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Subcutaneous layer deep to skin (not technically part of skin. It consists of mostly adipose tissue.
What does the Epidermis consist of?
1) Keratinized stratified squamous epithelium. 2) Lots and lots of cells (Keratinocytes, Melanocytes, Epidermal dendritic cells, tactile cells).
What are the four layers of the Epidermis? (California Girls Like Spring Bikinis)
1) Stratum Corneum 2) Stratum Granulosum 3) Stratum Spinosum 4) Stratum Basale
Stratum Basale (4th Layer of Epidermis)
Deepest layer, where you make new cells, attached to dermis, single row of stem cells, cells undergo rapid division, journey from basal layer to surface takes 25-45 days.
Stratum Spinosum (3rd Layer of Epidermis)
Cells contain a weblike system of intermediate prekeratin filamanets attached to desmosomes. Abundant melanin granules and dendritic cells.
Stratum Granulosum (2nd layer of epidermis)
Granuler layer, thin; three to five cell layers in which the cells flatten, keratohyaline and lamellated granules accumulate.
Stratum Corneum (1st layer of epidermis)
20-30 rows of dead, flat, keratinized membranous sacs. Functions to protect from penetration, waterproofs, and its a barrier against biological, chemical, and physical assaults.
Stratum Lucidum (Clear Layer)
In thick skin such as the soles and palms. It is thin, transparent band superficial to the stratum granulosum, a few rows of dead keratinocytes.
Papillary Layer of dermis
Consists of areloar connective tissue with collagen, elastic fibers, and blood vessels. Superior surface is called dermal papillae (Contain capillary loops, Meissner's corpuscles, and free nerve endings).
What decreases with age in the dermis?
The collagen and elastic fibers decrease which causes wrinkles.
Reticular layer of dermis
Accounts for 80% of the thickness of the dermis. Collagen fibers provide strength and resilency. Elastic fibers provide stretch-recoil properties.
Friction Ridges (skin markings)
Epidermal ridges lie atop deeper dermal papillary ridges to form friction ridges of fingerprints.
Cleavage Lines (Skin markings)
Collagen fibers arranged in bundles form cleavage (tension) lines. Incisions made parallel to cleavage lines heal more readily.
Dermal folds that occur at or near joints, where the dermis is tightly secured to deeper structures.
A polymer made of tyrosine amino acids. Its two forms range in color from yellow to tan to reddish brown to black. It's producted in melanocytes and forms "pigment shielsds" for nuclei. Local accumulations include freckles and pigmented soles.
Yellow to organge pigment found in certain plant products such as carrots. It is most obvious in the palms and soles.
What are the two main types of sweat glands?
1) Eccrine (merocrine) sweat glands 2) Apocrine sweat glands
Eccrine Sweat Glands
Most abundant on palms, soles, and forehead. The sweat is 99% water with some NaCl, Vitamin C, antibodies, dermcidin, metabolic wastes. The ducts connect to pores and these type of sweat glands function for the purpose of thermoregulation.
Specialized Apocrine Glands: Ceruminous Glands
Found in external ear canal (secrete cerumen: earwax), and mammary glands.
What are sebaceous glands?
Sebaceous glands, or oil glands, are simple branched alveolar glands that are found all over the body except in thick skin like palms and soles.
What do sebaceous glands secrete?
Oily substance called sebum. Sebum is bactericidal and softens hair and skin.
What are some functions of hair?
1) Alerting the body to presence of insects on the skin. 2) Guarding the scalp against physical trauma, heat loss, and sunlight. Hairs are distributed throughout the enitre surface except of palms, soles, lips, nipples, and portions of external genitalia.
What are the types of hair?
1) Vellus: pale, fine body hair of children and adult females 2) Terminal: Course, long hair of eyebrows, scalp, axillary, and pubic regions..
Functions of I. System: Protection
Three types of barriers: Chemical, Physical/mechanical, Biological
Functions of I. System: Body Temp. Regulation
Routine of "insensible perspiration" (handprint). At elevated temperature, dilation of dermal vessels and increased sweat gland acitivity (sensible perspirations) cool the body.
Functions of I. System: Metabolic Functions
Sythesis of vitamin D and collagenase, chemical conversions of carcinogens and some hormones.
What are the 3 major types of skin cancer?
1) Basal Cell Carcinoma 2) Squamous Cell Carcinoma 3) Melanoma
Basal Cell Carcinoma
Stratum Basale cells proliferate and slowly invade dermis and hypodermis. Cured by surgical excision in 99 percent of time.
Squamous Cell Carcinoma
Involves keratinocytes of stratum spinosum. Most common on scalp, ears, lower lip, and hands.
Rule of nines
Anterior and posterior trunk: 36%, Head & neck: 9%, Anterior and posterior upper limbs: 18% Anterior and Posterior lower limbs: 36%
If an individual was unable to produce sebum, what problem would they most likely develop?
They would be more prone to water loss when exposed to low humidity.
One main difference between thin skin and thick skin is that:
in thin skin the stratum lucidum appears to be absent.
The thickened proximal part of the nail bed containing germinal cells responsible for nail growth.
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