The respiratory rhythm in human beings

TRANSPORT OF GASES
• Blood is the medium of transport for O2 and CO2.
• About 97 per cent of O2 is transported by RBCs in the blood. The remaining 3 per cent of O2 is carried in a dissolved state through the plasma.
• Nearly 20-25 per cent of CO2 is transported by RBCs whereas 70 per cent of it is carried as bicarbonate. About 7 per cent of CO2 is carried in a dissolved state through plasma.

REGULATION OF RESPIRATION
• Human beings have a significant ability to maintain and moderate the respiratory rhythm to suit the demands of the body tissues. This is done by the neural system.
• A specialised centre present in the medulla region of the brain called respiratory rhythm centre is primarily responsible for this regulation.
• Another centre present in the pons region of the brain, called pneumotaxic centre, can moderate the functions of the respiratory rhythm centre. Neural signals from this centre can reduce the duration of inspiration and thereby alter the respiratory rate.
• A chemosensitive area is situated adjacent to the rhythm centre which is highly sensitive to CO2 and hydrogen ions. Increase in these substances can activate this centre, which in turn can signal the rhythm centre to make necessary adjustments in the respiratory process by which these substances can be eliminated.
• Receptors associated with aortic arch and carotid artery also can recognise changes in CO2 and H concentration and send necessary signals to the rhythm centre for remedial actions. The role of oxygen in the regulation of respiratory rhythm is quite insignificant.

DISORDERS OF RESPIRATORY SYSTEM

Asthma
• Asthma is a difficulty in breathing causing wheezing due to inflammation of bronchi and bronchioles.

Emphysema
• Emphysema is a chronic disorder in which alveolar walls are damaged due to which respiratory surface is decreased. One of the major causes of this is cigarette smoking.

Occupational Respiratory Disorders:

In certain industries, especially those involving grinding or stone-breaking, so much dust is produced that the defense mechanism of the body cannot fully cope with the situation. Long exposure can give rise to inflammation leading to fibrosis (proliferation of fibrous tissues) and thus, causing serious lung damage. Workers in such industries should wear protective masks.

To be continued…