Accessory Structures Flashcards
What is the subcutaneous layer of the skin?
Hypodermis; lowermost layer of the integumentary system
tissue types: areolar and adipose tissue
functions: elasticity, reduce heat loss, energy reserve, blood resevoir
What is a good site for injections?
Adipose tissue in the subcutaneous layer
What are the appendages of the skin?
Hair follicles and hair, nails, sweat glands, sebaceous glands, ceruminous glands
Where/what kind of hair are the following types ?
1) terminal hair
2) specialized terminal hair
3) vellus hair
4) lanugo
1) Terminal hair:
Head (scalp).
Armpits.
Pubic area.
Upper lip, cheeks and chin.
Chest and belly (abdomen).
Back.
Arms and legs.
Fingers and toes.
2) Specialized terminal hair:
eyelashes and eyebrows
3) Vellus hair:
body hair, peach fuzz
4) Lanugo:
baby hair
What are the (4) main functions of hair?
a) insulates and protects the scalp
b) protects nostrils and ear canals
c) detects movement through hair plexus and sensory nerve
d) arrector pili muscle stands up = goose bumps
What is the development of terminal (armpit) hair?
Prepubertal stage: vellus hair
+ androgens - testosterone
Adult stage: terminal hair
What is the hair growth cycle? (4 stages)
1) The active phase: lasts 2-5 years.
- hair grows continuously at a rate of approximately 0.33mm/day
2) The follow then begins to undergo regression and transitions to the resting phase
3) The resting phase: the hair loses its attachment to the follicle and becomes a club hair
4) when follicle reactivation occurs, the club hair is shed and the hair matrix begins producing a replacement hair
hair: dead keratinocytes
What are sebaceous glands?
Secrete oil through holocrine secretion
two types:
1) simple branched alveolar glands - share duct with the follicle and squeezed by arrector pill muscle
2) sebaceous follicles - not associated with hair follicles
What is the structure of the hair shaft of a hair follicle? ** check pg. 50
1) Medulla: innermost; matrix produces hair shaft and outer root sheaths
2) Cortex: thickest part of the hair shaft, contains the melanin
3) Cuticle: dead, shingle like cells
Matrix: where keratinocytes are made
1) hair papilla
2) melanocytes (hair colour)
What do sebaceous glands secrete?
Sebum (lipids + electrolytes + proteins + cholesterol)
What is the function of sebum?
- inhibits bacterial growth due to its acidity
- lubricates and protects keratinized cells (hair and skin)
- newborn’s vernix caseosa
- can fail to discharge; collecting sebum in “whiteheads” or “blackheads” which can become inflamed causing acne in teenagers as a result of hormonal changes
What produces hair colour?
Melanin in the cortex
Does hair become thinner as you age?
Yes
Do nutritional supplements stop graying?
No; cannot be prevented
Does everyone get less hair as they age?
Yes
Why do we get grey hairs?
Melanocytes slow
Do your nails change with age?
Yes
Do men get longer eyebrow, ear, and nose hairs with age?
Yes
What are merocrine sweat glands?
Merocrine sweat glands (=eccrine sweat glands)
structure: coiled tubular duct
controlled primarily by thermoregulatory center (hypothalamus)
sweat is watery
function:
-to cool surface of skin to reduce body temperature
-excrete water and electrolytes
-flushes chemicals
-contains dermicidin (antibiotic protein) to discourage microbes
What are sweat glands?
Sudoriferous glands that use exocytosis
merocrine and apocrine sweat glands
What are apocrine sweat glands?
Includes ceruminous glands of ear and mammary milk-producing glands
distribution: axillae, pubic region, around nipples
structure: coiled tubule structures that open into hair follicles
function: nutrient for bacteria which intensifies odour
secretion: sticky, cloudy, odourous, influenced by hormones
myoepithelial cells are contractile cells that squeeze the gland
What are ceruminous glands?
Modified apocrine sweat glands located in the external ear
secretion: cerumen = ear wax using apocrine mechanism
function: trap foreign particles protecting ear drum
Do apocrine sweat glands use apocrine secretion?
***** 48
What kind of cells are the keratinocytes in nails?
Densely packed dead keratinocytes
What are the common landmarks of nail structure?
Nail bed: body that covers an area of epidermis
Nail body: uppermost layer of the nail
Lateral nail groove
Lateral nail fold
Phalanx: bone of fingertip
Lunala: pale crescent near the root, where blood vessels may be obscured
Proximal nail fold
Eponychium
Hyponychium
What are the types of skin cancer from most to least dangerous?
Melanoma
Squamous cell carcinoma
Basal carcinoma
What is basal carcinoma?
Cancer of keratinocytes in stratum basale; generally forms a nodule with a ‘cratered’ center
- 2/3 on areas chronically exposed to sun
-relatively slow-growing
What is squamous cell carcinoma?
Cancer of keratinocytes in the stratum spinosum; forms plaques that bleed or ulcerate
-sun exposed areas
-Both basal and squamous cell skin cancers are relatively slow-growing, but squamous cell skin cancer is more likely to spread to other organs. If it spreads, it can be life-threatening.
What is melanoma?
Least common, most dangerous type of skin cancer
site of origin: melanocytes
can occur anywhere; sun exposure increases odds (spreads fastest)
malignant melanoma are cancer of melanocytes characterized by asymmetrical shape, irregular borders, blue-black colour, large diameter, and evolving nature
ABCD
a) asymmetry - irregular shape
b) border - irregular border
c) colour - mottled
d) diameter - more than 5 mm
What are burns?
Tissue damage caused by intense heat, electricity, radiation (including sunburn), some chemicals
What are first degree burns? What does it affect?
Affects only the surface of the epidermis; most sunburns; usually limited to redness with minor pain
What are second degree burns? What does it affect?
Affects epidermis and upper portions of the dermis, blistering, swelling
pain heals in 1-2 weeks if no infection
What are third degree burns? What does it affect?
Affects epidermis, dermis, sometimes hypodermis, and possibly deeper tissues
if >10% of the body, immediately life threatening because granulation tissue cannot form to cover area
problems: fluid loss, along with electrolytes, proteins occurs 5x faster than normal
What steps can you take to treat third degree burns (within 24 hours)?
1) replace lost fluids and electrolytes
2) provide massive amounts of nutrients
3) protect to try to prevent infection
4) assist in tissue repair, grafts
Process of scarring? injury to the skin
1) Inflammatory phase:
-mast cells trigger inflammatory response
-bleeding occurs at the site of injury
2) Migratory phase:
-scab forms at the surface
-patrolling macrophages remove debris and pathogens
-rapid cell division and migration along would edges to replace missing cells
-formation of granulation tissue
3) Proliferation phase:
-deeper portions of the clot dissolve
-fibroblasts produce new collagen fibres and ground substances
4) Scarring phase:
-scar tissue formation
