2 Boardworks IGCSE Biology The exchange of gasesBoardworks IGCSE BiologyBreathingAerobic respiration is the process of releasing energy through the oxidation of glucose molecules:carbondioxideglucose+oxygen+water( energy)+Oxygen is breathed into the lungs and is transported in blood.Carbon dioxide and water are formed as waste products in cells. They can be excreted when we breathe out.Teacher notesIt might be necessary to remind students that respiration is not the same as breathing. Respiration is the chemical process that takes place in cells to release energy from glucose, using oxygen. Breathing is the action of getting air into lungs (inhalation) and expelling it from the lungs (exhalation).Most of the organs of the respiratory system are found in the thorax.The respiratory system carries out gas exchange. It is made up of the lungs, intercostal muscles, diaphragm and airways.2
3 Parts of the respiratory system Boardworks IGCSE BiologyBreathing
4 The mechanism of ventilation Boardworks IGCSE BiologyBreathing
6 Running and breathing rates Boardworks IGCSE BiologyBreathingTeacher notesStudents could design and carry out their own experiments to investigate the effects of exercise and recovery on breathing rate. Breathing rate can me measured manually or with appropriate sensors and data loggers. Students should observe appropriate safety measures and you should make sure you are aware of any students with illnesses such as asthma.6
7 Boardworks IGCSE Biology Carbon dioxideBoardworks IGCSE BiologyBreathingThe brain can detect the level of carbon dioxide in cells.When the level of carbon dioxide increases during exercise, the brain must coordinate ways to prevent thelevels reaching toxic levels.One way the brain deals with a build up of carbon dioxide during exercise is by increasing the rate of breathing.Teacher notesSymptoms of carbon dioxide toxicity include drowsiness, reduced vision, dizziness, headache and an increased heart rate and blood pressure.This increases the rate of gas exchange and the removal of carbon dioxide from the lungs.