Eliminating the wear of friction, creating hydraulic forces, reducing the impact of blows, providing clear visual images, maintaining equilibrium … These are just a few of the feats that fluids achieve in our bodies, the most complex machines in the world.

What are these fluids? Where in your body do they operate? How does their existence affect—and enable—your entire life? In seeking answers to these questions, the one most important matter that we must not forget is that, like everything in the universe, the liquids in our bodies act under the inspiration of our Lord, and are under His control at every moment.

Your Internal Organs and Their Lubricant Protection

In the course of their daily activities throughout the body, our internal organs are in a constant state of motion. The friction that these activities generate represents the most important threat to these organs. God, the flawless Creator of all things, has created life-saving fluids that provide our internal organs with this protective lubrication. For example, between the two membranes that surround the lungs lies what is known as “pleural fluid.” With a volume of 5 to 15 milliliters, it reduces any friction as we inhale and exhale.

Another liquid assisting the internal organs is the so-called peritoneal fluid between the stomach membranes. Like the liquids in the heart and lungs, this lubricant fluid in the peritoneal membranes with an area of 2 square meters, has a volume of less than 100 cubic centimeters. Due to the stomach membrane’s fluid-absorbent properties, more than 100 cubic centimeters of this fluid is absorbed, thus keeping the internal organs constantly moist and supple.

In adults, some 50 milliliters of pericardial fluid is also found between the coronary membranes, where it serves a most important function. The noteworthy point is that despite though the surface area of the heart membranes is smaller than that of the lungs, they contain more than three times the amount of fluid. The reason for this is that the heart works five times as hard as the lungs. A person with a pulse rate of 72 beats per minute breathes an average of 13 to 14 times in that same period. Here, the more abundant fluid increases lubrication during the heart’s contractions and prevents any friction that its intense activity might create. Were it not for this fluid, friction affecting the heart-muscle tissues would develop the disorder known as hypertrophy. The heart would be unable to function, and would stop beating.

Another life-saving fluid is found lying between the brain, and the skull. Three membranes protect the skull from the inside and the brain from the outside. Between the two outer membranes is some 140 to 150 milliliters of cerebral spinal fluid. It is particularly interesting that it is only around 50 grams thanks to the lift force within this fluid while when the brain is removed from the skull and weighed it is 1,400 grams. In some diseases in which the level of this fluid is reduced, severe headaches result because of the brain’s pressure against the skull. At the same time, whenever a blow is inflicted on the head, this fluid can reduce or even eliminate any injury by reducing the impact on the brain.

Fluids Around the Sense Organs

As with our internal organs, your sense organs also contain vitally important fluids. .

There are different fluids in every part of the optical cavity; and the globe of the eye itself is divided into two parts: the iris and the lens. The anterior fluid is known as the aqueous humor, and the posterior one, the vitreous humor. The duty of the vitreous humor, which comprises two-third of the eyeball’s volume, is to maintain the eye’s spherical shape. This transparent fluid, around 24 milliliters in volume, is transparent and gelatinous in consistency. If this fluid were tinted yellow, like the fluids that keep our joints lubricated and permit us to move freely, then everything around us would appear to be yellow in color. This is just one of the matchless features in our Almighty Lord’s creation. Like the vitreous humor, aqueous humor is also transparent, and has a volume of around 0.125 milliliter and is produced in glands inside the iris, which gives the eye its color. Like the eyes’ other fluids, this vitreous humor also serves a vital function in facilitating vision: It enables images to be perceived in their actual, normal dimensions by reducing refraction in the anterior and posterior section of the lens in the eye by 25 percent. Were it not for this fluid, we would imagine ourselves to be surrounded by giant objects, or else we would experience an unrealistic sense of depth that would make it difficult to read print like this.

As most people already know, the ear is an organ of balance as well as of hearing. At any given instant, the position of the head and body is constantly determined by the inner ear. The fluid in the labyrinth, known as the perilymph, is dark in color and its viscosity makes it flow very slowly. It ensures a sense of balance by instantly coordinating with the muscles, nerves, and organs such as the cerebellum and the brain. The fluid’s high viscosity guarantees a slow flow when you change position by sitting down or standing up. If this perilymph had any lower viscosity, your nerves would be stimulated by even the slightest movement and change of position, resulting in a state of constant dizziness.

When you realize that this meticulous order exists within all the systems in the body, and that this sublime design is exhibited throughout its every detail, you will once again see the perfection of Almighty God’s flawless design.

God has revealed this in a verse:

That is God, your Lord. There is no god but Him, the Creator of everything. So worship Him. He is responsible for everything. (Qur’an, 6:102)

The Equilibrium of Pressure in Your Body

The human torso has two large, vitally important cavities: the chest and the abdominal cavity. The two are separated from each other by the diaphragm, a muscular membrane just below the lungs. The pressure inside the chest cavity is less than that of the outside atmosphere and has a negative value (of minus 2 mmHg). This negative pressure makes it easier for our lungs to fill with air. The abdominal cavity, on the other hand, has a positive value, higher than the outside air pressure. Our internal organs are attached to the abdominal cavity by rather weak ligaments; and the fact that the positive pressure inside the abdominal cavity is higher than the external pressure helps support the internal organs. This positive pressure prevents the organs from moving about when the abdominal muscles contract. The fact that these two cavities, separated from one another by the diaphragm’s very fine membrane of the, have just the required levels of different pressure is just one of the many proofs of creation, the product of God’s infinite knowledge.