The science of skin - Emma Bryce

Prevodilac: Milena Lakic Lektor: Ivana Korom

Between you and the rest of the world lies an interface

Između vas i ostatka sveta leži granična površina

that makes up 16% of your physical weight.

koja sačinjava 16% vaše fizičke težine.

This is your skin, the largest organ in your body:

To je vaša koža, najveći organ u vašem telu:

laid out flat, it would cover close to 1.7 square meters of ground.

kada bi se izravnala, pokrila bi gotovo 1,7 kvadratnih metara zemlje.

Its purpose may seem obvious— to keep our insides in.

Njena svrha može izgledati očigledna - da drži našu unutrašnjost unutra.

But a look beyond the surface

Ali jedan pogled ispod površine

reveals that it plays a surprising number of roles in our lives.

otkriva da ona igra iznenađujuće mnogo uloga u našim životima.

First, the basics.

Prvo, osnovni pojmovi.

Skin is the foundation of the integumentary system,

Koža je osnova pokrovnog sistema,

which also incorporates your hair, nails, and specialized glands and nerves.

koji takođe obuhvata vašu kosu, nokte i specijalizovane žlezde i nerve.

Made up of three layers,

Sačinjena od tri sloja,

the epidermis,

pokožice,

dermis,

krzna

and hypodermis,

i potkožnog tkiva,

skin’s thickness varies from 0.5 millimeters at its thinnest

debljina kože varira od 0,5 milimetera u najtanjem obliku

and up to four millimeters at its thickest.

do četiri milimetara u najdebljem.

It also carries out three key functions:

Ona takođe vrši tri ključne funkcije:

protecting,

štiti,

regulating,

reguliše

and sensing the world beyond its limits.

i opaža svet izvan svojih granica.

On a daily basis, its huge surface processes hundreds, if not thousands,

Njena ogromna površina svakodnevno obradi stotine, ako ne hiljade

of physical sensations,

fizičkih oseta,

relying mostly on large, pressure-sensitive skin components

oslanjajući se na velike komponente kože osetljive na pritisak

called Merkel cells.

zvane Merkelove ćelije.

In your fingertips alone,

Samo na vašim vrhovima prstiju

there are 750 Merkel cells per each square-centimeter of skin,

nalazi se 750 Merkelovih ćelija po svakom kvadratnom centimetru kože,

coupled with over 2,500 receptors that give you your sense of touch.

uparenih sa preko 2.500 receptora koji vam daju vaše čulo dodira.

This surface is also the body’s first major line of defense.

Ova površina je takođe prva velika linija odbrane tela.

Without it, you’d be a soggy mass of tissue and fluids,

Bez nje bili biste gnjecava masa tkiva i tečnosti,

fatally exposed to the elements.

fatalno izložena spoljašnjim uticajima.

Skin effectively seals off your insides

Koža efikasno zapečatira vašu unutrašnjost

and also absorbs pressure and shock

i takođe apsorbuje pritisak i šok

with flexible collagen that makes up most of its dermal layer.

fleksibilnim kolagenom koji čini veći deo krznatog sloja.

The epidermis is made up mainly of skin cells called keratinocytes

Pokožicu sačinjavaju uglavnom ćelije kože nazvane keratinociti

that are completely replaced every four weeks.

koje se u potpunosti zamenjuju na svake četiri nedelje.

As new cells form at the base of the epidermis, older ones are pushed up.

Kako nove ćelije nastaju u bazi pokožice, stare su izgurane na površinu.

When these cells move upwards,

Kada se ove ćelije kreću naviše,

they’re filled with a hardened protein called keratin.

one se pune očvrslim proteinom zvanim kreatin.

Once they reach the surface,

Kada dospeju na površinu,

they form a tightly-overlapping, waterproof layer

one formiraju jako zgusnuti vodootporni sloj

that’s difficult for invading microbes to breach.

koji mikrobi teško mogu da probiju.

Any harmful microbes that make it into the epidermis

Bilo koji štetni mikrobi koji dospeju do pokožice

will encounter Langerhans cells.

naići će na Langerhansove ćelije.

This group of protective skin cells detects invaders

Ova grupa zaštitnih ćelija kože detektuje uljeze

and communicates their presence to resident immune system T-cells,

i o njihovom prisustvu obaveštava prisutne T ćelije imunog sistema,

which react by launching an immune response.

koje reaguju tako što pokreću imunološku reakciju.

A crucial feature of this immune defense

Ključno svojstvo ove imunološke odbrane

is the several thousand species of microorganisms

je postojanje nekoliko hiljada vrsta mikroorganizama

that inhabit the planes,

koji nastanjuju površine,

folds,

pregibe

and crevices of your skin.

i pukotine vaše kože.

These microbes, which include bacteria and fungi,

Ovi mikrobi, koji uključuju bakterije i gljivice,

thrive in the sebum,

bujaju u sebumu,

an oily substance that’s secreted onto the skin’s surface

masnoj supstanci koju na površinu kože izlučuju

by sebaceous glands nestled inside the dermis.

lojne žlezde ušuškane unutar krzna.

These skin microbes keep the immune system in a state of constant surveillance,

Ovi mikrobi kože drže imuni sistem u stanju stalnog nadzora,

ensuring that it’s ready to react if the body really is at risk.

osiguravajući spremnost da reaguje ako je telo zaista u opasnosti.

Beyond this protective role,

Izvan ove zaštine uloge,

your skin is also a sensory organ that helps regulate your body’s temperature,

vaša koža je takođe čulni organ koji pomaže regulaciju telesne temperature

two roles that are closely interlinked.

koje su dve međusobno povezane uloge.

Nerves detect whether your skin is warm or cold

Nervi detektuju da li je vašoj koži toplo ili hladno

and communicate that information to your brain.

i prenose tu informaciju do mozga.

In return, the brain instructs localized blood vessels

Zauzvrat, mozak daje instrukcije lokalnim krvnim sudovima

to either expand if the body is too warm,

da se ili šire ako je telo pretoplo,

releasing heat from the blood through the skin,

oslobađajući toplotu iz tela kroz kožu,

or to constrict if the body is cold, which retains heat.

ili sužavaju ako je telo hladno, što zadržava toplotu.

At any given time, up to 25% of the body's blood is circulating through the dermis,

U bilo kom trenutku do 25% krvi u telu cirkuliše kroz krzno,

making this process extremely efficient.

čineći ovaj proces izuzetno efikasnim.

Under warm conditions,

U toplim uslovima,

the skin’s sweat glands will secrete sweat via ducts onto the surface,

znojne žlezde kože će lučiti znoj kroz kanale do površine,

transferring heat out of the body.

prenoseći toplotu izvan tela.

Hair can also be stimulated to conserve or release body warmth.

Kosa takođe može biti stimulisana da čuva ili oslobađa telesnu toplotu.

The average human has 5 million hair follicles

Prosečan čovek ima 5 miliona folikula dlake,

embedded everywhere on the body

koji su umetnuti svuda po telu

except the palms of your hands and soles of your feet.

osim na dlanovima ruku i tabanima.

Ninety to 150,000 of those are on your scalp,

Devedeset do 150.000 njih su na koži glave,

where they help shield the large surface area of your head

gde pomažu pri zaštiti ogromne površine glave

from physical damage and sunburn.

od fizičke povrede i opekotine od sunca.

When you're cold, tiny muscles called arrector pilli

Kada ti vam je hladno mali mišići zvani arrector pilli

cause hair to stand upright across the body.

čine da kosa stoji uspravno po celom telu.

That’s the phenomenon known as goosebumps and it traps body heat close to your skin.

To je fenomen poznat kao naježena koža i on zadržava toplotu blizu vaše kože.

Skin’s vast surface isn’t just a shield;

Ogromna površina kože nije samo štit;

it also enables us to interact and connect with the world.

ona nam takođe omogućava da interagujemo i povežemo se sa svetom.

Its multifunctional layer cools us down and keeps us warm.

Njen višefunkcionalni sloj nas hladi i greje.

The integumentary system may be many things,

Pokrovni sistem može biti mnogo toga,

but it’s certainly more than skin deep.

ali je sigurno više nego površan.