concept for respiratory system in human beings
Answers
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The respiratory system is a biological system consisting of specific organs and structures used for gas exchange in animals and plants. The anatomy and physiology that make this happen varies greatly, depending on the size of the organism, the environment in which it lives and its evolutionary history. In land animals the respiratory surface is internalized as linings of the lungs. The lungs with their alveolar gas exchange units are sometimes referred to as the gas exchanger.These communicate with the external environment via a system of airways, or hollow tubes, of which the largest is the trachea, which branches at the carina into the two main bronchi. These enter the lungs where they branch into narrower secondary and tertiary bronchi that branch into numerous smaller tubes, the bronchioles. In birds the bronchioles are termed parabronchi. The bronchioles, or parabronchi generally open into microscopic air sacs called alveoli in mammals and atria in birds. Gas exchange takes place across the very large surface areas created by the many millions of these microscopic air sacs, which have a very rich blood supply. Air has to be pumped from the environment into the alveoli or atria by the process of breathing which involves the muscles of respiration.
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