Skin and Integumentary System Flashcards
What does the integumentary system consist of?
- skin & accessory organs
- sweat glands, sebaceous glands, hair, nails
- largest organ of body
What is another name for the integumentary system?
the cutaneous membrane
What are some functions of the integumentary system?
- protection (pathogens, chemicals, fluid loss, abrasion)
- protection of underlying structures and prevention of invasion by pathogens
- sensory receptors for external stimuli
- fluid secretion (sweat)
- body temp regulation (sweat)
- vitamin D production
What vitamin is the integumentary system involved in producing?
vitamin D
How does the integumentary system help regulate body temperature?
sweating
What are the two layers of skin?
- epidermis
- dermis
What layer of skin is the outermost layer?
epidermis
What layer of skin is thicker, dense, irregular connective tissue?
dermis
What layer of skin is keratinized, stratified squamous epithelia found in layers (stata or stratum)?
epidermis
Is the subcutaneous layer a part of the skin?
no
What are the two stratums of the epidermis and how are they ordered?
- stratum basale (bottom/deep layer closest to dermis)
- stratum corneum (upper/superficial protective layer of epidermis)
What are some characteristics of stratum basale?
- constantly dividing and producing more cells
- cells pushed upward toward surface of skin producing many layers/strata
- nourished by capillaries of dermis (no direct blood supply, uses diffusion)
What are some characteristics of stratum corneum?
- cells become keratinized (die as they mature; cytoplasm replaced by large amounts of tough keratin protein; cells become flattened and scale or cornified; eventually shed)
- thickest in areas most susceptible to wear and tear (soles of feet, palms of hands)
What is melanin?
dark pigment produced by special epidermal cells called melanocytes when skin is exposed to UV light
Where are melanocytes found?
the depest layer of the epidermis
What is deposited in keratinocytes like an umbrella over the nucleus and absorbs UV rays?
melanin
What are freckles?
irregular patches of melanin
What is the dermis composed of?
- superficial areolar connective tissue
- deep dense irregular CT
- elastic fibres (stretch)
In what layer are the accessory structures (glands, hair follicles) located?
dermis
In what layer are the blood vessels located?
dermis
Is the dermis thick or thin?
depends of location - thick on palms/soles, thin over eyelids
What are dermal papillae?
- portions of dermis extending upward into epidermis - location of touch receptors
- capillaries to nourish epidermis
- form ridges (fingerprints)
Where are touch receptors located?
dermal papillae
Where is the subcutaneous layer? What are two other names for it?
- below the dermis
- hypodermis or superficial fascia
What does the subcutaneous layer do?
connects skin to surface of muscles
What is the subcutaneous layer composed of?
- loose connective tissue
- large amounts of adipose (fat) tissue
What layer contains larger blood vessels that supply the skin with nutrients and oxygen and help regulate body temp?
subcutaneous layer
Does the subcutaneous layer contain any accessory structures?
some (eg hair follicles) extend into this region
What are the accessory structures?
- glands (sebaceous, sudoriferous)
- hair
- nails
What are accessory structures?
structures that protect the skin but also have other functions
What are the sac-like glands that produce oil or sebum and open into hair follicles?
sebaceous glands
What are the tubular glands that produce a watery sweat for evaporative cooling of the blood in the dermal capillaries?
sudoriforous glands
What are the two types of glands? What do they do?
- sebaceous (produce oil or sebum)
- sudoriforous (produce watery sweat)
What is hair composed of?
shaft and root and protected by hair follicle
Which of the two glands is closer to the surface?
sebaceous gland
What secretion lubricates the skin and hair and prevents drying?
sebum
What gland opens into the hair follicles?
- sebaceous
- apocrine sweat glands (sudoriferous)
What are the two main types of sudoriferous glands?
- eccrine sweat glands
- apocrine sweat glands
Describe location/function of eccrine sweat glands.
- coiled tube-like structures in deep dermis
- secrete watery sweat containing a few ions and possibly wastes
- evaporative cooling (produce perspiration that draws heat from the underlying capillaries as the moisture evaporates at the surface)
- secretory portion in dermis and duct opens to pore on skin surface
Describe location/function of apocrine sweat glands.
- empty into hair follicles located mainly in armpits and groin
- watery sweat with additional substances (pheromones or airborne hormones released during stress or sexual stimulation
- become active at puberty
- body odour develops from colonizing bacteria living off the cellular material
What are the two modified sweat glands (limited locations)?
- ceruminous glands (in ear canal; produce wax)
- mammary glands (in breasts; can produce milk)
What is hair composed of?
dead keratin-filled epithelial cells
What are the functions of hair?
- protect head from cancer-causing UV rays (melanin)
- protect eyes from sweat and particles (eyebrows & lashes)
- detect stimulus (insects etc on arms, legs, back)
What are the three portions of hair?
- shaft (projects above skin)
- root (in skin within follicle)
- bulb (base of hair where joins follicle)
Describe some features of hair growth.
- mitotically dividing hair stem cells for hair growth located in the hair matrix at base of bulb
- periods of no mitosis followed by loss of hair and new hair growth
- genetically predetermined
- melanocytes add melanin pigment as the hair is produced at the base
What is the hair follicle?
sheath or protective covering of epithelia and connective tissue that enclose the hair within the dermis
What is the arrector pili muscle and what does it do?
- thin band of involuntary smooth muscle attached to hair follicle
- contracts to raise hair (goose bumps)
- makes furry animals look bigger when threatened or cold
What are the functions of the nails?
- protect the ends of fingers and toes
- help grasp objects
What are nails made of?
-hard dead keratin produced by cells that originate in the outer layer of the epidermis
What is the growth region of the nails called where new cells form continuously? Where is it located?
- nail matrix
- at the nail root under the skin at the base of the nail
What is the nail bed made of?
epithelial tissue
What is the lunula?
pale area that lies over the thicker growing region of the nail
What part of the nail seals the area between the nail plate and the skin above the root?
cuticle
What are some signs of disease that can be detected in the nail?
abnormal colour, thickness, shape, or texture
What does the skin as a barrier protect against?
- infection
- dehydration
- mechanical damage
What are some effects of aging on the skin(5)/nails(2)?
- wrinkles (loss of fat in hypodermis; loss of collagen and elastic fibres in dermis)
- thinner dermis, less elasticity
- decreased pigment (age spots localized areas of increased pigmentation)
- thinner, greying hair (melanocytes die off)
- less sweat glands (less perspiration and poorer temp regulation)
- flaking, brittle, ridged nails
- thick or discoloured toenails
What are three strategies to maintain skin health?
- proper nutrition/general good health
- regular cleansing (don’t touch face with hands)
- protect from sunlight
What are some disorders and diseases of the skin?
- atopic dermatitis
- psoriasis
- impetigo
- herpes simplex & zoster (shingles)
- fungal infections of nail
- alopecia
- pressure (decubitus) ulcers
What are three types of skin discolouration?
- vitiligo (patchy loss of melanocytes due to autoimmune attack)
- cyanosis (bluish colouration due to lack of oxygen)
- jaundice (yellow colouration due to liver failure and inability to breakdown pigment bilirubin)
What are four types of skin surface lesions?
- macule
- papule
- vesicle
- pustule
What are two types of deeper skin lesions?
- pressure sores (decubitus ulcers, bed sores)
- fissures (cracks in skin due to eczema, athletes foot, etc)
What are three types of skin cancer?
- basal cell carcinoma
- squamous cell carcinoma
- melanoma
What is the most deadly type of skin cancer?
melanoma
What is impetigo?
- highly contagious skin infection due to bacteria (staph or strep)
- pus filled lesions (usually on face, hands)
What are two types of fungal infections?
- mycoses (superficial causing blisters, scaling and discolouration)
- ringworm (on foot called Athlete’s foot)
What is herpes simplex and what are the two types of herpes simplex infections?
- viral infection that produces water blisters (can become infected with bacteria - pus)
- type I (cold sores usually)
- type II (genital)
What is herpes zoster?
- shingles
- usually older adults
- same virus that causes chicken pox in kids
- one side of body and usually chest area
- very painful itchy blisters
What is atopic dermatitis?
- itchy inflames skin
- redness, blisters, pimple like lesions
- can develop bacterial infections
- many causes (allergies)
- treated with corticosteroids
What is psoriasis?
- chronic overgrowth of epidermal tissue leading to red areas with silver plaques (especially on knees/elbows)
- genetic/autoimmune causes
- treated with UV light and corticosteroids
