Question

What is the respiratory organ of a bird?

Answer 1

Hint: Respiration is defined as the transfer of oxygen from the outside environment to cells within tissues, as well as the removal of carbon dioxide in the reverse way, and this oxygen is used to oxidize the digested food. The physiological meaning of respiration differs from the biochemical definition, which refers to a metabolic process in which an organism receives energy through the oxidation of nutrients and the release of waste products.
Although cellular respiration and thus life in animals are dependent on physiologic respiration, the two processes are distinct: cellular respiration occurs in individual cells of the organism, whereas physiologic respiration involves the diffusion and transport of metabolites between the organism and the external environment. Ventilation and perfusion are responsible for gas exchange in the lungs.

Complete answer:
Birds have evolved a directional respiratory system that helps them to receive oxygen at high elevations by enabling air to flow in one direction while blood flows in the opposite, allowing for effective gas exchange.
Birds' lungs are smaller than those of other vertebrates, and they have nine air sacs that play a significant role in breathing. Birds' lungs do not have the ability to inflate since they lack a diaphragm and a pleural cavity. Instead of alveoli, gas exchange occurs between air capillaries and blood capillaries in birds.
When it comes to breathing, flight presents a particular problem. Flying requires a lot of energy, thus birds need a lot of oxygen to help with their metabolic processes. Birds' respiratory systems have evolved to provide them with the oxygen they need to fly. Birds, like mammals, have lungs, which are specialised organs for gas exchange. Inhaled oxygen diffuses across the surface of the lungs into the bloodstream, while carbon dioxide diffuses from the blood into the lungs before being ejected during exhalation.
Birds have air sacs inside their bodies in addition to lungs. Air moves from the posterior air sacs to the lungs and out of the anterior air sacs in one direction. The flow of air is in the opposite direction of blood flow, allowing for far more effective gas exchange. This style of breathing allows birds to get the oxygen they need even at greater elevations where oxygen levels are low. To completely empty the lungs, this directionality of airflow necessitates two cycles of air intake and exhalation.
    

Note:
Because their oxygen consumption at rest is higher than that of all other vertebrates, including mammals, and it increases many times during flight, birds must be capable of large rates of gas exchange. The avian lung has a tiny gas volume compared to mammals', but it is connected to massive air sacs by a network of tubes, resulting in a total volume of the respiratory system that is roughly double that of mammals of comparable size. The trachea is divided into primary bronchi, which each run through a lung and on to the paired abdominal air sacs, as well as minor bronchi that supply the other air sacs.