Contains the full lesson along with a supporting toolkit, including teachers’ notes.
The lungs are a pair of organs located in the thoracic cavity. Their primary function is gaseous exchange, i.e. to get oxygen into and carbon dioxide out of the blood. Air is drawn in through the nose where it is filtered by hairs and mucus to remove dust, bacteria and viruses. As it passes through the nasal sinuses it is also warmed. The surface of the airways is covered bymucusproducing cells which trap anything that has not been filtered by the nose. Cilia [small hair like projections] waft the mucus up out of the lungs to the pharynx where it is normally swallowed. Any micro-organisms it contains are killed by the acid conditions in the stomach. About 1.5 litres ofmucus are produced daily. Anything that reduces the movement of air into or out of the lungs reduces the availability of oxygen to the body, with a resulting decrease in energy due to a decrease in respiration.
Bronchodilation, as the name suggests, is the widening of the bronchi when the smooth muscle surrounding the bronchi relaxes, allowing easier movement of air into and out of the lungs. This is brought on naturally by exercise or by the production ofadrenalin the "fight or flight hormone", noradrenalin has a similar effect.
bronchoconstriction, on the other hand, is the narrowing of the bronchi in the lungs due to any or all of the following: the contraction of surrounding smooth [involuntary] muscle or an accumulation of thick, difficult to expel mucus, which effectively blocks the bronchial tubes or inflammation of the bronchial tissue.