Biology: Gas Exchange and Lung Structure in Humans

What are alveoli?

Tiny air sacs in clusters at the ends of respiratory bronchioles.

What is the structure of alveoli?

Alveoli have walls that are one cell thick and are surrounded by a dense capillary network.

Why is the surface area of alveoli important?

It maximizes the rate of diffusion for gas exchange.

What is the role of surfactant in alveoli?

Surfactant coats the moist surface of alveoli to prevent their walls from sticking together.

What is the significance of the dense capillary network around alveoli?

It maintains concentration gradients for efficient gas exchange by continuously delivering O2 and removing CO2.

How do elastic tissues in the lungs assist in breathing?

They allow the lungs to stretch during inhalation and recoil during exhalation, aiding ventilation.

What are pleural membranes?

Membranes that cover the surface of the lungs (visceral) and line the inside of the chest cavity (parietal).

What is the pleural cavity?

The space between the pleural membranes, filled with pleural fluid.

What is the function of the diaphragm during inhalation?

The diaphragm contracts and flattens, increasing the volume of the thoracic cavity.

What happens during inhalation?

Muscles contract to increase thoracic cavity volume, decreasing pressure and allowing air to flow into the lungs.

What is Boyle's Law in relation to breathing?

It states that pressure and volume are inversely related; as lung volume increases, pressure decreases.

What occurs during expiration?

Muscles relax, decreasing thoracic cavity volume, increasing pressure, and forcing air out of the lungs.

What is external respiration?

The exchange of oxygen and carbon dioxide between air in the alveoli and blood in the capillaries.

What is internal respiration?

The exchange of oxygen and carbon dioxide between blood and tissue fluid.

What maintains concentration gradients in the respiratory system?

Continuous breathing and blood flow keep oxygen and carbon dioxide levels different between areas.

How does the body ensure a constant supply of oxygen?

By continuously bringing in fresh air with each breath and removing used air.

What is the role of intercostal muscles during breathing?

They move the rib cage upwards and outwards to increase chest volume during inhalation.

What is the effect of elastic recoil in the lungs?

It helps to push air out of the lungs during expiration.

What is the process of cellular respiration?

The process that produces ATP in mitochondria, requiring oxygen and releasing carbon dioxide.

What happens to oxygen levels in blood arriving at tissues?

Blood arriving at tissues has high O2 and low CO2 levels.

What is the significance of having millions of alveoli?

It creates a huge surface area for efficient gas exchange.

What is the purpose of gas exchange in the lungs?

To exchange oxygen and carbon dioxide between the air and blood.

What happens to carbon dioxide during external respiration?

CO2 diffuses from blood into the alveoli to be removed during exhalation.

What is the relationship between pressure and volume in the lungs?

Increased lung volume leads to decreased pressure, allowing air to flow in.

How does the diaphragm contribute to breathing mechanics?

It contracts to increase thoracic cavity volume, facilitating inhalation.

What is the role of pleural fluid?

It lubricates the pleural membranes, allowing smooth lung expansion and contraction.

What happens to lung volume during expiration?

Lung volume decreases as the thoracic cavity volume decreases, increasing pressure and forcing air out.

What maintains the concentration gradient for gas exchange?

Continuous ventilation and blood flow ensure oxygen and carbon dioxide can diffuse efficiently.

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