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11.4 Disorders of the Respiratory System
Disorders of the Upper Respiratory Tract
The Common Cold
• Most colds are mild viral infections of the upper respiratory tract
• Symptoms include runny nose, sneezing, mild fever
• Different viruses can cause colds (rhinoviruses are the most common)
• In most cases, the immune response can eliminate the virus within a week
• Treatment involves decongestants and anti-inflammatories
Pharyngitis, Tonsillitis, and Laryngitis
Pharyngitis
• Inflammation of the throat due to an infection
• “Strep throat” is pharyngitis caused by the bacterium
Streptococcus pyogenes
• Symptoms include severe sore throat, fever, and white
patches in the pharyngeal or tonsillar area
• Treatment includes antibiotics
Tonsillitis
• Occurs when the tonsils (a type of lymphoid tissue) become inflamed and enlarged
• If tonsillitis occurs frequently and the enlarged tonsils make breathing difficult, the
tonsils can be surgically removed
Laryngitis
• Inflammation of the larynx with accompanying hoarseness
• Usually disappears after resting the vocal cords and treating any infection
• Benign laryngeal polyps can develop in individuals who strain their vocal cords (e.g.,
professional singers)
Sinusitis
• Inflammation of the cranial sinuses (cavities that drain into the nasal cavities)
• Develops when nasal congestion blocks sinus openings
• Symptoms include postnasal discharge, headache, facial pain
• Treatment includes addressing the cause of inflammation and restoring proper drainage
of the sinuses
Otitis Media
• Inflammation of the middle ear
• Nasal infections can spread to the ear by way of the auditory
(eustachian) tubes that lead from the nasopharynx to the middle
ear
• Symptoms include pain, a sense of fullness, hearing loss, vertigo,
fever
• Treatment includes antibiotics (if the cause is bacterial), or
special tubes that are placed in the eardrums to prevent buildup
of pressure
Disorders of the Lower Respiratory Tract
Disorders of the Trachea and Bronchi
Choking
• Occurs when an object becomes lodged in the trachea
• The Heimlich manoeuvre can be performed to help someone who is choking
o Involves grabbing the choking person around the waist from behind, and
forcefully pulling both hands into their upper abdomen to expel whatever is
lodged
Acute Bronchitis
• Inflammation of the bronchi
• Symptoms include a cough that brings up mucus or pus
• Preceded by a viral infection that has led to a secondary bacterial
infection
• Can be treated with antibiotics
Chronic Bronchitis
• Airways are inflamed and filled with mucus
• Symptoms include a cough with mucus
• The bronchi have lost cilia and their normal cleansing action
• Most frequent cause is smoking
Asthma
• Disease of the bronchi and bronchioles
• Symptoms include wheezing, breathlessness, coughing
• Airways are hypersensitive to irritants (e.g., allergens such as
pollen, dust, animal dander, cigarette smoke, fumes)
o Smooth muscle in the bronchioles undergoes spasms
when exposed to irritants
o Diameter of the airways decreases
•
Treatment includes drugs that dilate the bronchioles, and drugs that control
inflammation
Diseases of the Lungs
Pneumonia
• Infection of the lungs in which the bronchi or alveoli fill with thick
fluid, making gas exchange difficult
• Symptoms include high fever, chills, headache, chest pain
• May be caused by bacteria, viruses, or other infectious agents
• Some types of pneumonia affect individuals with reduced
immunity
Pulmonary Tuberculosis
• Caused by the bacterium Mycobacterium tuberculosis
• Cells accumulate around the invading bacteria, isolating them
from the rest of the body and forming a tubercle
• Elasticity of lungs is reduced
• Symptoms include coughing up mucus, coughing up blood, fever,
fatigue, excess sweating, chest pain
• Treatment involves a combination of drugs that include
antibiotics
Emphysema
• Chronic and incurable disorder in which the alveoli are distended
and their walls are damaged, leading to decreased surface area for
gas exchange
• Often preceded by chronic bronchitis
• Elasticity of the lungs is reduced
• Symptoms include shortness of breath and coughing
• Usually associated with smoking
Cystic Fibrosis (CF)
• Inherited lung disease
o 1 in 25 Canadians carries the defective gene, but a child
must inherit two copies of the faulty gene before
developing the disease
• The defective gene codes for cystic fibrosis conductance
transmembrane regulator (CFTR), a protein needed to transport
Cl- ions out of the epithelial cells of the lungs
• Causes less water to be transported out of cells, leading to thick
mucus secretions that clog the lungs
• Symptoms include coughing and shortness of breath
• Treatment includes mucus-thinning drugs
Pulmonary Fibrosis
• Fibrous connective tissue (scar tissue) builds up in the lungs, causing a loss of elasticity
• Restricts the ability of the lungs to expand during inhalation, leading to decreased vital
capacity
• Can be caused by environmental exposure to silica (sand), dust, and asbestos
Lung Cancer
• Leading cause of adult cancer deaths
• 85% of lung cancers are associated with cigarette smoking
• First, cells that line the bronchi thicken and lose their cilia, allowing dust and dirt to
settle in the lungs
• Cells with atypical nuclei appear, followed by a tumour consisting of disordered cells
with atypical nuclei
o Cells may break loose and spread to other tissues (metastasis)
• Treatment includes a pneumonectomy, in
which a lobe or the whole lung is removed
• If cancer has spread, chemotherapy and
radiation are required