Integumentary System Flashcards
Summary of Functions
- protection
- sensory reception
- thermoregulation
- Vitamin D synthesis
- Excretion
Epidermis (overview)
- outermost layer
- keratinized
- mostly dead epithelial cells
Dermis (overview)
- CT embedded with hair follicles, nerves, blood vessels, glands, and receptors
Hypodermis (overview)
- adipose
- other CT
- arteries
EPIDERMIS
vascular or avascular?
where does cell division occur?
what does epidermal thickness depend on?
what is melanin and what does it contribute to?
- many layers (stratums) of varying age and morphology
- avascular, requiring diffusion to receive nutrients
- deepest layer (basale) where cell division occurs
- outermost layers consisting of dead cells
- epidermal thickness varies depending on weight-bearing and abrasion (#keratin)
- melanocytes found in deepest layer, produce melanin - major contributor to skin color
- DNA damage caused by UV-B triggers melanin production
DERMIS
what does it contain?
what are the epidermal derivatives?
- deep to epidermis, “true skin”
- contains small blood vessels to maintain metabolic rate, and temp regulation
- contains nerves, sensory receptors, smooth muscle around hair follicles, and macrophages
- epidermal derivatives include:
- HAIR
- NAILS
- SUDORIFEROUS GLANDS
- SEBACIOUS GLANDS
- CERUMINOUS GLANDS
HAIR
what does it grow from?
what is the muscle surrounding the follicles?
- grows from a follicle (where the cell division is happening)
FLAT: curly; ROUND: straight; OVAL: wavy
- follicles surrounded by a muscle called arrector pili
—–> sympathetic innervation; contraction triggers sebum secretion and piloerection (goosebumps)
NAILS
where does it grow from?
what is it made of?
what is it supplied by?
- grow from root under lunula (1mm/6-10 days)
- both hair and nail mostly keratin
- roots supplied by BV and nerves
SUDORIFEROUS GLANDS
(Merocrine)
- contain vesicles that secrete odorless water with few electrolytes (sweat proper)
- largest concentration in palms and soles, but found everywhere
- continuous excretion, though increased by sympathetic stimulation
- thermoregulation (max loss ranges from 1-3 L/hour)
SUDORIFEROUS GLANDS
(Apocrine)
- through exocytosis secrete sweat along with fatty acids, hormones, and other proteins into hair follicles
- largest concentration around genitalia and axillae
- odor produced by bacteria feeding on secretions
- become active after puberty; periodic excretion; ACh sensitive-triggered by emotions of fear, anxiety, stress, sexual arousal, and pain
SABACEOUS GLANDS
what does sebum do?
what are the glands stimulated by?
what is the composition of sebum affected by?
- produce an oily substance called sebum
- antimicrobial, moisturizing, and inhibits water loss
- stimulated by sex hormones
- decrease #s with age
- composition of sebum afected by the types of fatty acids in the diet
CERUMINOUS GLANDS
what is cerumen?
what does cerebum do?
what is composition affected by?
- a modified sudoriferous gland that produces cerumen
- cerumen is a mix of apocrine secretion, sebum, and dead epithelial cells
- antimicrobial, lubricating, and cleansing
- composition affected by diet, irritants, and genetics
HYPODERMIS
- also called the subcutaneous layer as it is below the skin (dermis)
- mostly adipose, though other CT fibers extend through both the dermis and hypodermis
FUNCTIONS OF THE SKIN
Protection
- keratin helps waterproof the skin
- sebum is acidic and bacteriostatic (controls bacteria and growth)
- melanin helps protect underlying tissue from UV light
- mechanical barrier to many external forces (1st line of defense)
FUNCTIONS OF THE SKIN
sensory reception
- contains neurologic receptors for hot, cold, touch, pressure, vibration, pain, and light
- motion of hair shaft is interpretable by the brain
