When smoke enters the mouth, many individuals experience an increase in salivation. This physiological response is the body’s reaction to foreign substances. Understanding why this happens involves exploring saliva’s natural functions, the irritating components found in smoke, and the nervous system’s role in saliva production.
The Purpose of Saliva
Saliva, primarily composed of water, contains various enzymes, electrolytes, and antimicrobial agents that serve multiple functions in the mouth. It acts as a lubricant, moistening food to aid in chewing and swallowing, and helps protect the oral mucosa from drying out. Saliva also plays a role in the initial stages of digestion through enzymes like amylase and lipase, which begin breaking down starches and fats. Beyond digestion, saliva is a protective agent, washing away food debris and harmful bacteria, maintaining the mouth’s pH balance, and promoting tissue repair. When irritants are present, the body increases saliva production to dilute and clear these substances, acting as a natural defense mechanism.
How Smoke Acts as an Irritant
Cigarette smoke contains many chemical components that irritate the mucous membranes of the mouth and throat. Components like nicotine, tar, and particulate matter directly stimulate the tissues they contact. The body perceives these substances as foreign, triggering a protective response. This irritation prompts the mucous membranes and salivary glands to react defensively.
Nicotine and other particulate matter directly activate the salivary glands. This leads to increased saliva production as the body attempts to dilute and wash away these elements, protecting the oral cavity from potentially damaging substances introduced by smoke.
The Nervous System’s Role in Salivation
The production of saliva is primarily controlled by the autonomic nervous system, which regulates involuntary bodily functions. The parasympathetic branch of this system is the main driver of increased salivation. When irritants from smoke are detected in the mouth and throat, sensory nerves send signals to the brainstem, which houses the salivatory nuclei. These nuclei integrate the incoming information and initiate a response.
From the brainstem, parasympathetic nerve fibers transmit signals to the major salivary glands. Nerve endings release acetylcholine, a neurotransmitter that binds to receptors on the salivary gland cells, leading to an increase in the secretion of watery saliva. This neural pathway ensures a salivary response to oral irritation.
Why Responses Vary
Individual responses to smoking, including the amount of salivation, can differ due to several factors. Individual sensitivity to the irritants present in smoke varies; some people may have more reactive mucous membranes or salivary glands. The type and intensity of smoking also play a role, as a stronger or more frequent exposure might elicit a more pronounced salivary response.
Over time, individuals may develop tolerance to the components of tobacco, which can lead to a reduction in the initial heightened salivary secretion. Pre-existing oral health conditions or hydration levels can also influence how much saliva is produced. While smoking often causes a short-term increase in salivation, long-term smoking can lead to changes in salivary gland function, sometimes resulting in a decreased overall salivary flow.