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Flashcards in Integumentary system 2 Deck (76):

hair is

dead, keratinized epidermal cells bonded together by extracellular proteins
Genetics and hormones determine thickness and pattern of distribution


Where does not hair grow?

palms, palmer surfaces of digits, soles, and plantar surfaces of the digits


Hair function (3)

1. Protection (injury, sun's rays, eyelashes and eyebrows protect eyes from foreign particles)
2. Senses light touch: touch receptors in hair root plexus are activated when hair moves
3. Prevents heat loss (scalp)


Structure of hair

Shaft - visible projects above the skin
Root - below the surface into the dermis and sometimes subcutaneous layer
Shaft and Root - consist of 3 concentric layers of cells (medulla, cortex, cuticle)


What surrounds the root of the hair?

hair follicle, consists of
1. external root sheath - downward continuation of the epidermis
2. internal root sheath
1+2=epithelial root sheath or hair follicle


what is at the base of each hair follicle

the bulb, nourishes the growing hair follicle
contains a germinal layer of cells called the hair matrix


Where the hair matrix cells arise from

The stratum Basale, the site of cell division


what does smooth muscle in dermis contracts with cold or fear

Arrector pili
forms goosebumps as hair is pulled vertically


What detects hair movement and senses touch

Hair root plexus


what secretes oil

Sebaceous (oil) glands


what is the three stages of hair growth cycle

Growth stage (2-6 years) matrix cells at base of hair root are active producing length

Regression stage (2-3 weeks)
Cells of matrix stop dividing, hair follicle atrophies and hair stops dividing

Resting stage (3 months)
following the resting stage, a new growth cycle begins
old hair falls out as growth stage begins again


What is the normal hair loss/day

70-100 hairs/day


Types of hair in Utero

Lanugo hair: fine non-pigmented downy hair that covers the fetus


Prior to birth, Lanugo hair is replaced by

Terminal hair: coarse, heavily pigmented hair that replaces hair on eyebrows, eyelashes and scalp

Vellus hair: short fine pale hair barely visible to the human eye replaces lanugo on the rest of the body


The type of hair at puberty

Terminal hair replace vellus hair in the axillae and pubic regions of girls and boys and face, limbs, chests of boys.


Hair color is due to....

the amount and type of melanin (passed into cortex and medullary cavity)


Graying of hair occurs because of....

Progressive decline in tyrosinase and decline in melanin production


Dark hair contains

true melanin


Blond and red hair contain

melanin with iron and sulfur added


white hair is due to

lack of melanin and air bubbles in the medullary shaft


partial or complete loss of hair

Alopecia, by genes, aging, endocrine disorders, chemotherapy, skin disease


Chemotherapy kills

rapidly dividing cells such as hair matrix cells (the 15% of hairs in resting stage are not affected0


Excessive body hair or body hair in areas that are not usually experienced by females or prepubertal males

Hirsutism - caused by tumor in the adrenal glands, ovaries or testes that produce an excessive amount of androgens


Genetic predisposition where androgens inhibit hair growth

Androgenic Alopecia or male pattern baldness


nails are

tightly packed hard dead keratinized epidermal cells that form a clear solid covering over the DORSAL surfaces of the distal portion of digits


Structure of nails

1. nail body: visible portion (like stratum corneum of skin)
2. Free edge may extend past distal end of the digit
white, because absence of capillaries
3. Nail root: portion of nail buried in a fold of skin


Whiter crescent shaped area of the nail

Lunula(capillaries don't show thickened epithelium)


Function of nails (4)

1 Protect the distal end of digits
2 provide support and counter pressure to the PALMAR surface of fingers to enhance touch perception and manipulation
3 Allow us to grasp and manipulate small objects
4 can be used to scratch and groom the body


Thickened St. Corneum beneath the free edge that secures nail to fingertips

Hyponychium or nail bed


Narrow band of epidermis that extends from and adheres to lateral side of nail wall

Epohychium or cuticle


Nail growth

Nail matrix proximal portion of the epithelium deep to the nail root who's cells divide mitotically

grow on average 1 mm per week


4 specialized exocrine glands of the skin

Sebaceous (oil) glands
sudiferous (sweat) glands (Eccrine - most body, especially palms, soles, forehead. Apocrine - into hair follicle, groin/axillae, emotional stress and sexual excitement)
Ceruminous (wax) glands
Mammary (milk)glands


Where are sebasecous (oil) glands found

found in lips, glans penis, labia minora and tarsal glands (prevents eyelids from sticking)

small in trunk and limbs, in the dermis and opens into neck of hair follicle, produce sebum
Absent in the palms and soles


what does sebum do

contains cholesterol, proteins, fats and salts
moistens hair
water proofs and softens skin
inhibits growth of bacteria and fungi (ringworm)


sudoriferous gland function: Eccrine sweat gland

1. Secretory portion in dermis with duct to surface that terminates at epidermal pores
2. regulates body temperature through evaporation (perspiration), the homeostatic regulation of body temperature called "thermoregulation"
3. Release sweat in response to emotional stress called "emotional sweating or cold sweat
4. Help eliminate wastes
5. start functioning at birth


Apocrine sweat gland function

1. secretory portion in dermis with duct that opens into hair follicle
2. secretions are more viscous appearing milky or yellowish
3. release in response to emotional stress and during sexual activity
4. apocrine sweat has musky odor aka body odor
5. start functioning at puberty


Ceruminous glands function

modified sudoriferous glands found in external auditory meatus
1 produce a waxy lubricating secretion
2. the compination of ceruminous and sebaceous secretions is called cerumen
3. secretory portion is in subcutaneous layer deep to sebaceous glands
4. excretory ducts open to EAM surface or into ducts of sebaceous glands
5. Function: barrier for entrance of foreign bodies and water proof canal


bacterial inflammation of sebaceous glands

Secretions are stimulated by hormones at puberty


An abnormal amount of cerumen in the external auditory meatus or canal

impacted cerumen: can result in impaction and prevent sound waves from reaching the ear drum


Thin skin

covers all parts of the body except thick skin
lacks epidermal ridges
has a sparser distribution of sensory receptors than thick skin
hair follicles and erector pili present


Thick skin (0.6 to 4.5mm)

covers the palms, palmar surfaces of the digits and soles
features a stratum lucidum and thick epidermal ridges
lacks hair follicles, arrector pili muscles and sebaceous glands and has more sweat glands than thin skin


how many % of blood skin reserves?

8-10% in resting adults


How does skin protect the body

1. Keratin - physical, chemical and biological barriers
2. Tight cell junctions prevent bacterial invasion
3. lipids released by lamellar granules retard evaporation
4. Sebum moistens skin and hair, kill bacteria
5. Acidic perspiration retards some microbe growth
6. Pigment protects somewhat against UV light
7. Langerhans cells alert immune system and macrophages in dermis phagocytize bacteria


Synthesis of Vitamin D

Activation of a precursor molecule in the skin by UV light
Enzymes in the liver and kidneys modify the activated molecule to produce calcitriol, most active form of vitamin D
Necessary vitamin for absorption of calcium from food in the gastrointestinal tract


Excretion and absorption

Excretes: 400 ml of water/day, small amounts salt, CO2, ammonia and Urea
Absorption: Certain lipid soluble materials - Vitamin A, D, E, K, Certain drugs, O2 & CO2, cortisone, nail polish remover, salts of lead/mercury, arsenic


method of drug passage across the epidermis and into the blood vessels of the dermis

Transdermal drug administration


Epidermal wound healing

1. Basal cells MIGRATE across the wound
2. CONTACT INHIBITION with other cells stops migration
3. Epidermal growth factor stimulates basal cells to divide and replace the ones that have moved into the wound
4. full thickness of epidermis


Deep Wound healing 4 phages

1. Inflammatory phase: clot unite wound edges and WBCs arrive from dilated and more permeable blood vessels
2. Migratory phase: begins the regrowth of epithelial cells and the formation of scar tissue by the fibroblasts (fibrin threads)
3. Proliferative phase is a completion of tissue formation
4. Maturation phase sees the scab fall off


skin thermoregulates by

perspiration (and its evaporation)
Shivering and constriction of surface vessels


Free nerve ending sensasions

vibration, tickle, heat, cold and pain


Touch sensation

Merkel cell



Pacinian corpuscle


Inflammatory phase

Clots unites the wound edge
Epithelial cells migrates across the wound
Vasodilation and increased permeability of blood vessels deliver phagocytic WBC (neutrophils, macrophages) and fibroblasts


Migratory phase

epithelial cells beneath the scab bridge the wound
* Fibroblasts begin forming scar tissue along fibrin threads - GRANULATION TISSUE: collagen fibres and glycoproteins


Proliferative phase

Extensive growth of epithelial cells under scab
Fibroblasts continue to lay down collagen RANDOMLY
continued growth of blood vessels


Maturation Phase

The scab sloughs off once epidermis is restored to normal thickness
Collagen fibers become more organized
fibroblasts begin to disappear
blood vessels are restored to normal


Scar tissue formation is called

Collagen fibres more densely arranged
Decreased elasticity
Fewer blood vessels
May have fewer hairs, glands or sensory structures


Excess scar tissue two types

1. Hypertrophic scar stays within the boundaries of the original wound
2. Keloid scar extends beyond boundaries


Epidermis develops from

Ectodermal germ layer


Hair, nail, and skin glands are

epidermal derivatives


Dermis develops from

mesenchmal mesodermal germ layer cells


what develops from mesoderm

the connective tissue and blood vessels associated with the gland


Slippery coating of oil and sloughed off skin for new born is call

vernix caseosa ( to protects fetus from amniotic fluid)


Age related structural changes

1. collagen fibres decrease in number and stiffen
2. Elastic fibers less elastic
3. Fibroblasts decrease in number
4. Decrease in number of melanocytes (gray hair, blotching)
5. Decrease in Langerhans cells (decreased immune responsiveness)
6. Reduced number and less efficient phagocytes


Aging and integumentary system

Most of the changes occur in the dermis
wrinkling, slower growth of hair and nails
dryness and cracking due to sebaceous gland atrophy
***subcutaneous fat is lost



Ultraviolet light (UVA and UVB) both damage the skin
acute overexposure causes sunburn
DNA damage in epidermal cells can lead to skin cancer
*UVA produces oxygen free radicals that damage collagen and elastic fibres and lead to wrinkling of he skin


Most common forms of skin cancer

Basal cell carcinoma
Squamous cell carcinoma
Malignant melanoma


78% of all skin cancers

basal cell carcinoma (rarely metastasize)


20 % of skin cancer

Squamous cell carcinoma (tumors in at st. spinosum) may metastasize


Most common cancer in young women

Malignant melanomas (metastasize rapidly)
arise from melanocytes, life threatening, die within months of diagnosis


How to detect Malignant melanomas

C-colour (different colors in the same place)
D-diameter (over 6 mm, pencil eraser) E- Evolving, changing size, shape and color
When AB and C present usually size is over 6 mm
Risks factors include skin color, sun exposure, family history, age and immunological status


Systematic Effects of a burn

1. large loss of water, plasma, plasma protein which causes shock
2. Bacterial infection
3. Reduced circulation of blood
4. Decreased production of urine
5. Diminished immune responses


Types of burns

First degree - only epidermis

Second degree - entire epidermis and part of dermis, blisters between epidermis and dermis, but epidermal derivatives are not damaged. Heals without grafting in 3-4 weeks and may scar

Third-degree or full thickness -
- destroy epidermis, dermis and epidermal derivatives and subcutaneous layer,
- most skin functions are lost, marble, white to mahogany colored,
-marked edema and damaged area is numb due to loss of sensory nerves


What % of the body burnt, more than 50% chance to die?

exceeds 70%


Major burn (3)

a. 3rd degree burn over 10 % of body
b. 2nd degree burn over 25% of body
c. any 3rd degree burn on face, hand, feet or perineum


caused by a constant deficiency of blood to tissues overlying a bony projection that has been subjected to prolonged pressure

Pressure sore, or pressure ulcers AKA decubitus ulcers