QS Study

Respiration is a physiological process by which Oxygen is transported from the atmosphere to the cells for oxidation of the ingested food materials and Carbon dioxide is eliminated from cells to the atmosphere. It is the act of inhaling and exhaling air in order to exchange oxygen for carbon dioxide.

Types of respiration

It is of two types –

(A) External respiration (B) Internal respiration.

External respiration: The absorption of Oxygen and removal of Carbon dioxide from the body as a whole is known as external respiration. It is simply the intake of oxygen from the surrounding medium (air or water) and giving out of carbon dioxide into that surrounding medium.

Humans and other mammals have a respiratory system with particular respiratory organs (lungs) and tissues. In the human body, oxygen is taken into the lungs by breathing and carbon dioxide is expelled from the lungs by exhalation.

It has four events-

(i) Pulmonary ventilation,

(ii) Diffusion of Oxygen and Carbon dioxide between alveoli and lung,

(iii) Transport Oxygen and Carbon dioxide in the blood and body fluid to and from the cells.

(iv) Regulation of respiration.

Fig: Types of Respiration

Internal respiration: The utilization of Oxygen and production of Carbon dioxide by cells and gaseous exchanges between the cells fluid medium is called internal respiration. Internal respiration involves the transportation of gases between the blood and body tissues. Oxygen within the lungs diffuses across the thin epithelium of lung alveoli (air sacs) into surrounding capillaries containing oxygen-depleted blood. This involves three steps: (a) uptake of oxygen by tissue cells; (b) oxidation of food inside the cells by oxidizing enzymes; and (c) elimination of carbon dioxide from tissues.

Phase of respiration

Respiration has two phases –

  1. Inspiratory phase – an Active process by which air is taken from atmosphere to lung.
  2. Expiratory phase – a Passive process by which air is expelled from the lungs to the atmosphere.