Ventilation and Breathing Mechanisms

The diaphragm contracts and moves downwards, expanding the thoracic cavity to draw air into the lungs.

The diaphragm relaxes and moves upwards, reducing the thoracic cavity volume, pushing air out of the lungs.

During exercise, additional muscles like the sternocleidomastoid, scalenes, and external intercostals help expand the rib cage further than at rest, creating a larger volume change.

Expiration during exercise involves the use of internal intercostals, and abdominal muscles (external, internal obliques, transverse abdominis, and rectus abdominis) to depress the ribcage and reduce thoracic cavity volume, expelling air.

Pressure changes, driven by changes in thoracic cavity volume, are the mechanism for air movement during breathing.

Inspiration involves the upward movement of the rib cage and the downward movement of the diaphragm, causing the thoracic cavity to increase in volume, creating lower pressure allowing air to enter.

Expiration involves the downward movement of the rib cage and the upward movement of the diaphragm, causing the thoracic cavity to decrease in volume and higher pressures, expelling air.

Ventilation is a closed system where pressure changes cause air to move into and out of the lungs.

Small air sacs in the lungs where gas exchange takes place.

The portion of ventilation that doesn't participate in gas exchange.

The volume of inspired air that reaches the respiratory zone of the lungs.

The sum of alveolar ventilation (VA) and dead space ventilation (VD).

The volume of air inhaled and exhaled in a single breath.

A substance that reduces surface tension in the alveoli, preventing them from collapsing.

The maximum volume of air the lungs can hold.

Breathing rate increases during exercise.

Chronic endurance exercise training does not significantly alter lung volumes. The lungs are highly adaptable and can support increased oxygen demand without needing to increase in size.

Swimming is the only sport that significantly impacts lung volumes. This is due to the unique demands of breath-holding and underwater movements.

Swimmers develop larger lung volumes due to the need to hold their breath for extended periods while swimming. This forces the lungs to adapt and increase their capacity.

Partial pressure is the pressure exerted by a specific gas in a mixture. In the context of breathing, it refers to the pressure of oxygen in the alveoli of the lungs.

Absolute pressure is the total pressure exerted by the atmosphere at a given location. This is also known as barometric pressure.

The maximum amount of air your lungs can hold. It's like the size of your lung 'bucket.'

Chronic exercise doesn't change your lung volume significantly. Your lungs are already pretty strong!

Swimming is the only sport that reliably increases lung volume.

The total pressure of the atmosphere at a given altitude. It's like the weight of the air above you.

The diaphragm contracts, moves downward, and expands the thoracic cavity, creating lower pressure that draws air into the lungs.

The diaphragm relaxes, moves upward, and reduces the thoracic cavity volume, increasing pressure to push air out of the lungs.

Accessory muscles like the sternocleidomastoid, scalenes, and external intercostals contract, pulling the ribs outwards to further expand the thoracic cavity.

Internal intercostals and abdominals (external and internal obliques, transversus abdominis, rectus abdominis) contract to pull the ribs inward and constrict the abdomen, reducing thoracic cavity volume and expelling air.

Changes in thoracic cavity volume, caused by diaphragm and rib cage movements, alter pressure within the cavity, driving air flow into or out of the lungs.

Air moves from areas of high pressure to areas of low pressure. During inspiration, the pressure in the lungs is lower than atmospheric pressure, drawing air in.

The pleural membrane is attached to the inside of the rib cage and the outer surface of the lungs. This connection allows the lungs to expand and contract as the rib cage moves.

The lungs are not directly attached to the chest cavity. Instead, they are enclosed in a fluid-filled space called the pleural space. The pressure changes in the pleural space, caused by diaphragm movement, cause the lungs to expand and contract.

Gas exchange happens in the tiny air sacs called alveoli in the lungs. Oxygen from the air diffuses into the blood, and carbon dioxide from the blood diffuses into the air.

Dead space ventilation refers to the portion of air breathed in that doesn't participate in gas exchange. This air fills the conducting zone of the airways, which includes the trachea, bronchi, and bronchioles, but doesn't reach the alveoli.

Alveolar ventilation is the volume of air that actually reaches the alveoli and participates in gas exchange.

Tidal volume is the amount of air inhaled and exhaled during a normal breath.

Inspiratory reserve volume is the maximum amount of air that can be inhaled after a normal breath.

Expiratory reserve volume is the maximum amount of air that can be exhaled after a normal breath.

Residual lung volume is the amount of air that remains in the lungs even after a forceful exhalation.