Functions of the Respiratory System

The Respiratory System
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1. What are the primary functions of the respiratory system?
The respiratory system's primary functions are to obtain oxygen from the external environment, provide it to the cells, and eliminate the carbon dioxide produced by cellular metabolism from the body (Marieb & Smith, 2016). The respiratory system is composed of the lungs, the airways, the parts of the central nervous system related to the control of the muscles of respiration, the diaphragm, and the intercostal muscles (Marieb & Smith, 2016). Other parts are the abdominal muscles and the rib cage. The function of the respiratory system is involved in gas exchange and defense and lung metabolism and the handling of bioactive materials. The respiratory system provides a surface area for gas exchange and moves air to and from the lungs. The stem also protects the respiratory surfaces from pathogens and environmental changes. Other functions include detecting odor and producing sound. 
2. Explain the roles of mucus and cilia in the respiratory system.
Mucus and cilia are the first levels of defense, and cilia are hair-like protuberances. The cilia propel mucus (produced by goblet cells) laden with dust particles, bacteria, and other debris (Marieb& Smith, 2016). Mucus covers the airways, which allows mucus to trap the particles, bacteria, and debris, preventing them from reaching the lungs. The trapped particles and pathogens can either be coughed out or swallowed when they move to the mouth. 
3. Explain the structure and function of the respiratory membrane.
The respiratory membrane (blood air barrier) is composed of the alveolar and capillary walls and their fused basement membranes (Marieb & Smith, 2016).The membrane allows
gasses to move between the alveoli in the lungs and the blood where oxygen enters the bloodstream and carbon dioxide exits. The alveoli are the site of gas exchange. The membrane has type I alveolar cells that are the thin, squamous epithelial cells where oxygen diffusion takes place across these cells (Marieb & Smith, 2016). There are type II cells that are cuboidal epithelial cells, which secrete pulmonary surfactant and the surfactant...