Are there bacteria in human saliva?

Saliva is a liquid that can lubricate the mouth. Saliva contains protein and various digestive enzymes, which can help the human body protect teeth and promote digestion of food. Saliva also contains bactericidal enzymes, so saliva also has bactericidal effects. People secrete a lot of saliva every day. Saliva is very important to the human body. So, does saliva with bactericidal effects contain bacteria?

Saliva contains a variety of digestive enzymes, such as salivary amylase, salivary protease, etc., which can promote the digestion and absorption of food. In addition, saliva contains bactericidal enzymes that can kill some bacteria; the amount secreted by people during the day is more than at night, which can keep the mouth clean.

Saliva is a colorless and thin liquid, commonly known as spit. Although it was called "golden saliva" in ancient times, it has always given people a sense of uncleanness and indecency in modern times.

It is mainly secreted by three salivary glands, namely the parotid gland, submandibular gland and sublingual gland. While being secreted, it is controlled by the cerebral cortex and is also affected by diet, environment, age, emotions or salivary gland diseases. It is normal for people to secrete 1,000-1,500 ml of saliva per day.

Advantages of saliva: The carbonates, phosphates and proteins it contains can provide chemical protection for teeth; the amylase it contains can help digestion; the ingredients can fight bacteria; it can clean the mouth; cancer and AIDS can be detected by testing saliva

Saliva's weakness: Saliva can also spread diseases through the human body that carries germs.

A digestive juice formed in the mouth by a mixture of fluid secreted by three pairs of large salivary glands (mandibular glands, rib glands, and sublingual glands) and mucus secreted by many small mucous glands on the oral wall. Saliva is colorless and odorless, with a pH of 6.6 to 7.1. The normal daily secretion volume for a person is about 1.0 to 1.5 liters (herbivorous animals such as cattle and sheep secrete up to 1/3 of their body weight in saliva every day).

99% of human saliva is water. The organic matter mainly includes salivary amylase, mucopolysaccharides, mucin and lysozyme, while the inorganic matter includes sodium, potassium, calcium, chlorine and thiocyanate ions. The composition of saliva varies with the type of animal. The saliva of humans and some mammals (rabbits, mice, etc.) contains amylase, while the saliva of dogs, cats, and horses contains almost no amylase. Human saliva mixed with food can dissolve the soluble components in the food, allowing them to act on the taste buds and cause taste. Saliva prevents the mouth from drying out and lubricates food; it also cleans the mouth and rinses away food debris remaining in the mouth.

When harmful substances enter the mouth, saliva can dilute and neutralize them and wash them off the oral mucosa. Saliva moistens the mouth and facilitates speaking. Before the food is mixed with gastric acid, the salivary amylase in the chyme in the stomach can break down the starch in the food into maltose. The lysozyme and thiocyanate ions in saliva have bactericidal effects. Mucin not only has a lubricating effect, but also can neutralize gastric acid after entering the stomach. Under the action of gastric acid, it adheres to the mucosa to resist the corrosion of gastric acid on the gastric mucosa.

Saliva also has an excretory function. Some substances and viruses in the body, such as potassium iodide, lead, mercury, rabies and polio bacteria, and HIV, can be excreted or transmitted through saliva. When the parotid gland is infected by the mumps virus, it can cause mumps (parotitis), in which the patient's parotid glands become swollen and painful, and saliva secretion decreases. The disease is contagious and is mainly spread by the patient's saliva droplets. The salivary glands of some birds are well-developed. They use saliva to glue seaweed together to build nests. For example, the nests built by swiftlets are the famous Chinese tonic "bird's nest".