Figure 10 3 shows the various activities carried out by
a person during a normal day. Can you say in which
activity, the rate of breathing will be the slowest and in
which it will be the fastest? Assign numbers to the
pictures in the order of increasing rate of breathing
according to your experience
Answers
Answer:
10.3 HOW DO WE BREATHE?
Let us now learn about the mechanism
of breathing. Normally we take in air
through our nostrils. When we inhale
air, it passes through our nostrils into
the nasal cavity. From the nasal cavity,
the air reaches our lungs through the
windpipe. Lungs are present in the
chest cavity (Fig. 10.4). This cavity is
surrounded by ribs on the sides. A large,
muscular sheet called diaphragm forms
the floor of the chest cavity (Fig. 10.4).
Breathing involves the movement of the
diaphragm and the rib cage.
During inhalation, ribs move up and
outwards and diaphragm moves down.
This movement increases space in our
chest cavity and air rushes into the
lungs. The lungs get filled with air.
During exhalation, ribs move down and
inwards, while diaphragm moves up to
its former position. This reduces the size
of the chest cavity and air is pushed out
of the lungs (Fig. 10.5). These
movements in our body can be felt
On an average, an adult human being
at rest breathes in and out 15–18
times in a minute. During heavy
exercise, the breathing rate can
increase upto 25 times per minute.
While we exercise, not only do we
breathe fast, we also take deep breaths
and thus inhale more oxygen.
Paheli wants to know why
we yawn when we are
sleepy or drowsy.
2020-21
112 SCIENCE
easily. Take a deep breath. Keep your
palm on the abdomen, feel the
movement of abdomen. What do you
find?
After having learnt that during
breathing there are changes in the size
of the chest cavity, children got involved
in the chest expansion competition.
Explanation:
Answer:
1 sleep in 2 reading 3 washing clothes 4 walking 5 climbing 6 running
Explanation:
hope it helps