Respiratory System Overview

Pressure inside the lungs, it changes during inspiration and expiration. It is negative during inspiration and positive during expiration.

Pressure in the space between the lung pleura and the chest wall pleura. It is always negative to maintain lung expansion.

Pressure exerted by the atmosphere, it is 0 mm/Hg at sea level.

Difference between intra-pulmonary pressure and intra-pleural pressure. It reflects the force that keeps the lung inflated.

Difference between intra-pleural pressure and atmospheric pressure. It reflects the force that expands the chest wall.

Normal, effortless breathing, involves contraction of the diaphragm.

Deep, forceful inhalation, requires additional muscle contraction.

Normal, passive exhalation, relies on elastic recoil of the lungs.

Active, forceful exhalation, requires contraction of abdominal muscles.

Nerve that innervates the diaphragm, responsible for breathing.

Dorsal Respiratory Group, a group of neurons in the medulla oblongata responsible for initiating inspiration.

Ventral Respiratory Group, a group of neurons in the medulla oblongata responsible for modulating breathing, particularly expiration and forceful exhalation.

A measure of how easily the lungs can expand in response to pressure changes. A higher compliance means less pressure is required to expand the lungs.

Factors influencing lung compliance include: elastic recoil of the lungs, elasticity of the chest wall, and surface tension.

The tendency of the lungs to return to their original size after being stretched or inflated.

The force exerted by water molecules on the surface of the lung tissue, pulling them together and resisting expansion.

Surfactant, produced by pneumocytes type II, reduces surface tension in the alveoli, preventing lung collapse.

Lung collapse due to insufficient surfactant production, leading to difficulty in breathing.

The inner layer of the pleura that directly covers the lungs.

The outer layer of the pleura that lines the chest wall, mediastinum, and diaphragm.

The space between the visceral and parietal pleura that contains pleural fluid.

A lubricating fluid in the pleural cavity that helps the lungs easily contract during inhalation and exhalation.

A condition where air enters the pleural space, causing transpulmonary pressure to become negative and the lung to collapse.

For a smaller alveoli radius (r), the pressure (P) required to counteract surface tension (T) increases to keep the alveoli open.

Small alveoli are more likely to collapse than larger ones due to surface tension and pressure forces.

Surfactant, produced by type II alveolar cells, reduces surface tension in alveoli, especially smaller ones, preventing collapse.

Boyle's Law explains how pressure inside the lungs changes during breathing. When volume increases (inspiration), pressure decreases. When volume decreases (expiration), pressure increases.

Laplace's Law states that pressure inside a sphere is inversely proportional to its radius. This means smaller alveoli have higher pressure, making them more prone to collapse.

Surface tension in alveoli is caused by the attraction of water molecules at the air-water interface. Smaller alveoli have higher surface tension, making them collapse more easily.

The opposition to air movement through the respiratory tract. Determined by the diameter of the airways, a wider diameter means less resistance and easier air flow.

The process of breathing in, where air is drawn into the lungs. This involves muscles like the diaphragm contracting and expanding the chest cavity.

The process of breathing out, where air is expelled from the lungs. This can be passive (relying on lung elasticity) or active (using muscles).

A lung disease where the tissue surrounding the air sacs (alveoli) becomes thickened and scarred, making it harder to breathe.

These are areas in the brainstem that are believed to control the basic rhythm of breathing, acting like a pacemaker for respiration.