6.4 Gas exchange Flashcards
What is ventilation in the context of respiratory physiology?
Ventilation is the process of bringing fresh air into the alveoli and removing stale air. This refreshes the air in contact with the blood in the alveoli’s capillaries, ensuring efficient gas exchange of oxygen and carbon dioxide.
Why is ventilation crucial for gas exchange in the lungs?
Ventilation maintains concentration gradients of oxygen and carbon dioxide between air in the alveoli and blood in adjacent capillaries, facilitating efficient gas exchange.
Describe type I pneumocytes and their function in the lungs.
Type I pneumocytes are extremely thin alveolar cells adapted for gas exchange. Their minimal thickness increases surface area and reduces diffusion distance, enhancing oxygen and carbon dioxide exchange with blood.
What are type II pneumocytes, and what role do they play in the lungs?
Type II pneumocytes are alveolar cells that secrete a surfactant-containing solution, creating a moist surface inside the alveoli. This prevents alveolar sides from adhering by reducing surface tension, facilitating easier gas exchange.
Outline the pathway air takes to reach the lungs for gas exchange.
Air is carried to the lungs via the trachea and bronchi, then to the alveoli through bronchioles. This pathway ensures air reaches the alveoli where gas exchange occurs.
How do muscle contractions facilitate ventilation in the lungs?
Muscle contractions alter thoracic pressure, causing air to move in and out of the lungs. Expansion of the thorax decreases pressure, drawing air in (inspiration), while contraction increases pressure, forcing air out (expiration).
What are examples of antagonistic muscles involved in ventilation?
The external and internal intercostal muscles, along with the diaphragm and certain abdominal muscles, serve as antagonistic pairs. They facilitate inspiration and expiration by contracting to move the thorax and alter lung volume.
How is ventilation monitored in humans, especially in different states of activity?
Ventilation can be monitored at rest and after exercise through direct observation or using apparatus like spirometers, which measure breathing rates and volumes to assess respiratory function.
What are the causes and consequences of lung cancer?
Causes include smoking, asbestos exposure, air pollution, and radon gas. Consequences range from coughing and shortness of breath to severe pain, weight loss, and potentially death due to metastasis and respiratory failure.
Discuss the causes and consequences of emphysema.
Caused by long-term exposure to cigarette smoke and pollutants, emphysema damages lung tissue, reducing oxygen exchange. Consequences include chronic shortness of breath, coughing, fatigue, weight loss, and decreased lung function.
Define ventilation and explain the concept of gas exchange in the respiratory system.
Ventilation is the process of moving air in and out of the lungs, involving inhalation and exhalation. Gas exchange is the diffusion of oxygen from the alveoli into the blood and carbon dioxide from the blood into the alveoli, facilitated by the ventilation process.
Why is ventilation crucial for maintaining concentration gradients of oxygen and carbon dioxide?
Ventilation is essential for maintaining high oxygen and low carbon dioxide concentrations in the alveoli compared to the blood. This gradient is critical for ensuring continuous diffusion of oxygen into the blood and carbon dioxide out of the blood.
Why are different muscles required for inspiration and expiration?
Different muscles are required because muscles can only perform work when contracting. Inspiration involves the contraction of muscles to expand the thoracic cavity, decreasing pressure to draw air in, while expiration involves muscle relaxation or contraction of different muscles to increase thoracic pressure and push air out.
