SEHS Topic 2.1 - Ventilatory System

2.1.1 - List the principal structures of the ventilatory system.

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

2.1.2 - Outline the functions of the conducting airways.

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

2.1.3 - Pulmonary Ventilation

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

2.1.3 - Total Lung Capacity (TLC)

Volume of air in the lungs after a maximum inhalation

2.1.3 - Vital Capacity (VC)

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

2.1.3 - Tidal Volume (TV)

Volume of air breathed in and out in any one breath

2.1.3 - Expiratory Reserve Volume (ERV),

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

2.1.3 - Inspiratory Reserve Volume (IRV)

Additional inspired air over and above tidal volume

2.1.3 - Residual Volume (RV)

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

2.1.4 - Explain the mechanics of ventilation in the human lungs

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

2.1.5 - Describe nervous and chemical control of ventilation during exercise

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

2.1.6 - Outline the role of haemoglobin in oxygen transportation.

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

2.1.7 - Explain the process of gaseous exchange at the alveoli

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