Pulmonary Tuberculosis (PTB) Case Study
LOWER RESPIRATORY TRACT
The lower respiratory tract begins with the trachea, which is just below the larynx. The trachea, or windpipe, is a hollow, flexible, but sturdy air tube that contains C-shaped cartilage in its walls. The inner portion of the trachea is called the lumen.
The first branching point of the respiratory tree occurs at the lower end of the trachea, which divides into two larger airways of the lower respiratory tract called the right bronchus and left bronchus. The wall of each bronchus contains substantial amounts of cartilage that help keep the airway open. Each bronchus enters a lung at a site called the hilum. The bronchi branch sequentially into secondary bronchi and tertiary bronchi.
The tertiary bronchi branch into the bronchioles. The bronchioles branch several times until they arrive at the terminal bronchioles, each of which subsequently branches into two or more respiratory bronchioles.
The respiratory bronchiole leads into alveolar ducts and alveoli. The alveoli are bubble-like, elastic, thin-walled structures that are responsible for the lungs’ most vital function: the exchange of oxygen and carbon dioxide.
Each structure of the lower respiratory tract, beginning with the trachea, divides into smaller branches. This branching pattern occurs multiple times, creating multiple branches. In this way, the lower respiratory tract resembles an “upside-down” tree that begins with one trachea “trunk” and ends with more than 250 million alveoli “leaves”. Because of this resemblance, the lower respiratory tract is often referred to as the respiratory tree.
In descending order, these generations of branches include:
- right bronchus and left bronchus
- secondary bronchi
- tertiary bronchi
- terminal bronchioles
- respiratory bronchioles
The thoracic cage, or ribs, and the diaphragm bound the thoracic cavity. There are two lungs that occupy a significant portion of this cavity.
The diaphragm is a broad, dome-shaped muscle that separates the thoracic and abdominal cavities and generates most of the work of breathing. The inter-costal muscles, located between the ribs, also aid in respiration. The internal intercostal muscles lie close to the lungs and are covered by the external intercostal muscles.
The lungs are cone-shaped organs that are soft, spongy and normally pink. The lungs cannot expand or contract on their own, but their softness allows them to change shape in response to breathing. The lungs rely on expansion and contraction of the thoracic cavity to actually generate inhalation and exhalation. This process requires contraction of the diaphragm.
To facilitate the movements associated with respiration, each lung is enclosed by the pleura, a membrane consisting of two layers, the parietal pleura and the visceral pleura.
The parietal pleura comprise the outer layer and are attached to the chest wall. The visceral pleura are directly attached to the outer surface of each lung. The two pleural layers are separated by a normally tiny space called the pleural cavity. A thin film of serous or watery fluid called pleural fluid lines and lubricates the pleural cavity. This fluid prevents friction and holds the pleural surfaces together during inhalation and exhalation.
- Ingestion of infected cattle
- Over fatigue
SIGNS AND SYMPTOMS
- Productive Cough – yellowish in color
- Low fever
- Night sweats
- Anorexia, general body malaise, weight loss
- Chest/back pain