Science Project: Breathing Mechanism

One of the project for form 3 science project in Malaysia is on the Breathing Mechanism.

AIM
The aim of the project is to build a functional model of the human respiratory system, to show the relationship between the air pressure in the thoratic cavity and the breathing mechanism.

APPARATUS AND MATERIALS:
Bell jar, Y-shaped glass tube, conical flask, rubber stopper, syringe, thin rubber sheet and balloon.

PROCEDURE
1. A model of the respiratory system was built as shown in the figure a below.

2. The rubber sheet was pulled down and what happened in the bell jar was observed and recorded.

3. The rubber sheet was pushed upwards into the jar and what happened to the balloons was observed and recorded.

OBSERVATION

	what is done	changes in balloon	pressure in the bell jar	inference
1	rubber sheet was pulled down	The balloons inflate	Air pressure decrease	higher air pressure caused the balloons to inflate
2	rubber sheet pushed up	the balloons deflate	the air pressure increase	the higher pressure in the jar pushed the air in the balloon out

DIAGRAMS

These were the questions given to the students after the experiement.

1. Name the parts of the respiratory system represented by the:
a. bell jar         ---> thoraicic cavity
b. the y-shaped glass tube -----> brochi
c. the balloons ----------------> lungs
d. rubber sheet ---------------> diaphragm

2. The lower diagram shows another project model that can be used to show the human breathing mechanism. Explain what happen?.
a.When the plunger of the syringe is pulled up, the air pressure in the jar reduced and the balloon will inflate.
b. When plunger is pushed down, the pressure will increase causing the balloon to deflate.

3. What is the relationship between the air pressure in the thoracic cavity and the breathing mechanism?.
As the air pressure in the thoracic increases, air is forced out of the lungs. This is called exhalation.
As the as air pressure in the cavity reduces the ambient air will rush into the lung, this phase is called inhalation.

CONCLUSION
The inflation and deflation of the lungs is caused by the movement of the thoracic diaphragm.

VIDEO from YOUTUBE