By Penelope A. Domogo, MD
June is National Kidney Month so let us talk about the kidneys and the urinary system. You see, our body parts work as a team, as systems, not individually, so that they can carry out their functions well. We, humans, do have a lot to learn from our body systems.
The urinary system is the excretory system of our body for liquid wastes – our built-in liquid waste disposal system. In the course of our day-to-day activities, our body uses oxygen and energy and in the process, waste is generated. That is the nature of living organisms like us. In general, wastes are carbon dioxide, liquid waste and solid waste. Carbon dioxide is excreted through the respiratory system. Solid waste is excreted through the digestive system. Liquid waste is excreted through the urinary system.
The urinary system is composed of 2 kidneys, 2 ureters, I urinary bladder and 1 urethra. The kidneys are located behind the intestines around our waistline. The ureters are tubes connecting kidneys to the urinary bladder. The bladder is located up front at the lowest part of our abdomen. The urethra is the tube that connects the bladder to the outside world. In women, the urethra ends in the vagina and in men, the urethra ends at the tip of the penis. What happens is that urine is formed in the kidneys, pass through the ureters to the urinary bladder where it is collected and when it is full, it releases the urine through the urethra to the garden or the toilet bowl.
The function of this system is to filter the blood to remove wastes and eliminate these wastes. These wastes need to be eliminated otherwise our body will be poisoned. This system works in harmony with the other systems in our body to maintain a healthy environment for our body cells to work in. We need at least one properly functioning kidney to survive so we thank God he gave us a spare.
We learn in biology that blood is pumped from the heart to the arteries to the capillaries then the veins carry the blood back to the heart then lungs and back to the heart and then pumped again to the arteries and the cycle goes on and on through a closed circuit. But it is not this simple. Many things happen as the blood flows round and round the circulatory system. The blood that flows from the heart to our arteries contains oxygen (from the air we breathe) and life-giving nutrients and other substances (from the food and drink we eat). When this blood reaches the capillaries (the smallest blood vessel that connect the artery to the vein), the blood unloads the oxygen and nutrients to the cells through passive diffusion. In return, this blood carries back, through the veins, waste materials that the body produces like carbon dioxide and urea.
In the urinary system, the kidneys are the filtration machine. Each kidney is only about the size of your fist. Inside the kidneys is a very interesting mix of cells and tissues and about one million convoluted tube systems called nephrons beautifully curled inside the kidneys. Can you imagine these? They are so tiny that they are invisible to the naked eye. You need a powerful microscope to see them. Side by side these nephrons are just as tiny blood vessels.
These nephrons are the actual filters- an ultra-fine mesh to filter your blood . The “holes” in these filters are so small that only water and small particles are able to get through and bigger particles (but still microscopic) like red blood cells and white blood cells stay in the bloodstream.
As blood passes through these nephrons, waste matter like urea, uric acid and those not needed in the body like excess vitamins and minerals, other toxins and excess water are excreted. Important substances like glucose are retained and needed water is reabsorbed. (Urea and uric acid are waste products of foods containing protein like meat, eggs, milk, cheese.)
Because of this intricate and complicated cleansing function, the kidneys are able to regulate the concentration of various components of the blood so that a normal pH is maintained. pH is the state of acidity or alkalinity of the blood. Good blood is slightly alkaline.
The kidneys also regulate how much urine is excreted – on a hot sweaty day, you will notice that less urine is produced so it’s more yellow because the waste matter is concentrated. On the other hand, more urine is produced if you drink so much and on cold days because you don’t sweat. Understandable.
Blood passes through the kidneys every five minutes – ensuring that waste materials don’t build up. This translates to about 180 liters of blood being processed daily by your amazing kidneys.
One other important function of the kidneys is to produce hormones needed to produce red blood cells and help in bone formation, among other things. Thus patients whose kidneys have failed and are undergoing dialysis need blood transfusion now and then, because the dialysis machine cannot produce these hormones. At present, they are the main recipients of donated blood.
As mentioned earlier, our kidneys strain blood. If your blood is too thick and heavy because of the excess sugar, salt and protein and fat you are eating and drinking, after sometime the “holes” will enlarge. Just like what happens to any filter or strainer. These microscopic filters can also be damaged by toxins like some chemicals in processed food, some medicines or too much of some medicines (that is why we always warn that there is no absolutely safe medicine.) Naturally, when these holes enlarge or destroyed, then bigger particles like red blood cells and white blood cells (also called pus cells) will pass through. So when you have your urine checked, the laboratory will see a lot of particles which should not be in your urine. These are warnings from your body- if you don’t heed these warning signs, be ready for bigger problems later, one of which is kidney failure.
All these complicated processes are done by our kidneys without any effort from us! The least we can do is just sincerely thank our amazing kidneys and take care of them. Thank you so much, dear kidneys and the urinary system! Thank you, dear God, for creating our wonderful built-in waste disposal system!****
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“Fools think they need no advice, but the wise listen to others.” – Proverbs 12:15
