Saliva

Spit is a wet liquid in your mouth.

It is mostly made of water. It also has tiny bits of food and salts in it.

Spit helps you eat. It wets your food so you can swallow it. It also helps break down food in your mouth.

Spit keeps your mouth healthy. It helps wash away things that can hurt your teeth. It can even help heal small cuts.

Some animals use spit in cool ways. Certain birds use sticky spit to build nests. Some snakes use it to hunt.

Your body makes a lot of spit every day. You make much less when you sleep.

Saliva is a clear liquid made in your mouth.

It is made of 99.5% water. It also has salts, mucus, and tiny cells.

Saliva helps you eat and digest food. It wets your food so you can swallow it easily. It also contains enzymes, which are special tools that break down food. One enzyme is called amylase. It starts breaking down starch into sugar. Another is called lipase, which helps break down fats.

Your saliva also keeps your mouth healthy. It helps wash away food bits from your teeth. This protects your teeth from decay. It also acts as a buffer. A buffer is something that keeps the acidity in your mouth at a safe level. This prevents minerals in your teeth from dissolving.

Many animals use saliva in unique ways. Some birds use sticky saliva to build nests. Certain snakes use venom in their saliva to hunt. Even some caterpillars use it to make silk.

Humans make about 1,500 mL of saliva every day. You make much less when you sleep. Doctors can even study saliva to learn about your health.

Saliva is a clear liquid made in your mouth.

It is mostly water, making up about 99.5% of the fluid. The rest is a mix of many important things. These include electrolytes, which are salts like sodium and potassium. It also contains mucus and tiny cells. Some of these cells are white blood cells that fight germs. This liquid is very important for keeping your body healthy. It helps you taste food and keeps your mouth from drying out.

Saliva works in many ways to help you eat. First, it wets your food to make a soft ball called a bolus. This makes it easy to swallow food into your esophagus. Saliva also has special tools called enzymes. One enzyme is called amylase, or ptyalin. It starts breaking down starch into simple sugars like maltose. Another enzyme is called lingual lipase. This one helps your body start to digest fats.

Your mouth also stays clean because of saliva. It acts as a buffer to control acidity. This means it keeps the pH level in your mouth safe. A safe pH is usually between 6.2 and 7.4. This prevents the hard parts of your teeth from dissolving. Saliva also has antibacterial compounds to fight germs. These include things like lysozyme and secretory IgA. These tools help protect your teeth from decay and keep your mouth healthy.

Different animals use their saliva for many amazing jobs. Some birds, like those in the Aerodramus genus, use sticky saliva. They use it like glue to build their nests. Humans even eat these nests as bird's nest soup. Other animals use saliva for hunting or making things. For example, cobras and vipers use venom in their saliva. Some caterpillars use special glands to store silk proteins. They use these proteins to make silk fibers.

Humans produce a lot of saliva every single day. A healthy person makes about 1,500 mL of saliva daily. Most of this comes from the submandibular gland. This gland provides about 70 to 75% of your saliva. The parotid gland makes about 20 to 25%. You make much less saliva while you are asleep. Doctors can even study your saliva to learn about your health. They can look for signs of different diseases in the fluid.

Saliva is an extracellular fluid produced by the salivary glands in the mouth.

It is a vital substance for maintaining oral and systemic health. In humans, saliva is approximately 99.5% water. The remaining portion contains electrolytes, mucus, white blood cells, and epithelial cells. It also contains various enzymes and antimicrobial agents. These components work together to protect the body and assist in digestion. Because it contains many biological markers, doctors can use it to diagnose diseases noninvasively.

The production of saliva involves a complex biological mechanism. It is stimulated by both the sympathetic and parasympathetic nervous systems. The parasympathetic nervous system facilitates digestion by releasing acetylcholine (ACh). This chemical binds to specific muscarinic receptors on the salivary acinar cells. This process increases the concentration of intracellular calcium ions. Higher calcium levels cause vesicles within the cells to fuse with the cell membrane. This fusion results in the secretion of saliva into the mouth. Additionally, the release of kallikrein causes vasodilation in the salivary glands. This increases blood flow, allowing the glands to produce even more fluid.

Saliva performs several distinct functions, primarily digestion and protection. As a lubricant, it coats the oral mucosa to prevent trauma during eating or speaking. It also helps create a food bolus, which is a soft mass of food. This bolus can then pass easily into the esophagus. Saliva also acts as a buffer to control the acidity of the mouth. It uses bicarbonate and phosphate to maintain a pH between 6.2 and 7.4. This prevents the minerals in dental tissues from dissolving. Furthermore, saliva aids the sense of taste by acting as a liquid medium. It carries chemicals to the taste receptor cells on the tongue.

Digestion begins in the mouth through the action of specific enzymes. One key enzyme is alpha-amylase, also known as ptyalin. It is secreted by the parotid and submandibular glands. This enzyme breaks down dietary starches into simpler sugars like maltose. About 30% of starch digestion occurs within the mouth cavity. Another enzyme, lingual lipase, is secreted by the sublingual gland. This enzyme begins the process of fat digestion. It is not fully activated until it reaches the acidic environment of the stomach. This is especially important for newborn infants whose pancreatic lipase is still developing.

Protection against infection is another critical role of saliva. It contains many antimicrobial enzymes and compounds. These include lysozyme, lactoferrin, and secretory immunoglobulin A. These substances work to kill bacteria and limit the growth of pathogens. Proline-rich proteins also assist in microbe killing and enamel formation. Saliva can contain as many as 8 million human cells and 500 million bacterial cells per milliliter. It also contains epidermal growth factor (EGF). This protein promotes cellular healing and protects the mucosa from gastric acid and bile acids.

Humans produce a significant amount of saliva every day. A healthy person is estimated to produce about 1,500 mL of saliva daily. The submandibular gland is the most productive, contributing 70% to 75% of this total. The parotid gland contributes about 20% to 25%. The remaining amounts come from other smaller salivary glands. Production levels change depending on activity, as the amount of saliva drops significantly during sleep. Some people suffer from xerostomia, which is a condition of reduced saliva. This can lead to mouth soreness and difficulty swallowing dry foods.

Beyond humans, many animals use saliva for specialized survival tasks. Certain swifts in the genus Aerodramus use sticky saliva to glue their nests together. These nests are sometimes used by humans to make bird's nest soup. Venomous animals, such as cobras and vipers, use venomous saliva to hunt prey. Some caterpillars use modified glands to store proteins for making silk fiber. Even the act of spitting has different meanings across the world. In Singapore, spitting can result in a fine of up to SGD$2,000. In other cultures, it may be used as a defensive maneuver by animals like camels.