Why Do We Sweat? - ESOL

LEVEL 3 CONTENT-BASED LEVELED READER

SWEAT IN T FO EX RM ATIONAL T

WHY DO WE

SWEAT? KID E-LIT

WHY DO WE

SWEAT?

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Word List temperature hot warm blooded sweat cold blooded bright red inside pig evaporate brains glands dilate liquid blood vessel pores expand body

rise shiver movement lizard snakes drop muscle environment tissue drink molecule water energy exercise gas fluids animals

Whew!

It's so hot!

I'm bright red!

I'm sweating like a PIG! WHEW SO H ! It's OT!

Why do we sweat?

Internal Temperature

3 7 °C

Internal Temperature

3 7 °C

Humans are warm-blooded -- this means our internal temperature always stays the same. Around 37°C or 98.6°F is a normal internal temperature.

Internal Temperature

3 8 °C

Snakes

Internal Temperature

Lizar ds

3 3 °C

Some animals are cold-blooded.

This means that their internal temperature varies, or changes, according to the temperature of their environment. For example, lizards and snakes are cold-blooded.

Internal Temperature

3 7 .2 °C

rnal e t x e The rature tempe RISES.

Internal Temperature

3 7 .1 °C

ternal n i r u O ature r e p m te RISES.

Internal Temperature

3 7 °C

When it gets hotter, and the external temperature of our environment rises, our internal temperature rises too.

External Temperature

3 8 .9 °C

pes a c s e Heat e from th body.

Internal Temperature

3 7 °C

When our internal temperature rises above 37°C, we sweat. Our sweat allows heat to escape from the body and our internal temperature returns to 37°C.

External Temperature

1 0 °C

B rrrr!

r e v i sh

When it gets cold, our internal temperature drops below 37°C, and we shiver.

rnal Our inetre re temp baatcuk up. goes

In Tempteernal ra tur e

g Shiverin tes genera heat.

37°

C

These shivers are contractions of the muscles.

This movement generates heat which makes our internal temperature go back up. shivers nt co ractions of the muscles

B ra

T

in

al re n r e Ext era tu em p

B lo

o

ss e V d

els

37°C

When the external temperature rises above 37°C, our brains send a signal to our blood vessels.

B r a in B

esse V d o o l

ls

D ila t e

Exp an

d

This signal causes the blood vessels to dilate. This means that the blood vessels expand, or get bigger.

t Hea apes esc m the fro dy. bo

When they dilate, our blood vessels allow heat to escape from the body more easily and faster.

Sweat

Sw ea

Pore t Swead G la n

t

Pore

Sweat Gland

Sw eat Pore

Sweat Gland

At the same time, our sweat glands fill with water that they pump to the exterior of our bodies. Sweat comes out of the pores in our skin.

Sweat

Sw eat

37.4°C

Pore t Swead G la n

Sw ea

Sw eat

t

Pore

Pore

In Tempteernal ra tur e

Sweat Gland

3 7 .4

°CSweat

The sweat is the same temperature as our internal temperature.

Gland

Internal re Tem p era tu Intern al Tempe rature

3 7 .4

°C Intern al Tempe rature

Sw eat

37.4°C

3 7 .3

°C Intern al Tempe rature

3 7 .2

°C Intern al Tempe rature

3 7 .1

°C Intern al Tempe rature

37°

C

How does sweat cool us off, if it is the same temperature as our internal temperature?

Gas

W a ter V a p

Sw eat

E v a p o r a t io

or

er t a W d i u q i L

n

Our sweat evaporates. The water changes from liquid into gas, or "water vapor".

Gas

W a ter V a p

or

EN ERG Y Sw eat

E v a p o r a t io

er t a W d i u q i L

n

To change from a liquid to a gas, the water molecules need energy.

W a ter H eat

L iq u id

E

V apor

n o i t a r vapo

H eat

W a ter

ENERGY

He

at

T is s u e s The molecules of liquid water capture heat from our tissues.

Internal re Tem p era tu

H eat

Whew !

Intern al Tempe rature

3 7 .4

°C Intern al Tempe rature

3 7 .3

°C Intern al Tempe rature

ENERGY

3 7 .2

Ahhhh ...

°C Intern al Tempe rature

3 7 .1

°C Intern al Tempe rature

s e u s s Ti

Reduced

37°

C

Our tissues get cooler. Our internal temperature is reduced, and we feel cooler.

External Temperature

3 9 °C

Internatlure a Tem per

3 7 °C

That is how sweat maintains our internal temperature at 37°C or 98,6°F when the external temperature rises above 37°C.

So when you feel sweat on your body you can rest assured it is a good thing.

We do need to be careful when we exercise and sweat a lot. We have to drink more fluids to stay hydrated. Hydration is replacing the lost fluid in our body from sweating.

Be sure to drink plenty of water when exercising or working in the heat.

WATER does a body good!