The New Childrens Encyclopedia

291

THE HUMAN BODY

STAY HEALTHY

HOW TO STAY HEALTHY

O

Vitamins and minerals are found

in many foods, and are essential

to general body health.

O

Exercise helps

strengthen the heart, lungs, and

muscles. It also helps to keep the

body supple.

O

Water is needed

for all of the body’s

processes to function

properly. Dehydrated cells will

not perform at their best.

O

Good hygiene helps to keep

germs away. Brushing teeth helps combat

tooth decay by cleaning teeth of the bacteria

that cause it.

HEALTH PROBLEMS

It’s not always easy for someone to stay well. There may not be

access to clean drinking water, or food may be restricted.

Malnutrition, which is when somebody doesn’t have enough

of one or more of the food groups, is a serious problem

in some parts of the world. But if your immune

system is working well, it will act to protect your

body from illness, fighting off the viruses and

bacteria that may cause you harm.

Allergies Sometimes

the immune system

doesn’t work properly,

identifying things as a

threat and attacking

them when they

aren’t. This can

cause an allergic

reaction. A person

might begin sneezing,

for example, when in

contact with pollen

or dust.

O Fungi usually cause

infection on the skin’s

surface, like dandruff,

but other fungi can

cause serious illness

inside the body by

damaging the cells.

O Viruses are far smaller

than bacteria. They attack

our cells from the inside,

taking them over. Colds

and flus are the result of

a viral infection.

O Bacteria are single-

celled organisms. Most

are harmless, but certain

bacteria invade our

bodies to cause illness.

Tuberculosis is caused

by bacteria.

WHAT MAKES US SICK

 HAYFEVER

Increasing numbers of

people around the world

are suffering from allergies,

such as hayfever. Hayfever

is an allergic response to

plant pollen. This can be

worse at particular times

of year, when the pollen

count is high.

White blood cells These cells fight

bacteria and viruses that might make you

sick. Some produce antibodies that work

to kill germs. Babies are born

with antibodies they inherit

from their mother, but they

begin to develop their own

as they grow.

White blood cell

Red

blood cell

KIDNEYS

O

Your two

kidneys are at

the back of your

abdomen.

O

The kidneys

control the

amount of fluid

in the body and filter liquid waste from

your blood.

O

Filtered waste is removed to the bladder

and then expelled as urine.