encyclopaedia – Page 25 – Jineral Knowledge

Viscera: Kidneys

Posted on 31/03/201310/03/2019 by Jinavie

(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.

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.

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.

Psychology & Medicine

Viscera: Pancreas

Posted on 17/03/201310/03/2019 by Jinavie

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

The pancreas is probably the most central organ in the human body. It is situated just under the liver and stomach, surrounded by the duodenum (first part of small intestine) and lies in front of the aorta. It is shaped like a fish and thus is divided into parts named the head, neck, body and tail. The head of the pancreas tucks into the loop of duodenum and drains its contents via the pancreatic duct, which joins with the common bile duct (from the liver and gallbladder).

The function of the pancreas is divided into two functions: exocrine and endocrine.

An exocrine gland is an organ that excretes its products out of the body (including the intestines), such as the salivary or tear glands. The exocrine function of the pancreas is the production and secretion of digestive enzymes that break down proteins, fats and carbohydrates in the small intestine. Because of this, injury to the pancreas often causes a leak of this digestive juice, causing the body to self-digest the pancreas (leading to pancreatitis) and surrounding organs.

An endocrine gland is the opposite in that it secretes its contents into the bloodstream. These glands typically produce hormones, such as the thyroid, ovaries and adrenal glands. The pancreas’ endocrine function is related to an extremely common yet deadly disease: diabetes. Within the pancreas, there are millions of cells that cluster into groups called islets of Langerhans. There are various types of cells, but the most common are the alpha-islet cells that secrete glucagon and beta-islet cells that secrete insulin. Insulin acts to lower blood sugar (glucose) levels by promoting storage and use of glucose after a meal. Glucagon acts to increase blood glucose by promoting the breakdown of glucose storage units (glycogen) and the production of more glucose by the liver. Diabetes occurs when beta-islet cells fail to produce insulin because they are destroyed by the immune system (type 1 diabetes mellitus) or become desensitised by chronically elevated blood glucose levels (type 2 diabetes mellitus).

Another important disease concerning the pancreas is pancreatic cancer. Pancreatic cancer is notorious for its deadliness as it carries a 5-year mortality rate of over 95%. This is because it usually remains hidden – without any symptoms – until it as grown substantially and spread to other organs. However, this prognosis only applies to the most common type of pancreatic cancer involving exocrine cells (adenocarcinoma). There are far rarer cancers of the pancreas that involve the endocrine cells (e.g. insulinoma), which tend to have extremely good prognoses and are usually curable.

Steve Jobs (founder of Apple Inc.) had this kind of pancreatic cancer – an islet cell neuroendocrine tumour. Despite his excellent chance of cure with chemotherapy and surgery, he refused treatment for nine months and instead relied on alternative medicine for cure. However, his disease worsened and he finally resorted to having surgery. By this stage, his disease had spread to the liver due to the nine-month delay in treatment. Spreading of cancer is called metastasis and is often an indication that the cancer is no longer curable. Jobs went against his doctors’ advice and opted for a liver transplant in the hopes of curing his cancer. Organ transplant involves suppressing the patient’s immune system (which also keeps cancers in check) to prevent rejection of the donor organ, which is why oncologists advise against transplants in cancer patients. Jobs’ condition deteriorated quickly after his liver transplant and his decisions ultimately led to his demise.

Psychology & Medicine

Viscera: Spleen

Posted on 16/03/201310/03/2019 by Jinavie

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

The spleen is one of the lesser known organs of the human body. If you asked the lay person, they would not know what the spleen does, let alone where it is. The spleen is a solid organ that lies in the left upper corner of the abdomen, tucked under the left diaphragm (opposite to the liver which lies under the right diaphragm). Its functions are mainly related to blood, such as removing old red blood cells (sequestration), storing platelets in case there is an emergency bleeding, making antibodies and releasing lymphocytes (type of white blood cell) to help fight infection and in times of need, creating red blood cells. Red blood cells are usually made in bone marrow in adults, but if the bone marrow fails (e.g. leukaemia), the spleen and liver can step in to create vital blood components (extramedullary haematopoiesis).

As most of the functions of the spleen are not technically necessary to sustain life, it can be removed without significant consequences. The spleen is sometimes removed when a patient has severe thrombocytopaenia (lack of platelets) or when the spleen is damaged by trauma. Because it is a solid organ, trauma to it such as a kick to the stomach can cause it to rupture (i.e. break in to pieces). Splenic rupture can cause life-threatening haemorrhage (bleeding) and may not be evident in trauma cases. A person without a spleen needs regular check-ups and immunisations to help fight infections as they have a weakened immune system.

The role of the spleen was a mystery for thousands of years and thus various cultures tried to explain various medical phenomena using the spleen. The ancient Greeks thought the spleen produced black bile, which was associated with melancholy. The spleen was also associated to anger by the English and laughter by the Talmud.

Psychology & Medicine

Viscera: Lungs

Posted on 14/03/201310/03/2019 by Jinavie

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

Everyone knows that we need oxygen to survive. The way we get oxygen from the atmosphere is through our lungs – the organ where gas exchange takes place. The pair of lungs take up a large proportion of the chest cavity and they link up with each other to form the trachea (windpipe). The left lung is slightly smaller to accommodate for the heart.

The lung is extremely soft and light, so much that it floats on water. It is essentially made up of an intricate tree-like system of airways, which become narrower and narrower as it divides out from the trachea. Since every airway divides up, the number of airways increases exponentially. Every bronchiole (small airways) ends in a bubble-like sac called an alveolus. Because of the sheer number of alveoli, the lungs actually have a total surface area the size of a tennis court. To picture this, scrunch up a piece of newspaper into a ball to pack a large surface area into a small space. The massive surface area allows for enough gas exchange to occur to give us the oxygen we need and excrete all the carbon dioxide we produce.

When we take a breath in, the chest cavity expands and stretches the lungs in all directions because of the negative pressure (like a vacuum). Air fills the airways all the way to the alveoli. The alveoli are extremely thin; so thin that the oxygen in the air effortlessly seeps through into the blood vessels that surround the alveoli. On the other hand, carbon dioxide seeps out of the blood into the alveoli, which is then breathed out as the muscles of your ribcage contract to force the air out. This process is called gas exchange and is driven by diffusion – the movement of particles from an area of high concentration to an area of low concentration (like how dye spreads throughout water).

It is well-known that smoking is bad for your lungs. This is because of two major reasons: COPD and lung cancer. COPD (chronic obstructive pulmonary disorder) is when your lungs become so damaged by smoking that they cannot function, leading to hypoxia (lack of oxygen) and hypercapnia (excess of carbon dioxide). Smoking causes inflammation in the lungs, which causes airways to shut down from swelling and mucus, while destroying the fine walls of the alveoli. This causes the alveoli to thicken from scarring and less elastic due to the destruction of elastic tissue. Ultimately, the lungs become hyperinflated as the patient cannot breathe out air properly and the lungs are not elastic enough to return to their original shape and size. Ergo, the patient becomes progressively breathless, gasping for breath as they suffer a sensation of impending death as the carbon dioxide level builds and the oxygen level falls.

Psychology & Medicine

Viscera: Liver

Posted on 11/03/201310/03/2019 by Jinavie

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

The liver is the second largest organ (next to the skin) in the human body, weighing about 1.4~1.6kg. It is found tucked under the right side of the ribcage, underneath the 5th to 10th rib in height and almost spanning the entire width of the trunk. When enlarged, the liver grows downward and can be felt in an abdominal exam (sometimes it is so large that it covers most of the abdomen).

It is a vital organ with many life-sustaining functions (hence “liver”) such as building various proteins, breaking down toxins, storing sugars in the form of glycogen, decomposing red blood cells and producing bile. The liver metabolises (breaks down) a large proportion of medications and drugs as it treats them as “toxins”. For example, the enzyme alcohol dehydrogenase breaks down alcohols into acetaldehyde, which causes hangovers and liver damage. Many Asians have a variant of this enzyme that is extremely efficient, causing a massive build-up of acetaldehyde when they drink alcohol. This is responsible for the so-called “Asian flush”.

Liver disease is associated a myriad of symptoms. The classic sign of jaundice (yellow skin and whites of eyes) is caused by obstruction of bile flow. Because of its location, pain in the right upper quadrant of the abdomen is commonly seen. As the liver is involved in synthesising various proteins, signs such as ascites (fluid in the abdomen) or bleeding may occur when the liver is damaged. A syndrome called portal hypertension is commonly seen in chronic liver disease such as cirrhosis as a major vein to the liver is blocked. This can cause an enlarged spleen, oesophageal varices that can bleed, ascites and prominent veins radiating from the belly button (caput medusae).

An interesting property of the liver is that it can regenerate at an amazing rate. A liver will regenerate to its original size even when a half of it is cut out (this is how live donor liver transplants work). What is more interesting is that the ancient Greeks probably knew of this fact as well. In Greek mythology, the gods punish Prometheus for bringing fire to humans by chaining him to a mountain and commanding an eagle to peck out his liver. The liver would then regenerate overnight and the eagle would return every morning to eviscerate him, causing him eternal anguish.

Psychology & Medicine

Viscera: Heart

Posted on 10/03/201310/03/2019 by Jinavie

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

Out of the numerous organs found in the human body, the heart is perhaps the most well-known. This is probably because since the dawn of time, man has put his hand on his chest and felt the rhythmic pounding of his heart – a reminder that he is alive. The function of the heart is to pump oxygenated blood from the lungs to the rest of the body via the circuit of blood vessels (vascular system).

The heart relies on electricity to pump blood in a rhythmic, autonomous way. Because of this property, a heart will beat on its own even if you took it out of the human body. Every muscle in the human body requires an electrical impulse for it to contract. This is also the case in the heart, but unlike the skeletal muscle in other parts of the body which receive their impulses from the brain and spinal cord, the heart has its own source of electricity.

The heart has a small group of pacemaker cells in the right atrium called the sinoatrial node, which always fires electrical impulses at a set rate and rhythm (sinus rhythm). The SA node will do this without any instruction from the brain. The impulse from the SA node spreads throughout the atria of the heart, causing the atrial muscles to contract simultaneously to squeeze blood into the ventricles. The impulses then reach the atrioventricular node, which filters the signals and sends a stream of electricity through a wiring system known as the Purkinje fibres. These fibres act like a high-speed internet cables running down the centre of the heart, sending rapid signals through out the ventricles to induce a strong, cooridnated contraction in both ventricles. This causes blood to be forcefully squeezed out through the two outlet vessels of the heart: the pulmonary artery (to the lungs) and the aorta (to the rest of the body).

Although the SA node is completely autonomous, it can be controlled using hormones, nerve signals and medications. For example, adrenaline will speed up the rate the heart beats at while massaging the carotid arteries in the neck will slow the heart down.

One thing people wonder about is what the doctors listen to when they put a stethoscope to a patient’s chest. Everyone knows the heart makes a rhythmic “lub dub” sound as it beats away, but what information could that give away? A doctor can gain much information about the heart from a cardiac examination by taking the pulse and blood pressure, but listening to the heart (auscultation) may reveal a medical sign known as a murmur. A murmur is any added sound other than the normal “lub dub” sound of the heart. For example, a heart with aortic stenosis may give the sound “shhhhhhh” as if it was giving off static. This sound is produced when blood flow in the heart is turbulent and not smooth. This may be for a number of reasons but the most common reason is because the valves of the heart are not functioning properly. For example, the valve between the left atrium and left ventricle may be leaky (mitral regurgitation) or the valve at the start of the aorta may be stiff and narrowed (aortic stenosis).

By carefully listening to the sound the heart makes, an experienced doctor may pick up on such structural abnormalities even without the use of fancy medical imaging technologies.

Science & Nature

Natural Design

Posted on 03/03/201310/03/2019 by Jinavie

We look around the world we live in and marvel in all its complexity and grandeur. But Mother Nature focusses on one thing when it comes to design: efficiency. That is to say, that nature strives to design things that will do the job best. For example, stars and planets are always round because a sphere is the most effective way to get all the mass as close to the planet’s centre of gravity as possible (a process known as isostatic adjustment). The wings of a bird have evolved to maximise the thrust generated at the least energy cost, while the sleek, teardrop body shape of fish allow for them to slip through water with minimal resistance. One of the best examples of nature coming up with the best design solution is beehives.

If you look closely at a beehive, you will find that it is made up of tiny hexagons. Each hexagon is a room that a bee can fit in and the walls are made from wax. The interesting thing about hexagons is that it has many properties that make it the ideal shape in construction.

Firstly, hexagons can fit together perfectly to tile a plane, meaning that bees can tile thousands of columns without wasting any space. The little columns even end in a unique pyramidal shape that allows them to tile up nicely with each other at the centre.

Secondly, a hexagon has 6 rotational symmetries and 6 reflection symmetries, making it very easy to tile as every bee will know what orientation to build their cell in using the side of any cell as a reference.

Lastly, in a hexagonal grid each line is as short as it can possibly be when tiling an area with the smallest number of hexagons. Therefore, bees can use much less wax when constructing hives, while achieving remarkable strength as hexagons gain lots of strength under compression. This design also allows for the maximum amount of honey stored in each cell.

Bees have mastered this architectural feat not through physics and mathematics, but through evolution – the driving force of nature. Over millions and millions of years, various types of bees will have experimented with square-celled hives or triangular-celled hives, but they could not survive as long as the hexagonal-celled bees because their hives were less efficient. This is exactly why nature is so good at coming up with the best solution to a problem. Because in nature, the best solution to the problem an environment offers is rewarded with survival.

Science & Nature

Cow Modelling

Posted on 21/02/201310/03/2019 by Jinavie

There is a farmer who is unhappy with the milk production from his dairy farm. To rectify this, he writes to the local university asking for advice. A theoretical physicist responds to the request and visits the farm. He then takes many measurements such as the size of the cow and proceeds to do some calculations. After finishing all of this, he tells the farmer: “I have a solution, but it only works for spherical cows in a vacuum.”

The point of the joke is that in science, models are frequently used to simplify reality. Because there are infinite amounts of variables, it is impossible to predict anything unless the scenario is simplified through certain assumptions and removal of factors. For example, many physics principles make assumptions such as not accounting for air resistance. Occam’s razor states that if you shave away all the complex details, the simplest answer remains. But perhaps we oversimplify some things?

History & Literature

Ponzi Scheme

Posted on 16/02/201310/03/2019 by Jinavie

Money is a human invention that acts as a medium of exchange and a store of value. It lets us easily carry around our assets in the form of paper, or nowadays, on a card. But because of its characteristics, money allows for some very intricate, complicated con schemes. One famous example is the Ponzi scheme – a type of investment scam.

In 1920, Charles Ponzi had a great idea. Back then, people would send an international reply coupon along with international mail so the receiver could send a reply using the coupon. Ponzi noted that since the value of these coupons were constant across nations, buying it cheap in one country then selling them in the United States would lead to profit. To kickstart his business idea, he began gathering investors, to whom he promised large returns that the investors could not refuse. However, when Ponzi began trading the coupons, he quickly found that it was not effective and he did not make the profit he expected. But instead of telling the investors that his plan failed and that they would not get the returns he promised, he decided to try something different.

Having not heard of Ponzi’s failure, new excited investors asked Ponzi to invest their savings too. Ponzi used the invested funds to pay off the original investors by redistributing the money. Happy that they got their promised returns, the original investors told their friends and family about the incredible opportunity. This brought more new investors to Ponzi, whose money he used to pay off the previous investors. Because Ponzi took a commission from each investment, he quickly raked in a massive amount of money – just by redistributing money around and not actually investing a single cent.

But Ponzi schemes do not last. Eventually, the amount of new investments were not enough to pay off the previous investors and people began investigating, only to discover that Ponzi was scamming them all along.

The Ponzi scheme relies on three things: enticing investors with the promise of high returns, intricate redistribution of money to feed the previous group of investors and the good reputation built through word of mouth. Because the scheme relies on paying old investors with money taken from new investors, a larger number of new investors is needed compared to the old investors. This leads to the formation of a pyramid. When the number of new investors is not enough, for example during a recession, the pyramid’s base becomes weak and the whole scheme collapses, with everyone losing money except for the schemer and the few original investors.

(Click Read More for diagram explaining a Ponzi scheme)

(Image source: http://browse.deviantart.com/art/Support-83476199)

Psychology & Medicine

Agonal Breathing

Posted on 14/02/201310/03/2019 by Jinavie

When a person is on the verge of death, they may show a very strange pattern of breathing. They will begin gasping for breath, take deep laboured breaths, begin to make strange noises and possibly have some muscle jerks (which may look like a seizure). The breathing makes it look as if the person is taking a deep breath and sighing, while gasping every now and then irregularly. This is called agonal breathing and it is most likely caused by an oxygen-starved brain sending weak signals to try kick up the respiratory drive for more oxygen.

Agonal breathing is not uncommon in cases of cardiac arrest. It is important to note that agonal breathing is not an efficient form of breathing and thus it cannot be said that the victim is “breathing” when this occurs. Because it looks like the patient is taking deep breaths, bystanders may be fooled into thinking that they have been resuscitated and have begun breathing again. But this is not the case and the patient is still clinically dead. Ergo, one should not stop CPR even if the patient begins taking deep breaths and sighs. The presence of agonal breaths usually indicate a better outcome for the patient.

(Link to video examples of what agonal breathing looks like: http://emsbasics.com/2011/04/21/what-it-looks-like-agonal-respirations/)