Latest news with #autonomic
Medscape
07-05-2025
- Health
- Medscape
Saliva Is a Critical but Underestimated Bodily Fluid
Human life would be difficult to sustain without saliva. Its fundamental role in keeping the oral mucosa hydrated is essential for core functions such as swallowing, tasting, and speaking. However, recent research has revealed that saliva does far more than previously understood. Specific components may eventually serve as noninvasive biomarkers for a variety of diseases. As with other bodily processes, the production and composition of saliva are regulated by intricate mechanisms under the control of the autonomic nervous system. The parasympathetic system stimulates the secretion of electrolytes and water via acetylcholine, while the sympathetic system regulates the release of salivary proteins through norepinephrine. External stimuli — such as smell, taste, and mastication — further influence both the volume and composition of saliva. For example, stimulated saliva contains significantly more bicarbonate but fewer proteins compared to resting saliva. Additional factors such as sex, age, time of day, medication use, and general health also affect salivary output and composition. Mucosal Health The moistening of the oral, pharyngeal, and esophageal mucosa is essential for several vital functions. In addition to hydration, saliva contains cytokines, chemokines, and growth factors that promote wound healing — often more rapidly than on skin. Among these, histatins are especially effective in accelerating tissue repair. Saliva also plays a crucial role in innate immune defense. It contains a broad range of antimicrobial proteins and peptides — including myeloperoxidase, lysozyme, lactoferrin, and others — produced by salivary glands, oral epithelial cells, and immune cells, all of which contribute to protection against infection. Saliva in Oral Health In dentistry, saliva is particularly valued for its protective effect against dental caries. Bicarbonate and phosphate ions help buffer oral pH, maintaining a range between 6.8 and 7.8. Salivary proteins bind calcium and phosphate, forming a supersaturated solution that supports the dynamic balance of enamel demineralization and remineralization — critical processes for caries prevention. Saliva also rapidly forms a thin protein-rich layer on tooth surfaces known as the acquired pellicle. This layer protects enamel against calcium loss, mechanical abrasion, and erosion. Over time, bacterial colonization of the pellicle also influences the composition of the oral microbiome. Diagnostic Biomarkers In recent years, research has increasingly focused on the potential of salivary components to serve as biomarkers for disease diagnosis. Compared with blood sampling, saliva collection offers clear advantages: it is easier, less invasive, and more cost-effective. These features make it particularly useful in populations such as children, older adults, and individuals with disabilities. Saliva contains a wide range of biologically active substances — including enzymes, hormones, antibodies, cytokines, and DNA/RNA fragments — that can reflect both local and systemic physiological processes. These biomarkers are being studied in connection with conditions ranging from periodontal disease and diabetes to neurological, psychiatric, and oncologic disorders. Glucose Levels in Saliva In patients with diabetes mellitus, saliva can reveal metabolic changes, including glucose fluctuations, elevated HbA1c levels, and markers of oxidative stress. These salivary findings may also correlate with periodontal health status. Research has additionally identified alterations in lipid levels, melatonin, and total protein in the saliva of diabetic patients. In clinical dental settings, an unusual salivary profile may help flag cases of undiagnosed or poorly controlled diabetes — a condition known to increase the risk of periodontal disease. Timely, multidisciplinary management may therefore improve outcomes both systemically and dentally. Cortisol and Other Stress Markers Psychiatric conditions such as anxiety disorders, schizophrenia, and depression are also associated with measurable changes in salivary composition. Cortisol, a key biomarker of chronic stress, is frequently elevated in these populations. Altered levels of other markers, such as alpha-amylase and lysozyme, have also been detected in individuals with anxiety. These salivary biomarkers may provide insights into psychosomatic interactions and could support more comprehensive care strategies for patients with conditions such as bruxism or dental phobia. Early Cancer Detection Saliva has also shown promise in the early detection of malignancies, including both head and neck tumors and systemic cancers such as pancreatic and breast cancer. Tumor-associated biomarkers — such as specific antibodies, antigens, and gene mutations — can be identified in salivary samples. One molecule of particular interest is sialic acid, which is elevated in patients with certain cancers. In a recent study, Elgendi and colleagues presented a portable device capable of quantifying salivary sialic acid, yielding promising results for early breast cancer detection. This type of technology could potentially be used not only in oncology centers but also in primary care and dental practices. Future Diagnostic Tool These findings suggest that saliva analysis could play an important role in the future of diagnostic medicine. For dental professionals in particular, salivary diagnostics may offer a valuable tool for identifying high-risk patients, supporting clinical decision-making, and monitoring disease progression. In patients with periodontal disease, it may serve as a practical adjunct to traditional examination methods. The use of noninvasive, affordable rapid tests in everyday practice appears increasingly feasible — especially as integrated, interdisciplinary approaches to healthcare continue to gain importance.
Health Line
06-05-2025
- Health
- Health Line
What Does Your Sympathetic Nervous System Do?
The sympathetic nervous system, which helps your heart and other vital organs function all the time, increases activity in response to danger or stress, preparing the body for extra demands. Stress is a part of everyday life, and the sympathetic nervous system, which increases activation in response to increased physical demands, may also increase activity in response to stress if we don't learn how to manage it. This system, called the sympathetic nervous system (SNS), is part of the autonomic nervous system, which operates automatically without conscious effort. The SNS plays a key role in what is known as the ' fight-or-flight ' response, preparing your body to respond to temporary increases in physical demands, which can happen during times of danger, or during physically demanding, but non stressful situations, like playing competitive sports. Primary functions of the SNS The sympathetic nervous system activity is always functioning in balance with the parasympathetic nervous system, and has effects on organs throughout your body that can potentially help you with physically demanding actions. These changes can happen in an instant and include: Increased respiration rate: Your breathing quickens to bring in more oxygen. This oxygen is directed to your muscles to give you the strength and energy needed to respond. Elevated blood pressure: Some blood vessels in the body constrict, and some blood vessel in the body dilate. The heart also beats faster, which helps move blood more efficiently to vital organs like the heart and brain. Constricted blood vessels in non-essential areas: Blood flow is reduced to systems that are not immediately needed, such as the digestive system, and redirected to the muscles and brain. Water retention: Your body retains water to help maintain blood volume, which is essential for sustaining circulation. Ultimately, the primary function of the sympathetic nervous system is to help the body maintain balance and stay alert by continuously regulating heart rate, blood pressure, breathing, oxygen flow, vision, and attention. During periods of stress or challenge, it temporarily increases activity to enhance strength, focus, and energy by boosting oxygen delivery and circulation. Why the fight-or-flight response exists The fight-or-flight response is your body's way of putting survival first. Imagine you're hiking and suddenly see a snake. Even before you have time to think, your heart rate jumps, your muscles tense, and your senses sharpen. That is your sympathetic nervous system at work. It bypasses conscious thought to trigger immediate physical reactions that can help keep you safe. This reaction has deep evolutionary roots. Our ancestors relied on it to survive threats in their environment, such as predators or natural dangers. While most modern stressors aren't life-threatening, our bodies can still respond as if they are. A traffic jam, a job interview, or even a loud noise can trigger the overactivation of the sympathetic nervous system, leading to symptoms like jitters, trouble focusing, or feeling frozen. In these situations, the fight-or-flight response may actually get in the way, which is why learning to manage our stress response is so important. How the body response to triggers The sympathetic nervous system can be triggered by many types of stress, both real and perceived. These triggers vary from person to person but often include loud sounds, conflict, pressure at work, or even scrolling through upsetting news. When the system is activated, you might notice: Increased heart rate: Your heart pumps faster to send blood to the muscles and brain. Dilated pupils: Your eyes open wider to allow more light in, improving vision. Heightened alertness: You feel more aware and focused, sometimes almost jittery. Changes in digestion: Blood is pulled away from your stomach and intestines, which can lead to a 'butterflies in the stomach' feeling or even nausea. Energy release: Your liver releases stored glucose, giving your body quick fuel to act. Some people may feel the effects of sympathetic nervous system activation more intensely, while others may simply be more aware of them. For example, someone with anxiety might both experience stronger physical symptoms and be more attuned to those changes, even in response to minor stressors. This kind of awareness can be helpful, as it's the first step toward understanding and managing the body's stress responses more effectively. Balance with the parasympathetic system The sympathetic nervous system speeds things up, abd its counterpart, the parasympathetic nervous system, slows things down. This is the 'rest and digest' system. After the threat passes, it helps your body return to a calm state. Heart rate slows, digestion resumes, and your breathing returns to normal. The balance between these two systems is essential for good health. If your sympathetic system is activated too often or for too long, it can become dysregulated, making it harder for your body to return to a calm state. This overactivation can lead to symptoms like chronic anxiety, fatigue, irritability, and even physical issues such as digestive problems or high blood pressure. That is why learning to engage the parasympathetic system is so important. How to manage your response Understanding how your sympathetic nervous system works can help you manage stress more effectively. Here are a few strategies: Deep breathing: Slow, deep breaths help stimulate the parasympathetic system and reduce the impact of the fight-or-flight response. Exercise: Physical activity helps your body redirect the effects of stress hormones and can regulate both systems. Mindfulness and meditation: These practices calm the mind and body, encouraging a return to balance.
