What Are Body Fluids Made Of?

What Are Body Fluids Made Of?

The human body is a complex amalgamation of bones, flesh and tissue, but how often have you considered the fluids that make life possible? The body creates these fluids to meet our physical, emotional and metabolic needs. Knowing the composition of body fluids is important in medicine as learning to detect the presence of certain chemicals called biomarkers can indicate particular conditions.

Let’s take a look at some of the most common types of body fluids and what they’re made of.

Cerebrospinal Fluid

You may not have heard of it but Cerebrospinal Fluid (CSF) is a clear fluid that encases the brain and spinal cord. It cushions the brain and spinal cord, while also providing nutrients, as well as removing waste products from the nervous system. CSF is composed of many vitamins, ions and proteins, including:
• Sodium
• Chloride
• Potassium
• Magnesium
• Ascorbic acid
• Folate
• Thiamine
• Leptin
• Insulin
• Transthyretin


Everyone has seen blood at some point in their lives, and most will know its importance. Blood is pumped from the heart and circulates through to arteries and veins, carrying important oxygen and minerals to the body. The blood is made from four main components:
• Plasma, a yellow liquid that makes up a majority of the blood’s fluid. Plasma contains ions including sodium, chloride and bicarbonate, as well as organic acids and proteins
• Leukocytes, white blood cells which possess immune functions
• Erythrocytes, red blood cells which carry oxygen
• Platelets, cells that are involved in clotting

Saliva and Mucous

Mucous is a clear liquid that contains inorganic salts, leukocytes, dead skin cells and glandular secretions. Saliva is a specific type of mucus secreted by the parotid, sublingual, submaxillary, and sublingual glands and is used to soften and break down food. Saliva contains the enzyme α-amylase which breaks starch down into the sugar maltose. Some other main components include mucin, potassium, serum albumin, thiocyanate and globulin.


Tears are another specific type of mucus secreted by the lacrimal glands that create a protective film over the eye. Tears also flush dirt, dust, irritants and other foreign particles away and help to oxygenate the eyes.

Breast Milk

Breast milk contains all of the nutrition needed to support the growth of newborn babies. Some of its components include:
• Vitamins and minerals
• Fats
• Carbohydrates and proteins
• Amino acids
• Hormones such as antimicrobial factors, digestive enzymes and growth modulators


Semes is a combination of components, including sperm, the male reproductive cells, which reside in a nutrient plasma. Three glands secrete to form the whole liquid, including the Cowper, Littre gland and prostate gland.


Bile is a fluid produced by the liver and stored in the gallbladder, which is released into the intestine to help with digestion. Bile is a brown-green liquid, which and is responsible for the colour of vomit and stools. Bile salts act like soap and break down fats so that they can be processed.


Urine is a waste product created by the kidneys and stored in the bladder and on average an adult produces about 1.5 litres each day. Urine removes many unwanted substances from the body to maintain health, including byproducts of protein metabolism, which can be toxic if they accumulate in the blood. Urine is largely made from water, however, it also contains:
• Ammonia
• Sodium
• Potassium
• Chloride and bicarbonates
• Heavy metals such as copper, mercury, nickel and zinc

Dr Arianayagam is an expert in the field of urology and is widely considered one of the top urological oncologists in Australia.

If you have any questions, or would like to book an appointment, please feel free to contact or call Dr Arianayagam’s office on 1300 307 990 and his staff will be able to assist.

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