Respiratory System: Breathing
1. Identify whether the following movements occur to initiate inhalation or exhalation by selecting the correct term for each description.
Diaphragm contracts, it flattens and moves downwards.
External intercostal muscles contract, drawing the ribcage upwards and outwards.
Diaphragm and external intercostal muscles relax, they return to their original positions.
2. Describe the mechanics involved during pulmonary ventilation (breathing). Use all the keywords below in your answer. Type your answer in the box then check your answer against the model answer.
During inhalation (breathing in), the diaphragm contracts and moves down whilst the intercostal muscles contract pulling the rib cage up and out. This leads to an increase in the volume of the lungs which reduces the pressure inside the lungs. As the pressure inside the lungs is lower than the air pressure in the atmosphere, air is drawn into the lungs from the atmosphere.
During exhalation (breathing out), the diaphragm relaxes and moves up whilst the intercostal muscles relax meaning the rib cage moves down and in. This leads to a decrease in the volume of the lungs which increases the pressure inside the lungs. As the pressure inside the lungs is higher than the air pressure in the atmosphere, air is drawn out from the body to the atmosphere.
3. Outline 3 differences between the mechanics of breathing at rest and during exercise. Type your answer in the box then check your answer against the model answer.
Rest – only diaphragm and external intercostals contract during inhalation whereas when exercising additional/subsidiary muscles contract also.
Greater change in long volume and pressure during exercise.
When exercising exhalation is forced/active whereas when resting exhalation is passive.