From the nostrils the air enteres our nasal passages which are above our mouth when we breathe through our nose the hairs and mucous membranes in our nasal passage filter out dust and bacteria when we breathe through our mouth these advantages of filtering are lost The trachea is sometimes called the windpipe from the nasal passages air goes through the pharynx throat the trachea is lined with cartilgae soft bones to support its walls. The trachea is also lined with hair like cilia the upper end of the trachea is called the larynx voice box The main structure of our respiratory system is our lungs the lungs are two elastic sacs lying inside the thoracic cavity protected by the ribcage they are connected to the air ouyside the body by the indpipe or the trachea the trachea divides at its lower end into two branches called bronchi each bronchus ends at each lung. the bronchus then divides into many smaller bronchioles. the endings of bronchioles are called alveoli therea re two types of elss covering the air passages one type has tiny hairs called cylia the other type produces a sticky liquid called mucus
the function of the mucus is to trap or to stick small dust particales and bacteria.
inhalation
the intercostal muscles between the ribs contract this contraction will lift the ribcage up and out this wil expand the chest At the same time, other muscles contract to flatten the diaphragm. This makes the space inside the ribcage bigger and reduces the air pressure in the lungs.
Air moves into the lungs from outside because the outside air pressure is higher Theintercostal and diaphragm muscles relax. This lowers the chest and raises the diaphragm. The space in the ribcage gets smaller so the air pressure increases. This forces air out of the lungs.
The cells of our body use up oxygen at the same time they produce carbon dioxide and water. the function of our lungs is to suppy oxygen to the blood and remove carbon dioxide and some water from our body