Pathophysiology for Dietetics 2: Respiratory Diseases

Course Information

• Course Title: Pathophysiology for Dietetics 2
• Course Code: NDT2359
• Course Description: Diseases of the respiratory system
• Instructor: Ms Jamilah Abd Jamil
• Email: [email protected]

Key References

• Nelms M, Sucher K.P, Lacey K. Nutrition Therapy and Pathophysiology. 2nd edition. Cencage Learning, 2016
• Escott-Stumps S (2012). Nutrition and Diagnosis-Related Care. 7th edition.
• Mahan KL and Escott – Stumps (2009). Food Nutrition and Diet Therapy. 12th edition. W.B. Saunders Company, Philadelphia

Learning Outcomes

• Describe the normal anatomy and physiology of the respiratory system: pulmonary function
• Explain the etiology, pathophysiology, and clinical manifestations of: asthma, chronic obstructive pulmonary disease, cystic fibrosis, pneumonia, patients with tracheostomies, respiratory failure, and transplantation

Normal Anatomy and Physiology of the Respiratory System

• The respiratory system has two divisions: upper respiratory tract and lower respiratory tract
• Lungs obtain oxygen and support cellular metabolic functions, and remove carbon dioxide.
• The air enters the lungs through the trachea, which divides into the right and left bronchi.
• Bronchi further divide into smaller and smaller bronchioles.
• Bronchioles end in small air sacs called alveoli.
• Alveoli are paper thin, containing millions of capillaries involved in oxygen and carbon dioxide exchange.
• The alveolar-capillary unit covers an area about the size of a tennis court and contains more than 100 million capillaries.

Role of Lungs in Protecting the Body

• Lungs protect against infection and harmful environmental toxins.
• Inhaled particles (smoke, bacteria, viruses) are trapped by sticky mucus.
• Hair-like structures (cilia) in the trachea, bronchi, and bronchioles move mucus and trapped particles upward toward the pharynx for removal (coughing or swallowing).
• Macrophages in the alveoli engulf and destroy inhaled bacteria

Measures of Pulmonary Function

• Spirometer: measures the amount of air the lungs can hold and the rate the air can be inhaled and exhaled.
• Impulse Oximetry: measures the percentage of oxygen in the blood.
• Gas diffusion: measures how well oxygen and other gases pass through the lung's air sacs and are absorbed by the blood..
• Arterial blood gases (ABG) test: measures the acidity (pH), oxygen, and carbon dioxide levels in the blood. This test is used to determine how well the lungs move oxygen and remove carbon dioxide from the blood

Nutrition and Pulmonary Health

• Malnutrition negatively affects clinical outcomes.
• Malnutrition can weaken respiratory muscles (especially the diaphragm) and reduce lung parenchyma (including bronchioles, alveoli, and capillaries).
• Dietary antioxidants, like vitamin C, vitamin E, beta-carotene, and selenium, are associated with healthy lung function.

Asthma

• Definition: Chronic inflammatory disorder of the airway involving many inflammatory cells
• Etiology (Causes): Allergic (most common) triggered by inhaled allergens (dust mites, pet dander, pollen); Non-allergic (triggered by anxiety, stress, exercise, cold air, dry air, hyperventilation, smoke, viruses, or other irritants)
• Pathophysiology: Bronchospasm (contraction of smooth muscle), which leads to inflammation and edema, and increased mucus production. This results in partially or totally obstructed airways

Clinical Manifestations of Asthma

• Initial symptoms: cough, dyspnea, tight chest feeling
• Signs include: wheezing, increased respiratory rate, labored breathing, increased heart rate (tachycardia), and hypoxia (low oxygen levels in the tissues)

Chronic Obstructive Pulmonary Disease (COPD)

• Definition and Etiology: Progressive disease limiting airflow. Often involves both bronchitis (inflammation of bronchial tubes) and emphysema (destruction of alveoli).

Bronchitis

• Definition: Inflammation of the main airways (bronchi) due to infection.
• Types: Acute (lasts up to 3 weeks); Chronic (productive cough and shortness of breath for at least 3 months of the year, for 2 or more consecutive years)

Chronic Bronchitis - Pathophysiology

• Repeated exposure to irritants (e.g., cigarette smoke) causes increased mucus production in the airways and decreased cilia function
• Increased mucus and edema lead to airway obstruction
• Increased risk of bacterial infection due to thickened mucus

Chronic Bronchitis - Clinical Manifestations

• Decreased airflow, dyspnea (shortness of breath), hypoxemia (low oxygen), and hypercapnia (high carbon dioxide levels) in the blood.
• Cyanosis (bluish discoloration), a sign of chronic hypoxia, may occur

Emphysema - Pathophysiology

• Damage to air sacs (alveoli): walls weaken and rupture, leading to larger air spaces.
• Reduced surface area for gas exchange: limits the amount of oxygen reaching the bloodstream.
• Exhalation difficulties; old air gets trapped
• This leads to difficulty breathing.

Emphysema - Clinical Manifestations

• Symptoms: coughing, wheezing, shortness of breath, chest tightness, and increased mucus production
• Often, symptoms aren't noticed until significant lung tissue damage occurs.
• Increased risk of pneumonia, bronchitis, and other lung infections

COPD Treatment

• Smoking cessation and avoidance of pollutants
• Good nutrition
• Exercise, as tolerated

Cystic Fibrosis (CF)

• Definition: Inherited disorder characterized by abnormally thick mucus secretions from epithelial surfaces (leading to lung disease, pancreatic insufficiency, and gastrointestinal/genitourinary dysfunction).
• Etiology: Mutation of the cystic fibrosis transmembrane conductance regulator (CFTR) gene, located on chromosome 7.
• Pathophysiology: Defective CFTR protein results in thick, sticky mucus that obstructs glands, ducts, and airways
• Increased risk of infection due to impaired mucus clearance

CF - Pathophysiology

• Pancreatic insufficiency: problems digesting food due to blocked ducts
• Symptoms: Frequent bulky, foul-smelling, oily stools (steatorrhea)
• Electrolyte imbalances: Increased sodium and chloride in sweat

CF Treatment

• Aerosol therapies: increase airflow, reduce mucus accumulation, and reduce infection risk
• Inhaled medications: bronchodilators, anti-inflammatory agents, mucolytics, and antibiotics
• Chest physiotherapy: reduce airway obstructions
• Lung transplantation: aggressive treatment for end-stage respiratory failure
• Pancreatic enzyme replacement therapy: supplementation for digestive enzyme deficiencies.

Test your knowledge on the anatomy and physiology of the respiratory system. This quiz covers key topics such as asthma, COPD, cystic fibrosis, and more, focusing on their etiology and clinical manifestations. Perfect for students in the Pathophysiology for Dietetics course.