SCIENCE OF RESPIRATION

RESPIRATION

1. Human beings need to breathe to sustain life.

2. Breathing involves the movement of air into and out of the respiratory system.

3. The process of breathing in is called inhalation whereas the process of breathing out is called exhalation.

4. The respiratory system consists of the following organs:-

   i.   nasal cavity

   ii.  pharynx

   iii. larynx

   iv.  trachea

   v.   bronchus

   vi.  bronchiole

   vii. lungs

   viii. rib cage

   ix.  diaphragm

   x.   intercostal muscles

LUNGS

1. The lungs are the respiratory organs.

2. The lungs are soft and spongy and filled with air sacs. They are situated in the thoracic cavity and are protected by the rib cage.

3. The lungs are connected to the trachea by two tubes. These tubes are the left bronchus and the right bronchus. These bronchi (plural for bronchus) divide into smaller tubes known as bronchioles.

4. The bronchioles end in clusters of tiny air sacs called the alveoli (singular, alveolus).

5. Air enters through the nasal cavity, and then moves through the pharynx, larynx, trachea, bronchi, bronchioles and finally the alveoli.

6. The exchange of respiratory gases (oxygen and carbon dioxide) occurs through diffusion in the alveoli.

7. Oxygen from the atmospheric air diffuses out of the alveolus into the blood capillaries. At the same time carbon dioxide from the cells diffuses out of the blood capillaries into the alveolus.

8. The wall of the alveolus is one-cell thick, moist and surrounded by blood capillaries. This is to facilitate diffusion.

FUNCTIONS OF RESPIRATORY STRUCTURE

STRUCTURE	FUNCTION
Nasal cavity	Warms, moistens, and filters air as it is inhaled.
Pharynx	Passageway for air, leads to trachea.
Trachea (Windpipe)	The passage leading from the pharynx to the lungs. Rings of cartilage in the trachea keep the trachea "open".
Bronchi (Pleural)  Bronchus (Singular)	Two branches at the end of the trachea, each lead to a lung.
Bronchioles	A network of smaller branches leading from the bronchi into the lung tissue and ultimately to the alveoli (air sacs).
Lungs	The lungs are the respiratory organs. They are protected by the rib cage.
Intercostal muscles	The contraction and relaxation of the intercostal muscles helps in the breathing mechanism.
Ribs	Bones supporting and protecting the chest cavity. They move to a limited degree, helping the lungs to expand and contract.
Diaphragm	Strong wall of muscle that separates the chest cavity from the abdominal cavity. By moving downward, it creates suction to draw in air and expand the lungs.
Alveoli(Plural) Alveolus(Singular)	Very small air sacs where gases (oxygen and carbon dioxide) are exchanged (enter and exit the blood stream).
Cilia	Very small hairs that have a wave-like motion. This motion carries mucus (sticky phlegm or liquid) upward and out into the throat, where it is either coughed up or swallowed.

BRAIN TWIST

The process of moving air into and out of the lungs is something most people take for granted. But for millions of people living with asthma, this simple activity requires significant effort.

Asthma cannot be cured, but with proper treatment it can be effectively controlled.

Without satisfactory control of asthma, long-term damage can occur in the respiratory system. Poorly controlled asthma can lead to reduced physical activities, and extra visits to the emergency department.

Asthma is a condition that affects the air passages of the lungs. 

Millions of people suffer from asthmatic attacks every day.