THE 8 MAIN BODY FLUIDS - ANATOMY AND PHYSIOLOGY - 2025

The body fluids are fluids that originate within the body. These include blood, urine, saliva, tears, mucus, bile, and sweat, among others.

These fluids found in the body play a major role in the proper functioning of the body. Each of the body fluids has an important role.

These fluids are found in the fluid compartments of the body. The main liquid compartments are intracellular and extracellular. The chemical composition of the fluids in the various compartments is carefully regulated by the body.

For example, in a normal 70 kg adult man, 60% of his total body weight will be made up of water; in an adult woman about 55% of her total body weight will be water.

The 8 most important body fluids

1- Blood

Blood is probably the most relevant body fluid. The body of a common adult contains about six liters of blood, which carry oxygen into the cells and the metabolic waste products out of the cells.

Additionally, they transport white cells, glucose, hormones and other essential substances.

Blood also contains cell fragments called platelets, and clotting factors that help seal off any spillage that may develop in the blood vessels.

2- Bile

It is a brown or green liquid produced by the liver and stored in the bladder, which is released into the intestines in the middle of the feeding process. It is partially responsible for the color of vomit and stool.

Its most important ingredient is bile salts, which work like a kind of soap that breaks down dietary fats, so that both these and fat-soluble vitamins can be absorbed.

It also helps prevent bladder stones from forming as a result of the cholesterol contained in bile.

About 15 grams of bile salts are excreted into the intestine each day; however, the human body contains only about 5 grams in total.

This is because the bile salts are recycled, being reabsorbed by the blood through the small intestine and then secreted again by the liver.

3- mucus

It is a clear, slippery liquid produced by the mucous glands. It covers the cells of the bronchi in the lungs, stomach and intestines, the urinary and reproductive tracts, the eyes and the ears.

Mucus contains a variety of important substances, including antiseptic enzymes, antibodies, and mucin, which give mucus characteristics that make it look like a gel. The regular adult produces about 1 liter of mucus each day.

The mucus prevents the covering of the respiratory system from drying out, and it also filters out dust and infectious agents that are in the air.

4- Saliva

Saliva is secreted by the salivary glands of the mouth. The common adult produces about 1 liter of saliva daily; the greatest secretion occurs when feeding. Like mucus, saliva contains antibacterial enzymes and antibodies.

Saliva helps moisten food, which is important in lubricating food when chewing and swallowing. It also improves taste: if the chemicals in the food were not in a liquid medium, they could not be detected by the taste receptors.

Some of the enzymes in saliva also begin to break down substances in food.

These enzymes are generally neutralized as soon as they reach the acid secretions of the stomach; therefore, they work to break down food particles trapped in teeth, helping to prevent cavities.

5- Tears

Tears are produced by the tear glands located on the top and side of the eyes. They are spread over the ocular surface when blinking and are drained into the nasal cavity.

Tears have three functions: lubricate the eye, remove irritants (such as smoke and certain chemicals) and be associated with emotional states, such as sadness and excitement.

6- sweat

Sweat, like saliva, consists almost entirely of water; however, it also contains minerals that make it taste salty.

The production of sweat can vary widely between 1/10 of a liter and 8 liters per day; during intense exercise an adult can produce up to 2 liters per hour or more.

There are about 3 million sweat glands in the body: eccrine glands are found throughout the body and apocrine glands are located in the armpits.

Sweat's most important role is thermoregulation, helping to cool down the body when it begins to overheat. The brain stimulates sweat through the nerves, so it can also increase in response to emotional states.

7- Water

Many of the body fluids are made up of water. Water occupies about 75% of the body mass of infants, about 50 or 60% in adults, and 45% in the elderly.

Body water percentage changes with development, as the body's given ratios to each organ, muscle, fat, bone, and other tissue vary from infancy to adulthood.

The brain and kidneys have the highest proportions of water, making up about 80-85% of their total mass. In contrast, the teeth have the lowest proportion of water, since it is 8 to 10%.

The heart, blood, liver, lungs, muscles, and skin are also made up of a significant amount of water.

8- Urine

The average adult produces 1.5 liters of urine daily. This fluid is produced by the kidneys and stored by the bladder. Urine contains many substances that must be removed by the body to maintain good health.

This includes the breakdown products of protein metabolism, which would be toxic if they accumulated in the blood. Urine also serves as the body's primary method of removing excess salt and water.

References

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