
Releases water repellent sealant that decreases water entry and loss.
inhibits the entry of foreign materials.
Melanin
Yellow-red or brown black pigment that contributes to skin color and absorbs ultra violet light.
Synthesized by amino acid: tyrosine
Found in: penis, nipples, face and limbs
Keratinocytes
90% of cells in skin
Produces protein: keratin and Lamellar granules
Melanocytes
8% of skin cells
Developed from the ectoderm of a developing embryo
Produces pigment: melanin
Intraepidermal Macrophages
Arise from red bone marrow
Migrate to epidermis
Easily damaged by uv light
Destroys pathogens
Tactile Epithelial Cells
Least numerous of epithelial cells
Located deepest to the dermis, contact with tactile disc
Epidermal Strata
From deepest to superficial layer
- Stratum Basale
- Stratum Spinosum
- Strata Granulosum
- Strata Lucidum
- Strata Corneum
Strata Basale
Deepest layer. Composed of cubodial or columnar keratinocytes
Contains scattered keratin and intermediate filaments
Site of cell divsion
Stratum Spinosum
Rows of many sided keratinocytes with bundles of keratin
Contains melanocytes and intraepidermal macrophages
Stratum Granulosum
Rows of flattened keratinocytes, organelles begin to degenerate
Contains keratonyalin protein and lamellar granules
Keratonyalin Protein
Converts keratin into keration
Stratum Lucidum
Present only in thick skin
Rows of clear, flat, dead keratinocytes with large amounts of keratin
Stratum Corneum
Top Layer
Rows of dead flat keratinocytes. Contain mostly keratin.
Mechanical stress would increase this layer.
Dermis
Second, deepest part to skin
Contains collagen, elastic fibers
Papillary region
1/5 thickness of dermis layer. Not attached to SC layer
Dermal Papilae
Increase surface area of dermis. Project into under surface of epidermis.
Contains: capillary loop (blood vessels), corpuscles of touch (free nerve endings)
Reticular Region
Attached to SC layer
Contains:
Bundles of thick collagen fibers, scattered fibroblast, wandering cells
Collagen and Elastic Fibers
Produces strength (extensibility) and stretch (elasticity)
Epidermal Ridges
Appear as either straight lines, loops or whorls. Series of grooves and ridges found on surface of palms, fingers, soles and toes.
3 pigments of skin color
- Melanin
- Hemoglobin
- Carotene
Hair
Or pili
Found on most skin surface, expect palms and feet
Hair shaft
Superficial portion of hair, projects above surface of skin
Hair root
Deep to the shaft, penetrates into dermis, sometimes SC layer
3 layers of the Shaft and Root of Hair
- Medulla - inner. May be lacking in thinner hair
- Cortex - middle. Forms major part of shaft. Elongated cells
- Cuticle of the hair - outer most. Heavily keratinized.
Hair Follicle
Surrounds root of hair
Made of: external root sheath and internal root sheath
Epithelial Root Sheath
External and internal root sheath
Dermal Root Sheath
Dense dermis that surrounds the hair follicle
Hair Bulb
Base of each hair follicle and surrounding dermal root sheath
Onion shaped
Papilla of the Hair
Contains areolar CT and many blood vessels that nourish growing hair
Hair Matrix
Contained in the bulb
Arises from the stratum basale, site of cell division
Responsible for growing hairs, and producing new hairs
Arrector Pili
Sebaceous oil glands with bundle of smooth muscle cells.
Under stress the nerve endings are stimulated cause goosebumps
Hair Root Plexus
Surrounds each hair follicle
Are dendrites of neurons, sensitive to touch
Sebaceous Gland
Oil Gland
Located in dermis, termination of gland at the hair follicle
Secretes: sebum
Sebum
Secreted from sebaceous gland into hair follicles.
Mixture of: triglycerides, cholesterol, proteins, inorganic salts
Prevents hair from drying out, water loss from skin, keeps skin most and inhibits growth of bacteria
Sudoriferous Gland: Eccrine
Sweat glands
Found through most regions of skin, esp forehead, palms and soles.
Deep to dermis, termination surface of epidermis
Secretes: perspiration
Stimulated during emotion stress
Perspiration
Consists of water, Ions (Na, Cl) Urea, Uris acid, ammonia, amino acid, glucose, lactic acid
Regulates body temp, waste removal
Ceruminous Glands
Found in external auditory canal
Located in SC layer
Termination of duct in external auditory canal or ducts of sebaceous glands
Secretes cerumen (ear wax)
Prevents entrance of foreign objects and microbes from entering ear
Nails
Plates of tightly packed, hard, dead keratinized epi cells. Form a clear solid covering over dorsal surfaces of digits.
Nail Body
Visible portion of nail, does not shed cells. Cells filled with hard type of keratin.
Nail Body Color
Appears pink due to the blood flow through capillaries in underlying dermis.
Free Edge
Part of nail body that extends past the distal end of digit.
Nail Root
Portion of nail that is buried in a fold of skin
Lunula
White crescent shaped area of the proximal end of nail body
Hyponychium
Thickest region of stratum Corneum. Junction between free edge and skin of finger tip. Secures nail to finger tip.
Nail Bed
Skin below nails plate. Extends from the lunula to the hyponychium. Lacks stratum Granulosum.
Eporychium
Cuticle, narrow bend of epidermis. Extends from and adheres to the margin of nail wall.
Hangnail
Has nothing to do with nail. Small torn piece of skin at base of fingernail or toenail.
Caused by dryness of eponychium.
Thick Skin
Hairless, 0.6-4.5 due to thicker corneum. Found in areas such as palms, surface of digits and soles.
Thick due to presence of :
Stratum lucidum, ticker stratum spinosum and corneum.
Sudoriferous glands are numerous
Thin Skin
Hairy 0.10-0.15 epidermal layer
Found in all parts of the body expect palms, surface of fingers and soles.
Thin due to :
Stratum lucidum, lacking thinner strata Spinosum and corneum
Sebaceous glands present
Hair follicles and a rector pili present
Function of Skin
- Thermoregulation: liberating sweat at its surface and adjusting flow of blood in the dermis
- Blood Reservoir: houses an extensive network of blood vessels
- Protection: provides protection to underlying tissue from microbes, abrasion, heat and chemicals.
- Cutaneous Sensations: includes tactile sensations - touch, pressure, vibration and tickling.
- Excretion and Absorption: eliminates substances from the body
- Synthesis of Vitamin D: Requires activation of precursor molecules in the skin by ultraviolet, aids absorption of Ca2+.
Skin
Known as cutaneous membrane. Largest organ of the body.
Difference of Skin Color
This is due to the amount of pigment of melanocytes that produce and transfer to keratinocytes.
Sudoriferous Gland: Apocrine
Sweat gland
Found in skin of axilla, groin, arolae, breaded and face regions, clitoris and labia minora.
Located deep to dermis and upper SC layer. Termination of duct at hair follicles.
Secretes perspiration.
Stimulated during emotional stress and sexual excitement.
