Unit 1 Respiratory System
Unit 2 Digestive System
Unit 3 Circulatory System
Unit 4 Blood
Unit 5 Immune System
Unit 6 Urinary System
Unit 7 Reproduction
Unit 8 Healthy Lifestyle
Unit 9 First Aid
Unit 10 Mental Health
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Introductory Remarks
The respiratory system is a biological system consisting of specific organs and structures used for the process of respiration in an organism. The respiratory system is involved in the intake and exchange of oxygen and carbon dioxide between an organism and the environment.
Human as aerobic organisms must automatically obtain oxygen from their environment and breathe out carbon dioxide in order to survive. Air is breathed in through the nasal passageways, travels through the trachea and bronchi to the lungs. This breathing occurs owing to the respiratory system, which includes the nose, throat, voice box, windpipe and lungs delivering sufficient oxygen to the bloodstream through the capillary walls and removing carbon dioxide that is produced as a waste product in the system.