Lungs

Definition

Lungs are specialized respiratory organs in many animals, including humans, that facilitate the exchange of gases, primarily oxygen and carbon dioxide, between the body and the environment. They play a crucial role in the respiratory system, allowing for the inhalation of oxygen-rich air and the exhalation of carbon dioxide, which is a byproduct of cellular metabolism. This gas exchange process is vital for sustaining life, as it ensures that oxygen is delivered to cells while removing waste gases.

5 Must Know Facts For Your Next Test

1. The lungs are composed of millions of tiny alveoli that greatly increase the surface area for gas exchange, making the process more efficient.
2. The right lung has three lobes, while the left lung has two lobes, accommodating space for the heart.
3. Gas exchange in the lungs relies on diffusion, where oxygen moves from an area of higher concentration in the alveoli to lower concentration in the blood.
4. The lungs are protected by a double-layered membrane called the pleura, which also provides lubrication during breathing movements.
5. Breathing is primarily controlled by the diaphragm and intercostal muscles, which work together to expand and contract the thoracic cavity.

Review Questions

• How do the structure and function of alveoli contribute to efficient gas exchange in the lungs?
  • The alveoli are structured as tiny air sacs that maximize surface area for gas exchange. Each alveolus is surrounded by capillaries where blood flows, creating a thin barrier for diffusion. The large number of alveoli ensures that there is enough surface area for oxygen to enter the blood and carbon dioxide to be expelled efficiently. This design allows for rapid gas exchange, meeting the metabolic needs of the body.
• Discuss how the diaphragm and intercostal muscles interact during the process of breathing.
  • During inhalation, the diaphragm contracts and moves downward while the intercostal muscles between the ribs contract to pull the ribcage upward and outward. This coordinated action increases thoracic volume and decreases pressure inside the lungs, causing air to rush in. Conversely, during exhalation, these muscles relax, reducing thoracic volume and increasing pressure in the lungs, forcing air out. This interplay is crucial for effective ventilation.
• Evaluate the impact of environmental factors on lung function and gas exchange efficiency.
  • Environmental factors such as pollution, altitude, and humidity can significantly affect lung function and gas exchange efficiency. For instance, air pollution introduces harmful particles that can reduce lung capacity and impair gas exchange by damaging alveoli. High altitudes lower oxygen availability, which can hinder effective oxygen uptake in the lungs. Additionally, high humidity levels can affect breathing comfort but may also impact how efficiently gases diffuse due to changes in air density. Understanding these impacts is essential for maintaining respiratory health.

Related terms

Alveoli: Tiny air sacs in the lungs where gas exchange occurs, allowing oxygen to enter the blood and carbon dioxide to be expelled.

Bronchi:

The major air passages that branch from the trachea into each lung, leading to smaller bronchioles and ultimately to the alveoli.

Diaphragm: A dome-shaped muscle located at the base of the thoracic cavity that plays a key role in breathing by contracting and relaxing to change lung volume.