Sistemul tegumentar, partea 2 – Skin Deeper: Curs intensiv Anatomie și fiziologie #7

12 liters of sweat?????? Seriously??????

Notes for Integumentary System Part 2

When we notice what integumentary system is doing, results are often uncomfortable

sweat glands -> smell, oil glands -> zits

skin -> scaly or greasy

1st & most vital purpose of integumentary system = protective barrier

skin, hair, nails, sweat, & oil glands all work together to shield from excessive sunlight, infections, abrasions,

how you sense the world

Cutaneous sensory receptors/corpuscles – structures part of nervous system in skin

receive stimuli from outside environment & send stimuli to brain

part of nervous system

register diff sensations that associate w/ touch

Types of Corpuscles

tactile corpuscles – transmits sensations of light touch & low-frequency vibrations from periphery -> central nervous system

lamellar corpuscles – register sense of pressure

Hair follicles have receptors too -> why can feel slight breeze on skin or through hair

More Functions of Integumentary system: removing waste, storing blood, and regulating body temperature

Waste Removal

Integumentary system excretes small amounts of waste eliminated through skin via sweat

most nitrogen-containing wastes like urea, uric acid, and ammonia are disposed via urine

isn’t much evidence that suggests heavy sweating rids body of any extra toxins, just losing more water

Blood Storage Unit

~5% of entire blood volume retained in skin @ any given time

when need more blood supplied to organs, (i.e.) when working out -> nervous system constricts dermal blood vessels to squeeze extra blood into circulation

Body Temp Regulation

During times of exertion, both blood & sweat glands work together to perform a key function: regulating body temp

insensible perspiration = unnoticeable sweat

even w/out exercise, body oozes out about 1/2 a liter of sweat per day to keep comfy temp

No solute lost, just pure water

sensible perspiration = noticeable sweat

both solute & solvents lost

could produce as much as 12 L of sweat per day

To regulate heat loss dermal blood vessels constrict -> blood heads deeper into tissues & help keep vital organs warm

Once things warm up, blood vessels in skin gradually relax & allow blood to return to surface

Skin Discoloration: Cyanosis, Jaundice, and Erythema

Changes in the color of skin can indicate homeostatic imbalances

Cyanosis = Blue skin

in Caucasian people may indicate heart failure, poor circulation, or severe respiratory issues

cause blood that’s been depleted of oxygen turns darker in color, and when seen through lips/skin tissue, can look bluish

Jaundice = yellowing of the skin

usually signifies liver disorder

Yellow bile starts accumulating in bloodstream

Erythema = Reddened skin

could indicate fever, inflammation, or allergy

all of these conditions cause blood vessels to expand & more blood to flow to skin’s surface

Human skin color wide spectrum, so some of these conditions easier to diagnose by looking for discolorations of other tissues (i.e. mucous membranes & beds of finger & toenails)

Melanin, Vitamin D, and Skin Tone

Melanin – pigment produced by melanocyte cells in epidermis

2 forms: produces pigments that range reddish yellow -> brownish black

main job = protect from sun’s ultraviolet rays

Historically, where solar radiation more intense -> higher concentrations of deep-colored melanin

closer to poles, where solar rays weaker & more diffused, lower melanin concentrations allowed people to collect what sunlight was available, to manufacture vitamin D

Vitamin D – required by bones to keep producing new bone cells & only vitamin body can produce on its own

skin cells have a molecule that converts to vitamin D when it comes in contact w/ UV light

Vitamin path: skin -> bloodstream -> liver & kidneys

where vitamin D is activated (calcitriol)

Then calcitriol circulated to all bones of body

Skin appendages – hair, nails, sweat, & sebaceous/oil glands

Hairs/pili – flexible strands of dead keratin protein cells, like fingernails

Cuticle – outermost layer of dead keratin cells

looks like overlapping roof shingles

conditioner evens out rough surface between those cuticle cells to make hair look smooth

2 Main Regions of Hair

shaft – where keratinization is completed

root – part inside follicle where keratinization is still happening

follicle – tube of epidermal cells

just like in epidermis, cells @ bottom of each follicle are young & fresh, continually dividing & pushing older cells up through skin, into open air

Finger & toenails pretty much grow same way

start at @ back of nail bed where new cells divide @ root & get pushed forward

creates scaly-hard keratin top layer

2 Types of Sweat Glands

Up to 3 million tiny sudoriferous/sweat glands distributed throughout body & secrete salty, watery sweat

1. Eccrine glands – simple coiled tubes that start in dermis, extend through a duct, & open into a pore on skin’s surface

more abundant than apocrine

in palms, forehead, & soles

2. Apocrine glands

only have about 2000 apocrine sweat glands

Activated around puberty, empties into hair follicles around armpits & groin

secrete sweat w/ fats & proteins in it

More viscous & sometimes yellowish in color

when bacteria on skin combine with this sweat, it gets odorific- body odor

Deodorants don’t affect amount of sweat, but reduces smells by attacking stink-making bacteria,

antiperspirants are opposite, uses ingredients (i.e. aluminum) to block sweat glands & stop perspiration

Some researchers believe these glands are human equivalent of musky sex scent glands, might help w/ mate acquisition

Types of Apocrine Glands

Mammary glands – secrete milk in lactating people

Ceruminous glands – make cerumen/earwax

Sebaceous (Oil) Glands – found everywhere but thick skin in

ducts are smaller on limbs, but they’re pretty big on face, and neck, and upper chest

Most secrete sebum/oily substance into hair follicles where it can travel to skin’s surface- cause pimples

primary goal: soften & lubricate skin & hair

help slow water loss from skin in dry environments