Structure and Function

Lungs are paired organs located in the thoracic cavity, protected by the ribcage and separated from the abdominal cavity by the diaphragm. These spongy, elastic organs are essential components of the respiratory system, enabling the vital process of breathing.

Anatomical Components

• Bronchi: Main airways that branch from the trachea
• Bronchioles: Smaller branches of the bronchi
• Alveoli: Microscopic air sacs where gas exchange occurs
• Pulmonary vessels: Network of blood vessels supporting gas exchange

Gas Exchange Process

The primary function of lungs is facilitating gas exchange through a process called respiration. This involves:

1. Inhalation of oxygen-rich air
2. Transfer of oxygen into the bloodstream
3. Collection of carbon dioxide from blood
4. Exhalation of carbon dioxide-rich air

Respiratory Mechanics

Breathing relies on the coordinated action of several structures:

• The diaphragm contracts and relaxes
• Intercostal muscles expand and contract the ribcage
• Pleural membrane maintains negative pressure

Protection and Defense

Lungs incorporate several defensive mechanisms:

• Mucus production traps particles
• Cilia move debris upward
• Alveolar macrophages protect against pathogens

Clinical Significance

Several conditions can affect lung function:

• Asthma
• Pneumonia
• Chronic Obstructive Pulmonary Disease
• Lung Cancer

Adaptation and Evolution

Lungs have evolved various adaptations across vertebrates:

• Avian lungs feature unique air sac systems
• Amphibians use both lungs and skin for gas exchange
• Marine mammals have enhanced oxygen storage capacity

The efficiency of lung function is closely tied to the cardiovascular system and is essential for maintaining cellular respiration processes throughout the body.