Chapter 6.
Respiratory System
The basic functions of the respiratory system is to transfer oxygen from the atmosphere to the tissues in the body, and to transport carbon dioxide from the tissues to the outer air. Water vapor is also transferred to the air.
The respiratory system consists of the lungs and air passages. The two lungs are side by side, but are not equal in size. The right lung has three lobes, the left has two lobes, and together they weight about 2.9 lbs. The lungs have a spongy structure, and about 1.5 gallon capacity.
In its course to the lungs, the air passes through the following structures: the nasal cavities (the nose), the pharynx, the larynx, the trachea, the bronchi, the bronchioles, the air sacs (alveoli). The bronchi, bronchioles, and air sacs form the lungs. Air is warmed and filtered from particles in the nasal cavity.
The larynx contains the “voice box“, the vocal cords. The trachea is also known as the windpipe. The bronchi divide into right and left sides. There are two lungs, each enveloped in a serious membrane called the pleura. The lungs occupy most of the thoracic cavity.
Respiration consists of two parts: inhalation when air is drawn in from the atmosphere, and exhalation when the air is breathed out into the atmosphere. Air that is inhaled contains more oxygen (21%), while air that is exhaled contains more carbon dioxide (but still about 16% oxygen). When counting respirations, an inhalation and an exhalation count for one breath.
The diaphragm forces the lungs to move (expand and contract), for the respiration. The normal respiratory rate per minute is 16 to 20, depending on a variety of factors which include age, health, and activity.
Please watch the following videos:
- Meet the lungs | Respiratory system physiology | NCLEX-RN | Khan Academy (about 10 minutes)
- The Respiratory System (Bozeman Science) (about 9 minutes)
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