Overview of the Respiratory System

CHAPTER 17

Christina Bell, PharmD | Sandra B. Earle, PharmD, BCPS

LEARNING OBJECTIVES KEY TERMS AND DEFINITIONS After completing this chapter, you should be able to Alveoli— terminus (end) of bronchial tree where primary gas exchange 1. Identify components of the upper and lower respiratory systems occurs in the lung. 2. Recall basic physiology of respiratory system Bronchi— main branches of airways 3. Describe the process of respiratory gas exchange between oxygen and carbon connecting the trachea to the bronchioles in the lung. dioxide and explain its importance Bronchioles— airways connecting 4. Identify and explain the different respiratory function tests that are used to evaluate the bronchi to the alveoli. respiratory function Dry powder inhaler (DPI) — 5. Describe proper technique for administration of medication via respiratory routes device used to deliver medication to the lungs using a dry powder and without aerosol propellant. It requires some inspiratory effort and may not xygen is essential to sustain life; it is needed by all cells throughout the be useful in small children. O body to perform normal metabolic functions. Carbon dioxide is a waste Hemoglobin — component of red blood cells that transports oxygen byproduct of cellular metabolism and must be removed from the body. The from lungs to cells and tissues primary function of the respiratory system is breathing; inhalation of oxygen and throughout the body. PART the exhalation of carbon dioxide with an exchange of gases (oxygen and carbon Larynx — portion of the respiratory 6 dioxide) between the air and blood. Oxygen is transported into the lungs through tract connecting the pharynx to the trachea. It contains the vocal cords, passageways via inhaled air and once in the lungs, passively diffuses (moves) into which vibrate and allow a person the blood. Once in the blood, it can be transported to cells and tissues throughout to vocalize. The larynx is sometimes the body. Carbon dioxide is released from cells, where it moves into the blood referred to as the voice box. to be carried to the lungs where it is expelled by exhalation. Epithelial cells line Lungs — the two organs (left and right) located in the chest that take the respiratory system; these cells are thin and moist to enable gas exchange in oxygen from the air and distribute between the blood and the air in the lungs. it to the bloodstream for use by the body, while removing waste carbon The respiration process involves the whole respiratory system. The upper and dioxide from body processes by exhalation into the outside air. lower respiratory systems are essentially several tubes or passageways allowing Metered dose inhaler (MDI)— air to travel to the lungs. The passageways are lined with the mucus-secreting a device that delivers aerosolized goblet cells and hair-like cilia that protect the respiratory system from any medication to the lungs. It is often foreign bodies. The mucus traps foreign bodies, which allows the cilia to sweep used with a spacer. the foreign body up out of the respiratory system to be expelled. Nebulizer— a device used to deliver medications to the lungs in a ﬁ ne mist and requires a compressor (mechanical device) and nebulizer cup. Pharynx — is also called the throat; it is part of both the respiratory and gastrointestinal tracts. It connects the mouth and nasal cavity to the larynx and trachea.

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Spacer— a tube-like device that Respiratory Anatomy and Physiology connects to the mouthpiece of an MDI. The purpose of the spacer is to increase the amount of medication Upper Respiratory System that reaches the lungs. The primary function of the upper respiratory system is to deliver air through passage- Spirometry— a breathing test to ways to the lungs. The upper respiratory system primarily involves the head and neck diagnose and monitor lung disease. region including the nose, pharynx , and larynx (Figure 17-1). It measures pulmonary function with results being given in the pulmonary Air is inhaled through the nose where it is warmed and moistened within the nasal function tests (PFTs) . cavity. The nose also functions as a fi lter and removes dust particles from the air to Thoracic diaphragm— the primary protect the lungs from foreign bodies. The nasal cavity empties to the back into the muscle involved in respiration. pharynx, the passageway that connects the nose and mouth commonly referred to as Trachea— connects the larynx to the the throat. The pharynx is a component of both the respiratory and digestive systems bronchi. The trachea is also called the as it delivers both air to the lungs and food to the stomach. It has three distinct regions: windpipe. the nasopharynx, oropharynx, and laryngopharynx. The nasopharynx is the uppermost portion (encompassing the upper part of the throat) that is connected to the nasal cavity. The oropharynx is the portion of pharynx directly below that extends between the soft palate and base of the tongue; it contains the tonsils. The oral cavities empty into the oropharynx. The laryngopharynx lies directly below the oropharynx; it connects to both the larynx (respiratory system) and the esophagus (digestive system), and carries both air and food. The epiglottis is a small piece of cartilage that acts as a tiny “ lid ” to cover the larynx when food and drink are being swallowed, directing them to the esophagus; in the absence of solids and liquids, it remains open, allowing air to be delivered to the larynx. The larynx (also called the voice box) is located directly below the laryngopharynx and leads into the trachea of the lower respiratory system. Lower Respiratory System The lower respiratory system encompasses primarily the chest area of the body and includes the trachea, the lungs , and the thoracic diaphragm. The primary function of the lower respiratory system is the absorption of oxygen and removal of carbon dioxide from the body. The trachea (commonly referred to as the windpipe ) is the fi nal passageway leading to the lungs. It is a fl exible tube that is approximately 1 inch in diameter that branches into the left and right primary bronchi that enter the left and right lung respectively. The bronchi

Bronchiole Branch of the Pharynx (throat) Branch of pulmonary the pulmonary artery Larynx vein (voice box) Alveoli Trachea (windpipe) Right lung Bronchus

Bronchiole Blood Pleura capillaries

Diaphragm (breathing muscle) Figure 17-1. Anatomy of the respiratory system.

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