The Nervous Connection

Besides inflammation, another path leads to tightening of the bronchial muscles. A network of nerves (autonomic nervous system) exists throughout our bodies to regulate bodily functions on a moment-to-moment basis. This autonomic network is independent of our thought processes in that we have no control over it at all.

The autonomic nervous system serves all parts of the body. Controlling the heart and blood vessels, it adjusts blood pressure and pulse rate. In the digestive tract it controls movement of food and production of enzymes needed for digestion. It coordinates muscle movements and controls our balance. There is no bodily function that does not involve the autonomic nervous system.

In the lungs, the autonomic network has two types of connections. There are nerves that cause the bronchial muscles to contract (parasympathetic nerves) and others that cause them to relax (sympathetic nerves). These networks also regulate secretions of mucus in the respiratory tract. The nerve fibers that contract the bronchi also increase secretions of the bronchial mucous membranes. The fibers that relax the bronchial muscles tend to decrease secretions. Activity of the parasympathetic nerves is one immediate cause of tightening of the bronchial muscle-tubes.

Autonomic nerves, both sympathetic and parasympathetic, connect the sinuses and the lungs. As a result, blockage of outflow from the nose or sinuses may cause tightening of the bronchial muscles, one mechanism by which infection of the sinuses can cause bronchospasm and bronchial asthma. There are, however, many other pathways that lead to bronchospasm.