Posted in Psychology & Medicine

Viscera: Kidneys

(Learn more about the organs of the human bodies in other posts in the Viscera series here: https://jineralknowledge.com/tag/viscera/?order=asc)

Despite being a vital organ that one cannot survive without, the kidneys are not very famous to the general populace. Not many people know what the kidneys do, let alone where exactly they lie in the body. The kidneys (of which there are two) are the major excretory organs of the human body. They are found in the back of the abdomen (in an area called the retroperitoneal space), tucked under the lower three ribs below the diaphragm. This is higher than where most people think the kidneys lie, because the abdomen extends quite high into the ribcage, as seen from the location of the liver.

image

The kidneys undertake many functions, but they can broadly be grouped into three groups: making urine, filtering blood and maintaining homeostasis.

Although the organ associated with urine is the bladder, it only stores urine, which is made by the kidneys and sent to the bladder via the ureters. Urine is the body’s main way of disposing excess water, salt and other byproducts such as urea. The kidneys fine-tune how much water we lose to urine depending on how much water is in the body. For example, if you drink a lot of water, the kidney senses the blood vessels being dilated and the blood being diluted, then allows more water to leave the body. Conversely, if you are dehydrated, the kidney does everything in its power to hold on to as much water as possible, resulting in concentrated urine.

The kidneys literally act as filters for the blood using a fine, intricate network of sieve-like blood vessels. These vessels have walls that have various sized holes that causes water and small molecules to pass into the kidney, while leaving large proteins in the blood. The filtered blood (containing water, various electrolytes and other metabolites) travel through a pipe network called nephrons, which reabsorb things the body needs (like water when you are dehydrated or salts like sodium), while leaving toxic products like urea and various medications.

image

Lastly, the kidneys maintain homeostasis (the status quo of the body) in various ways, such as fine-tuning the water and salt levels of the body. If you have renal failure where your kidneys do not function properly, you will retain too much water and may suffer a build-up of potassium, which can cause fatal changes in your heart rhythm. It is also involved in controlling the acidity of your blood and your blood pressure, through very complex mechanisms.

One way kidneys are famous is that they are popularly mentioned in the context of organ transplants. If you have renal failure, you may be able to get a kidney from a healthy, live donor as you can live with one kidney. When you take out a kidney from a healthy person, the remaining kidney will grow in size to compensate for the other kidney, while the transplanted kidney will go on to save the patient’s life by doing the many jobs mentioned above.

image

Posted in Science & Nature

Goldilocks

In the children’s story Goldilocks and the Three Bears, the protagonist is found trying out various porridges, chairs and beds until she finds the one that is just right for her. Because of this, the name “Goldilocks” has become a symbol for something that is “just right”. A Goldilocks economy is one where there is high growth but no inflation; a Goldilocks planet is one which is not too hot or too cold, making it an ideal planet for life; the Goldilocks effect is when success is achieved because something was not too great or too little.

The Goldilocks effect is a law of nature that is far more important than you would think. Nature always seeks consistency, as shown in the human body. For something as complex as life to exist, a cell must maintain its internal environment in a perfect, ideal state. French physiologist Claude Bernard observed that a cell’s internal environment does not change even with changes in the external environment, and commented that “The stability of the internal environment is the condition for the free and independent life”. This is the basis for homeostasis. Without homeostasis, life cannot exist and all living things put in all their effort in keeping homeostasis. Our body constantly strives to keep various factors such as pulse, blood pressure, oxygen saturation, temperature, blood glucose, electrolytes and numerous hormones etcetera in a stable range. One could possibly argue that the meaning of life is “to maintain homeostasis” – a rather cyclical argument.

To understand the importance of homeostasis, let us look at how changes in the external environment affect us. Our core temperature is maintained in a tight range around 36.5 degrees. If it is altered even a couple of degrees, we exhibit symptoms of hypothermia or hyperthermia. If the weather is too hot, we sweat to cool ourselves; if the weather is too cold, we shiver to raise our temperature. After a meal, we secrete insulin to lower our blood glucose, while we secrete glucagon when starving to raise our blood glucose. Failure of either system leads to either diabetes or hypoglycaemic shock respectively. Homeostasis is an extremely complicated and intricate self-repair system that cannot be imitated.

The Goldilocks effect can be applied beyond physiology to our lives. Everything in moderation; to go beyond is as wrong as to fall short. If we have too little money, it is a problem. If we have too much money, it causes other problems. Whether we work or play, doing too much or too little of either can be bad for us. Medicines become poison in excess and even love in excess becomes obsession. In the marathon that is life, if you run too fast you end up collapsing from exhaustion, while running too slow will mean you never get anywhere.

The secret to happiness lies in understanding what is “just right”.