SEHS Topic 2.1 - Ventilatory System

Nose, mouth, pharynx, larynx, trachea, bronchi, bronchioles, lungs and alveoli.

Low resistance pathway for airflow
Defence against chemicals and other harmful substances that are inhaled
Warming and moistening the air

Inflow and outflow of air between the atmosphere and the lungs (also called breathing)

Volume of air in the lungs after a maximum inhalation

Maximum volume of air that can be exhaled after a maximum inhalation

Volume of air breathed in and out in any one breath

Volume of air in excess of tidal volume that can be exhaled forcibly

Additional inspired air over and above tidal volume

Volume of air still contained in the lungs after a maximal exhalation

During inhalation, diaphragm contracts, ribs move up and out expanding chest cavity, lowering pressure, causing air to rush in. During exhalation, diaphragm relaxes, ribs move down and in, decreasing chest cavity volume, increasing pressure, forcing air out. Accessory muscles aid during intense physical activity

During exercise, ventilation increases due to rising blood acidity levels (low pH) due to increased carbon dioxide content of the blood detected by the respiratory centre. This results in an increase in the rate and depth of ventilation. Neural control includes lung stretch receptors, muscle proprioceptors, and chemoreceptors

98.5% of oxygen in the blood is transported by haemoglobin as oxyhemoglobin within red blood cells

Oxygen diffuses into the blood and carbon dioxide diffuses out, facilitated by thin capillary walls