Skin, Hair, Nails

integumentary system

largest organ in the body; skin, hair, nails, and several exocrine glands; guards the body from injury, protects against infection, and controls temperature

cutaneous sensation

contact with warmth, cold, or pain

the skin is made up of 2 layers

epidermis & dermis

epidermis

thin, outer layer

epidermis consists of 5 layers called strata (stratum)

corneum, basale, lucidum, granulosum, spinosum

stratum corneum

squamous cells; the surface layer that is periodically cast off or shed

stratum basale

basal (basic) cells; located under the squamous cells at the foundation of the epidermis & lays on top of the dermis; the deepest of the 5 layers

stratum lucidum

the surface of the palms of the hands & soles of the feet; clear layer that forms as a protective layer in response to heavy use

stratum granulosum

granular layer of cells; contains 2 types of granules: keratohylin & lamellated

keratohylin granules

secrete protein used to make keratin

lamellated granules

secrete lipids to hold cells together

stratum spinosum

composed of prickle cells that are interwoven for protection

melanocytes

spotted at the base of the epidermis; make melanin which givens the skin its pigment

dermis

middle layer

dermis contains

blood vessels, lymph vessels, hair follicles, sweat glands, collagen bundles, fibroblasts, nerves, sebaceous glands

blood vessels

channels that carry blood throughout the body

lymph vessels

thin walled tubes that carry lymph

hair follicles

supports each hair in the skin; responsible for growing hair

sweat glands (sudoriferous/sudoriparous glands)

small tubular structures that produce sweat

collagen bundles

string fibers that support most tissues & provide cell structure

fibroblasts

most common type of cell found in connective tissue; produces collagen & other fibers that make up the skin

nerves

collection of fibers made up of neurons that use electrical & chemical signals to communicate sensory & motor data from one body part to another

sebaceous glands

small oil producing glands present in skin; usually attached to hair follicles

dermis has 2 stratum layers

stratum papillare & stratum reticulare

stratum papillare

thin external layer woven with the epidermis

stratum reticulare

thick layer of dense, irregular connective tissue

subcutaneous fat layer (hypodermis)

not considered to be a layer of skin; composed of a weave of collagen & fat cells; main function is to anchor the skin to the underlying musculature

superficial fascia

fibrous connective tissue found within the hypodermis layer

skin tags (acrochordons)

simple benign growths of skin; flesh colored pieces of soft tissue attached to the skin by a stalk; not associated with cancer and do not progress to become cancerous

3 major types of skin cancer

basal cell carcinoma (BCC), squamous cell carcinoma (SCC), melanoma

basal cell carcinoma (BCC)

most commonly diagnosed skin neoplasm; forms in the cells at the base of the epidermis; treatable & does not commonly metastasize verses other cancers; develops after years of sun exposure or indoor tanning

squamous cell carcinoma (SCC)

second most commonly diagnosed skin neoplasm; can grow deep into the skin and cause possible disfigurement; by receiving early diagnosis/treatment, it can be prevented from spreading to other areas of the body

melanoma

most serious skin cancer because it tends to spread quickly; can appear within a mole that is currently present

kaposi sarcoma (KS)

type of cancer that arises from the cells lining blood or lymphatic vessels; stongly associated with infection by human herpesvirus 8 (HHV8)

medulla

inner core of the hair shaft; surrounded by the cortex

cortex

makes up the bulk of the hair follicle

shaft cuticle

the outermost layer of a hair follicle: consisting of a single layer of cells

arrector pili muslce

tiny muscles inserted at the level of the follicle base & connected to the papillary layer of the dermis; during periods of cold temperature, they will contract causing the hair to stand erect (goose bumps)

folliculitis

infection if the hair follicle; can be caused by bacteria, viruses, or fungi

nails

produced by the cells in the epidermis but are deemed as an accessory organ of the skin; made of keratin

nail body

the portion of the nail you can see

nail root

hidden; lies beneath the cuticle groove

lunula

portion of the nail body closest to the root

nail bed

layer of the epithelium which lies under the nail

cyanosis

bluish hue of the skin due to insufficient oxygen in the blood or improper circulation

skin receptors

enable us to respond to related stimuli like coarse touch, vibration, temperature, pain

lamellar corpuscle

skin receptor that detects pressure deep in the dermis

superficial tactile corpuscle

skin receptor that detects light touch

glands located in the skin

sebaceous & sweat glands

sweat glands

coiled tubular structures that regulate human body temperature (thermoregulation)

3 types of sweat glands

eccrine, apocrine, apoeccrine

eccrine sweat glands

primarily secrete water & electrolytes directly onto the surface of the skin; 10x smaller than apocrine glands; not as deep in the dermis; not present in the lips, ear canals, labia minor, clitoris, prepuce, or glands penis

apocrine glands

specifically located in the regions with hairy skin (armpits, genitals, anus, breasts); produce oily substances including steroids, proteins, lipids through hair canals; responds to emotional stimulus (anxiety or fear)

apoeccrine gland

develops during puberty; secrets watery fluids; larger than the eccrine glands & smaller than the apocrine gland; found in the armpits & perianal region with ducts opening onto the skin

sebaceous glands

secrete a lipid rich sebum which lubricated both the hair & skin; found in the ducts of the hair follicles; protects the hair & provides the skin with a hydrophobic barrier that can serve as protection

blackhead (open comedone)

sebum that darkens as it has become exposed to air

2 regions of breasts

circular body & axillary tail

circular body

largest & most prominent part of the breast

axillary tail

smaller part, tuns along the inferior lateral edge of the pectoralis major towards the axillary fossa

areola

surrounds the nipple; darker pigmented area full of sebaceous glands that become enlarged during pregnancy & secret oil to protect the nipples during lactation/nursing

mammary glands

modified sweat glands comprised of a series of ducts & secretory lobules

fibrous stroma

all connective tissue in the breast; holds the mammary glands in place, separates the secretory lobules, anchors the breast to the dermis & underlying muscles