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UNIT
2
What happens when we eat?
1. Mouth: The teeth
crush the food and
then mix it with saliva.
3. Stomach: The food
mixes with gastric
juices.
5. Small intestine:
Here the food mixes
with bile from the liver.
Nutrients are absorbed
here and they pass
into the blood.
2. Esophagus: The food travels
down the esophagus to the
stomach.
4. Liver: It produces a liquid
called bile that helps break
down food.
6. Large intestine: The
undigested food is
transformed into faeces.
7. Rectum: The faeces pass
through it and leave the
body through the anus.
What happens when we breathe?
Mouth and nose: air enters
the body through the mouth
and nose.
Vocal cords: as air
passes our vocal cords,
they vibrate and enable
us to speak.
Trachea: this long, rigid
tube connects our
mouth and nose to our
two bronchi. Air travels
down the trachea into
the bronchi.
Lungs: these two large bags
are connected to the
bronchi. The bronchi branch
into millions of smaller
tubes, or bronchioles, here
in the lungs.
Bronchi: these two smaller
tubes connect the trachea to
the lungs.
How does the circulatory system
work?
1. The heart acts like a pump. It has four chambers. The two
upper ones are called the atria and the two lower ones are
called ventricles. When blood enters the heart, it’s then
pumped to the lungs. In the lungs, the red blood cells absorb
oxygen. That oxygenated blood is pumped back into the
heart. The heart then pumps the oxygenated blood around
the body.
2. The blood vessels connect the heart to the rest of
the body. There are two types: arteries and veins.
Arteries carry a lot of oxygenated blood away from the
lungs and then the heart. Veins carry small quantities of
blood which contains carbon dioxide back to the lungs.
3. The blood containing carbon dioxide travels back to
the heart. It’s pumped into the lungs again so that the
red blood cells can absorb more oxygen.
What’s excretion?
What happens when we go to the toilet?
SOLID WASTE
1. Undigested food and
waste pass through the small
intestine. They still contain a
lot of water. In the large
intestine, most of the water
is absorbed back into the
body. The solid waste that
remains forms solid lumps
are called faeces.
2. They pass into the rectum, where they’re
stored. Finally, they are expelled through the anus.
LIQUID WASTE
1. The blood passes
through our kidneys.
They filter the blood,
removing extra water
and waste, forming a
liquid called urine.
2. The urine travels to the
bladder where it’s stored.
Finally, it’s expelled
through the urethra.
Why is healthy food important?
Vitamins are essential for our bodies, but we don’t
produce them. Without these vitamins, we can feel tired
or get ill easily. If we eat a healthy diet, our bodies will get
all the vitamins we need and we’ll feel healthy.
Food that contains high levels of sugar or fats is called junk
food. Our bodies don’t need much sugar or fat. If we eat too
much of them, they can accumulate in our bodies. This
causes us to gain weight and sometimes causes illness too.
We should eat the right kinds of foods in the right proportions. For example:
**more grains and vegetables than other types of food**
**not too many dairy products such**