During the distributed classroom sessions (November-December 2011) we got a lot of interesting questions from students attending the sessions. We would like to share a few of these questions with more elaborate answers with you.
This question was asked by Pushan- When a python engulfs a prey how does the prey die of suffocation when its nose is not blocked?
Answer:
Mammals receive oxygen from air through nose and it is finally absorbed in lungs. This exchange of air is called breathing. Intake of air is called inhaling and giving out air is called exhaling. The lungs expand during inhalation and contract during exhalation. For expansion, they need space within the thoracic cavity. This is space is created by movement of diaphragm muscle. The diaphragm contracts to increase space in thoracic cavity and lungs expand. When it relaxes, the lungs contract and air is exhaled. Thus movement of diaphragm is very crucial for breathing. Remember that nose is just a passage for air to enter the body but actual gas exchange occurs only in the lungs.
A python kills its prey by a process known as constriction. You know that oxygen is required for cellular respiration. If supply of oxygen stops, cellular respiration cannot occur. When a python engulfs its prey it constricts movement in the thoracic cavity with its strong grip. Hence, inhalation cannot occur. Because of this, oxygen supply to the different tissues stops. This results in death by asphyxiation.
Further Questions:
- Do you know location and structure of diaphragm?
- Do you know function of rib-cage in breathing?
- What is the difference between respiration and breathing?
The rib cage is attached to diaphragm by muscles, When the diaphragm contracts the rib cage expands increasing volume within the thoracic cavity. Hence, lungs expand. Thus it plays important role in expansion and contraction of lungs.
The muscles in between the ribs are called inter coastal muscles