Respiration investigation
INTRODUCTION
The aim of this experiment is to measure three aspects of human breathing.
Tidal volume; volume of air that moves in and out of the lungs during one cycle of breathing.
Breathing rate – the rate at which breathing takes place.
Vital capacity – the measure of the volume of the subjects lungs
The respond of the tidal volume and breathing rate to oxygen demand will also be measured.
PLAN
The lungs are the site where gaseous exchange occurs. Breathing is the way in which air enters and leaves the lungs, passing through the trachea, bronchi and bronchioles.
Breathing consists of two parts, taking air into the chest (inhalation) and breathing air back out again (exhalation). Pressure changes are involved in breathing; these changes bring about the movement of air in and out of the lungs. The ribs support the body wall of the thorax, which has a dome shape base formed by the diaphragm. When inhaling air the intercostals muscles contract raising the ribs upwards and outwards. The diaphragm contracts and is lowered and flattened. This then results in the volume of the thorax increasing, which means the pressure in the thorax decreases. As the pressure is lower in the chest cavity than the atmospheric pressure of the air outside the lungs, the air is drawn in the chest cavity via the upper respiratory passage. When exhaling, muscles of the diaphragm and the intercostal muscles relax. The ribs move inwards and down, resulting in a decrease in the volume of the thorax. This causes an increase in pressure. The pressure is now higher in the lungs the atmospheric pressure, air moves out of the lung through the same upper passage as in inhaling.
