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channeled by a flap like valve, the epiglottis that protects the tube to the
lungs, arresting entry of food. Observe the following figures and discuss
in your class how epiglottis works while breathing or swallowing
This valve is partly closed when we swallow food; it deflects food
down to the stomach and keeps it out of the trachea or wind pipe which is
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the route to the lungs. The epiglottis opens more widely when we take a
breath, and air enters the lungs. Nervous regulation is important in guiding
the function of epiglottis and passage of food and air. Let us try to do an
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activity to feel what happens when we swallow food.
Why are we advised not to talk while eating food ?
Activity-1
Activity
Keep your palm around an inch away from your nose, feel you are
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breathing out, do not remove it until you have finished the activity. Breathe
steadily for 1-2 minutes. Now take a piece of any fruit, chew and before
swallowing it keep the fingers of the other palm on your throat, now swallow
it.
What did you notice? What happens to your breath as you try to
swallow?
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What is helping you to swallow without deflecting it to the wind pipe?
Mechanism of respiration in human beings
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rib bones We know that breathing is the
process of inhaling and exhaling. The
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chest wall organs involved are mainly the lungs.
muscles You can’t see your lungs, but it’s easy
to feel them in action. Put your hands
on your chest and breathe in very
lung deeply. You will feel your chest getting
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slightly bigger. Now breathe out the air,
and feel your chest return to its regular
diaphragm abdomenal cavity size. You’ve just felt the power of your
lungs! The lungs themselves can neither
draw in air nor push it out. Instead, the
fig-6: Diagram showing lungs and diaphragm chest wall muscles and another flexible
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flattened muscle called diaphragm helps the lungs in moving air into and
out of them. See how the diaphragm works in the figure.
What is the role of diaphragm and ribs in respiration? Are both
active in men and women?
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The chest wall is made up of ribs, muscles, and the skin. The ribs are
attached at an angle to the spine (if you run your finger along one of your
ribs, you will notice that it extends downward from the spine). When we
inhale, the chest wall moves up and expands. This causes an increase in the
volume of the chest cavity.
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The diaphragm may be imagined as the ‘floor’ if you think of the chest
cavity as a “room.” When the diaphragm is relaxed when we breath out, it
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is in the shape of a dome with the convex side of the dome extending into
the chest cavity. When the diaphragm contracts during inhalation it flattens
out a bit or the dome moves downward. As a result, the volume of the
chest cavity is increased.
When the diaphragm flattens and the volume of the chest cavity is
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increased, its internal pressure decreases and the air from the outside rushes
into the lungs. This is inspiration (inhalation).
fig-7: Movement Then the reverse occurs. The chest wall is lowered and moves inward,