Lecture 10: Respiratory System Physiology (Pt.2)

When the diaphragm contracts during inspiration, what happens to intrapleural pressure?

It becomes more negative

During inspiration, alveolar pressure becomes

Negative relative to atmosphere

What happens when inspiration is finished, but before expiration begins?

All pressures equal atmospheric pressure

As expiration begins, alveolar pressure becomes

Positive relative to atmospheric pressure

What causes air to leave the lungs during expiration?

Positive alveolar pressure relative to atmosphere

Relaxation pressure is produced by

Nonmuscular forces of the respiratory system

Relaxation pressure is greatest when

Lung volume is highest

At rest, lung typically contain about what percentage of vital capacity?

38%

At resting lung volume, alveolar pressure is approximately

0 cm H2O

Above 38% of vital capacity, which process is active?

Inspiration

Below 38% of vital capacity, which process becomes active?

Expiration

Approximately how much vital capacity is typically used during speech?

50%

Louder speech generally requires

Deeper inhalation

During normal breathing without speech, approximately what percentage of the cycle is inhalation?

40%

During speech breathing, inhalation takes approximately

10% of the cycle

How many breaths per minutes does an average person take whether speaking or not?

12

What subglottal pressure is required for low-intensity speech?

3-5 cm H2O

Higher intensity speech typically requires approximately

15-20 cm H2O

Subglottal pressure during a cough or sneeze can reach up to approximately

200 cm H2O

Which muscles are used to slow or “check” expiratory airflow during speech?

Inspiratory muscles

The relationship between subglottal pressure and loudness is

Direct relationship

Which respiratory condition involves chronic inflammation of bronchioles and increased mucus production?

Asthma