Consists of two layers: 1) Epidermis 2) Dermis
Subcutaneous layer deep to skin (not technically part of skin. It consists of mostly adipose tissue.
What is the Epidermis?
Superficial region of skin.
What is the Dermis?
Middle region of skin.
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.
What are the two layers of the dermis?
1) Papillary 2) Reticular
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.
What are the 3 pigments that contribute to skin color?
1) Melanin 2) Carotene 3) Hemoglobin
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.
Responsible for the pinkish hue of skin.
What are the appendages of the skin?
Sweat glands, oil glands, hairs and hair follicles, nails.
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.
What are the glands resposible for thermoregulation?
Eccrine Sweat Glands
Apocrine Sweat Glands
Confined to axillary and anogenital areas.
What are the glands that function from puberty onward?
What are the ducts in apocrine glands connected to?
What is the sebum in apocrine sweat glands composed of?
Sweat, fatty substances, and proteins.
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 is hair composed of?
Dead keratinized cells.
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..
Chief region of hair?
Shaft (keratinization is complete)
What part of hair is the keratinization still ongoing?
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.
Funcitons of I. System: Cutaneous Sensations
Temperature, touch, and pain.
Functions of I. System: Metabolic Functions
Sythesis of vitamin D and collagenase, chemical conversions of carcinogens and some hormones.
Functions of I. System: Blood Reservoir
Skin has up to 5% of bodys blood volume.
Functions of I. System: Excretion
Excretion of nitrogenous wastes and salt sweat (as well as urea).
Most skin cancers are ______?
Risk factors of skin cancer?
Overexposure to UV radiation, frequent irritation of the skin.
What are the 3 major types of skin cancer?
1) Basal Cell Carcinoma 2) Squamous Cell Carcinoma 3) Melanoma
What is the most dangerous type of skin cancer?
What is the second most common skin cancer?
Squamous cell carcinoma
What is the most common type of skin cancer that is usually least malignant?
Basal Cell Carcinoma
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.
Involves melanocytes. These are highly metastic and resistnat to chemotherapy.
Rule of nines
Anterior and posterior trunk: 36%, Head & neck: 9%, Anterior and posterior upper limbs: 18% Anterior and Posterior lower limbs: 36%
First degree burn
Epidermal damage only
Second Degree Burn
Epidermal and upper dermal damage
Third Degree Burn
Epidermal, dermal, and hypodermal damage. The entire thickness of skin is damaged
Epidermis forms from _____?
Dermis and Hypodermis form from ______?
Covering of delicate hairs in 5th and 6th month
Sebaceous gland secretion; protects skin of fetus
When does sebaceous gland activity increase?
Tactile cells Function
Protection from UV radiation
Langerhans cells Function
Activate the immune system
Make a fibrous protein for skin protection
The role of ceruminous glands is to:
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.
are not functional until puberty.
If dermal papillae were missing then what would be absent?
One main difference between thin skin and thick skin is that:
in thin skin the stratum lucidum appears to be absent.
Sebacious Glands secrete...
Mammory Glands secrete...
Sudoriferous glands secrete...
Ceruminous glands secrete...
Hirsutism is a condition that is characterized by:
Excessive Hair Growth
Function mainly to produce keratin.
Spidery black cells that producethe brown-to-black pigment called melanin.
Epidermal dendritic cells (Langerhans cells)
cells the play a role in immunity.
Tactile (Merkel) cells
Form touch receptors
The Visible attached portion.
Nail "Free edge"
The portion of the nail that grows out away from the body.
The part that is embedded in the skin and adheres to an epithelial nail bed.
Skin folds that overlap the borders of the nail.
The thick proximal nail fold commonly called the cuticle.
Extension of the stratum basale beneath the nail.
The thickened proximal part of the nail bed containing germinal cells responsible for nail growth.
The proximal region of the thickened nail matrix, which appears as a white crescent.
Skin is blue when blood inadequately oxygenated.
Diagnostic for liver disease.
Bronzing of the skin hints that a person's adrenal cortex is hypoactive.
The central core of the a hair.
A bulk lyaer surrounding the medulla, consists of several layers of flattened cells.
When you see "hydrostatic pressure" you should automatically think ______?