When you take in oxygen rich air (inhale) your nostrill contains a passage lined with mucus and cilia . these act as filtering agents in which mucus sticks the dust particles and cilia fiters the air. the pure air travels through trachea which is rings of cartilage and enters he lungs through bronchi and it diffuses into alveoli through bronchioles this oxygen is trapped by haemoglobin of the blood that comes frm heart through pulmonary arteries. the pulmonary veins carries back the oxygenated blood to the heart from where it is pumped to all the organs,their tissues and thier cells according to their needs through aorta the oxygen reaches different organs and the capillaries helps this blood to reach their cells where oxygen breaks down the gulucose into 3 carbon pyruvate which is further broken by the oxygen to give energy+water+carbon dioxide this energy is required by the cells to carry their metabolic activities and hence this is how respirarory system works 1) take a balloon like a heart shape and fix a straw to it . 2) then place it in a bottle and cut the bottle half 3) when you blow in through the straw he balloon will expand showing inhaling and when you will blow ot the balloon shrinks showing exhaling. PLZ MARK IT BRAINLIEST