Respiratory system: anatomy and associated disorders
The respiratory system consists of two lungs, a trachea and the upper respiratory tract, and its principal function is to extract enough oxygen from the atmosphere to maintain cellular health and simultaneously dispose of excess carbon dioxide.
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Overview
The respiratory system consists of two lungs, a trachea and the upper respiratory tract, and its principal function is to extract enough oxygen from the atmosphere to maintain cellular health and simultaneously dispose of excess carbon dioxide (Beachy, 2017). Human cells require a continuous supply of oxygen to survive. As cells use oxygen, carbon dioxide is produced, which, if allowed to accumulate, can disrupt cellular activity and homeostasis (Beachy, 2017). The respiratory system ensures cells receive a plentiful supply of oxygen and that excess carbon dioxide is exhaled via respiration. Respiration follows four distinct processes:
- Pulmonary ventilation: commonly referred to as breathing
- External respiration: also known as gaseous exchange
- Transport of gases: oxygen delivery to tissues and carbon dioxide delivery to the lungs
- Internal respiration: oxygen delivery to tissues and carbon dioxide collection from cells (Beachy, 2017)
In addition to respiration, the respiratory system also has the following functions:
- regulation
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Anatomy and physiology
The respiratory system is divided into two sections: the upper and lower respiratory tracts. The lower respiratory tract consists of the lungs and the major airways and is the location of the main respiratory physiological functions. Many of the structures within the lower respiratory tract are fragile and easily damaged by inflammation and infection. A major function of the upper respiratory tract, therefore, is to protect the lower respiratory tract (Tortora and Derrickson, 2017).
The upper respiratory tract
The upper respiratory tract consists of the oral cavity, the nose and the nasal cavity, the pharynx and the larynx (Figure 1). Air enters the respiratory system via the nasal and oral cavities. The nasal cavity is divided into two spaces by the nasal septum, each space is divided into three passageways – the nasal meatuses – which are formed by three shelf-like projections – the superior, middle and inferior conchae. The
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Aetiology of disorders
Table 1 outlines five common respiratory diseases, their main assessments and key treatments.
| Table 1. Examples of respiratory diseases, their assessment and treatment | ||
| Common associated disorder | Assessment | Treatments |
| Asthma | Peak expiratory flow rate: episodic reductions of peak expiratory flow rate (less than predicted or best) with asymptomatic periods | Oxygen, to maintain SpO2 above 92% Bronchodilator therapy, such as salbultamol, ipratropium bromide, terbutaline, salmeterol, theophylline Steroid therapy, such as beclametasone, budesonide, fluticasone, prednisolone, hydrocortisone |
| Chronic obstructive pulmonary disease | Spirometry FEV1 less than predicted FEV1/FVC ratio less than 80% |
Promotion of self-management, such as pulmonary rehabilitation, smoking cessation, coping strategies, vaccinations Oxygen, to maintain SpO2 above 92% Bronchodilator therapy, such as salbultamol, ipratropium bromide, terbutaline, salmeterol, theophylline |
| Pneumonia | CURB-65 C: new-onset confusion U: urea greater than 7 mmol R: respiration rate greater than 30 respirations per minute. B: systolic blood pressure less than 90 mmHg 65: aged 65 years or older |
Antibiotic therapy, such as amoxicillin, clarithromycin, co-amoxiclav Oxygen, to maintain SpO2 above 92% |
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Case study
Presenting complaint
James was taken to the local accident and emergency department after coughing had kept him awake all night and he had been expectorating a rust-coloured sputum.
Social history
James is a 75-year-old man, who is retired after running many successful public houses. James’ wife passed away 5 years ago from cancer, and he lives alone in a small house in a rural area. He has two children, but he only sees his daughter regularly. His son runs his own business and lives with his partner 200 miles away. James only sees his son at Christmas and in the summer, but speaks to him on the phone every weekend. His daughter lives a short distance away with her husband and three teenage children. His daughter and her husband visit James two to three times a week and help him with his shopping, laundry and gardening. James employs a cleaner,
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Resources
Beachy W. Respiratory care anatomy and physiology: foundations for clinical practice. 4th edn. St Louis (MO): Elsevier; 2017
Imperial College Academic Health Science Centre. Lung disease. 2024. https://ahsc.org.uk/lung-disease/ (accessed 18 November 2024)
Lumb AB. Nunn’s applied respiratory physiology. 9th edn. London: Elsevier; 2020
Paramothayan S. Essential respiratory medicine. Chichester: Wiley Blackwell; 2018
Tortora GJ, Derrickson BH. Principles of anatomy and physiology. 15th edn. Hoboken (NJ): John Wiley & Sons; 2017
Ward JPT, Ward J, Leach RM. The respiratory system at a glance. 5th edn. Chichester: Wiley Blackwell; 2022
Wheatley I. Respiratory rate 3: how to take an accurate measurement. Nursing Times. 2018;114(7):21–22
Wheeldon A. The respiratory system and associated disorders. In: Peate I (ed). Fundamentals of applied pathophysiology: an essential guide for nursing and healthcare students. 4th edn. Chichester: Wiley Blackwell; 2021
World Health Organization. Chronic respiratory diseases. 2024. https://www.who.int/health-topics/chronic-respiratory-diseases#tab=tab_1 (accessed 18 November 2024)
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