Pathophysiology of Respiratory System Lecture 6

Respiration and Gas Exchange

• Respiration involves the movement of oxygen (O2) from the atmosphere to cells and carbon dioxide (CO2) from cells to the environment.
• The pulmonary system's primary role is to facilitate gas exchange between the environment and blood.

Components of the Respiratory System

• Ventilation: Air movement between the atmosphere and lung respiratory portions.
• Perfusion: Blood flow through the lungs, transporting blood into and out of lung capillaries to body organs.
• Diffusion: Gas transfer between air spaces in the lungs and blood.

Control of Ventilation

• Breathing is primarily controlled by centers in the medulla and pons.
• Chemoreceptors: Detect changes in CO2, hydrogen ions, and O2 levels in blood and cerebrospinal fluid (CSF).
  • Central Chemoreceptors: Located in the medulla.
  • Peripheral Chemoreceptors: Located in the carotid bodies.

Ventilation Responses

• Hypercapnia: Increased blood CO2 levels stimulate the respiratory center, causing hyperventilation and leading to respiratory acidosis.
• Hypoxemia: Significant decrease in oxygen triggers chemoreceptor response, particularly in those with chronic lung disease, often leading to a hypoxic drive.

Asthma Overview

• Asthma is a progressive respiratory disease characterized by airway narrowing due to muscle tightening, swelling, and excessive mucus production.
• Contributing factors include allergens, infections, exercise, drugs, hormonal changes, and airborne pollutants.

Chronic Bronchitis Characteristics

• Associated with smoking, onset typically occurs between ages 30-40.
• Symptoms include shortness of breath, frequent sputum production, cyanosis, and potential cor pulmonale and polycythemia.

Chronic Obstructive Pulmonary Disease (COPD)

• Comprises diseases with increased airflow resistance, including emphysema and chronic bronchitis.
• Emphysema: Permanent alveolar enlargement and lung tissue destruction.
• Chronic Bronchitis: Characterized by small airway obstruction and goblet cell hyperplasia; results in decreased ventilation and potential complications.

Cor Pulmonale

• Right heart failure due to chronic lung disease and pulmonary hypertension is termed cor pulmonale.
• Treatment focuses on correcting alveolar hypoxia, with accompanying symptoms of primary lung disease and right-sided heart failure.

Acute Respiratory Distress Syndrome (ARDS)

• ARDS is a life-threatening condition caused by lung inflammation leading to fluid accumulation in air sacs, hindering oxygen transfer.
• Causes of ARDS include aspiration, major trauma, sepsis, and hematologic disorders.

Common Respiratory Infections

• Upper respiratory infections can lead to inflammation and swelling, manifested by increased mucus production.
• Infectious pneumonia involves inflammation of lung structures, commonly caused by bacterial or viral agents.

Pneumonia Stages

• Hyperemia: Initial inflammatory response causing increased blood flow and capillary permeability, leading to fluid buildup.
• Red Hepatization: Alveoli fill with red blood cells, exudates, and fibrin.
• Gray Hepatization: White blood cells invade the infected area; fibrin deposits accumulate.
• Resolution: Removal of cell debris, with macrophages dominating the response.

Smoking Effects on Respiratory Defense

• Smoking weakens respiratory defenses, increases mucus production, and paralyzes cilia, leading to trapped particles and a higher risk of infections.

This quiz focuses on the pathophysiology of the respiratory system, highlighting the gas exchange processes between the atmosphere and body cells. It is designed for students to assess their understanding of key concepts discussed in Lecture #6 by Prof. Zeinab Al-Wahsh during the Summer 2024 term.